Prolonged loss of leg myogenic motor evoked potentials during thoracoabdominal aortic aneurysm repair, without postoperative paraplegia

Abstract

No postoperative paraplegia occurred in a patient whose leg myogenic motor evoked potentials (mMEPs) disappeared during thoracoabdominal aortic aneurysm repair. A 69-year-old man underwent resection and repair of a type III (Crawford classification) thoracoabdominal aneurysm. An epidural catheter was placed into the epidural space for epidural cooling, and a Swan-Ganz catheter was placed into the subarachnoid space for cerebrospinal fluid (CSF) drainage. Continuous CSF pressure and temperature measurement was carried out the day before surgery. The mMEPs gradually disappeared 10 min after proximal double aortic clamping and complete aortic transection. Selective perfusion of intercostal arteries was started about 20 min after the loss of the mMEPs, but the mMEPs were not restored. Possibly, spinal cord hyperemia, induced by selective perfusion of the intercostal vessels, narrowed the subarachnoid space so that CSF could not be satisfactorily drained during surgery. The spinal cord hyperemia may have decreased spinal function and suppressed the leg mMEPs. The persistence of the loss of mMEPs was undeniably due to the influence of the anesthetic agent or a perfusion disorder in the lower-extremity muscles. Of note, moderate spinal cord hypothermia and postoperative CSF drainage probably resulted in improved lower-limb motor function.

Neuromonitoring Using Motor and Somatosensory Evoked Potentials in Aortic Surgery

“…They retrospectively reviewed SSEP and MEP monitoring in 60 patients who underwent thoracoabdominal repairs, with a paraplegia rate of 10.5%. Denda et al reported a similar case study in which a TAAA surgery patient had persistent loss of MEPs with no subsequent paraplegia, resulting in a false positive. Both studies utilized epidural cooling as a protective adjunct against spinal cord ischemia.…”

Heat shock proteins as biomarkers for the rapid detection of brain and spinal cord ischemia: a review and comparison to other methods of detection in thoracic aneurysm repair

“…MEPs are elicited through transcortical electrical stimulation and may provide increased sensitivity and specificity for identification of spinal cord ischemia when compared to SSEPS (Jacobs et al 2006;Denda et al 2006;Kakinohana et al 2007;Kawanishi et al 2007;Shine et al 2008). Myogenic potentials are recorded from muscles in the extremities by delivering multipulse, electrical stimulation to the scalp overlying the motor cortex.…”