Awake Craniotomy -Monchai

Review Article

AwakeCraniotomy

IntroductionAnesthetic care of neurological patients increasingly involves management issues not only to “asleep patients” ,but also to “awake and waking-up patients”

IntroductionThe challenge for the anesthetist is to provide

1.adequate analgesia and sedation

2.a safe airway3.awake patient4.cooperate patient for

neurological testing

Why awake craniotomy?•1.Intraoperative functional cortical mapping–epileptogenic lesion ,tomor,AVM

–steriotactic surgery–importance of alert,cooperative patient

Why awake craniotomy?

•2.Intraoperative electrocorticography–epileptogenic lesion–importance of avoidance of confounding drugs

Preoperative Evaluation

The preoperative visit represent the most important factor contributing to a successful perioperative period

Preoperative Evaluation

•Patient selection–chronic refractory epilepsy –candidate for GA–uncomplicated airway

Preoperative Evaluation•Patient assessment

–anxiety–psychological profile–seizure pattern( preictal ,ictal and post-ictal,including behavioural concerns)

Preoperative Preparation

•Detailed verbal description of procidure–noise ,sensation and environment

–PCA ,neurological testing


•Videotape session–conduct of anesthetic–conduct of the surgery


•Premedication–anticonvulsant–sedative drugs

Intraoperative Management

Intraoperative Management

•Positioning–temporal lobe surgery:lateral position

–patient comfort and safety

Patient Comfort

•Extra thick mattress•warming blanket or warm room

•padded horse-shoe•rigid back support

Patient Comfort

•Pillow between legs•no urinary catheter•a hand to hold•eye to eye contact

Intraoperative Monitoring

•NIBP•EKG•Pulse oximetry•Endtidal CO2

Intraoperative Monitoring

•Additional monitoring added as appropriate for the patient –arterial or central venous monitoring depending on cardiovascular status

Intraoperative Conduct

The Asleep-Awake-Asleep technique


•Oxygen supplement:via nasal canular with capnography sampling

•Sedation and Analgesia•Antiemesis•Antiepileptic


•Sedation and Analgesia–administration of sedative is usually begun following placement of monitors and positioning of the patient


•Sedation and Analgesia–neuroleptic analgesia:droperidol and fentanyl

–propofol sedation


•During the early intraoperative period,light sedation is the goal

•If local anesthetic blockade of the scalp and dura mater is adaquate,the procedure is comfortable during the period


•Sedation and Analgesia–the objective is to ensure a cooperative patient when cortical mapping is performed and to minimized sedation prior to ECoG recording


•To avoid anxiety,patient should be forewarned of these activities–lound noise levels when burr holes are drilled

–stimulation during ECoG recording


•Pain is related to traction and distortion of dura and blood vessles

•This discomfort can be allevaited with injection of local anesthetic into the dura or deeper level of sedation


•The surgeon must exercise patient and use of gentle technique, and inform ithe patient regularly of the progress of the operation


•The anesthesiologist must attend to the patient–to ensure the patient–to provide supplemental analgesia

–to manage nausia, emesis and convulsion if they occur

Postoperative Care

•Monitoring for evidence of neurologic deterioration

•The early postoperative period may be complicated by cerebral edema,intracranial hemorrhage and seizure

Postoperative Care

•Neurological assessment include–the level of consciousness–language–orientation and motor function

Regional Scalp Block

•Greater Occipital Nerve :2-4 cm lat. To inion,just below sup.nuchal line

•Lesser Occipital Nerve ($Gr. Auricular n.):1.5 cm posterior to ear at the level of tragus over 2cm

Regional Scalp Block

•Auriculotemporal Nerve : 1 cm anterior to tragus above zygoma, direct posteriorly then anteriorly

•Supraorbital Nerve ($Supratrochlear n.):palpation of supraorbital notch,1 cm fan

•Up to 20 ml 0.5%bupivacaine with 1:200000 adr for regional scalp block 1-2 hrs pre-op

Field Block

•Up to 60 ml 0.33% bupivacaine with 1:200,000 adrenaline–along incision line–into deep portion of temporalis from supraorbital ridge to posterior margin of zygoma

Field Block

•Dural leaflets:lidocaine 1% plain via insulin syringe

Laryngeal Mask Airway in anesthesia for awake

craniotomy•A. Sarang and J. Dismore (British Journal of Anesthesia,2003.90,163-165)

•There were 99 procedures carried out between 1989 and 2002

Laryngeal Mask Airway in anesthesia for awake

craniotomy•Patient in Gr 1were sedated throuhout

the procedure•Patient in Gr 2 were anesthetized with

a propofol infusion and fentanyl,and breathed spontaneeously through LMA

•Patient in Gr 3 had total iv. Anesthesia with propofol and remifentanil and ventilation was controlled using LMA

Non -invasive positive pressure ventilation in anesthesia for awake

craniotomy•F.Yamamoto, R. Kato,J Sato and T. Nishino( British Journal of Anesthesia 2003;90:381-385)

•Reported 2 casses of anesthesia for awake craniotomy using non-invasive pressure ventilation

•This technique provided adequate lung ventilation,smooth transition between anesthesia and arousal

Endotracheal Intubation in anesthesia for awake

craniotomy•Kate Huncke et al: Neurosurgery 1998•This technique, induce general anesthesia with endotracheal intubation and then to awaken and extubate the patient for speech mapping

•After the latter, endotracheal reintubation and general anesthesia were planed

Endotracheal intubation in anesthesia for awake

craniotomy•Topically anesthetized the airway with lidocaine that was delivered through a spraying catheter

•Use fiberoptic endotracheal intubation

Selection and Use of Drugs

•Appropriate dosing and careful titration to the patient’s need

•The success of any sedative technique is based on the effectiveness of local anesthetic blockade


•Propofol•Opioids•Droperidol•Dexmeditomidine


•Propofol•Drug of choice:titratable,anxiolytic,antiemitic

•Administration in repeated small boluses or a continuous infusion

•Dose-dependent changes in the EEG

Porpofol

•Many reports suggest that propofol has potent anticonvulsant effects and may depress epileptiform activity

•Because of the short duration of action,propofol administration could be suspended in advance in ECoG recording

Sedation and Use of Drugs

•Opioids•The rapid onset ,short-acting potent synthetic opioids: fentanyl ,sufentanil and alfentanyl–Can all be given by either bolus or infusion

–Comparative study show no difference(Can J. Anesth/40:5)


•Droperidol–Sedative and antiemetic–Long duration of action(onset 6 to 8 minutes duration 6 to 12 hours)

–Side effects:adrenergic blockade, extrapyramidal symptoms,and anticholinergic effects

Sedative and Use of Drugs

•Dexmedetomidine:infusion for awake craniotomy–A higly specific alpha2-agonist–Sadative and analgesia– It does not suppress ventilation–Small dose infusion provided sedation that could be easily reversed with verbal stimuli(Anesth Analg;92(5).May2001.1251-1253)

Patient-Controlled Intraoperative Sedation

•PCS is safe ,effective and associated with a high degree of patient satisfaction

•Technique use PCS propofol combined with a basal propofol infusion

•Supplemental by fentanyl•(Anesth Analg.1997;84:11285-91)

Intraoperative Problems

•Potential intraoperative problems are as follows–Inadequate analgesia–Excessive sedation–Airway obstruction–Restless,uncooperate patient

Intraoperative Problems

•Potential intraoperative problems are as follows–Nausia and vomitting–Excessive blood loss–“Tight” brain–Seizure

Nausia and Vomitting

•Incidence of nausia and vomitting range from 8% to 50%

•Antiemitics:including droperidol (15-50mcg/kg) dimenhydrinate (0.5-1.0mg/kg) and propofol(10-20mg)

Awake Craniotomy -Monchai

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