Endoscopy Lamina Terminal Is

Neurosurgery Publish Ahead of Print DOI: 10.1227/NEU.0b013e31825b1e8d

Efficacy and Safety of Endoscopic Transventricular Lamina Terminalis Fenestration for Hydrocephalus Leonardo Rangel-Castilla1,2,3 MD; Steven W. Hwang2 MD; Andrew Jea2 MD; Jaime TorresCorzo3 MD 1) Department of Neurosurgery, The Methodist Neurological Institute, The Methodist Hospital, Weill Cornell Medical College, Houston, Texas USA 2) Division of Pediatric Neurosurgery, Texas Children's Hospital, Department of Neurosurgery, Baylor College of Medicine, Houston, Texas USA

3) Department of Neurosurgery, Instituto Potosino de Neurociencias, Facultad de Medicina de la Universidad Autonoma de San Luis Potosi, San Luis Potosi, Mexico

Leonardo Rangel-Castilla MD

Department of Neurosurgery, The Methodist Neurological Institute,

6560 Fannin, Suite 944, Houston, TX 77030 USA Phone: 713 203 2816

Email: [email protected] Acknowledgments: The authors would like to recognize the assistance and effort provided by Olga Elias-Chalita in the collection of the data and acknowledge work from Kathy Relyea in producing the illustration. Disclosure: All the authors have no financial support, personal or institutional financial interest in drugs, material or devices in the article to disclose.

Copyright Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited.

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Fax: 713 793 1001

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The Methodist Hospital, Weill Cornell Medical College

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Corresponding author:

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Abstract Background: Endoscopic third ventriculostomy (ETV) has become the procedure of choice in the treatment of obstructive hydrocephalus. In certain cases, standard ETV might not be technically possible or may engender significant risk. Objective: We present an alternative through the lamina terminalis (LT) by a transventricular, transforaminal approach with flexible neuroendoscopy. Indications, technique, neuroendoscopic

Methods: Between 1994 and 2010, all patients who underwent endoscopic LT fenestration as an

LT fenestration was made intraoperatively.

Results: Twenty-five patients underwent endoscopic LT fenestration, ranging in age from 7 months to 76 years (mean: 28.1 years). Patients had obstructive hydrocephalus secondary to:

in 5. Thirteen (52%) patients had had at least one VP shunt that malfunctioned; six (24%) had undergone a previous endoscopic procedure. Intraoperative findings that lead to an LT fenestration were: ETV not feasible to perform, basal subarachnoid space not sufficient, or

period was 63.76 months. Overall, 19 (76%) patients had resolutions of symptoms, no evidence of ventriculomegaly, and did not require another procedure. Six (24%) required a VP shunt. Conclusion: Endoscopic transventricular transforaminal LT fenestration with flexible neuroendoscopy is feasible with a low incidence of complications. It is a good alternative to standard ETV. Adequate intraoperative assessment of ETV success is necessary to identify patients that will benefit. Running Title: Endoscopic Transventricular Lamina Terminalis Fenestration Keywords: aqueductoplasty; Endoscopic third ventriculostomy; flexible neuroendoscopy; Hydrocephalus; lamina terminalis; lamina terminalis fenestration

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adhesions in the third ventricle. No perioperative complications occurred. The mean follow-up

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neurocysticercosis in 11 patients, neoplasms in 6, congenital aqueductal stenosis in 3, and other

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alternative to ETV were analyzed and prospectively followed up. The decision of performing an

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findings, and outcome are discussed.

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Introduction Over the last two decades, indications for neuroendoscopy and neuroendoscopic procedures have been defined and expanded. The most common procedure performed is endoscopic third ventriculostomy (ETV) for obstructive hydrocephalus. It has become the treatment option of choice in obstructive hydrocephalus (HCP).1-4 Other endoscopic procedures include: fenestration of the septum pellucidum, foraminoplasty (Monro and Magendie), aqueductoplasty, aqueductal stenting, temporal ventriculostomy, cyst fenestration and extraction, ventricular and

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paraventricular tumor biopsy and resection, and lamina terminalis (LT) fenestration.1,

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indications for some of these procedures have been proposed and for others there is still debate

Very few articles discuss the use of endoscopic LT fenestration1,

describing the surgical technique, indications, complications, and clinical outcomes are nonexistent in the literature. Fenestration of the LT during open microsurgery had been proposed as hemorrhage.7-9 Few studies, mostly limited to cadaveric dissection, and case reports have proposed an endoscopic fenestration of the LT by a subfrontal approach as an alternative to ETV.5, 10, 11 Recently, Oertel et al described the first endoscopic transventricular fenestration of

transventricular transforaminal route is feasible and could represent an alternative to an ETV for a selected subgroup of patients. In their publication they called for results and outcome with the flexible neuroendoscope. Therefore, herein the authors present their experience with endoscopic transventricular transforaminal LT fenestration after 16 years of flexible endoscopic neurosurgery.1, 4, 12-15

Material and Methods From November 1994 to June 2010 more than 850 intracranial neuroendoscopic procedures were performed by the senior neurosurgeon (J.T.C.). Permission from the Institutional Review Board was obtained. All patients were prospectively followed clinically and radiographically. After identifying the patients who underwent LT fenestration, we reviewed medical records,2


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the LT on four cadaveric human heads and 4 clinical cases. They concluded that a

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an alternative to reduce the incidence of shunt-dependent HCP after aneurysmal subarachnoid

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and ongoing investigation.

, and detailed reports

radiographs and operative videos to assess complications and outcomes. We evaluated the presence of previous surgeries (ventriculoperitoneal (VP) shunt and endoscopic procedures), indications, intraoperative endoscopic findings, results, risks, complications, and clinical and radiographic outcomes. Follow-up examinations were performed at 2, 6 and 12 months postoperatively and then on a yearly basis.

We use three different types of flexible neuroendoscopes for intraventricular neuroendoscopy.

channel diameter, and a tip-bending range of 120 degrees down and 90 degrees up. The second one (Olympus Optical Co.) has an outside diameter and a working channel diameter of 4.2 mm and 2 mm, respectively, with a tip-bending range of 120 degrees up and down. The third one is a

mm and 1.2 mm with a tip that bends 120 and 90 degrees down and up, respectively. They incorporate automatic exposure facilities when they are used with an appropriate cold light supply and television camera. The endoscopic instruments include monopolar and bipolar electrocauteries, biopsy and grasping forceps, puncture needles, Fogarty balloons, and an articulated arm that is used as an endoscope holder. Under general anesthesia, the patient is positioned supine with the head slightly flexed at 30 degrees. In all cases an ETV and/or aqueductoplasty were considered as the initial endoscopic procedure. The right frontal area was prepped and draped in a standard sterile fashion. The burr

dura, the brain cortex was coagulated and the lateral ventricle was entered with a ventricular needle and then replaced with the plastic peel-away work sheath. The endoscope already fixed to the arm holder was inserted into the lateral ventricle. When possible, a detailed inspection of the lateral ventricles, third ventricle, cerebral aqueduct, and the fourth ventricle was performed. Endoscopic procedures such as fenestration of the septum pellucidum, ETV, or aqueductoplasty were performed if indicated and technically feasible. After the ETV was created the basal subarachnoid cisterns were carefully inspected, looking for adequate space, presence of adhesion3


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hole was placed 2.5-mm from the midline just anterior to the coronal suture. After opening the

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pediatric scope (Wolf GmbH) with an outside diameter and a working channel diameter of 2.6

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The first one (Codman/Johnson & Johnson) has a outside diameter of 4mm, a 1-mm working

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Neuroendoscopic Equipment and Surgical Technique

or scarring, and thick arachnoid membranes. The adequacy of the ETV was judged by the motion of the free edges of the fenestration, which should move freely with the CSF pulsations if there is appropriate communication between the ventricular system and the basal subarachnoid space. Fenestration of the LT was performed last as a rescue procedure based on the intraoperative assessment of ETV success.

After a complete exploration of the lateral and third ventricles and only if a successful ETV or

findings, an LT fenestration was considered. The flexible endoscope with the tip in a neutral position is initially placed in the center of the third ventricle looking down directly at the floor of the third ventricle (mammillary bodies and infundibulum) (Fig. 1b). The tip is bent anteriorly and

suprachiasmatic recess (Fig. 1c), the anterior cerebral and communicating arteries, the LT, and anterior commissure (Fig. 2d). The LT is a thin, transparent, triangular shaped sheet of gray matter between the anterior commissure and optic chiasm (Fig 1c). An initial blunt perforation is made in the midline and 2-3 mm above the optic chiasm. After a small perforation is made, the flaccid lamina is further enlarged with grasping forceps (Fig. 1d) or a balloon catheter (Fig 2). Attention was directed at avoiding injury to the small vessels that arise from the anterior circulation complex; coagulation was never used to extend the fenestration. A final inspection of the fenestration is performed to identify the anterior cerebral and anterior communicating arteries and small perforating arteries (Fig. 1(h and i) and Fig 2). The maneuverable tip is brought to neutral position and the endoscope is withdrawn from the ventricle. A detailed presentation of the surgical technique from 2 different patients is given in Figures 1 and 2, and in Supplemental Videos 1 and 2.

Results Demographics4


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the following structures are identified: infundibular recess (Fig. 1b), optic chiasm (Fig. 1b),

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aqueductoplasty could not be achieved safely or would not be successful based on the previous

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Lamina Terminalis Fenestration Technique

A total of 25 fenestrations of the LT were performed in 25 patients. All patients had obstructive hydrocephalus on CT and/or MRI at admission. The initial pathology was intraventricular and subarachnoid neurocysticercosis in 11 patients, neoplasms (3 medulloblastomas, 1 chordoma, 1 pineoblastoma, and 1 anaplastic ependymoma) in 6 patients, congenital aqueductal stenosis in 2 patients, neonatal acquired aqueductal stenosis secondary to meningitis (ventriculitis) and intraventricular hemorrhage in 2 patients, congenital aqueductal stenosis associated with a suprasellar arachnoid cyst in 1 patient, giant suprasellar arachnoid cyst in 1 patient, Type 2

mean age of the patients was 28.1 (SD: 19.31) years (range: 7months-76 years). There were 15 female and 10 male patients. The main symptoms and signs at the time of presentation were headaches in 15 (60%) patients, visual disturbances (diplopia, blurry vision, Parinauds syndrome, or strabismus) in 14 (56%) patients, nausea and vomiting in 5 (20%) patients, increased head circumference in 5 (20%) patients, gait ataxia in 3 (12%) patients, and other (including vertigo, tinnitus, seizures, weight loss) in 5 (20%) patients. Thirteen (52%) patients had had at least one VP shunt placement with a shunt malfunction. Six (24%) patients had previously undergone an endoscopic procedure (4 ETVs, 1 aqueductoplasty, and 1 cyst fenestration) with current symptoms suggestive of a failure. Three (12%) patients had a previous craniotomy and tumor resection. Twelve (48%) patients had a concurrent ETV performed that criteria.16 See Table 1 for patient demographics.

Neuroendoscopic Findings and Procedures The initial endoscopic procedure performed was an ETV and/or an aqueductoplasty and the decision to convert to an LT fenestration was made intraoperatively. Endoscopic third ventriculostomy was not technically possible in 7 (28%) patients due to abnormal anatomy or thickness of the floor of the third ventricle. We defined abnormal anatomy specifically as: asymmetry of the mammillary bodies, rotation of the floor of the third ventricle creating a difficult working angle to perform the ETV, or difficulty in identifying the correct site for ETV through the floor of the third ventricle. In 12 (48%) patients an ETV was performed but the basal subarachnoid space was not patent or sufficient for adequate CSF flow and there was an absence5


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we thought to have a high likelihood of failure based on previously reported intraoperative

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Chiari malformation in 1 patient, and Down syndrome with basilar invagination in 1 patient. The

of pulsation of the floor of the third ventricle after the ETV. Aqueductal stenosis was observed in 22 (88%) patients due to congenital etiology, secondary to severe ependymal inflammation, or to mass effect (from tumor or cyst) on the quadrigeminal plate or midbrain causing indirect occlusion of the cerebral aqueduct. Aqueductoplasty was attempted in 13 (52%) patients with stenosis secondary to inflammatory processes and failed in all of them; in the other 7 (28%) patients aqueductoplasty was not indicated (congenital aqueductal stenosis, indirect mechanical occlusion). Other endoscopic findings were absence of the septum pellucidum, signs of severe

multiseptated ventricles, and intraventricular tumors that were already diagnosed on imaging. Other endoscopic procedures performed included: tumor biopsy, cysticercal cyst extraction, and cyst fenestration. Intraoperative findings that might indicate a low ETV success rate included: very narrow and limited basal subarachnoid space in 7 patients, severe ependymal thickening causing adhesions between the lateral walls of the third ventricle in 4 patients, basal subarachnoid space occupied by cysticercal cysts in 3 patients and by tumor (clivus) in 1 patient, abnormal anatomy of the third ventricle in 8 patients, thick floor of the third ventricle difficult to perforate in 3 patients, and adhesions in the basal subarachnoid space in 3 patients. A clinically silent small contusion of the fornix at the foramen of Monro was seen in 6 (24%) patients. Follow-up and Outcomes

The mean follow-up period was 63.76 (SD: 31.13) months (range, 6-105 months). Nineteen lamina terminalis fenestrations remained patent from the 25 patients (76%) at last evaluation, based on the absence of clinical and radiological evidence of hydrocephalus. These 19 (76%) patients had resolutions of symptoms, no radiographic evidence of ventriculomegaly, and did not

multiple antiepileptic drugs, and 2 suffered from post operative transient VI nerve palsies (1 patient with clival chordoma and 1 with neurocysticercosis). Six (24%) patients remained with clinical and radiological evidence of hydrocephalus requiring a VP shunt placement within 0.52 months later (mean, 1.5 months) after the LT fenestration. These 6 patients had initial diagnoses of: neurocysticercosis (4), neonatal meningitis, medulloblastoma, and Chiari malformation. Three patients with malignant neoplasms (2 medulloblastomas and 1 anaplastic ependymoma) died 11-40 months after the initial diagnosis; death was not related to the endoscopic procedure.6


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require another surgical procedure (Fig. 3). Three patients continued to have seizures requiring

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ependymal inflammation and ventriculitis, intraventricular and subarachnoid cysticercal cysts,

Nine (36%) patients had a concurrent non-satisfactory ETV and LT fenestration with a successful outcome, whereas 10 (63%) of the remaining 16 patients had a successful rate with LT fenestration alone. Post-op MRI with special sequence (e.g. sagittal T2 weighted, FIESTA/CINE protocol, MR ventriculography) would have added extra information regarding the patency of the LT fenestration; unfortunately they are not part of our follow-up evaluation protocol.

Discussion

hydrocephalus.1, 2, 15-18 The success rate of the standard ETV averages around 80%.1, 2 The other 20% of patients are typically managed with a VP shunt after ETV failure, although some other surgeons will attempt to repeat ETV. Therefore, investigation on new sites for a third

the lateral recess of the floor next to the posterior cerebral artery, perforation of the floor between the basilar artery, superior cerebellar artery and dorsum sellea, and the suprapineal recess.19, 20 Opening of the LT has been frequently investigated; different approaches have been proposed including: subfrontal endoscopic approach10, and microsurgical LT fenestration by a

viable alternative in the treatment of obstructive hydrocephalus when a standard ETV fails or is not possible.

Endoscopic Anatomy and Technique of the Lamina Terminalis Fenestration Knowledge regarding the endoscopic anatomic features and neurovascular relationships of this structure and adjacent anatomy are imperative to achieve safe efficacious outcomes. Endoscopic anatomy of the LT is different from the microsurgical extraventricular approach,8 with which most neurosurgeons are more familiar, and a few key points need to be highlighted. The anterior wall of the third ventricle extends from the optic nerve below to the anterior commissure and foramen of Monro above. The LT is a thin sheet of gray matter covered by pia that attaches to the optic chiasm and the rostrum of the corpus callosum.8 It is one of the thinnest structures of the brain. The LT forms a sharp angle with the wide flattened surface of the chiasm, giving rise7


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pterional approach.8, 9, 21, 22 These prior studies similarly conclude that fenestration of the LT is a

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ventriculostomy may carry significant benefit. Other alternatives include the lamina terminalis,

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Currently, ETV is gaining popularity and has become the mainstay therapy for obstructive

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to the optic recess bordered inferiorly by the upper surface of the chiasm and ending in a bay on both sides (Fig. 2).8 The LT constitutes the widest part of the third ventricle. When viewed from within, the structures of this wall that are visible by a transventricular transforaminal approach with the flexible neuroendoscope are: the optic chiasm, optic recess, LT, anterior commissure, and the most ventral part of the rostrum of the corpus callosum (Figs 1 and 2).4 The LT is intimately related to the complex of the anterior cerebral artery and its branches. In most cases, the anterior communicating artery is situated anterior to the LT, and is the first and most

the A1-Acomm complex and perforators (Fig 2 and Supplemental Videos 1 and 2). Other arterial branches that can be encountered are A1 and A2 segments of the anterior cerebral artery, the recurrent artery of Heubner, and frontoorbital arteries. Injury to the vessels of the anterior communicating artery complex is the most significant complication from this procedure. The highest risk of injury is during the initial opening of the LT and can be minimized by performing this initial perforation with a closed grasping forceps (1 mm-size instrument), looking through the translucent LT and guiding the forceps away from the vessels, usually towards the midline and below the acomm complex.

The endoscopic transventricular transforaminal approach to the LT has been barely mentioned before in the literature.1, 4, 5, 11, 12 Recently, Oertel et al described this approach on 4 clinical cases

with a longer follow-up have not been addressed. In the present work, an adequate opening of the LT was achieved without any intraoperative complications or injury to the neurovascular structures in all 25 patients. Particularly, attention was paid to the fornix, optic chiasm, anterior communicating artery, and the perforating branches from A1. Based on our results, we agree with Oertel et al5 that adequate opening of the LT can be achieved by an endoscopic transventricular transforaminal approach with a flexible endoscope. The LT is a very thin layer that can be easily perforated and enlarged with small instruments, such as the small grasping forceps used in the flexible neuroendoscope. The ideal location for the fenestration is above the suprachiasmatic recess. We found the maneuverable properties of the flexible neuroendoscope tip very useful in achieving a perforation in this precise location.1 One relative contraindication to perform an LT fenestration includes a thickened LT that precludes the surgeons ability to identify the optic chiasm or the presence of an anterior communicating artery aneurysm.8


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and 4 cadavers.5 However, indications, neuroendoscopic findings, and outcome in a larger series

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commonly seen after endoscopic LT fenestration, followed by perforating branches arising from

Neuroendoscopic Findings, and Candidates for a Lamina Terminalis Fenestration This procedure was performed only when ETV or aqueductoplasty were thought to likely be unsuccessful, thus this group of patients suffered from more complex obstructive hydrocephalus that inherently had a higher failure rate. The decision to perform this procedure was always made intraoperatively, taking into consideration previously described risk factors for ETV failure.13, 16

factors included a history of neonatal intraventricular hemorrhage, neonatal meningitis, shunt infection and malfunction, age less than 2 years old, spontaneous subarachnoid hemorrhage, and intraventricular inflammatory processes.16 Our cohort had 5 patients whose age was less than 2 years, 2 had diagnoses of neonatal meningitis, and 9 patients had intraventricular inflammatory processes (neurocysticercosis). These factors can contribute to reclosure of the fenestration site, scarring in the subarachnoid space, and arachnoid granulations that can increase the failure rate which patient is a candidate for an LT fenestration. Souweidane at al16 introduced a grading scale for intraoperative ETV assessment that takes into account several criteria, which independently have been used by other neurosurgeons to rate the likelihood of achieving a successful outcome. of ETV.6, 16 Intraoperative assessment of possible ETV failure is vital in making the decision of

scarred membranes in the basal subarachnoid space, absence of pulsation of the third ventricle floor at ETV completion, closure of previous ETV, and very narrow or non-patent basal subarachnoid space. These intraoperative findings are very similar to ours, and would support an expected high ETV failure rate in our cohort, which may validate our indications for LT

tuberculosis, fungus), LT fenestration may be more successful because the suprachiasmatic cistern is less frequently involved. Extensive scarring and non-patent basal cisterns limit the CSF flow through the ETV. This had been previously described as extraventricular intracisternal obstructive hydrocephalus. However, we believe that LT fenestration may function by allowing CSF egress from the third ventricle into the suprachiasmatic and LT cisterns that are usually patent ultimately communicating with convexity arachnoid granulations and allowing CSF drainage into the venous circulation. Likely in cases with severe diffuse inflammation, true9


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fenestration. In patients with inflammatory pathology of the basal cisterns (neurocysticercosis,

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These intraoperative findings include abnormal anatomy of the third ventricle, thickened or

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These factors are separated into two preoperative and intraoperative categories. Preoperative

communication hydrocephalus, fenestration of the LT is unlikely to provide any additional benefit and is probably why only the 76% of our patients had successful outcomes.

Flexible Neuroendoscopy in Lamina Terminalis Fenestration As discussed by Oertel et al5, the preoperative selection of candidates for opening of the LT via a transventricular route by using rigid endoscope through a posterior bur hole remains appealing. However, since the decision of performing an LT fenestration is made at the same time of the endoscopic procedure based on the intraoperative findings, it is difficult to plan an LT

within the ventricles. Then, maneuverable properties of the tip are very useful in reaching areas of the ventricular system and subarachnoid space without requiring additional entry points other that the standard precoronal burr hole.4, 12-14, 23, 24 It is possible to visualize the anterior wall of the

endoscopes (Fig. 1 and Supplemental Videos 1 and 2). Also, the use of a flexible neuroendoscope avoids the need of a more posterior burr hole that can potentially harm the primary sensory and motor areas. A flexible neuroendoscope could permit the avoidance of any damage to the anterior fornices. In our series, we found a small and clinically silent forniceal contusion in only 6 patients. The value of all these advantages of the flexible neuroendoscope has to be weighed against the lesser quality of images obtained as compared with the rigid endoscopes. We agree that the rigid endoscope has a better quality image; however, in our experience of more than 15 years, the quality of imaging from flexible neuroendoscope has not been a limitation in achieving an adequate fenestration of the LT.1, 4, 12-15 We found the image quality of the flexible neuroendoscope sufficiently good to perform endoscopic intraventricular surgery as seen in Figure 1 and Supplemental Videos 1 and 2. Patients in whom previous endoscopic procedures (ETV and/or aqueductoplasty) and VP shunt have already failed are known to have lower success rates with repeat ETV procedures. The fact that 76% of our cohort had a favorable outcome after LT fenestration suggests that this endoscopic procedure is a good salvage procedure. Although intraoperative findings in 9 patients were suboptimal for ETV success, the concurrent use of ETV in these patients may slightly10


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third ventricle from the optic chiasm up to the rostrum of the corpus callosum using flexible

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fenestration as the first option. The flexible neuroendoscope allows more versatility navigation

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confound our interpretation of results. When excluding these patients, the remaining 10 (66%) of the 16 patients who did not have an ETV still had a successful outcome. However, further series are needed to investigate its use upfront as an initial procedure when standard ETV is likely to fail. Also, it would be interesting to further assess if the criteria associated with ETV failure can be similarly applied to LT fenestration.

Endoscopic transventricular transforaminal lamina terminalis fenestration is a feasible and safe

flexible neuroendoscopy. We present the largest clinical series reporting this procedure with long-term follow up. No intraoperative complications related to the procedure occurred, such as optic chiasm or anterior cerebral artery injury. Endoscopic LT fenestration is a good alternative

possible to perform an ETV. Adequate intraoperative assessment of ETV success is necessary to identify patients that will benefit from this procedure. An overall 76% success rate with good clinical outcomes was seen in our cohort, but 24% of patients still required a VP shunt placement. Endoscopic LT fenestration has a relatively high percentage of success as a salvage procedure for failed ETV and VP shunt malfunction in obstructive hydrocephalus.

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Figure Legends Figure 1. A. Sagittal T2-weighted MRI depicting the midline third ventricle anatomy. B-I. Intraoperative endoscopic images showing step-by-step the lamina terminalis fenestration procedure. B. Once in the third ventricle the infundibular recess (ir) and the optic chiasm (oc) are identified. C-D. The tip of the flexible neuroendoscope is bent forward until the suprachiasmatic recess (sr) and the lamina terminalis (lt) come into sight. E-F. The initial fenestration with a blont instrument is performed slightly above the suprachiasmatic recess (sr), most of the time the complex of the anterior communicating artery (acoma) is visible throught the thined lamina terminalis. G. The fenestration is progressively

After the fenestration has been enlarged the complex of the anterior communicating artery and performators can be seen. Other abbreviations: Anterior cerebral artery (aca), premammillary membrane (pm), basilar artery (ba).

aqueductal stenosis and an abnormal thick floor of the third ventricle in which an standard ETV is not feasible to perform. The image at the bottom left illustrates the flexible neuroendoscope approaching the third ventricle through the foramen of Monro

the lamina terminalis perforation performed above the optic chiasm; notice the relation with perforation with the anterior communicating artery complex. Figure 3. Graph of a Kaplan-Meier successful curve illustrating the overall successful rate after lamina terminalis fenestration in patients with obstructive hydrocephalus. There was an

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initial decline in the successful in the first 8 months. After 8 months there was a steady

successful rate of 76% in the long term follow-up.

C C

and perforating the lamina terminalis. The third image illustrates and endoscopic view of

EP

Figure 2. Artists illustration representing a brain with obstructive hydrocephalus secondary to

TE

enlarged with fogarty balloon or grasping forceps with a blunt dissecting technique. H-I.

D

14


Supplemental Video Legends Supplemental Video 1. Intraoperative endoscopic video of the lamina terminalis fenestration procedure. The video starts with a standard endoscopic third ventriculostomy and exploration of the basal cisterns. Very limited space for adequate CSF flow within the cisterns was noted. Proceeding with the LT fenestration, the tip of the flexible neuroendoscope is bent ventraly. The optic chiasm is identified. Utilizing a closed grasping forceps for the initial fenestration, the lamina terminalis is perforated. The ostomy is slowly enlarged with the neuroendoscope itself. The anterior communicating artery complex is identified. The ostomy is further enlarged if necessary.

Supplemental Video 2. Intraoperative endoscopic video of the lamina terminalis fenestration procedure. The video starts with the neuroendoscope in the third ventricle looking at the tuber cinerum and optic chiasm. After identifying the optic chiasm, the tip of the flexible neuroendoscope is bent anteriorly, the suprachiasmatic recess and the lamina terminalis

is perforated. The ostomy is slowly enlarged with the grasping forceps or with the neuroendoscope itself. The anterior communicating artery complex and its branches are identified. The ostomy is further enlarged if necessary. The free edges of the ostomy

video is to show that the position of the anterior communicating artery may vary, in this case the ostomy was made closer to the artery but still below it.

A

C C

move with the pulsation of the brain indicating CSF flow. The purpose of this second

EP

are identified next. Once in position, with a closed grasping forceps, the lamina terminalis

TE

D

15


Table 1. Summary of patients that underwent endoscopic LT fenestration Patient Age/Sex Diagnosis Signs and Symptoms Increased head circumference H/A, gait ataxia Previous procedure none Endoscopic findings Simultaneous Endoscopic Procedures ETV Required VP shunt No Outcome / Follow-up Asymp, no HCP / 12 months Dead / 11 months VI CN palsy, asymp from HCP / 30 months Asymt, occasional HA / 36 months Asymp / 85 months Asymp, occasional H/A / 60 months Good, transient diplopia / 56 months Good / 12 months

1

5 m/F

Chiari type 2 with HCP Tumor (medullobl astoma) Tumor (clivus chordoma)

Absence of SP, severe congenital AS, very narrow basal subarachnoid space Very narrow basal subarachnoid space, distal AS due to tumor ETV insufficient due to tumor occupying the prepontine cistern with mass effect on the brainstem causing AS

2

10 y/F

none

D

ETV

No

3

27y/F

Diplopia, gait ataxia, VI CN palsy

none

TE

ETV

No

4

33 y/F

NCC

H/A, tinnitus

none

C EP

Ependimitis, cyst attached to the floor of the floor ventricle, severe AS

None

No

5

49y/F

NCC

H/A, N/V

none

Severe ependimitis, AS, basal cisterns occupied by rasemous cyst Severe ependimitis, very thick premammillary membrane, severe AS

7

45y/M

NCC

H/A, diplopia, weight loss

A

C

6

76y/F

NCC

H/A, AMS

none

ETV Cyst extraction Failed ETV

Yes

No

none

Severe AS, reduced basal cisterns space, arachnoid with thick exudates and adhesion

ETV

No

8

7m/F

Neonatal meningitis and

Increase head circumference, strabismus,

none

Severe ependimitis, severe AS, very thick premammillary membrane

None

Yes


9

2y/M

ventriculiti s Tumor (pineoblast oma)

11

2y/F

N/V, diplopia

13

40y/M

NCC

H/A, N/V

2 VP shunts

C EP

12

28y/M

NCC

H/A, diplopia, gait ataxia

ETV Craniotomy for tumor resection VP shunt

Distal AS due to tumor, previous ETV patent, None reduced subarachnoid space due to brain stem displacement Severe ependimitis, multiple intraventricular and subarachnoid cysticercal cysts, abnormal anatomy of the floor of the third ventricle Severe ependymitis with adhesions between walls of the 3rd ventricle making ETV technically difficult Multiple cysticercal cysts in attached to the floor of the third ventricle distorting its anatomy. Ventriculitis with ependymitis, IV ventricle obstructed by tumor. ETV

TE

D

10

20y/F

Down Sd., basilar invaginatio n and HCP Medullobla stoma

tense fontanelle Increase head circumference, strabismus, tense fontanelle H/A, blurry vision

none

Tumor occupying the posterior portion of 3rd ventricle and occluding aqueduct. ETV technically difficult due to distorted anatomy. Tumor biopsy. very narrow basal subarachnoid space, fourth ventricle outlet occluded

None

No

Fair / 6 months

none

ETV

No

Asymp / 12 month

Yes

Dead / 16 months

Yes

None

Yes

Asymp / 105 months Asymp / 88 Asymp / 48 months Death / 40 months

14

42/M

NCC

Dizzines, vertigo H/A, diplopia, VP shunt malfunction

VP shunt

Cyst extraction ETV

No

15

54y/F

16

10 m/M

Suprasellar arachnoid cyst

Increase head circumference, parinaud Sd, VP malfunction

A

Tumor (anaplastic ependymo ma)

C

VP Shunt Craniotomy and partial tumor resection VP Shunt

No

Agenesis of septum pellucidum, abnormal anatomy of the floor of the third ventricle, AS.

Cyst fenestration

No

Good Seizures / 24 months


17

25y/M

Congenital AS and cerebral palsy

Blurry vision, vertigo, VP shunt malfunction

VP shunt

Congenital AS, deformed anatomy of the floor of the third ventricle.

Failed ETV

No

Good Neurologic al baseline. Seizures / 92 months

19

30y/M

H/A, N/V, diplopia,

20

33y/F

NCC

H/A, N/V, VP shunt malfunction H/A, blurry vision ,VP shunt malfunction Blurry vision, vertigo, VP shunt malfunction Seizures, increased head circunference, VP shunt malfunction

C EP

Craniotomy and parcial tumor resection tumor VP shunt

Distal AS by tumor, reduced basal subarachnoid space due to brain stem displacement

TE

D

18

26y/F

Congenital AS and suprasellar arachnoid cyst. Tumor (Medullobl astoma)

H/A, diplopia, VP shunt malfunction

VP shunt

Congenital AS, deformed floor of the third ventricle.

Failed ETV Cyst fenestration

No

Good / 85 months

ETV

No

Good / 12 months

Severe ependimitis, AS, multiple cysticercal cyst blocking the basal cisterns and adherent to neurovascular structures Severe ependimitis with thick floor of the third ventricle, occluded ETV, AS

ETV Cyst extraction ETV

No

21

35 y/F

NCC

VP shunt ETV

No

22

25 y/F

23

2 y/M

HCP secondary to germinal matrx IVH

A

Congenital AS

C

Good Occasional H/A / 36 months Good, mild H/A / 18 months Asymp / 9 months

VP shunt ETV

VP shunt occluded by choroid plexus and cysts, ETV open, AS, very narrow subarachnoid basal cistern Multiloculated HCP, restenosis of CA, trapped 3rd ventricle with disturbed anatomy of the floor, ETV technically difficult

None

No

Aqueductop lasty Cyst fenestration VP shunt

Cyst fenestration Failed ETV

No

Seizures Good / 24 months


24

27 y/F

NCC

25

42y/M

NCC

H/A, blurry vision, VP shunt malfunction H/A, N/V

VP shunt

Ependimitis causing deformity of the floor of the third ventricle and severe AS.

None

No

Asymp / 75 months

ETV 2 VP shunts

Ependimitis, previous ETV closed, severe adhesions in the basal subarachnoid space

ETV

Yes

Asymp / 24 months


A

C

C EP

TE

D


A

C C

EP

TE

D


A

C C

EP

TE

D


A

C C

EP

TE

D

Endoscopy Lamina Terminal Is

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