Anesthetic Considerations for Awake Craniotomy for Epilepsy ... - Vtr

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248 Erickson & Cole Box 2 Considerations for preoperative anesthetic evaluation of the patient for awake craniotomy for epilepsy or for awake DBS implantation Patient cooperation Age/maturity Anxiety/claustrophobia/emotional stability Psychiatric disorders Airway Intubation history Airway patency (obesity, obstructive sleep apnea, asthma or other pulmonary disease) Airway examination (ease of ability to mask ventilate, to insert laryngeal mask airway [LMA], to intubate) Gastroesophageal reflux Disease state Epilepsy Form Frequency Treatment (medications taken) Movement disorder Type of symptoms Severity in off-medication state Treatment (medications taken) Intracranial pressure Nausea and vomiting Hemodynamic stability Adapted from Bonhomme V, Born JD, Hans P. Prise en charge anesthesique des craniotomies en état vigile. Ann Fr Anesth Reanim 2004;23:391; with permission. for intracranial pressure control because brain relaxation by hyperventilation is not attainable in sedated, spontaneously breathing patients. As with any type of anesthetic, anticipation of specific difficulties is a mainstay of care in the awake craniotomy. Type and frequency of seizures, medication regimen, and serum levels, if applicable, may limit candidacy. Other factors, including size of tumor (if present), hemorrhagic risk, and hemodynamic stability, are considered in conjunction with the surgeon. PATIENT PREPARATION Epilepsy Surgery The procedure is discussed between the patient and the neurosurgeon; although awake brain surgery initially sounds frightening to a patient, once its purpose is carefully explained and reassurance given, the response is usually one of acceptance. 48,114,117,118 After initial preparation, the surgeon, neurologists,
neurophysiologists, and speech pathologists review specific language testing (naming, reading, repeating, and responding) or motor testing (facial and extremity movement) that is done in the operating room. In some centers, a test run of patient positioning and language testing in the operating room is done the day before surgery. 119 Deep Brain Stimulator Implantation As for awake craniotomy for epilepsy, detailed descriptions of the rationale and of the procedure reassure and motivate patients. A multidisciplinary team reviews and optimizes current treatment and ensures that patients are well informed and have appropriate expectations. Some patients must be in an off-medication state. Similar to awake craniotomy, pediatric patients have also tolerated DBS well with good preparation. 120–123 POSITIONING Positioning of awake patients is paramount. The anatomy of interest to all involved— anesthesiologist, surgeon, neurologist, and neurophysiologist—is the patient’s head. Access to the surgical field, airway, speech, sight, and facial expression must all be made possible without causing the patient to feel smothered. The patient must remain in rigid pinion fixation or, at minimum, lie motionless on an operating table for several hours. If pinion or epidural skull clamp fixation is not used (necessary for stereotactic techniques), the patient’s head may rest in a donut-shaped gel pad or other conformed pillow but must nonetheless remain immobile for several hours. 124 Both the supine and lateral positions are described for epilepsy surgery without report of difficulty. When the supine position is used for seizure focus resection, the head is turned to expose the temporal lobe and to allow gravity to aid frontal lobe retraction (Fig. 4). A supine or semisitting position is used for DBS implantation (see Fig. 3). A soft mattress, padding of the extremities, and avoidance of extreme head rotation allow the patient to remain still and provide protection from injuries of stretch and pressure. A wide-open geometry of surgical drapes helps to minimize claustrophobia, whereas sufficient blanket coverage and a forced air-warming blanket maintain modesty and body temperature (see Figs. 2 and 3). This arrangement also allows eye contact with the patient and provides a clear view for the patient to name objects or pictures. If motor testing is done, a view of the patient’s arm and hand as well as face is important (see Figs. 2 and 3). In some centers, a microphone is placed near the patient’s head or a video camera records the patient’s face for viewing by the surgical team. 125,126 ANESTHETIC MONITORING Epilepsy and Functional Neurosurgery 249 Little more than routine monitoring is necessary for either epilepsy surgery or DBS implantation. At the authors’ institution, invasive measures are usually not used because neither laboratory assessment nor beat-to-beat blood pressure monitoring is usually indicated intraoperatively, although at some centers these are reportedly used routinely. Type and size of venous access can be directed by the expectations of blood loss and need for administration of hypertonic solutions (eg, hypertonic saline or mannitol). Medical comorbidities should guide this determination. Exhaled carbon dioxide monitoring is essential to both airway vigilance and prevention of cerebral edema/increased brain volume. Precordial Doppler is placed to monitor for venous air embolism in sitting or semisitting patients. A urinary catheter, if used, may be placed under sedation and prevents discomfort due to bladder distention (although the urinary catheter may cause a sense of urgency in some patients).
Page 1 and 2: Anesthetic Considerations for Awake
Page 3 and 4: Table 1 Indications and target area
Page 5 and 6: Epilepsy and Functional Neurosurger
Page 7: PATIENT SELECTION AND PREOPERATIVE
Page 15 and 16: Dexmedetomidine infusion without lo
Page 17 and 18: for DBS insertion, however, venous

Anesthetic Considerations for Awake Craniotomy for Epilepsy ... - Vtr

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