Thoracic and thoracoabdominal aortic aneurysm repair: use of evoked potential monitoring in 118 patients.
OBJECTIVE
Paraplegia is the most dreaded and severe complication of surgery on the descending thoracic aorta (TAA) and thoracoabdominal aorta (TAAA). The functional integrity of the spinal cord can be monitored by means of intraoperative recording of myogenic-evoked responses after transcranial electrical stimulation (tcMEP) and somatosensory-evoked potential (SEP) monitoring. In this study, we evaluated the results of evoked potential monitoring and the adequacy of the strategy followed.


METHODS
The spinal cord of 118 patients (78 men; age, 65 +/- 12 years; 79 TAAAs, 39 TAAs) undergoing surgery on the TAA or TAAA was monitored with tcMEP and SEP. Spinal cord protection was achieved by means of a multimodality approach: moderate hypothermia (32 degrees C rectal temperature), continuous cerebrospinal fluid drainage to keep the pressure less than 10 mm Hg, reimplantation of intercostal arteries, left ventricular bypass grafting, and staged clamping. In the case of evoked potential changes more than 50% of baseline, the strategy was adjusted: reattachment of more segmental arteries when technically feasible, higher distal and proximal perfusion pressures, and enhanced cerebrospinal fluid drainage.


RESULTS
Forty-two of 118 patients (35.6%) had a more than 50% of baseline tcMEP reduction during cross-clamping. At this point, only 5 of those 42 cases were also associated with SEP reduction of more than 50% of baseline. On the basis of the tcMEP findings, the strategy was adjusted. Five patients had postoperative paraplegia (4.2%).


CONCLUSIONS
tcMEP monitoring seems to be a useful adjunct of the protective techniques and may cause substantial adjustments in strategy, reducing the incidence of postoperative paraplegia.
van Dongen
E P
EP
Department of Anesthesiology and Intensive Care, St. Antonius Hospital, Nieuwegein, The Netherlands.
Schepens
M A
MA
Morshuis
W J
WJ
ter Beek
H T
HT
Aarts
L P
LP
de Boer
A
A
Boezeman
E H
EH
D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000401:mortality / Q000601:surgery*; D017545:Aortic Aneurysm, Thoracic / Q000401:mortality / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods; D003250:Constriction; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods*; D005073:Evoked Potentials, Somatosensory; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007431:Intraoperative Complications / Q000175:diagnosis* / Q000209:etiology / Q000517:prevention & control; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D010264:Paraplegia / Q000175:diagnosis* / Q000209:etiology / Q000517:prevention & control; D011379:Prognosis; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013908:Thoracotomy / Q000379:methods; D013997:Time Factors; D016896:Treatment Outcome