Changes of Motor Evoked Potentials in Global and Focal Ischemic Models of Cats

Ohba Shinji

Uozumi Tohru

Arita Kazunori

Kurisu Kaoru

Nakahara Toshinori

Kuwabara Satoshi

Hiroshima Journal of Medical Sciences

[PISSN] 0018-2052

[EISSN] 2433-7668

[NCID] AA00664312

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.

Cerebral ischemia

Middle cerebral artery

Controlled hypotension

Motor evoked potentials

Medical sciences [ 490 ]

eng

Hiroshima University Medical Press

[ISSN] 0018-2052

[NCID] AA00664312