Craniotomy for excision of tumor with motor mapping

General: Patients may be symptomatic or asymptomatic. Symptoms may be due to location of tumor or due to increased ICP. You should know the location, kind (if known) and size of the tumor(s), any preop neurological deficits and symptoms and if the patient is at risk for increased ICP. Patients are often taking dilantin, tegretol or keppra and/or steroids.
Preop: Start an IV on ipsilateral hand to the tumor. Premedicate with up to 2 mg of midazolam. None if altered mental status (prevent further increase in ICP).
Monitors: Arterial (ipsilateral to tumor) catheter inserted after induction of anesthesia.
Anesthesia: Goals are to decrease ICP (if high), to maintain adequate CPP (at least 70 mmHg) to prevent cerebral ischemia from brain retraction, and to allow intraoperative cortical motor mapping. Patients typically receive 1-2 g of Cefazolin, and 4 mg of decadron before skin incision, and sometimes up to 1 g/kg of mannitol on skin incision (verify all with surgeon). Keep the room warm and patient covered as the goal is to have the esophageal temperature above 36 C° during motor mapping. Induction with propofol. In case of increased ICP, have patient hyperventilate during preoxygenation and continue hyperventilation with mask as soon as possible after induction of anesthesia. Fentanyl 5 μg/kg in divided doses throughout induction, prior to intubation. Verify adequate neuromuscular blockade prior to intubation to avoid coughing/straining. Tape eyes, insert esophageal temperature probe, and at least one additional large bore IV (don’t use the contralateral hand/arm). Maintain neuromuscular relaxation (rocuronium or vecuronium) untill skin incision. Then let it wear off for motor mapping. Don’t reverse. Patient position will depend on location of tumor. Maintain anesthesia with 70% nitrous oxide in oxygen, low dose inhalation agent (less than 0.5 MAC), and a fentanyl infusion 2 μg/kg/hr. Maintain euvolemia (Lactated Ringer’s). Use mild hyperventilation (PaCO2 35 mmHg). Once the bone flap is removed, have the surgeon assess the tightness of the dura. Decrease ICP further if necessary (pCO2, mannitol, propofol, head up etc.). Once the dura is open, the goal is to avoid “brain shift” so that stereotactic navigation system can be used optimally. During motor mapping, have the arm, leg and face uncovered to observe for movement. In case of poststimulation continuation of motor activity, surgeon will try to stop it by applying cold saline on the cortex. Have propofol (10 mg/ml) in line in case of intraoperative seizures (1 mg/kg for seizure suppression). May use neuromuscular relaxants after the last motor mapping. Fentanyl infusion is usually stopped at the beginning of closure. At this point, use of inhalation agent may be replaced with a propofol infusion (50-100 μg/kg/min). Normalize pCO2 to facilitate spontaneous breathing at the end of the operation. Use of inhalation agents (or propofol) is usually stopped about 10-15 min before end of surgery, and nitrous oxide at the end of surgery. Reverse residual neuromuscular blockade once the Mayfield pins have been removed. Consider prophylactic use of labetalol to attenuate emergence hypertension.
Potential complications: Intra- and postoperative seizures. Delayed awakening from anesthetics and/or intracranial pathology. Postoperative intracranial bleeding.
Recovery: Wake patient up and extubate immediately after the operation to allow neurologic examination. Coughing and bucking on the endotracheal tube must be minimized. Use a hemodynamic monitor and supplemental oxygen during patient transport to ICU. Prevent postoperative hypertension to avoid intracranial bleeding (labetalol).

Last revised 05/2013 Talke