Usefulness of monitoring brain tissue oxygen pressure during awake craniotomy for tumor resection: a case report.

Awake craniotomy is indicated for surgical resection of tumors located near eloquent areas of the brain. The anesthetic technique is based on a combination of local anesthesia, sedation, and analgesia. Usually only clinical parameters are assessed and no other cerebral oxygenation monitoring techniques are applied. The authors report the use of brain tissue oxygen pressure monitoring during awake craniotomy. A 48-year-old right-handed man with a left temporoparietal mass was scheduled for awake craniotomy, cortical stimulation, and selective tumor removal. Monitoring included electrocardiography, pulse oximetry, end-tidal CO2, bladder temperature, invasive and noninvasive arterial pressure, and brain tissue oxygen pressure (PtiO2). The anesthetic technique consisted of continuous perfusions of 0.02 to 0.05 microg/kg/min remifentanil, propofol (target concentration, 0.5 to 1.2 microg/mL), and 25 to 50 microg/kg/min esmolol, and local anesthetic blockade of the head pin insertion sites and surgical incision area (a mixture of 0.2% ropivacaine, 1% lidocaine, and epinephrine, 1:200 000). Intraoperative cortical stimulation was performed to guide the resection according to the patient's verbal response. A change in PtiO2 was observed, gradually falling from 28 mm Hg at the beginning of the intervention down to 3 mm Hg. At this stage, surgical resection was concluded. On arrival at the intensive care unit, mixed dysphasia and slight weakness of the right arm were noted. Three weeks after surgery, the patient's speech is improving and the motor deficit has disappeared. This case suggests a possible role of PtiO2 in awake craniotomy as an aid in detecting intraoperative adverse events, but further experience with PtiO2 in this setting is needed.