The value of motor evoked potentials in reducing paraplegia during thoracoabdominal aneurysm repair.
OBJECTIVE
Paraplegia after thoracoabdominal aortic aneurysm (TAAA) repair mainly occurs in patients with Crawford extent I and II. We assessed the impact of monitoring spinal cord integrity and the subsequent adjusted surgical maneuvers on neurologic outcome in repairs of type I and II TAAAs.


METHODS
Surgical repair of TAAAs was performed in 112 consecutive patients with extent type I (n = 42) and type II (n = 70) aneurysms. The surgical protocol included cerebrospinal fluid drainage, moderate hypothermia, and left heart bypass with selective organ perfusion. Spinal cord function was assessed by means of monitoring motor evoked potentials (MEPs). Significant decreased MEPs always generated adjustments, including raising distal aortic and mean arterial pressure, reattachment of visible intercostal arteries, or endarterectomy of the excluded aortic segment with revascularization of back bleeding intercostal arteries.


RESULTS
Motor evoked potential monitoring could be achieved in all patients. By maintaining a mean distal aortic pressure of 60 mm Hg, MEPs were adequate in 82% of patients. Increasing distal aortic pressure restored MEPs in all patients. In 19 patients (17%), MEPs decreased significantly during aortic cross-clamping because of critical spinal cord ischemia. MEPs returned in all patients after spinal cord blood flow was re-established except in three patients with type II TAAA in whom MEPs could not be restored, and absent MEPs at the end of the procedure corresponded with neurologic deficit. Delayed paraplegia developed in two patients owing to hemodynamic instability with insufficient mean arterial blood pressure to maintain adequate spinal cord perfusion.


CONCLUSIONS
Monitoring MEPs is a highly reliable technique to assess spinal cord ischemia during TAAA repair. A surgical protocol including cerebrospinal fluid drainage, left heart bypass, and monitoring of MEPs can reduce the paraplegia rate significantly. Adjusted hemodynamic and surgical strategies induced by changes in MEPs could restore spinal cord ischemia in most patients, preventing early and late paraplegia in all type I patients. In type II patients, early paraplegia occurred in 4.2% and delayed neurologic deficit in 2.9%. Despite all available measures, complete prevention of paraplegia in type II aneurysms seems to be unrealistic.
Department of Vascular Surgery, University Hospital Aachen, The Netherlands. m.jacobs@surgery.azm.nl
Michael J
MJ
Jacobs
Werner
W
Mess
Bas
B
Mochtar
Robbert J
RJ
Nijenhuis
Randolph G
RG
Statius van Eps
Geert Willem H
GW
Schurink
D000328:Adult; D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology / Q000601:surgery*; D017545:Aortic Aneurysm, Thoracic / Q000503:physiopathology / Q000601:surgery*; D001794:Blood Pressure; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009046:Motor Neurons; D010264:Paraplegia / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D020760:Spinal Cord Ischemia / Q000150:complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects*