During the surgery, the neurosurgeon performs cortical mapping to identify vital areas, called the "eloquent brain", that should not be disturbed while removing the tumor.
[1][2][3][4] It can also be used for epilepsy surgery to remove a larger amount of the section of tissue causing the seizures without damaging function, for deep brain stimulation placement, or for pallidotomy.
[5] The procedure for deep brain stimulation placement is similar, though instead of skull being removed, a burr hole is drilled for the electrodes instead and the MAC surgery is more common.
[4] Awake surgery in gliomas is known to cause postoperative language and other cognitive impairments, however the frequency and severity is not well established due to e.g. differences in patient selection, test methods and how deficits are defined.
[5] Additionally, patients with obstructive sleep apnea are usually considered poor candidates due to problems with oxygenation, ventilation, and a potentially difficult airway.