Neurophysiological mechanisms underlying motor evoked potentials in anesthetized humans.

Motor Evoked Potential Monitoring with Supratentorial Surgery

“…This is in contrast to recent convincing evidence that with spinal surgery, transcranially evoked myogenic MEPs yield an all-or-nothing characteristic, with only complete MEP loss indicating impending new paresis (11,22).…”

Intraoperative monitoring during decompression of the spinal cord and spinal nerves using transcranial motor-evoked potentials: The law of twenty percent

“…The other method involves high voltage (several hundred volts) transcranial stimulation using screw electrodes that have been placed in the scalp [11,[14][15][16]. Transcranial stimulation of the motor area with recording of the peripheral electromyogram (EMG) is the most popular method of MEP monitoring during spinal surgery and it has also been shown to be very sensitive [17][18][19].…”

Neurophysiological Changes in Deformity Correction of Adolescent Idiopathic Scoliosis With Intraoperative Skull-Femoral Traction

“…The amplitude of the MEP response is a refl ection of the contribution of motor units, which in turn are depolarized by axons within the spinal cord. [18][19][20][21] These MEP responses are measured as voltage fl uctuates and represent the signal amplitude. Any injury of the spinal cord, whether through mechanical insult or ischemia, will result in a decrease of motor unit depolarization, and a reduction of the amplitude.…”