Background. Despite tremendous development in surgical and anesthetic techn
iques, resection of the thoracic and thoracoabdominal segments of the aorta
remain associated with the risk of paralysis. Routine use of somatosensory
-evoked potential (SEP) monitoring in patients undergoing surgery of the th
oracic aorta has become a standard intra- and postoperative procedure at ou
r institution since its first use in 1993. il
Methods. One hundred forty nine (149) thoracic aortic operations were perfo
rmed during January 1993 through January 1998 using SEP-directed serial sac
rifice of paired intercostal arteries. Full, partial, or no cardiovascular
bypass was variably used, dictated by anatomy; 49 patients required deep hy
pothermic circulatory arrest (DHCA). Patients were monitored during both th
e intraoperative procedure as well for the post-anesthesia period until neu
rologic stability and/or ability to reproducibly demonstrate lower extremit
y neurologic competency was established. Postoperative neurologic function
was compared to ischemic intervals, extent of aortic resection, number of i
ntercostal arteries sacrificed, type of perfusion, and underlying aortic pa
thology.
Results. Overall mortality in the group was 13 patients (8.7%), with no one
cause predominating. Nine patients sustained permanent paraplegia, only 1
of whom lost SEPs during the procedure. Abnormal SEPs were seen in 19 patie
nts, 14 of whom had normal neurologic function after awakening. Three of 19
(15.8%) developed late paraplegia that resolved with medical therapy. Elev
en patients (7.4%) developed cerebrovascular accidents (CVA), with the majo
rity (8) appearing in the group undergoing DHCA. The risk of CVA was signif
icantly higher in DHCA patients (p < 0.01) than other patients. No patient
with CVA had abnormal SEPs; 4 DHCA patients developed abnormal SEPs, 1 with
permanent paralysis.
Conclusions. The routine use of SEP monitoring during thoracic and thoracoa
bdominal aortic surgery as well as during the postoperative period may be u
seful in decreasing the observed incidence of paraplegic events associated
with these procedures. (C) 1999 by The Society of Thoracic Surgeons.