Avtor/Urednik		Kržan, Matevž J
Naslov		Intraoperative neurophysiological mapping of the spinal cord's dorsal columns
Tip		članek
Vir		In: Deletis V, Shils JL, editors. Neurophysiology in neurosurgery: a modern intraoperative approach. Amsterdam: Academic press,
Leto izdaje		2002
Obseg		str. 153-65
Jezik		eng
Abstrakt		Intramedullary lesions distort the anatomical features of the spinal cord dorsum, making it difficult for the surgeon to perform a myelotomy precisely at the midline. Myelotomies not perfotrned at the midline may damage the dorsal columns. To help establish neurophysiological landmarks on the dorsal cord surface to compensate for distorted anatomy and provide reliable guidance, a highly selective miniature mapping multielectrode was placed on the exposed dorsal cord surface in patients undergoing resection of intramedullary lesions. This miniature electrode records somatosensory evoked potentials (SEPs) after tibial and median nerve stimulation. The electrode consists of eight parallel wires spaced 1 mm apart, each having a diameter of 76 microm and an exposed recording surface of 2 mm. After each of the tibial nerves at the ankles was electrically stimulated, SEPs were recorded with the miniature electrode separately from each of the eight parallel recording sites with a reference needle electrode placed in nearby muscle. Recordings were obtained in 55 patients and revealed an amplitude gradient across the eight recording sites with maximum amplitude toward the midline and decreasing amplitude toward the dorsal root entry zone. SEPs consisted of multispike activity lasting about 10 ms with mean amplitudes ranging from 0.7 to 43 microV. SEPs recorded over the cervical spinal cord after median nerve stimulation showed an amplitude gradient as well, but in the opposite direction of the tibial nerve SEPs. For median nerve SEPs, the site with the highest amplitude was always lateral to the site with the highest amplitude of SEPs after tibial nerve stimulation. The two recording sites with highest-amplitude SEPs after stimulation of either left or right tibial nerve identified the neurophysiological midline between the dorsal columns. In the patients in whom the anatomy had not been distorted, the neurophysiological midline corresponded with the anatomical one.
Deskriptorji		INTRAOPERATIVE PERIOD EVOKED POTENTIALS, SOMATOSENSORY SPINAL CORD INJURIES ELECTRODES