title: Changes of motor evoked potentials in global and focal ischemic models of cats.
abstract: In order to evaluate the significance of motor evoked potentials (MEPs) in central nervous system monitoring, the authors conducted two sets of experiments using feline ischemic models. Twenty-three adult mongrel cats were divided into two groups: global (n = 9) and focal ischemic (n = 14) groups. In the case of global ischemia, which was induced by hypovolemic hypotension due to blood letting, deterioration of the D wave began when the mean arterial blood pressure (MABP) approached 45 mmHg, and regional cerebral blood flow (rCBF) dropped to 40% of control. Complete disappearance of the D wave was observed below 30 mmHg in MABP and 20% of control in rCBF. In the case of focal ischemia, which was induced by transorbital occlusion of the middle cerebral artery, the percentages of rCBF at which the D wave disappeared ranged from 9 to 20%. Changes in the amplitude of the D wave--an increase and following decrease--preceded the prolongation of its latency. In contrast with the D wave I waves were too easily affected by ischemia. Moreover, rCBF at the point of disappearance of the I wave varied greatly. In conclusion, the D wave is stable in mild ischemia and is a reliable indicator of critically profound ischemia (%rCBF < 40%). Monitoring the D wave of MEPs seems to be a useful method for avoiding the deterioration of motor function by ischemic insult.
authors.affiliation: Department of Neurosurgery, Hiroshima University School of Medicine, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohba
authors.forename: T
authors.initials: T
authors.lastname: Uozumi
authors.forename: K
authors.initials: K
authors.lastname: Arita
authors.forename: K
authors.initials: K
authors.lastname: Kurisu
authors.forename: T
authors.initials: T
authors.lastname: Nakahara
authors.forename: S
authors.initials: S
authors.lastname: Kuwabara
mesh_terms: D000818:Animals; D001810:Blood Volume; D002545:Brain Ischemia / Q000503:physiopathology*; D002415:Cats; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000503:physiopathology; D004195:Disease Models, Animal; D005071:Evoked Potentials; D007022:Hypotension / Q000503:physiopathology; D017078:Laser-Doppler Flowmetry