The problems of transcranial MEP are low sensitivity in cranial surgery, low specificity in spinal cord surgery, and anesthetic fade. The usefulness of compound muscle action potential (CMAP) after peripheral nerve stimulation normalization for these was examined. Sensitivity and specificity were calculated by ROC analysis in 524 muscles of in 238 craniotomy cases and 1536 muscles of spinal cord surgery in 423 cases without preoperative paralysis. The ratio of amplitude relative values and amplitude relative values of less than 1 before and after the operation time when anesthetic fade began was compared with the presence or absence of CMAP normalization in 505 muscles of 215 craniotomy and 1598 muscles of 416 spinal cord surgery without change in motor nerve symptoms before and after surgery. The sensitivity of craniotomy was 84.0% without CMAP normalization and 95.2% with normalization. The specificity of spinal surgery was 95.2% without normalization and 96.9% with normalization. Anesthetic fade was observed in surgery of 160 minutes for craniotomy and 270 minutes or more for spinal surgery, all of which were corrected by CMAP normalization. Conclusions: In transcranial MEP, CMAP after peripheral nerve stimulation normalization is useful in increasing sensitivity in craniotomy, increasing specificity in spinal surgery, and avoiding anesthetic fade.

Patients with acute stroke sometimes develop epileptic seizures, which are recently called acute symptomatic seizures (ASS). ASS is quite important in two ways as follows. First, it could pathologically affect the brain condition after stroke, thereby worsening the functional outcome; second, ASS itself could be a risk for post-stroke epilepsy. Status epilepticus (SE) including nonconvulsive status epilepticus (NCSE) can be associated with clinical deterioration after acute stroke. Especially, although being easily overlooked, NCSE is not a rare complication in acute stroke. Prolonged SE including NCSE has also recently been reported to be a risk for development of epilepsy. Because poorly controlled SE can cause secondary brain damage, the importance of controlling this condition to improve the outcome of patients with neurological diseases, including stroke, is a focus of attention in the field of neurointensive care. Various observational studies have identified acute symptomatic seizures as a high-risk factor for developing epilepsy after stroke. Recently, high accuracy in prediction of developing epilepsy was reported in the SeLECT score for cerebral infarction and the CAVE score for cerebral hemorrhage. Early intervention to suppress epileptogenesis would be crucial to reduce the incidence of post-stroke epilepsy in high-risk patients identified based on these scores.