Craniotomy for extracranial-intracranial revascularization

Craniotomy for extracranial-intracranial revascularization

File:EC-IC Bypass .jpg
Anesthesia type	General
Airway	ETT
Lines and access	PIV x 2 Art line CVC
Monitors	Standard ASA 5-lead EKG Core temp UOP ABG CVP EEG
Primary anesthetic considerations
Preoperative	Characterize neurologic deficits Consider anxiolytic
Intraoperative	Smooth induction Maintain CPP Maximize flow to ischemic areas Decrease CMRO2 Decrease intracranial volume
Postoperative	Careful control of BP PONV prophylaxis
Article quality
Editor rating	Comprehensive
User likes	2

Extracranial-intracranial (EC-IC) revascularization (also referred to as EC-IC bypass) is a surgical procedure to increase cerebral blood flow. The procedure involves connecting a branch of the external carotid artery (typically the superficial temporal artery) to a branch of the internal carotid artery (typically the middle cerebral artery). The anastomosis can be achieved via a vein graft or a direct connection.

EC-IC bypass is generally indicated for severe stenosis or occlusion of intracranial arteries that is resulting in focal neurological symptoms. In children, this procedure is used to treat Moya-moya disease.

Preoperative management

Patient evaluation

System	Considerations
Neurologic	Patients typically presenting with focal neurologic symptoms. Pre-existing deficits should be well characterized and documented.
Cardiovascular	Hypertension is a common adaptive response to maintain CPP. A normal BP may be undesirable in the setting of severe cerebrovascular disease. Patients may have generalized vascular disease, including CAD.
Hematologic	Patients often on aspirin through day of surgery Anticoagulants impacting PT/PTT typically discontinued 1 week prior to surgery

Labs and studies

• EKG
• Echo (if concern for cardiovascular disease)
• Coronary angiography (depending on cardiac risk factors)
• Complete blood count
• Chemistry panel
• Coagulation panel
• Cerebral angiography performed to identify cause of neurologic symptoms

Operating room setup

• Infusion pumps
• Surface cooling device (i.e. cold-water circulating blanket)
• Warming device
  • Patient will need aggressive rewarming post-anastomosis
  • Consider bladder irrigation, warm-water circulating blanket, forced warm air blanket
• Consider central heat exchanger, especially if patient has high surface-to-volume ratio

Patient preparation and premedication

• Consider pre-op acetaminophen 1000mg PO
• Consider pre-op aprepitant if patient has history of severe PONV
• Consider small dose of anxiolytic
• Detailed discussion with patient regarding anesthetic plan

Regional and neuraxial techniques

• Avoid scalp blocks, as they may interfere with donor vessel blood flow

Intraoperative management

Monitoring and access

• Standard ASA monitors
• 5-Lead EKG
• Core temperature
• Urine output
• Arterial blood pressure
• Central venous pressure
• EEG

Induction and airway management

• Smooth induction is essential
• Goal is to maintain CPP
• Have vasopressors ready to maintain CPP during induction
• Use narcotic to blunt response to laryngoscopy
• Muscle relaxant used to facilitate tracheal intubation

Positioning

• Supine
• Table typicaly turned 180
• Mayfield skull fixation
• Shoulder roll
• Have all lines directed towards patient's feet, where anesthesiologist typically positioned

Maintenance and surgical considerations

• Remifentanil (2-4mcg/kg) to minimize BP elevations during pinning
• Maintenance of anesthesia can be achieved with combination of remifentanil, propofol, and/or volatile agent
• Keep PaCO2 around 40 mmHg
  • Hypocarbia may cause unwanted cerebral vasoconstriction in these patients
• Goal net zero fluid balance / Maintain normovolemia
• Dexamethasone may be used to decrease PONV
  • Avoid scopolamine for PONV, as it may confound post-op neurologic exams
• Mild hypothermia (33-34°C) can be used to decrease CMRO2 and increase the brain's tolerance to ischemia
• Confirm pre-incision antibiotics
• Avoid long-acting opioids
• Phenylephrine infusion typically used to maintain CPP during procedure
  • Phenylephrine typically preferred because it is not arrhythmogenic
• Continuous neuromuscular blockade typically not needed
• Establish burst suppression (i.e. propofol 1mg/kg) immediately prior to cross clamping of cerebral artery for anastomosis
  • A bolus dose of phenylephrine and/or ephedrine typically needed to counterbalance hypotensive effect of propofol.
• Aggressive rewarming should start as soon as revascularization is complete

Emergence

• As anesthetic is titrated down, patient's BP will generally increase
• Beta-blockers (esmolol, labetalol) and vasodilators (clevideipine, SNP) may be needed to maintain tight BP control during emergence
• Close regulation of blood pressure is essential
• Reverse any residual neuromuscular blockade
• Prophylactic antiemetics should be given before extubation
• Consider IV acetaminophen
• If patient begins to buck or cough on ETT, extubate or suppress cough reflex (IV lidocaine)
• Achieve appropriate core body temperature prior to extubation

Postoperative management

Disposition

• ICU (typically monitored overnight in ICU)
• Supplemental O2
• Head of bed at 20-30°
• Tight BP monitoring and management post-op (typically maintain at baseline levels)
• Regular neuro checks post-op

Pain management

• Multimodal pain management
• Consider post-op acetaminophen
• Avoid scalp blocks, as they can interfere with donor vessel blood flow

Potential complications

• Seizures
• Stroke
• Hemorrhage at anastomosis
• Brain swelling can be caused by hyperemia in revascularized areas