Direct Cortical Stimulation in Neurosurgical Emergencies: Single-Center Experience in 2 Patients

Intraoperative neuromonitoring (IONM) is widely used for elective resection of eloquently located brain tumors to increase safety and extent of resection. Owing to the need for specially trained personnel for IONM and the sophisticated, time-consuming technical setup, standard IONM is usually not suitable for emergency situations. We report the use of a device that can be operated by the neurosurgeon autonomously for monopolar brain mapping in 2 emergency cases.

Both patients were initially scheduled for elective neurosurgery under IONM. Acute neurological deterioration in both cases led to emergency surgery. For monopolar cortical/subcortical stimulation, a standard monopolar probe was connected to a new device enabling electromyography real-time tracking of 8 muscles. Preoperative application of subdermal electromyography needles and intraoperative handling of the device were performed by the neurosurgeons independently.

Cortical mapping of the motor cortex was performed in both patients with a threshold of 4 mA in case 1 and 14 mA in case 2. Gross total resection with residual tumor volume of <2 mL in case 1 and subtotal resection with residual tumor volume of 4.2 mL in case 2 were achieved under use of the new device without any new neurological deficit. Grade IV glioblastoma was diagnosed in both patients.

We demonstrate the feasibility of monopolar stimulation in 2 patients undergoing emergency neurosurgery using a device autonomously operated by the surgeon. Owing to fast setup and nondemanding handling, monopolar stimulation could be used during emergency neurosurgery to extend resection with preservation of neurological function in both cases.