A case series of 5“awake” craniotomies with intraoperative electrocortical mapping

Introduction: “Awake” craniotomy is standard for resection of intracranial tumourslocated near the eloquent areas of the cortex however functional mapping and stimulation in an awake patient is recent. Case Summary: We report a case series of 5 patients that underwent an “awake” craniotomy for resection of tumours in eloquent areas of the cortex. All patients were clinically evaluated, airway assessed, counselled, a rapport developed andoptimised preoperatively. Functional MRI was done with activation mapped for finger, lip andtongue movement, word generation and counting paradigms. In the operation theatre, pre- oxygenation via nasal cannula was commenced and SpO2, EtCO2, NIBP, EKG, BIS monitoring initiated. A scalp block was given to all patients with 1% lignocaine and 0.25% bupivacaine. Conscious sedation with a titrated dose of dexmetetomidine (0.2-1 µg/kg/hour) provided reversible sedation, mild analgesia, controlled hemodynamics (target SBP <140 mm Hg), a patent airway and spontaneous ventilation. After craniotomy, electro cortical mapping and stimulation was performed to map the eloquent areas, correlating these findings with preoperative fMRI. Functional electrographic mapping and stimulation testing was performed during resection of tumour, to reconfirm the location and check for any new neurological deficit development. Intraoperative seizures, if any, due to electrocortical stimulation, were treated with irrigation with cold saline, titrated doses of intravenous midazolam. All hemodynamic parameters, sedation levels (RASS), intraoperative complications, as well postoperative development of new neurological deficits were noted. All patients cooperated, tolerated and participated for this procedure. Intraoperative and postoperative neurological deficits were noted in none. Conclusion: An effective scalp block, combined with dexmetetomidine conscious sedation is a safe and effective technique for awake craniotomy for functional testing with electrocorticography. An anticipation and appreciation of likely intraoperative events and interventions required is key. Interdisciplinary team work and collaboration between neurologist, neurosurgeon, neuroradiologist and the neuroanesthesiologist is mandatory for successful outcomes.