EEG Monitoring to Assess Emergence From Neuroanesthesia

A highly desired result in neuroanesthesia is a prompt, controlled emergence following a neurosurgical procedure. Considerable strides have been made in this direction with volatile anesthetic agents such as sevoflurane or desflurane administered in association with the narcotic remifentanil. It is characteristic that patients will emerge within 5 to 10 minutes of cessation of these agents at the end of a neuroanesthetic. However, there are cases where emergence is delayed, especially after periods of deep anesthesia for i) cerebral protection with temporary clipping of cerebral aneurysms and ii) with microvascular decompression for trigeminal neuralgia. Deep levels of anesthesia are standard for these procedures in the posterior fossa, which utilize motor evoked potentials to assess cranial nerve function. In these cases, EEG monitoring is standard. Using the EEG to monitor emergence to aid its progress makes sense. A monitor which could predict emergence in these patients would be valuable. EEG monitoring engineered to provide this information is now available in the form of the EEGo. This study is designed to test the hypothesis that the EEGo monitor will be superior to the BIS monitor to assess emergence following neuroanesthesia.