What is the recommended anesthesia regimen for an awake craniotomy?

Anesthesia Regimen for Awake Craniotomy

The recommended anesthesia regimen for awake craniotomy consists of conscious sedation using propofol and remifentanil (or dexmedetomidine as an alternative), combined with scalp nerve blocks using local anesthetics, following an asleep-awake-asleep or monitored anesthesia care approach. 1, 2, 3

Core Anesthetic Agents

Primary Sedation Options

• Propofol with remifentanil is the most commonly used combination, providing reliable conditions for intraoperative brain mapping while allowing rapid titration for neurological testing 1, 3, 4
• Dexmedetomidine (with or without remifentanil) offers an alternative that provides sufficient analgesia and amnesia without interfering with electrophysiologic monitoring 5, 2
• Propofol-based regimens demonstrate significantly lower incidence of intraoperative seizures compared to dexmedetomidine (P = 0.03) 2

Local Anesthesia

• Scalp nerve blocks are mandatory using a mixture of bupivacaine and lidocaine with epinephrine for all patients 1
• Maximum lidocaine dose must not exceed 9 mg/kg lean body weight from all sources combined 6, 7
• Topical lidocaine should be calculated based on lean body weight, not actual body weight, to prevent systemic toxicity 6

Anesthetic Technique Selection

Asleep-Awake-Asleep (Most Common)

• Induce anesthesia with propofol and remifentanil infusions 4
• Use laryngeal mask airway (LMA) during craniotomy phase 4
• Wake patient for cortical mapping and tumor resection 4
• Consider re-sedation during closure if needed 1

Monitored Anesthesia Care

• Maintain conscious sedation throughout with ability to rapidly decrease sedation level for neurological testing 1, 3
• Titrate sedatives to facilitate intermittent intraoperative neurological assessment 1

Essential Monitoring

• Bispectral index (BIS) monitoring significantly decreases anesthetic use (P<0.001) and shows a trend toward reduced complications including respiratory depression and deep sedation 1
• Standard ASA monitors including continuous capnography, ECG, non-invasive blood pressure, and pulse oximetry are required 6
• Arterial line placement should be considered for beat-to-beat blood pressure monitoring 1

Adjunctive Medications

• Haloperidol and ondansetron should be administered at induction to all patients for antiemetic prophylaxis 1
• Anticonvulsants as premedication may be considered, though evidence for routine use is limited 6

Common Complications and Management

Intraoperative Issues (in order of frequency)

• Hypertension (16-19%): Most common complication requiring active management 1, 2
• Focal seizures (9-28%): More common with dexmedetomidine than propofol 1, 2, 4
• Tight brain (7-14%): May require conversion to general anesthesia 1, 2
• Respiratory depression and desaturation (2-7%): Monitor closely and have airway equipment immediately available 1, 2, 4

Postoperative Complications

• Postoperative nausea and vomiting (19-20%): Despite prophylaxis 1, 2
• Seizures (10-17%): Require immediate treatment 1, 4
• New neurological deficits (20-24%): Often transient 1, 2

Critical Safety Considerations

• Patient selection is paramount: Patients must be cooperative and able to tolerate the awake phase 3
• Conversion to general anesthesia occurs in approximately 2-7% of cases due to complications such as tight brain, airway issues, or hemorrhage 2, 4
• Have emergency airway equipment immediately available, including endotracheal tubes and LMAs for urgent airway control 1
• Avoid excessive sedation during the awake phase as this is the primary cause of respiratory complications 1, 2

Airway Management Contingencies

• One patient in 42 may require endotracheal intubation during closure 1
• LMA placement may be needed for airway control in select cases 1
• CPAP may be required perioperatively for patients experiencing significant desaturation 1