Usefulness of transcranial motor evoked potentials during thoracoabdominal aortic surgery.
BACKGROUND
The purpose of this study was to evaluate the efficacy of myogenic transcranial motor evoked potentials (tc-MEPs) for spinal cord ischemia in the repair of descending thoracic or thoracoabdominal aortic aneurysms.


METHODS
Intraoperative tc-MEPs was used in 72 patients who underwent the repair of descending thoracic (n = 24) or thoracoabdominal aortic aneurysms (n = 49) classed as Crawford I in 10 patients, II in 12, III in 23, and IV in 3. There were 52 men and 20 women, and their mean age was 64.9 +/- 12.8 years. Tc-MEPs were recorded by transcranial electrical stimulation and compound muscle action potentials.


RESULTS
The hospital mortality rate was 5.6% (n = 4), and the incidence of neurologic deficits was 11.1% (n = 8). All patients whose MEP amplitude recovered to more than 75% of the baseline showed normal spinal function, and 8 of 9 patients whose MEP amplitude decreased to below 75% of the baseline at the end of the procedure showed neurologic deficits postoperatively. The sensitivity of tc-MEPs was 100% and specificity was 98.4%. Latency in patients with postoperative paraplegia was 123% +/- 9% and was significantly prolonged at the end of the procedure.


CONCLUSIONS
Tc-MEPs were very sensitive and specific to spinal cord ischemia with reduced amplitude and prolongation of the latency period. Tc-MEPs are considered a useful monitor of spinal cord ischemia during descending thoracic or thoracoabdominal aortic surgery.
Kawanishi
Yujiro
Y
Division of Cardiovascular, Thoracic, and Pediatric Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
Munakata
Hiroshi
H
Matsumori
Masamichi
M
Tanaka
Hiroshi
H
Yamashita
Teruo
T
Nakagiri
Keitaro
K
Okada
Kenji
K
Okita
Yutaka
Y
D000200:Action Potentials; D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000401:mortality / Q000503:physiopathology* / Q000601:surgery*; D017545:Aortic Aneurysm, Thoracic / Q000401:mortality / Q000503:physiopathology* / Q000601:surgery*; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D010264:Paraplegia / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D011930:Reaction Time; D015427:Reperfusion Injury / Q000175:diagnosis / Q000209:etiology; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000098:blood supply / Q000503:physiopathology; D014656:Vascular Surgical Procedures / Q000009:adverse effects