1. 1. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Front of Book > Authors Authors Carol E. H. Scott-Conner M.D., PH.D., M.B.A. Professor and Head Department of Surgery; Professor, Anatomy & Cell Biology, University of Iowa Roy J. and Lucille A. Carver College of Medicine Iowa City, Iowa David L. Dawson PH.D. Senior Lecturer of Anatomy, Faculty of Life Sciences University of Dundee, Dundee, Scotland With Illustrations By Mark K. Shirazi Gary G. Wind M.D., F.A.C.S. Thomas Weinzerl Contributors Laura A. Adam Fellow Department of Surgery, Barnes-Jewish Hospital, St. Louis, Missouri Beth A. Ballinger M.D. Mayo Clinic, Rochester, Minnesota Phillip C. Camp M.D. Division of Thoracic Surgery, Brigham and Women's Hospital, Boston, Massachusetts Adam J. Dinnewitzer M.D. Research Fellow
2. 2. Department of Colorectal Surgery, Cleveland Clinic Florida, Weston, Florida M. Victoria Gerken M.D. Visalia, California Sean P. Hedican M.D. Associate Professor Division of Urology, Department of Surgery, University of Wisconsin-Madison, University of Wisconsin Hospitals and Clinics, Madison, Wisconsin Jamal J. Hoballah M.D. Professor Division of Vascular Surgery, Department of Surgery, University of Iowa, Roy J. and Lucille A. Carver, College of Medicine, Iowa City, Iowa James R. Howe M.D. Professor, Director Endocrine Surgery, Department of Surgery, University of Iowa, Roy J. and Lucille A. Carver, College of Medicine, Iowa City, Iowa G. Patrick Kealey M.D., F.A.C.S., F.C.C.M. Professor Department of Surgery, University of Iowa, Roy J. and Lucille A. Carver, College of Medicine, Iowa City, Iowa John Kellum Professor Division of General Surgery, Department of Surgery, Virginia Commonwealth University, School of Medicine, Richmond, Virginia Kemp H. Kernstine M.D., Ph.D. Director Thoracic Surgery, City of Hope, Duarte, California Timothy F. Kresowik M.D. Professor Division of Vascular Surgery, Department of Surgery, University of Iowa, Roy J. and
3. 3. Lucille A. Carver, College of Medicine, Iowa City, Iowa Geeta Lal M.D., M. Sc. Assistant Professor Division of Surgical Oncology and Endocrine Surgery, Department of Surgery, University of Iowa, Roy J. and Lucille A. Carver, College of Medicine, Iowa City, Iowa James W. Maher M.D., F.A.C.S Professor Division of General Surgery, Department of Surgery, Virginia Commonwealth University, School of Medicine, Richmond, Virginia Samuel M. Maurice M.D. Fellow Department of Plastic and Reconstructive Surgery, Rush University Medical Center, Chicago, Illinois Amanda M. Metcalf M.D. Professor Division of Gastrointestinal, Minimally Invasive and Bariatric Surgery, Department of Surgery, University of Iowa, Roy J. and Lucille A. Carver, College of Medicine, Iowa City, Iowa Stephen C. Rayhill M.D. Associate Professor of Surgery Director of Pancreas Transplantation, Division of Liver/Pancreas Transplantation, Oregon Health & Science University, Portland, Oregon Isaac Samuel M.D., F.R.C.S. Assistant Professor Section of Gastrointestinal Surgery, Department of Surgery, University of Iowa, Roy J. and Lucille A. Carver, College of Medicine, Iowa City, Iowa W. John Sharp M.D. Sidney E. Ziffren M.D. Professor of Surgery Division of Vascular Surgery, Department of Surgery, University of Iowa, Roy J. and Lucille A. Carver, College of Medicine, Iowa City, Iowa
4. 4. Kenneth B. Simon M.D., M.B.A. Medical Officer and Consultant Centers for Medicare and Medicaid Services, Baltimore, Maryland Timothy L. Van Natta M.D. Department of Surgery, Harbor-UCLA Medical Center, Torrance, California Steven D. Wexner M.D., F.A.C.S., F.R.C.S. Professor The Cleveland Clinic Foundation, Health Sciences Center of the Ohio State University, Clinical Professor, Department of Surgery, University of South Florida, College of Medicine, Chairman and Residency Program Director and, Chief of Staff, Department of Colorectal Surgery, Cleveland Clinic Florida, Weston, Florida Neal W. Wilkinson M.D. Clinical Associate Professor Division of Surgical Oncology and Endocrine Surgery, Department of Surgery, University of Iowa, Roy J. and Lucille A., Carver College of Medicine, Iowa City, Iowa Richard D. Williams M.D. Professor and Chair Department of Urology, University of Iowa, Roy J. and Lucille A., Carver College of Medicine, Iowa City, Iowa You Min Wu M.D. Professor Transplantation Division, Department of Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas
5. 5. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Front of Book > Dedication Dedication Dedicated to the students, residents, and fellows ! who continue to amaze and instruct us.
6. 6. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > Introduction Introduction This anatomically complex region is presented in four sections: the face and parotid region (Chapter 1), endoscopy of the upper respiratory tract (Chapter 2), the midline of the neck and structures approached through the midline (Chapters 3, 4, 5, 6 and 7), and the lateral neck and structures approached from the side (Chapters 8, 9, 10, 11, 12 and 13). Within each section, procedures commonly performed by general surgeons are used to illustrate regional anatomy. For descriptions of more complex procedures, the reader should consult an atlas of plastic surgery or surgery of the head and neck (see references listed below). References 1. Lore JM, Medina JM. An Atlas of Head and Neck Surgery. Philadelphia: Saunders; 2004. (This classic text provides detailed information on specialized surgical techniques.) 2. Thorne CH, Beasley RW, Aston SJ, et al., eds. Grabb and Smith's Plastic Surgery. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2007. (A brief but comprehensive overview of plastic surgery, this book includes information on suturing facial lacerations and local flaps.)
7. 7. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > The Face > Introduction Introduction Facial incisions are designed to preserve facial symmetry and motion and to minimize scarring. To remove small skin tumors, make elective incisions in natural skin !wrinkle lines,!! if possible (Fig. 1). Generally, these lines run perpendicular to the underlying muscles of facial expression, as they are formed by the repetitive pleating of the skin caused by the action of these muscles. Scars that fall in these lines will be less conspicuous than those that cross these lines. Traumatic lacerations that cross these lines can sometimes be dbrided or modified by Z-plasty to conform to natural wrinkle lines. Approximate the eyebrow and vermilion border of the lip with special precision because even a small degree of malalignment will be permanently obvious. Never shave the eyebrow as regrowth of eyebrow hair is unpredictable. The muscles of facial expression (Fig. 2) are innervated by the seventh cranial nerve, aptly named the facial nerve. The anatomy of the facial nerve and parotid region are illustrated in Chapter 1. Deep lacerations of the cheek may divide branches of the facial nerve or the parotid (Stensen's) duct. Evaluate nerve function by asking the patient to raise and lower the eyebrows (temporal branches of the facial nerve), close the eyes tightly (zygomatic branches), and smile (zygomatic and buccal branches). If a nerve injury is diagnosed, attempt primary repair. Look inside the mouth, gently retracting the cheek with a tongue blade, and identify the internal opening of the parotid duct as a small punctum opposite the maxillary second molar. Cannulate this with a fine Silastic tube. The appearance of the tube within the wound confirms injury to the duct. Identify both ends of the duct, repairing it with fine, interrupted sutures of an absorbable material. Use the Silastic tube to stent the repair. Close deep lacerations in layers, carefully approximating muscle, fascia, and skin. Complex injuries involving muscle, nerve, or the parotid duct are best repaired in the operating room.
8. 8. P.4
9. 9. References 1. Kreissl CJ. The selection of appropriate lines for elective surgical incisions. Plast Reconstr Surg. 1951;8:1. (This brief classic paper discusses the rationale for choosing various incisions to minimize scarring.) 2. Hollier L Jr, Kelley P. Soft tissue and skeletal injuries of the face. In: Thorne CH, Beasley RW, Aston SJ, et al., eds. Grabb and Smith's Plastic Surgery. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2007:315!332. 3. Brown DJ, Jaffee JE, Henson JK. Advanced laceration management. Emerg Med Clin North Am. 2007;25:83!99. 4. Armstrong BD. Lacerations of the mouth. Emerg Med Clin North Am. 2000;18:471!480.
10. 10. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > The Face > 1 - Parotidectomy 1 Parotidectomy The parotid gland is divided into a superficial lobe and a deep lobe for purposes of surgical dissection. Because 70% to 80% of the parotid tissue lies in the superficial lobe, most tumors, whether benign or malignant, arise in this lobe. Superficial lobectomy remains the standard treatment for small benign tumors. Simple enucleation is unwise, even when technically feasible, because even histologically benign tumors are likely to recur. A recurrent tumor is much more difficult to resect with preservation of the facial nerve and is more likely to be malignant. Steps in Parotidectomy Creation of incision and elevation of flaps Identification of main trunk of facial nerve Dissection in plane between superficial and deep lobe, preserving facial nerve branches (superficial parotidectomy) 0r: Dissection of deep lobe from around branches of facial nerve and ligation of parotid duct Hallmark Anatomic Complications Partial facial paralysis resulting from facial nerve injury Gustatory sweating (Frey syndrome) resulting from aberrant reinnervation Patchy facial numbness resulting from damage to auriculotemporal nerve List of Structures Parotid Gland and Associated Structures Parotid gland Superficial lobe Deep lobe Parotid duct Superficial parotid lymph nodes Parotid fascia
11. 11. Deep cervical fascia Nerves Facial nerve Temporofacial division Temporal branches Zygomatic branches Buccal branches Cervicofacial division Marginal mandibular branch Cervical branch Great auricular nerve Auriculotemporal nerve Muscles Masseter Sternocleidomastoid Digastric Posterior belly of digastric Platysma Vessels External carotid artery Superficial temporal artery Transverse facial artery Maxillary artery External jugular vein Superficial temporal vein Maxillary vein Retromandibular vein Facial vein Landmarks Lateral palpebral commissure (canthus) External acoustic meatus Mandible Ramus of mandible Zygomatic arch Temporal bone Tympanic portion
12. 12. P.6 P.7 Mastoid process Styloid process Styloid vaginal process Stylomastoid foramen Atlas Transverse process The safe performance of superficial parotidectomy involves careful identification and preservation of the facial nerve and its branches (Fig. 1.1A). Total parotidectomy is sometimes required when the deep lobe is involved. This procedure is briefly described in Fig. 1.5. More complex problems, including reconstruction of branches of the facial nerve, are covered in the references at the end of this chapter. In this chapter, the anatomy of the parotid region is illustrated as it is demonstrated during the performance of parotidectomy. There are three potential anatomic complications of parotid surgery. The first one, injury to the facial nerve or its branches, can be avoided by careful dissection as emphasized here. The second complication, gustatory sweating or Frey syndrome, appears to result from aberrant regeneration of nerve fibers divided, of necessity, during dissection. Several techniques have been proposed to prevent it, including interposition of a flap of sternocleidomastoid muscle or use of a bioprosthesis. This interposed material presumably acts as a barrier to nerve fiber regrowth. The third complication is division of the auriculotemporal nerve, which results in patchy numbness. Positioning the Patient (Fig. 1.1) Technical Points Position the patient supine on the operating table. General anesthesia is preferred; however, avoid muscle relaxants, so that nerve function can be assessed intraoperatively, if necessary. Place the operating table in a head-up position to improve exposure and minimize bleeding. Turn the head to the contralateral side and slightly hyperextend the neck to enhance exposure of the preauricular region. Place a cotton plug in the external ear to prevent blood accumulation within the external acoustic meatus and on the eardrum. Drape an operative field that includes the external ear and mastoid process, the neck, the angle of the mouth, and the lateral palpebral commissure of the eye. This allows you to observe motion of the angle of the mouth or eyelid in response to stimulation of facial nerve branches, which may assist in safe dissection.
13. 13. Figure 1-1 Positioning the Patient Plan the preauricular skin incision so that it lies in a skin fold (Fig. 1.1B). Draw an incision in the skin fold anterior to the ear and extend the line of incision along the inferior margin of the mandible anteriorly. This incision provides adequate exposure to the area, can be extended if necessary, and lies in an inconspicuous position behind the mandible. Extend the incision posteriorly in an inverted T to provide additional exposure in difficult cases. Deepen the incision through the platysma muscle and achieve hemostasis with electrocautery.
14. 14. Anatomic Points The parotid region is bounded anteriorly by the mandibular ramus, posteriorly by the tympanic part of the temporal bone and the mastoid process, and superiorly by the external acoustic meatus, zygomatic arch, and temporomandibular joint (Fig. 1.1C). The deep structures in this region include the styloid process and, more inferiorly, the transverse process of the atlas. The gland overlies portions of the surrounding masseter muscle, the sternocleidomastoid muscle, and the posterior belly of the digastric muscle. The parotid is enclosed in a sheath derived from the superficial (investing) lamina of deep cervical fascia. Branches of the great auricular nerve (the largest sensory branch of the cervical plexus, with fibers derived from C2 and C3), part of the platysma muscle, and a variable number of superficial parotid lymph nodes (draining the auricle, external acoustic meatus, eyelids, and frontotemporal region of the scalp) are superficial to the gland. Elevation of Flaps to Expose the Parotid Gland (Fig. 1.2) Technical Points Elevate flaps in the plane just superficial to the dense superficial parotid fascia. Use skin hooks or fine-pointed rake retractors to exert upward traction on the skin flap because the plane is developed between subcutaneous tissue and superficial parotid fascia by sharp dissection. Identify the main trunk of the great auricular nerve and preserve it. Branches from the great auricular nerve will enter the substance of the parotid gland and must be divided. Divide the posterior facial vein, but preserve the retromandibular vein to avoid venous engorgement. As the dissection progresses anteriorly, peripheral branches of the facial nerve will emerge from the parotid to innervate facial muscles. Look for them, and take care to preserve them by dissecting in a plane superficial to these terminal branches. Terminate the dissection at the anterior and inferior margins of the parotid gland to avoid injuring these tiny terminal branches. Anatomic Points The flap to be elevated includes the skin, superficial fascia, and platysma muscle. The anterior branches of the great auricular nerve, which lie deep to the platysma but superficial to the parotid fascia, give the surgeon a guide for attaining the proper plane of dissection. As the anterior margin of the parotid gland is reached, however, motor branches of the facial nerve (VII) that innervate the very superficial muscles of facial expression will begin to emerge into the operating field. Although branches of the great auricular nerve must necessarily be sacrificed, branches of the facial nerve must be preserved. Identification of the Main Trunk of the Facial Nerve (Fig. 1.3) Technical Points Locate the anterior border of the sternocleidomastoid muscle and mobilize it from the
15. 15. P.8 P.9 posterior aspect of the parotid gland by incising the fascia. The alternative approach of following the tail of the parotid gland to define the inferior border risks injury to the mandibular branch of the facial nerve. Incise the connective tissue between the external acoustic meatus and the parotid. Visualize the posterior belly of the digastric muscle. Careful sharp and blunt dissection in the plane along the periosteum of the mastoid process provides a safe route to deeper structures. Spread the tissues gently, using the tips of a fine-pointed hemostat, in a direction parallel to the anticipated path of the nerve. Expose the main trunk of the facial nerve about one fingerbreadth inferior to the membranous portion of the external acoustic canal and the same distance anterior to the mastoid process (Fig. 1.3A). Identify the nerve by its position and the characteristic appearance of a nerve trunk (white, glistening, with a faintly discernible linear structure, and often with one or two minute longitudinal blood vessels visible on the surface). The nerve will be a sizeable structure, commonly about 2 to 3 mm in diameter. Trace the trunk of the facial nerve into the parotid gland and commence dissection, progressing from proximal to distal, by spreading a fine hemostat parallel and superficial to the nerve. Some surgeons prefer to use a blunt Freer elevator to develop the plane. Anatomic Points Bony landmarks of this region include the zygomatic arch (superior), the ramus of the mandible (deep), and the styloid process (posterior) (Fig. 1.3B). Although it would seem reasonable to locate the stylomastoid foramen, and thus the main trunk of the facial nerve, by locating the interval between the mastoid process and the styloid process, this cannot be accomplished reliably. The superficial lamina of the deep cervical fascia, here investing the sternocleidomastoid muscle and the parotid gland and fusing with the perichondrium and periosteum with which it comes into contact, effectively prevents palpation of deeper structures. In addition, the styloid process is quite variable in that it may be shielded by the variably developed styloid vaginal process, is frequently absent, and can vary in length from 0.1 to 4.2 cm.
16. 16. Figure 1-2 Elevation of Flaps to Expose the Parotid Gland
17. 17. Figure 1-3 Identification of the Main Trunk of the Facial Nerve By cutting the fascia and retracting the sternocleidomastoid muscle posteriorly and the parotid gland anteriorly, one can visualize the posterior belly of the digastric muscle and the anterior border of the mastoid process (Fig. 1.3C). At this point, the main trunk of the facial nerve (VII) is directed almost in a coronal plane, running from the stylomastoid foramen to the !plane!! between the superficial and deep lobes of the parotid gland, where it makes an approximate right-angle turn to run anteriorly in the sagittal plane. If the trunk of the nerve cannot be located easily, bluntly dissect slightly anteriorly rather than posteriorly, restricting the vertical extent of the dissection to the region from the tip of the mastoid craniad to about 1 to 2 cm. This will prevent trauma to the only other sizeable nerve in this region, the auriculotemporal nerve. The auriculotemporal nerve is a sensory branch of the mandibular division of the trigeminal nerve, which innervates the temporomandibular joint, external acoustic meatus,
18. 18. tympanic membrane, most of the anterior part of the external ear, and most of the temporal region. It enters the region at the level of the external acoustic meatus. Removal of the Superficial Lobe (Fig. 1.4) Technical Points Remove the superficial lobe by dissection in the plane of the branches of the facial nerve. Elevate the parotid by traction with a gauze sponge, by grasping it with forceps, or by placing traction sutures. Identify the two major divisions of the facial nerve and trace each by spreading in the plane immediately superficial to the nerve trunks. Gently stimulate any structure in doubt before division. This may be done by very gentle mechanical stimulation (gentle squeezing with forceps or hemostat) or by the use of a disposable nerve stimulator. Stimulation of a motor nerve, such as a branch of the facial nerve, will cause a twitch of the innervated muscle in a nonparalyzed patient. Motion of the eyelids or the corner of the mouth, which were purposefully left exposed when the operative field was draped, can easily be observed. Do not stimulate branches of the facial nerve unless truly uncertain of the anatomy because paresis may result from mechanical or electrical stimulation. Attain hemostasis using fine suture ties. Use cautery judiciously, taking care not to contact nerve fibers. Anatomic Points The facial nerve usually separates into two major divisions at a point posterior and slightly medial to the mandibular ramus, about one third of the distance from the temporomandibular joint to the angle of the mandible. The more superior temporofacial division is usually smaller than the more inferior cervicofacial division. Anatomists still debate the existence of distinct superficial and deep parotid lobes, which are separated by the plane through which the facial nerve passes. The anatomy is variable, and one or more isthmi of parotid tissue connect the superficial and deep lobes. However, by careful dissection immediately superficial to the facial nerve, an apparent superficial lobe can be removed with a minimum of trauma to other important structures traversing the substance of the parotid gland. Isthmi of parotid tissue are divided sharply as encountered. The facial nerve is immediately superficial to the external jugular vein and its tributaries, which are themselves superficial to the external carotid artery and its regional branches (superficial temporal and maxillary arteries).
19. 19. P.10 Figure 1-4 Removal of the Superficial Lobe Dissection of the Deep Lobe, Ligation of the Parotid Duct, and Closure of the Wound (Fig. 1.5) Technical Points If the tumor involves the deep lobe, dissection of parotid tissue from underneath and around the facial nerve branches is necessary. Elevate the branches of the facial nerve gently with a nerve hook and dissect parotid tissue from around and beneath them (Fig. 1.5A). Do not hesitate to sacrifice nerve branches that are involved by tumor. Perform an immediate reconstruction using a nerve graft (see references). Ligate the parotid duct. Check the field for hemostasis and close with fine, interrupted sutures. Leave a small drain under the flap (Fig. 1.5B).
20. 20. Figure 1-5 Dissection of the Deep Lobe, Ligation of the Parotid Duct, and Closure of the Wound Anatomic Points Removal of the deep lobe presents many technical difficulties, which may ultimately result in picking out parotid tissue piecemeal. Care must be taken to avoid trauma to the terminal branches of the facial nerve. The number of branches of the facial nerve within the parotid gland is variable, and there are fine anastomoses between the terminal points of some branches. It is convenient to consider five major branches that correspond to the common anatomic pattern and the typical pattern of innervation. The first branch after the facial nerve exits the stylomastoid foramen is the posterior auricular, which passes posterosuperiorly
21. 21. P.11 between the parotid gland and anterior border of the sternocleidomastoid to supply the muscles of facial expression posterior to the external acoustic meatus. The main trunk of the facial nerve then supplies the muscles originating from the styloid process and the posterior belly of the digastric muscle. On entering the parotid gland proper, the nerve divides into its temporofacial and cervicofacial divisions. The temporofacial division subsequently divides into several branches. The temporal branches supply the auricular muscles, muscles of the forehead, and most of the orbicularis oculi. The zygomatic branches innervate part of the orbicularis oculi, muscles of the nose, and most elevators of the upper lip. The buccal branches innervate the muscles of both lips and the buccinator muscle. The cervicofacial branches typically include a single marginal mandibular branch and a single cervical branch. The marginal mandibular branch supplies the muscles of the lower lip. Damage to this branch causes a severe deformity, which is especially pronounced during phonation. There are frequently multiple anastomoses between branches, resulting in the information of a parotid plexus (pes anserinus of the face). This is especially true with the temporofacial branches. The external jugular vein and its regional tributaries, the superficial temporal vein, maxillary vein, and facial vein, can all be ligated with impunity. The still deeper external carotid artery and its regional ramifications, the superficial temporal artery (and its sole major branch, the transverse facial artery), and the (internal) maxillary artery can also be ligated. The deepest parotid tissue should be approached very cautiously because of the relationship of the gland to deeper structures!notably, the lateral pharyngeal wall. The buccal branches of the facial nerve typically lie just inferior to the duct. When ligating the parotid duct, be careful not to injure this structure. The transverse facial artery lies just superior to the duct and will generally need to be ligated. Surgical References 1. Byers RM. Operations involving the submandibular and sublingual glands. In: Fischer JE, Bland KI, eds. Mastery of Surgery. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2007:284!290. (Describes the anatomy of the submandibular region in detail and gives surgical technique.) 2. Beahrs OH. The surgical anatomy and technique of parotidectomy. Surg Clin North Am. 1977;57:477. (An excellent description of anatomy and safe technique backed by vast experience.) 3. Beahrs OH, Adson MA. The surgical anatomy and technique of parotidectomy. Am J Surg. 1958;95:885. (Detailed analysis of the anatomy of the region as it relates to surgical technique.)
22. 22. 4. De Ru JA, van Benthem PP, Hordijk GJ. Morbidity of parotid gland surgery: results one year post-operative. Eur Arch Otorhinolaryngol. 2006;263:582!585. 5. Filho WQ, Dedivitis RA, Rapoport A, et al. Sternocleidomastoid muscle flap preventing Frey syndrome following parotidectomy. World J Surg. 2004;28:361 !364. (Description of interposition technique.) 6. Johnson JT, Ferlito A, Fagan JJ, et al. Role of limited parotidectomy in management of pleomorphic adenoma. J Laryngol Otol. 2007;121:1126!1128. 7. Loree TR, Tomljanovich PI, Cheney RT, et al. Intraparotid sentinel lymph node biopsy for head and neck melanoma. Laryngoscope. 2006;116:1461!1464. (Discusses the rationale for including parotidectomy when radical neck dissection is performed for malignant melanoma of the head and neck and provides an alternative technique of staging.) 8. Picon AI, Coit DG, Shaha AR, et al. Sentinel lymph node biopsy for cutaneous head and neck melanoma: mapping the parotid gland. Ann Surg Oncol. 2006;May 23:e-pub ahead of print. 9. Prattico F, Perfetti P. Images in clinical medicine: Frey's syndrome. N Engl J Med. 2006;355:66. (Concise description of syndrome with illustration). 10. Sinha UK, Saadat D, Doherty CM, et al. Use of AlloDerm implant to prevent Frey syndrome after parotidectomy. Arch Facial Plast Surg. 2003;5:109!112. (Interposition of bioprosthesis.) 11. Terrell JE, Kileny PR, Yian C, et al. Clinical outcome of continuous facial nerve monitoring during primary parotidectomy. Arch Otolaryngol Head Neck Surg. 1997;123:1081. 12. Woods JE. Parotidectomy: points of technique for brief and safe operations. Am J Surg. 1983;145:678. (Presents surgical shortcuts, emphasizing safety.) 13. Woods JE, Beahrs OH. A technique for the rapid performance of parotidectomy with minimal risk. Surg Gynecol Obstet. 1976; 142:87. (Summarizes the Mayo Clinic technique; an excellent brief description.) 14. Zumeng Y, Zhi G, Gang Z, et al. Modified superficial parotidectomy: preserving both the great auricular nerve and the parotid gland fascia. Otolaryngol Head Neck Surg. 2006;135:458!462.
23. 23. Anatomic References 1. Bernstein L, Nelson RH. Surgical anatomy of the extraparotid distribution of the facial nerve. Arch Otolaryngol Head Neck Surg. 1984;110:177. (Reviews the common variants in facial nerve anatomy.) 2. Davis RA, Anson BJ, Budinger JM, et al. Surgical anatomy of the facial nerve and parotid gland based upon a study of 350 cervicofacial halves. Surg Gynecol Obstet. 1956;102:385. (Offers a detailed description of the anatomy of the region, including variations in facial nerve distribution, parotid gland and duct anatomy, and bony structures.) 3. McCormack LJ, Cauldwell EW, Anson BJ. The surgical anatomy of the facial nerve with special reference to the parotid gland. Surg Gynecol Obstet. 1945;80:620. (Gives particular attention to the relationship between deep and superficial lobes of the parotid gland and the facial nerve.) 4. McKenzie J. The parotid gland in relation to the facial nerve. J Anat. 1948;82:183. (Clearly demonstrates the lobulated nature of the parotid gland enfolding the facial nerve.) 5. McWhorter GL. The relations of the superficial and deep lobes of the parotid gland to the ducts and to the facial nerve. Anat Rec. 1917;12:149. (Provides an original description of the isthmus of parotid tissue connecting the superficial and deep lobes.) 6. Ruhalter A. Anatomy of the parotid gland, submandibular triangle, and floor of the mouth. In: Fischer JE, Bland KI, eds. Mastery of Surgery. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2007:290!298. (Comprehensive review of regional anatomy.) 7. Saunders JR, Hirata RM, Jaques DA. Salivary glands. Surg Clin North Am. 1986;66:59. (Discusses anatomy and surgical techniques for excision of submandibular gland tumors as well as parotid gland tumors.)
24. 24. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > Head and Neck Endoscopy > Introduction Introduction Although not strictly operative procedures, laryngoscopy and endotracheal intubation are frequently performed by surgeons. Accurate diagnosis and management of upper airway problems demand a thorough understanding of the anatomy of this region.
25. 25. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > Head and Neck Endoscopy > 2 - Laryngoscopy and Endotracheal Intubation 2 Laryngoscopy and Endotracheal Intubation Laryngoscopy, or visualization of the larynx, is performed for both diagnostic and therapeutic purposes. In this chapter, indirect (or mirror) laryngoscopy and the visualization of the larynx for the purpose of endotracheal intubation are discussed. The use of the fiberoptic laryngoscope is not presented here because visualization of the upper airway using this instrument is similar to that described for fiberoptic bronchoscopy (see Chapter 24). Steps in Indirect Laryngoscopy Adequate topical anesthesia Warm the mirror to avoid fogging Gently introduce into back of oropharyns Steps in Endotracheal Intubation Sniffing position C-spine stabilization if trauma Adequate relaxation Straight blade goes over the epiglottis Curved blade goes in front of the epiglottis Gentle pressure toward the spine may be needed Pass Tube through Cords under Direct Visualization Presence of CO2 confirms position in trachea Secure in place Chest x-ray to verify position Anatomic Complications Esophageal intubation Right mainstem bronchus intubation List of Structures
26. 26. P.14 Larynx Laryngeal inlet Rima glottides Thyroid cartilage Vestibular folds Tongue Uvula Epiglottis Hyoid bone Hyoglossus muscle Hyoepiglottic ligament Trachea Cricoid cartilage Carina Pharynx Nasopharynx Oropharynx Laryngopharynx Palatine tonsil Palatoglossal arch Indirect Laryngoscopy Mirror Laryngoscopy (Fig. 2.1) Technical Points The patient should be seated facing the examiner for this procedure. Adequate topical anesthesia of the posterior pharynx is essential. Ask the patient to open the mouth and stick out the tongue. Spray a topical anesthetic over the tongue, soft palate, uvula, and posterior pharynx. Gently grasp the tongue with a dry sponge or deflect it down with a tongue blade to improve visibility. Use a headlamp to provide illumination. Warm a dental mirror by holding it under hot running water so that it does not fog when placed in the warm, moist environment of the posterior pharynx. Place the mirror in the oropharynx, just anterior to the uvula. Push back gently on the uvula and visualize the larynx by adjusting the angle of the mirror slightly (Fig. 2.1). Observe the vocal cords for color, symmetry, abnormal growths, and mobility during phonation. The mirror can also be used to inspect the lateral pharyngeal wall and can be reversed to view the posterior nasopharynx.
27. 27. Figure 2-1 Mirror Laryngoscopy Recognize that the mirror produces an apparent reversal of anterior and posterior regions. Visualization of the anterior commissure and base of the epiglottis, the ventricles, and the subglottic regions is limited by overhanging structures. Anatomic Points The upper aerodigestive tract is divided into the oral cavity proper and the pharynx on the basis of embryologic origin. The oral cavity is lined by epithelium of ectodermal origin. It ends at about the level of the palatoglossal arch. The pharynx is lined with epithelium that is endodermally derived. It is divided into the nasopharynx, the oropharynx, and the laryngopharynx. The nasopharynx is posterior to the nose and superior to the soft palate. The oropharynx extends from the soft palate to the hyoid bone. The laryngopharynx extends from the hyoid bone to the cricoid cartilage. Endotracheal Intubation
28. 28. P.15 Positioning the Patient to Straighten and Shorten the Airway before Intubation (Fig. 2.2) Technical Points Position the patient supine with the neck slightly flexed and a small roll under the head. Stand at the head of the operating table or bed. If you are intubating a patient in bed, remove the headboard whenever possible to gain better access to the patient. The !sniffing position!! (Fig. 2.2A) decreases the distance from the teeth to the larynx and facilitates visualization of the larynx. Hyperextension of the neck (Fig. 2.2B) increases the distance from the teeth to the larynx and makes intubation more difficult. Flexion of the head on the neck compresses the airway, again making intubation more difficult. Achieve the correct position by placing a small pillow or folded sheet under the head. Do not manipulate the head and neck in a patient with a known or possible cervical spine injury. Displacement of vertebrae can cause irreversible damage to the spinal cord. In the situation of known or suspected injury to the cervical spine, fiberoptic laryngoscopy, blind nasotracheal intubation (generally only successful in breathing patients), or cricothyroidotomy is safer than orotracheal intubation. These difficult airway problems are discussed in the references. Anatomic Points Note the relative orientation of the structures involved in endotracheal intubation. In the anatomic position, the orientation of the horizontally displaced oral cavity is about 90 degrees with respect to the vertical laryngeal pharynx. The laryngeal inlet forms the anterior wall of the cranial portion of the laryngeal pharynx. The rima glottidis is again approximately horizontal, but the infraglottic cavity and trachea are oblique, coursing from superoanterior to inferoposterior. With the neck gently flexed and the atlantooccipital joint extended, the involved pathway has gentle curves rather than acute angles. Straightening the airway in this manner also shortens the distance from the teeth to the trachea. Allow for this when tube length is estimated before intubation.
29. 29. Figure 2-2 Positioning the Patient to Straighten and Shorten the Airway before Intubation Using Straight and Curved Laryngoscope Blades (Fig. 2.3) Technical Points Preoxygenate the patient by bag-and-mask ventilation with 100% oxygen before attempting intubation. This allows intubation to progress in an orderly, unhurried fashion. Check all equipment carefully. Verify that the laryngoscope light works and that the proper size of endotracheal tube is available, and check the cuff on the endotracheal tube. Have suction available and working, and have at hand an assortment of laryngoscope blades, endotracheal tubes, and a stylet. Use the fingers of your gloved dominant hand to open the jaws by spreading apart the upper and lower incisors. Hold the laryngoscope by its handle in your nondominant hand and gently introduce the blade, sliding it over the tongue toward the oropharynx. When opening the jaws and inserting the laryngoscope, be very careful to avoid chipping the teeth or using them as a fulcrum to lever the laryngoscope blade. Think of
30. 30. P.16 the laryngoscope as a lighted tongue blade with a handle that is used to elevate the tongue, mandible, and epiglottis to expose the larynx. Two types of laryngoscope blades (straight and curved) are commonly used. To some extent, personal preference dictates which blade is used. Many people prefer the curved blade for routine intubation, using the straight blade only when exposure is difficult. Insert the curved (MacIntosh) blade to a point just in front of the epiglottis (Fig. 2.3A). The curve of the blade tends to follow the curve of the tongue and is advanced downward until the tip of the blade rests against the hyoepiglottic ligament. Gentle upward and forward pressure elevates the epiglottis and reveals the larynx. Be careful not to injure the teeth. Insert the straight (Miller) blade past the epiglottis (Fig. 2.3B). Elevate the epiglottis by direct pressure to expose the vocal cords. Careful positioning of the patient to align the airway before insertion of the blade will help to ensure success. Note that the view obtained is slightly different because the straight blade covers and obscures the view of the epiglottis. Figure 2-3 Using Straight and Curved Laryngoscope Blades Anatomic Points Note that the base of the tongue and the anterior surface of the epiglottis are apposed.
31. 31. P.17 Both have attachments to the hyoid bone (the tongue via the hyoglossus muscle, the epiglottis via the hyoepiglottic ligament). Elevating the tongue and mandible will reduce tension on the hyoid bone and epiglottis and will allow increased mobility of the epiglottis. Moving the epiglottis anteriorly is accomplished with a straight blade by applying gentle pressure on the epiglottic cartilage itself. The curved blade presses on the hyoepiglottic ligament to pull the epiglottis anteriorly. Visualization of the Vocal Cords (Fig. 2.4) Technical Points The larynx and vocal cords should be easily visible (Fig. 2.4). The view of the larynx obtained is similar to that seen in Fig. 2.1. Although one is now looking at the larynx directly, rather than using a mirror, the examiner's position relative to the airway has changed, and thus the view obtained has the same orientation. If the cords cannot be visualized, press down on the thyroid cartilage to bring an anterior larynx into view. Sellick maneuver is used to prevent regurgitation from the stomach by occluding the esophagus. An assistant presses down on the cricoid cartilage (if palpable), using the rigid back wall of this cartilaginous structure to compress the esophagus against the vertebral column. The assistant must be instructed not to release the pressure until the cuff of the endotracheal tube is inflated in the trachea. Anatomic Points The true vocal cords appear whitish. The more cephalad vestibular folds (false vocal cords) are pink and are not as prominent. Gentle downward pressure on the thyroid cartilage will compress the esophagus and other soft tissues posterior to the larynx, thus enhancing the alignment of the laryngeal cavity with the passageway from mouth to vocal cords. Passage of the Endotracheal Tube Through the Cords (Fig. 2.5) Technical Points If the patient is awake, anesthetize the throat with topical anesthetic. Introduce the tube at the angle of the mouth and pass it along the side of the laryngoscope, usually on the right (for a right-handed operator). It can thus be introduced without blocking the view of the cords. Pass the tube under direct vision through the vocal cords (Fig. 2.5A). The endotracheal tube is constructed with a gentle curve, which aids in passage through the cords (Fig. 2.5B). If a greater curvature is needed because of a very anterior larynx, use a stylet. This stiffens the tube but increases the risk for laryngeal damage if the tube is forced. The tube should pass easily. The patient may react to passage of the tube into the trachea by coughing.
32. 32. Figure 2-4 Visualization of the Vocal Cords Anatomic Points Observe the epiglottis, aryepiglottic folds, vestibular folds, and vocal cords, along with the intervening rima glottidis, during the preceding steps (Fig. 2.5A, inset). In inserting the tube, guide it through the rima glottidis to inflict as little trauma as possible to the laryngeal mucosa. Such trauma can denude regions of the larynx and elicit involuntary reflexes carried by sensory fibers of the internal branch of the superior laryngeal nerve cephalad to the vocal cords and fibers of the recurrent laryngeal nerve inferior to the vocal cords. Positioning the Tube (Fig. 2.6)
33. 33. P.18 P.19 Technical Points Inflate the cuff of the tube and confirm its placement within the trachea. The cuff should be inflated until no air leak is detected around it while maintaining the cuff pressure below 25 mm Hg. This ensures that the cuff pressure is lower than the tracheal capillary perfusion pressure, thereby minimizing pressure necrosis of the trachea. The esophagus lies directly posterior to the trachea; blind passage of the tube, particularly when the larynx is more anterior than usual, may result in esophageal intubation. Guard against this by always passing the tube under direct vision and ascertaining the position of the tube by confirming that there is easy exchange of air during respiration as well as the presence of bilateral breath sounds. The presence of CO2 in the expired gas provides confirmation!use a !quick look!! CO 2 detector if you are not in the operating room. This is a disposable plastic device that is placed between the endotracheal tube and the breathing circuit. An indicator changes color when CO2 is detected. In the operating room or intensive care unit, pulse oximetry or end-tidal CO2 measurement can help to confirm adequacy of ventilatory exchange. Inflate the cuff using the recommended volume of air for the tube. Overinflation may rupture the cuff or cause pressure and ischemic damage to the trachea. The tip of the tube should lie 2.5 cm above the carina to allow downward migration with increasing neck flexion (Fig. 2.6B). Confirm the position of the tube by auscultation. Breath sounds should be heard clearly over both lung fields. If the tube is inserted too far, it will enter one of the principal bronchi, usually the right. Overinflation of one lung and collapse of the contralateral lung will result. When this occurs, deflate the cuff and reposition the tube. Confirm the position of the tube by obtaining a chest radiograph. Anatomic Points The blood supply to the trachea, derived from branches of the inferior thyroid arteries, is not particularly rich. In addition, the tracheal cartilages provide a relatively rigid framework. Thus overinflation of the cuff can easily compromise the blood supply to the mucosa!in particular, that covering the cartilages.
34. 34. Figure 2-5 Passage of the Endotracheal Tube through the Cords
35. 35. Figure 2-6 Positioning the Tube Estimate the distance from the incisor teeth to the carina in order to ensure that the tip of the tube is properly placed. The distance from incisors to vocal cords and then to the carina increases with age. Further, there is a disproportionate increase in the length of the trachea. The length of the trachea (cords to carina) essentially triples from birth to age 65 years, whereas the length of the oropharyngeal cavity (incisors to vocal cords) essentially doubles. The approximate length of tube needed can be determined before intubation by placing the tube alongside the face and neck and extending it to the sternal angle (of Louis), which approximates the level of the carina. The tube should be 2 to 3 cm shorter than this distance. At the carina, the trachea divides into left and right principal bronchi. The left principal bronchus is smaller in diameter than the right and takes off at a more acute angle. This explains why endotracheal tubes, if inserted too far, typically enter the right principal bronchus. References 1. Applebaum EL, Bruce DL. Tracheal intubation. Philadelphia: WB Saunders; 1976. (This monograph describes basic intubation techniques, including tracheostomy.) 2. Blanc VF, Tremblay NAG. The complications of tracheal intubation. Anesth
36. 36. Analg. 1974;53:202. 3. Dripps RD, Eckenhoff JE, Van Dam LD. Intubation of the trachea. In: Dripps RD, Eckenhoff JE, Van Dam LD, eds. Anesthesia: The Principles of Safe Practice. 6th ed. Philadelphia: WB Saunders; 1982. 4. McGovern FH, Fitz-Hugh GS, Edgeman LJ. The hazards of endotracheal intubation. Ann Otolaryngol. 1971;80:556. 5. Orringer MB. Endotracheal intubation and tracheostomy: indications, techniques, and complications. Surg Clin North Am. 1980;60:1447. (Provides a clear description of blind nasotracheal intubation, as well as of other techniques; also discusses what to do if intubation is not possible after induction of anesthesia.) 6. Thierbach AR, Lipp MD. Airway management in trauma patients. Anesth Clin North Am. 1999;17:63!81. (Discusses options when possible cervical spine injury complicates management.) 7. Wilson WC, Benumof JL. Pathophysiology, evaluation, and treatment of the difficult airway. Anesth Clin North Am. 1998;16:29!75.
37. 37. P.21 Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > The Midline and Structures Approached Through The Midline > Introduction Introduction The fascial spaces and anatomic triangles of the neck provide a good orientation to the complex anatomy of the neck. An understanding of the infrahyoid deep (or investing) cervical fascia is essential to good surgical technique in the neck. For simplicity, visualize the cervical fascia as a set of !tubes within tubes!! (Fig. 1). The outermost tube, or superficial fascia, which invests all cervical structures, splits to encompass the sternocleidomastoid muscle, trapezius muscle, the corresponding motor nerve (cranial nerve XI), and the strap muscles. This fascial layer attaches posteriorly to the ligamentum nuchae. In the root of the neck, the fascia is attached to both the anterior and posterior surfaces of the manubrium. The intervening suprasternal space (of Burns) contains the lower portion of the anterior jugular veins and their connecting branch, the jugular venous arch. Four tubes are located within this superficial tube. Two of these tubes, the carotid sheaths, are paired. The carotid sheaths contain the vagus nerve, carotid artery complex, and internal jugular vein and compose the major neurovascular bundles of the neck. One of the four tubes, the prevertebral fascia, encompasses the cervical vertebrae and their associated muscles, the emerging cervical spinal nerve roots and branches thereof (including the phrenic nerve), the cervical portion of the sympathetic chain, and the cervical part of the subclavian artery. Pretracheal fascia forms the fourth tube. This fascial tube surrounds the larynx, esophagus, thyroid and parathyroid glands, and recurrent laryngeal nerve. In the vicinity of the thyroid gland, the tube splits to invest entirely the thyroid and parathyroid glands, forming the false capsule of the thyroid gland. Between the deep surface of the thyroid gland and the upper two or three tracheal rings, this fascia is strongly adherent to the gland and trachea, forming the so-called !adherent zone!! or lateral suspensory ligament (of Berry). The recurrent laryngeal nerve can pass anterior to, posterior to, or through (about 25% of cases) this ligament. Parathyroid glands are typically located within the capsule derived from pretracheal fascia, but outside the true capsule of the thyroid gland.
38. 38. Figure 1
39. 39. Figure 2 The superficial neck is divided into triangles (Fig. 2) for convenience. These triangles are bounded by bony or muscular fixed landmarks and provide important guides to the location of nerves and other critical structures. Two major triangles, both of which are roofed by deep (investing) cervical fascia on each side of the neck, are based on the location of the sternocleidomastoid muscle (Fig. 3). Each triangle can be further subdivided. The anterior triangle is bounded posteriorly by the sternocleidomastoid muscle, superiorly by the body of the mandible, and anteriorly by the midline. The posterior triangle is bounded anteriorly by the sternocleidomastoid muscle, inferiorly by the clavicle, and posteriorly by the trapezius muscle. The anterior triangle can be divided into four lesser triangles. The submandibular triangle lies between the body of the mandible and the two bellies of the digastric muscle. The carotid triangle is delimited by the sternocleidomastoid muscle, the superior belly of the omohyoid muscle, and the posterior belly of the digastric muscle. The muscular triangle is bounded by the sternocleidomastoid muscle, the superior belly of the omohyoid muscle, and the midline. The submental triangle is bounded by the hyoid bone, the midline of the neck, and the anterior belly of the digastric muscle.
40. 40. P.22 The posterior triangle is subdivided into two triangles. The larger of these is the occipital triangle, which is bounded by the trapezius muscle, the sternocleidomastoid muscle, and the inferior belly of the omohyoid muscle. The much smaller omoclavicular triangle is delimited by the inferior belly of the omohyoid muscle, the clavicle, and the sternocleidomastoid muscle. It is quite important to realize that several important structures of the neck are not, in the strictest sense, located in either the anterior or posterior triangle or their subdivisions but, rather, are located deep to the sternocleidomastoid muscle itself. These structures are typically rendered accessible either by lateral retraction of the sternocleidomastoid muscle or, immediately superior to the clavicle, by dissecting in the interval between the sternal and clavicular heads of the sternocleidomastoid muscle, a space known as the minor supraclavicular fossa or scalene triangle. General surgical procedures involving the neck can be divided into those that are performed through a midline approach and those that are performed through a lateral incision. Accordingly, the anatomy of the neck is explored in this section first through structures approached through the midline (trachea, thyroid, parathyroid) and then through structures approached laterally (lymph nodes, major vessels, cervical esophagus). Figure 3 Important structures of the midline of the neck include the thyroid and parathyroid glands, the trachea, and the esophagus. In this section, the anatomy of the trachea (Chapters 3 and 4), thyroid (Chapters 5 and 6), and parathyroids (Chapter 7) will be developed. Although the esophagus is a midline structure, it is approached laterally because it lies
41. 41. deep to the trachea. Surgical anatomy of the cervical esophagus (Chapters 12 and 13), therefore, is included with other structures approached from the side. References Demetriades D, Salim A, Brown C, et al. The neck with complex anatomic features and dense concentration of numerous vital structures. Curr Probl Surg. 2007;44(1):6!10.
42. 42. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > The Midline and Structures Approached Through The Midline > 3 - Tracheostomy and Cricothyroidotomy 3 Tracheostomy and Cricothyroidotomy Tracheostomy is necessary when long-term access to the airway for ventilatory support or respiratory toilet is required. This chapter describes formal tracheostomy; percutaneous tracheostomy (Chapter 4) is an alternative in selected patients. Formal tracheostomy is best performed over a previously placed endotracheal tube in a fully equipped operating room where adequate lighting, electrocautery, and suction are available. Percutaneous tracheostomy may be performed at the bedside, generally in the intensive care unit, but requires the same attention to airway control as formal tracheostomy (see Chapter 4). Steps in Procedure (TRACHEOSTOMY) Position patient, check equipment, test balloon of tracheostomy tube Identify five midline landmarks Transverse or vertical incision centered just below cricoid cartilage Divide tissues in midline Retract or divide thyroid isthmus Expose trachea and count rings down from cricoid Incision between second and third ring Pull back endotracheal tube slightly Spread incision and insert tube Confirm position of tube by passage of suction catheter; secure tube Steps in Procedure (CRICOTHYROIDOTOMY) Position patient, check equipment, check balloon of tracheostomy tube Transverse incision over cricothyroid membrane Control bleeding by manual pressure Stab into membrane Spread and insert tube, secure tube, pack wound to control oozing Hallmark Anatomic Complications
43. 43. P.24 Supraglottic tracheostomy Tracheoinnominate artery fistula (delayed complication) List of Structures Larynx Thyroid cartilage Cricoid cartilage Median cricothyroid ligament Cricothyroid artery Trachea Landmarks Mental protuberance Hyoid bone Laryngeal prominence Manubrium sterni Jugular (suprasternal) notch Associated Structures Thyroid gland Isthmus Pyramidal lobe Anterior jugular vein External jugular vein Platysma muscle Brachiocephalic (innominate) trunk Brachiocephalic (innominate) vein Jugular venous arch Brachial plexus
44. 44. Figure 3-1 Positioning the Patient Tracheostomy may also be required in an emergency when the patient cannot be intubated in the normal fashion (e.g., when massive facial trauma or edema precludes safe intubation). In this situation, cricothyroidotomy (see Fig. 3.8) can be performed more quickly and more safely than formal tracheostomy. Positioning the Patient (Fig. 3.1) Technical Points Slightly hyperextend the neck by placing a small roll under the patient's shoulders (Fig. 3.1A). If the roll is placed under the neck instead of the shoulders, a larger roll will be needed and the head may be elevated as well, thereby preventing the desired hyperextension. Do not hyperextend the neck in a patient with a known or suspected cervical spine injury because the resulting vertebral motion may cause irreversible
45. 45. P.25 damage to the spinal cord. Select a tracheostomy tube appropriate to the size of the patient; for an average-sized adult, a number 7 or 8 tube will work well. Test the balloon and then deflate and lubricate it with sterile lubricant. Place the obturator inside the tube. Be sure that a soft rubber suction catheter is available on the sterile field for suctioning the tracheostomy after the tube is inserted. Anatomic Points The phrenic nerve arises from spinal cord levels C3 to C5, and the brachial plexus is derived from C5 to T1. Spinal cord damage at or above C3 will result in death secondary to paralysis of all respiratory muscles. Damage of the cord at levels involving the brachial plexus can result in quadriplegia. Hyperextension of the neck stretches the cord and may compress the cord against a damaged cervical vertebra; such a maneuver may also result in complete transection as the cord is caught between broken fragments of cervical vertebrae. Landmark structures of this region are shown in Fig. 3.1B. The thyroid gland, often with a pyramidal lobe, overlies the trachea. The paired sternocleidomastoid muscles are located well lateral to it. The thyroid cartilage and cricoid cartilage are easily palpable above the thyroid gland. The hyoid bone can be palpated above the thyroid cartilage. Identification of Landmarks (Fig. 3.2) Technical and Anatomic Points Palpate five midline landmarks, including the mental protuberance, or tip of the chin; the body of the hyoid bone; the laryngeal prominence of the thyroid cartilage (Adam's apple); the cricoid cartilage; and the suprasternal or jugular notch of the manubrium sterni. All of these constant bony or cartilaginous landmarks should be identified with certainty to avoid inadvertent supraglottic incision. Repeated palpation of these readily identifiable midline structures will help ensure that the dissection remains in the midline.
46. 46. Figure 3-2 Identification of Landmarks Skin Incision (Fig. 3.3) Technical Points A vertical incision about midway between the cricoid cartilage and the jugular notch provides the best exposure and is preferred in emergency situations. With this incision, there is less bleeding and less risk for damage to nerves and vessels. The incision shown is slightly larger than usually required. Do not hesitate to make a generous incision if exposure is difficult. A transverse incision, made at the same level, yields a somewhat better cosmetic result; however, the advantage is marginal because scarring occurs around the tracheal stoma. Formal tracheostomy is performed between the second and third tracheal rings. Cricothyroidotomy is done through the median cricothyroid ligament. If a transverse incision is used, it should be planned to lie directly over the appropriate level, confirmed by palpation of the anatomic landmarks. Anatomic Points The theoretic cosmetic advantage of a transverse incision is that it follows the direction of Langer's lines (resulting from the predominant orientation of dermal collagen bundles and elastic fibers in the skin) and also parallels the natural wrinkle lines of the area.
47. 47. P.26 Figure 3-3 Skin Incision
48. 48. Figure 3-4 Dissection down to the Trachea Dissection down to the Trachea (Fig. 3.4) Technical Points Proceed with sharp and blunt dissection in the midline, confirming correct placement by repeated palpation of anatomic landmarks. Anatomic Points The paired platysma muscles, which should be identified and retracted, are deficient in the median plane. The superficial veins in this region (anterior and external jugulars and their tributaries) run in a predominantly vertical direction deep to the platysma. With the exception of the jugular venous arch, these superficial veins do not cross or occupy the median plane. No motor nerves, and only the terminal branches of sensory nerves, cross or occupy the median plane. Isthmus of Thyroid Gland (Fig. 3.5) Technical Points The next important structure to identify is the isthmus of the thyroid gland. The isthmus may be retracted cephalad or
49. 49. P.27 caudad, or divided, to obtain access to the appropriate segment of the trachea. To facilitate retraction of the isthmus, spread the tissues with a blunt-tipped hemostat (such as a small Kelly clamp) in the plane between the thyroid and the trachea. Then place a vein retractor on the isthmus to retract it away from the second and third tracheal rings. Decide whether to divide the isthmus according to the amount of dissection necessary to expose the second and third tracheal rings and the space between. Generally, it is possible to achieve this exposure by retraction. Figure 3-5 Isthmus of Thyroid Gland If it is necessary to divide the isthmus of the thyroid partially or completely, first confirm that the plane between the thyroid and trachea has been developed adequately. Then double-clamp and oversew or suture-ligate the highly vascular thyroid tissue before proceeding. Anatomic Points The thyroid begins its development as a diverticulum in the region of the incipient tongue and migrates from its site of origin (marked by the foramen cecum) to its definitive location. Although the large lobes are paratracheal, the isthmus is in the median plane and typically covers the second and third tracheal rings. Further, its developmental route is frequently indicated by the presence of a pyramidal lobe, the result of !residual!! thyroid tissue being deposited along the path of descent. This lobe is usually slightly to the left of the midline, but it may be in the midline or on the
50. 50. P.28 right. Exposure of Pretracheal Fascia (Fig. 3.6) Technical Points Dissect the pretracheal fascia (which invests the thyroid gland) from the trachea to provide a clear view of the trachea. To perform a formal tracheostomy, count the rings down from the cricoid cartilage. Incise and spread the tissue between the second and third rings (Fig. 3.6A). A simple transverse incision is generally all that is required; however, some prefer to make an H-shaped or T-shaped cut. It is rarely necessary to excise any cartilage. Have an assistant at the head of the table deflate the cuff of the endotracheal tube and withdraw it slowly until it is just below the vocal cords but above the tracheal stoma. With the stoma spread, insert the pretested tracheostomy tube, with the obturator in place, by pushing it straight in and then downward (Fig. 3.6B). Push downward only after feeling the tube pop into the tracheal lumen; otherwise, it is possible to place the tube in the pretracheal space. Inflate the cuff, have the endotracheal tube removed, and connect the tracheostomy to the ventilator or to oxygen. Pass a soft- suction catheter down the tracheostomy tube to remove blood and mucus from the airway. Free passage of the catheter into the bronchial tree confirms position of the tracheostomy tube within the airway. A tracheostomy hook!a small, sharp, hooked device!may be used to pull the trachea up into the field and maintain visibility when the incision is deep. However, care must be taken to avoid puncture of the cuff of the tracheostomy tube when using the hook. A better method is to place a 2-0 monofilament suture through the third tracheal cartilage and use that for retraction. The suture can be left long and brought out through the skin incision to aid in replacing the tube if it becomes dislodged. Anatomic Points It is critical that the incision not be made through the cricoid. This is the only totally circumferential cartilage in the airway and provides important stability. Repeated identification of anatomic landmarks and careful dissection in a bloodless field will prevent such an error as well as the equally unfortunate circumstance of entering the airway above the glottis. Tracheobrachiocephalic Artery Fistula (Fig. 3.7) Technical and Anatomic Points If a tracheostomy is performed below the level of the fourth ring, the tip of the tracheostomy tube may erode into the brachiocephalic (innominate) arterial trunk, which runs obliquely across the thoracic outlet immediately anterior to the trachea (Fig. 3.7A). This will result in delayed massive bleeding into the airway. The left brachiocephalic (innominate) vein often lies in the jugular notch in its passage from the root of the neck to the superior vena cava (Fig. 3.7B). A very low incision could injure
51. 51. this vessel. Figure 3-6 Exposure of Pretracheal Fascia Figure 3-7 Tracheobrachiocephalic Artery Fistula
52. 52. P.29 Should bleeding from either of these vessels occur, obtain temporary control by placing a finger in the stoma and pressing anteriorly or by inflating the balloon of an endotracheal tube. This will compress the vessel against the undersurface of the manubrium, allowing time to transport the patient to the operating room for open or endovascular repair. Definitive management of this difficult problem is detailed in the surgical references at the end of this chapter. Cricothyroidotomy (Fig. 3.8) Technical Points Cricothyroidotomy is performed through the median cricothyroid ligament, which is the most superficial part of the airway (closest to the skin) and hence affords the easiest approach during emergency situations. In a dire emergency, percutaneous needle cannulation of this ligament may be lifesaving, allowing time for subsequent, more orderly control of the airway. The landmarks for this procedure are the thyroid cartilage, the cricoid cartilage, and the hyoid bone (Fig. 3.8A). To perform an emergency cricothyroidotomy, first stabilize the larynx with the fingers of the nondominant hand and palpate the space between the larynx and cricoid. (Fig. 3.8B). Stab into the median cricothyroid ligament transversely with a scalpel. Spread the hole with a Kelly clamp and insert a tracheostomy tube. Be careful to avoid injury to the cricoid cartilage! Most bleeding will be venous; control it by direct pressure with the fingers of your nondominant hand until the tube is in and the patient is successfully ventilated. Then expose and ligate individual bleeders. If time permits, cricothyroidotomy may be performed by dissection in a manner similar to that described for tracheostomy. Visualize the median cricothyroid ligament and incise it transversely, then spread the tissues and insert the tracheostomy tube as discussed previously (Fig. 3.8C). Anatomic Points The cricoid cartilage is the narrowest part of the airway. Concern about subglottic stenosis limits the application of this approach. A branch of the superior thyroid artery!the cricothyroid artery (and its accompanying vein)!runs transversely across the median cricothyroid ligament. This artery occasionally has a branch that penetrates the median cricothyroid ligament to anastomose with the laryngeal arteries. It is typically closer to the thyroid cartilage than to the cricoid cartilage. Thus, to avoid injury to these vessels, and to avoid damage to the closely situated vocal cords, cricothyroidotomy should be performed by making a transverse incision along the superior border of the cricoid cartilage, rather than along the inferior border of the thyroid cartilage.
53. 53. Figure 3-8 Cricothyroidotomy Surgical References 1. Chew JW, Cantrell RW. Tracheostomy: complications and their management. Arch Otolaryngol. 1972;96:538. (Provides an excellent review of complications, including tracheoinnominate artery fistula.) 2. Dulguerov P, Gysin C, Perneger TV, et al. Percutaneous or surgical tracheostomy: a meta-analysis. Crit Care Med. 1999;27:1617. (Compares complications as reported in literature.)
54. 54. P.30 3. Eliachar I, Zohar S, Golz A, et al. Permanent tracheostomy. Head Neck Surg. 1984;7:99. (Describes construction of a permanent stoma.) 4. Gysin C, Dulguerov P, Guyot JP, et al. Percutaneous versus surgical tracheostomy: a double-blind randomized trial. Ann Surg. 1999;230:708. (Details complications associated with both techniques.) 5. Heffner JE, Miller KS. Tracheostomy in the intensive care unit. I. Indications, techniques, management. Chest. 1986;90:269. (Offers a good description of the management of a patient with a tracheostomy.) 6. Higgins KM, Punthakee X. Meta-analysis comparison of open versus percutaneous tracheostomy. Laryngoscope. 2007;117:447!454. (Trend in favor of percutaneous techniques). 7. Orringer MB. Endotracheal intubation and tracheostomy: indications, techniques, and complications. Surg Clin North Am. 1980; 60:1447. 8. Van-Hasselt EJ, Bruining HA. Elective cricothyroidotomy. Intensive Care Med. 1985;11:207. (Provides reviews of clinical experience.) Anatomic References 1. American Association of Clinical Anatomists, Educational Affairs Committee. The clinical anatomy of several invasive procedures. Clin Anat. 1999;12:43. 2. Ger R, Evans JT. Tracheostomy: an anatomico-clinical review. Clin Anat. 1993;6:337. 3. Salassa JR, Pearson BW, Payne WS. Gross and microscopical blood supply of the trachea. Ann Thorac Surg. 1977;24:100. Technical Complications: Management of Tracheoinnominate Artery Fistula References 1. Allan JS, Wright CD. Tracheoinnominate fistula: diagnosis and management. Chest Surg Clin N Am. 2003;13:331!341. 2. Cohen JE, Klimov A, Rajz G, et al. Exsanguinating tracheoinnominate artery
55. 55. fistula repaired with endovascular stent-graft. Surg Neurol. 2008;69:306!309. 3. Marone EM, Esposito G, Kahlberg A, et al. Surgical treatment of tracheoinnominate fistula after stent-graft implantation. J Thorac Cardiovasc Surg. 2007;113:1641!1643. 4. Palchik E, Bakkien AM, Saad N, et al. endovascular treatment of tracheoinnominate artery fistula: a case report. Vasc Endovascular Surg. 2007;41:258!261. 5. Ridley RW, Zwischenberger JB. Tracheoinnominate fistula: surgical management of an iatrogenic disaster. J Laryngol Otol. 2006;120: 676!680.
56. 56. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > The Midline and Structures Approached Through The Midline > 4 - Percutaneous Dilatational Tracheostomy 4 Percutaneous Dilatational Tracheostomy Timothy Van Natta G. Patrick Kealey Percutaneous dilatational tracheostomy is now an accepted operative technique. There are two slightly different technical approaches to this procedure, which differ primarily in the use or omission of bronchoscopic guidance. Both are discussed in this chapter. Steps in Procedure Position patient, check equipment, including balloon of tracheostomy tube Bronchoscopic visualization of proximal trachea (optional) Vertical incision (or horizontal) extending 2 cm inferiorly from cricoid cartilage Visualize space between second and third tracheal rings Insert needle, aspirate air, inject lidocaine Exchange needle for plastic catheter and pass guidewire (bronchoscopic control) Pass lubricated dilator(s) Using dilator as obturator, pass lubricated tracheostomy tube and secure Hallmark Anatomic Complications Bleeding Injury to posterior wall of trachea Tracheal ring fracture Tracheal stenosis List of Structures Trachea Cricoid cartilage
57. 57. P.32 Percutaneous dilatational tracheostomy is generally not recommended for achieving emergency airway control or access. Endotracheal intubation or cricothyrotomy is the most appropriate emergency technique to achieve adequate airway control and ventilation. Percutaneous dilatational tracheostomy is a safe and appropriate technique for use in the intubated patient who requires elective tracheostomy. It may be done at the bedside in the intensive care unit. Contraindications to percutaneous dilatational tracheostomy include the following: 1. Inability to extend the cervical spine 2. Unstable cervical spine 3. Inability to palpate anatomic landmarks because of edema, obesity, or anatomic abnormalities 4. Patients who are not intubated 5. Calcification of the tracheal rings on chest radiograph 6. Pediatric patients (younger than 16 years of age) and adults with small airways 7. Need for emergency airway management (relative) Appropriate positioning and preparation of the patient are essential to achieving good operative results. Therefore, in both techniques, the following preparations must be made. Place the intubated patient in a supine position. Continuous monitoring should include electrocardiographic monitoring of heart rate, blood pressure, pulse oximetry, inspired title volume, and ventilator pressures. Increase the inspired oxygen fraction to 100% and ensure adequate ventilation. Because a firm operating surface is necessary, place a cardiopulmonary resuscitation board under the patient's upper torso. Extend the cervical spine by placing a rolled towel between the shoulder blades (see Fig. 4-1A). Prep and drape the anterior neck with sterile towels. Percutaneous Dilatational Tracheostomy without Bronchoscopic Guidance (Fig. 4.1) Technical and Anatomic Points Palpate the anterior neck and identify the landmarks, including the cricoid cartilage (see also Fig. 4.1B). Infiltrate the skin and subcutaneous tissues with 1% lidocaine solution with epinephrine before making the skin incision. Make the skin incision starting at the inferior edge of the cricoid cartilage and extending inferiorly 2 cm. Divide the subcutaneous tissues bluntly with hemostats until the trachea is visualized and its cartilage rings are palpable. This allows for a clear visual delineation of tracheal anatomy, including the location of the tracheal midline, and obviates the need for concomitant bronchoscopy. Achieve hemostasis with absorbable suture or electrocautery as necessary. Partially deflate the cuff of the endotracheal tube and slowly withdraw it until the cuff is palpable at the level of the cricoid cartilage. Attach a 17-gauge needle with an overlying plastic catheter to a syringe partially filled with 1% lidocaine solution with
58. 58. epinephrine. Insert this into the trachea between the first and third cartilage rings under direct vision. Confirm entry into the trachea by free aspiration of air. Advance the overlying plastic catheter into the trachea and withdraw the needle. Again confirm the position of the plastic catheter within the trachea by aspirating air, and inject 1 mL of 1% lidocaine with epinephrine into the trachea for local anesthesia and hemostasis. Advance a 1.32 J-tipped guidewire through the catheter into the trachea (Fig. 4.1A) and remove the overlying plastic catheter. Next, place a dilator guide over the guidewire, followed by a lubricated, flexible, tapered dilator up to its external 38 French mark (Fig. 4.1B, C). Perform this dilation carefully and without excessive force. Remove the dilator, leaving the dilator guide and guidewire in place. Pass a size 6 or 8 cuffed Shiley tracheostomy tube over the appropriate dilator, which will function as an obturator. Lubricate the tracheostomy tube and dilator and pass these into the trachea (Fig. 4.1D). When the tracheostomy tube is seated in its final position, remove the dilator, dilator guide, and guidewire as a unit. Inflate the tracheostomy balloon. Leave the endotracheal tube in place, but disconnect it from the ventilator. Connect the tracheostomy tube to the ventilator tubing with a flexible adaptor. Initiate ventilation. Confirm satisfactory oxygenation and minute ventilation before withdrawing the endotracheal tube. Apply the CO2 detector to ensure proper endotracheal position of the tracheostomy tube. Secure the tracheostomy tube by four-point fixation using sutures and a tracheostomy tape. Obtain a portable upright chest radiograph to determine proper positioning of the tracheostomy tube and to evaluate for pneumothorax, hemothorax, or significant atelectasis.
59. 59. P.33 Figure 4-1 Percutaneous Dilatational Tracheostomy without Bronchoscopic Guidance (From Singh RK. Timing and type of tracheostomy. Probl Gen Surg. 2000;17:101!109, with permission.) Figure 4-2 Percutaneous Dilatational Tracheostomy with Bronchoscopic Guidance Percutaneous Dilatational Tracheostomy with Bronchoscopic Guidance (Fig. 4.2) Technical and Anatomic Points After preparing the patient as described previously, attach a bronchoscopy adapter between the endotracheal tube and the ventilator tubes. Perform a bronchoscopic inspection of the airway. Withdraw the endotracheal tube to immediately below the vocal folds. Reinflate the cuff of the endotracheal tube to ensure adequate ventilation. Bronchoscopic transillumination of the anterior trachea is a useful guide, but does not absolutely guarantee an initial midline tracheal puncture. Palpate and define the cricoid and tracheal rings. Infiltrate the skin and subcutaneous tissue over the second and third tracheal rings with 1% lidocaine solution with epinephrine. Insert a 17-gauge needle with an overlying plastic catheter percutaneously between the first and third tracheal rings into the trachea. Attach the needle to a syringe partially filled with the lidocaine solution. Confirm the presence of air by aspirating with a syringe. Use the bronchoscope to confirm that the needle entry is midline (Fig. 4.2A). Withdraw the needle, leaving
60. 60. P.34 the plastic catheter in place as previously described. Pass the J wire until bronchoscopic observation, confirming that the J wire passes toward the carina (Fig. 4.2B). Make a 2-cm transverse or vertical skin incision 1 cm on either side of the guidewire. Insert the dilator guide over the guidewire into the trachea. Dilate the trachea using the tapered flexible dilator up to its external 38 French mark. In both techniques, perform the dilatation carefully and without excessive force. Remove the tapered dilator. Place a size 6 or 8 Shiley tracheostomy tube snugly over the appropriate dilator. Lubricate the tracheostomy tube and dilator and pass them over the guidewire and into the trachea. Use bronchoscopic visualization to confirm that the tracheostomy tube is within the trachea (Fig. 4.2C). Withdraw the dilator, dilator guide, and guidewire as a single unit. Insert the inner cannula of the tracheostomy tube, inflate the cuff of the tube, and attach the ventilator. Insert the bronchoscope into the tracheostomy tube to confirm the intratracheal position of the tracheostomy tube and to inspect for bleeding. Withdraw the oral endotracheal tube only after confirmation of appropriate positioning of the tracheostomy tube. Secure the tracheostomy tube using four-point fixation sutures and the tracheostomy tape. Obtain a portable upright chest radiograph to evaluate the tracheostomy position and for the presence of pneumothorax, hemothorax, or significant atelectasis. The key to successful percutaneous dilatation tracheostomy is careful surgical technique preceded by appropriate positioning of an intubated patient. Bronchoscopically directed guidewire insertion into the trachea ensures anterior midline placement of the tracheostomy tube and eliminates the anterior dissection of the neck structures and paratracheal tissues. References 1. Ciaglia P, Graniero K. Percutaneous dilatational tracheostomy: results and long- term follow-up. Chest. 1992;101:464!467. 2. Ciaglia P, Firsching R, Syniec C. Elective percutaneous dilatational tracheostomy: a new simple bedside procedure, preliminary report. Chest. 1985;87:715!719. 3. Moe KS, Schmid S, Stoeckli SJ, et al. Percutaneous tracheostomy: a comprehensive evaluation. Ann Otol Rhinol Laryngol. 1999;108: 384!391. 4. Fernadez L, Norwood S, Roettger R, et al. Bedside percutaneous tracheostomy with bronchoscopic guidance in critically ill patients. Arch Surg. 1996;131:129 !132. 5. Rosenbower TJ, Morris JA Jr, Eddy VA, et al. The long-term complications of
61. 61. percutaneous dilatational tracheostomy. Am Surg. 1998;64:82!87. 6. Van Natta TL, Morris JA Jr, Eddy VA, et al. Elective bedside surgery in critically injured patients is safe and cost-effective. Ann Surg. 1998;227:618!626. 7. Hinerman R, Alvarez F, Keller CA. Outcome of bedside percutaneous tracheostomy with bronchoscopic guidance. Intensive Care Med. 2000;26:1850 !1856. 8. Higgins KM, Punthakee X. Meta-analysis comparison of open versus percutaneous tracheostomy. Laryngoscope. 2007;117: 447!454. 9. Byhahn C, Wilke HJ, Halbig S, et al. Percutaneous tracheostomy: Ciaglia blue rhino versus the basic Ciaglia technique of percutaneous dilatational tracheostomy. Anesth Analg. 2000;91: 882!886. 10. Cheng E, Fee Jr WE. Dilatational versus standard tracheos-tomy: a meta- analysis. Ann Otol Rhinol Laryngol. 2000;109: 803!807. 11. Norwood S, Valina VL, Short K, et al. Incidence of tracheal stenosis and other late complications after percutaneous tracheostomy. Ann Surg. 2000;232:233 !241.
62. 62. Authors: Scott-Conner, Carol E. H.; Dawson, David L. Title: Operative Anatomy, 3rd Edition Copyright 2009 Lippincott Williams & Wilkins > Table of Contents > Section I - The Head and Neck > The Midline and Structures Approached Through The Midline > 5 - Thyroglossal Duct Cyst 5 Thyroglossal Duct Cyst In this section, the anatomy of the upper midline of the neck is explored, and the embryology of the thyroid gland and associated anomalies is discussed through the operation of removal of thyroglossal duct cyst. Thyroglossal duct cysts form along the path of descent of the thyroid gland. They present as upper midline neck masses. Often, these cysts become infected and present as abscesses. Incision and drainage or simple excision of the cyst results in a high recurrence rate. Complete removal of the cyst and its associated tract is necessary for cure. Steps in Procedure Position patient: neck hyperextended, lower face and mouth draped into field Transverse incision (include sinus tract if present) Retract sternohyoid muscles and expose cysts Dissect cyst free of surrounding tissues medially, laterally, cephalad, and caudad Seek and dissect fibrous tract leading to hyoid bone Trace to hyoid and resect midportion of hyoid bone in continuity with tract Follow tract to base of tongue, using pressure on foramen cecum if necessary; ligate termination Hallmark Anatomic Complication Recurrence resulting from inadequate dissection List of Structures Embryologic Structures and Terms Thyroid anlagen Pharyngeal arches Tuberculum impar (pharyngeal arch I) Copula (pharyngeal arches II through IV)
63. 63. P.36 Thyroglossal duct Adult Structures Tongue Foramen cecum Hyoid bone Suprahyoid muscles Mylohyoid muscle Geniohyoid muscle Sternohyoid muscle Genioglossus muscle Hypoglossal nerve (XII) Mandibular division of trigeminal nerve (V) Mylohyoid nerve Lingual nerve Thyroid gland Pyramidal lobe Thyroid cartilage Positioning the Patient and Incising the Skin (Fig. 5.1) Technical Points Position the patient supine, with the neck hyperextended and the chin directly anterior. Include the lower face and lips in the surgical field. (Access to the mouth may facilitate subsequent dissection.) Make a transverse skin incision over the cyst (Fig. 5.1A). If previous drainage of the cyst has resulted in an external sinus tract or scar, excise this in transverse elliptical fashion with the skin incision. Plan the incision to lie parallel to, or within, the natural skin lines. Elevate flaps in the plane deep to the platysma muscle to expose the deep cervical fascia and paired sternohyoid muscles overlying the cyst. Incise this fascia in the midline.
64. 64. Figure 5-1 Positioning the Patient and Incising the Skin
65. 65. P.37 Anatomic Points Thyroid anlagen begin as an epithelial thickening of endodermal origin during the fourth intrauterine week. This thickening is located in the floor of pharyngeal arch II, between the tuberculum impar (pharyngeal arch I) and copula (arches II through IV) that participate in the formation of the tongue. The anlage rapidly evaginates, coming into contact with the aortic sac of the developing heart. Owing to differential growth, the thyroid migrates from its point of origin, marked by the foramen cecum of the mature tongue (at the junction of the anterior two thirds and posterior one third), to its definitive location. During this migration, the gland is connected to the tongue by the thyroglossal duct (Fig. 5.1B). The path of migration passes anterior to the developing hyoid bone, whose paired anlagen, from pharyngeal arch II, fuse in the ventral midline and also undergo some rotation. Because of the relationship of the thyroglossal duct to the developing hyoid bone, the duct can be drawn posterocranially with respect to the hyoid, be enveloped in hyoid periosteum or hyoid bone proper, or pass posterior to the hyoid. Typically, the duct degenerates, leaving a short diverticulum at the foramen cecum proximally, a longer cord distally that develops into the pyramidal lobe of the thyroid gland (typically displaced slightly to the left of the median plane), and an intervening fibrous cord. If the discontinuous epithelial cells present in the fibrous remnant differentiate and subsequently assume a secretory function, a thyroglossal duct cyst results. A thyroglossal duct cyst should be suspected in any person presenting with a median or paramedian lump in the neck, especially if the lump is superior to the level of the cricoid cartilage and if it moves with the excursion of the hyoid bone during swallowing or tongue protrusion (Fig. 5.1C). A lingual thyroid, usually the result of maldescent of the thyroid, has to be considered if the lump is located intralingually. In this case, preoperative evaluation with a radioisotope scan is essential because 65% to 75% of patients with this condition lack other thyroid tissue. Dissection of the Cyst (Fig. 5.2) Technical Points Retract the paired sternohyoid muscles laterally to expose the cyst. Carefully dissect the cyst from the surrounding soft tissues on all sides. Often, the inferior border can be delineated most easily. Start the dissection here and divide any attachments to the pyramidal lobe of the thyroid that may be present (Fig. 5.2A). Search for and identify the tract leading up to the hyoid bone. This will be palpable as a firm, cordlike structure passing superiorly and deep in a relatively straight path to the midportion of the hyoid (Fig. 5.2B). If the cyst is densely adherent to the hyoid and the tract cannot be identified, simply proceed to excise the cyst and midportion of the hyoid en bloc. Anatomic Points The tract typically is to the left of midline, juxtaposed to the thyroid cartilage. If a pyramidal lobe is present, the dissection should start at its apex and proceed superiorly
66. 66. P.38 to the body of the hyoid bone. Although the tract typically ascends posterior to the body of the hyoid and then is recurved to pass superficial to the anterior surface of the hyoid, it must be emphasized that the tract can lie within the hyoid periosteum or within the bone, or it can continue its ascent to the foramen cecum posterior to the hyoid. Dissection through the Hyoid to the Base of the Tongue (Fig. 5.3) Technical Points Detach the mylohyoid and deeper geniohyoid muscles from the hyoid superiorly and the sternohyoid muscles inferiorly. Divide the hyoid laterally with a small, heavy scissor. Excise a block of the midportion of the hyoid bone in continuity with the cyst and its tract (Fig. 5.3A). Continue the dissection proximally. Excise a core of tissue surrounding the fibrous tract (Fig. 5.3B). Anatomic Points Because of the variability of the path of the thyroglossal duct with respect to the hyoid, resect a portion of the body of the hyoid bone in continuity with soft tissues to ensure that no part of the duct remains. Figure 5-2 Dissection of the Cyst
67. 67. Figure 5-3 Dissection through the Hyoid to the Base of the Tongue Tract Followed to the Foramen Cecum (Fig. 5.4) Technical Points Place a second surgical glove (one-half size larger than the size normally worn) over the glove of your nondominant hand or have an assistant do this. Insert the index and second finger of this hand into the mouth and press downward in the vicinity of the foramen cecum. Then continue the dissection up toward the foramen cecum, using the hand within the mouth as a guide. Excise the tract. Do not excise the foramen cecum through the cervical incision. Suture-ligate the base of the tract just below the foramen cecum. Check hemostasis in the operated field. If only a small portion of the hyoid bone has been resected, reapproximate it with a monofilament nonabsorbable suture. When a large cyst necessitates removal of a large portion of the hyoid bone, close the defect by suturing the sternohyoid muscle inferiorly to the mylohyoid muscle superiorly. Then close the cervical fascia and skin. Anatomic Points As the tract is followed to the foramen cecum, the surroundi