Spinal cord monitoring using intraoperative somatosensory evoked potentials for spinal trauma.
BACKGROUND
Intraoperative spinal cord monitoring is commonplace in scoliosis surgery as an adjunct to evaluate functional integrity of the cord; however, limited information is available on its applicability in spinal trauma.


METHODS
We investigated the efficacy of somatosensory evoked potential (SEP) recording during reconstructive procedures in 82 patients who sustained 20 cervical, 8 thoracic, 6 thoracolumbar, and 48 lumbar vertebral fractures or fractures-dislo-cations. Seventy-one patients underwent single anterior or posterior operations and 11 combined anterior-posterior procedures. Forty patients had incomplete injuries, and 42 had no preoperative neurologic deficit. SEP trace amplitude at insertion of electrode was considered as the baseline value and was compared with the lowest intraoperative signal amplitude and the amplitude at completion of operation.


RESULTS
Fifty-nine patients had a depression in wave amplitude of >25% during surgery; in 25 patients, the trace fell by >50%, and in 7 cases, a >75% diminution was recorded. A loss of 50% in SEP signal amplitude showed 67% sensitivity and 71% specificity in predicting neurologic outcome. Increasing trace deterioration threshold from 50% to 60% improved specificity to 81% without compromising sensitivity. A loss of >50% in SEP amplitude occurred with significantly increased incidence during the anterior compared with the posterior spinal procedures. More than 20% recovery in signal amplitude at the conclusion of the procedure in patients with incomplete injuries was correlated with favorable neurologic function.


CONCLUSIONS
Persistent intraoperative decrement in SEP amplitude and poor restitution at completion of surgery increase the risk for postoperative neurologic compromise.
Tsirikos
Athanasios I
AI
Royal National Orthopaedic Hospital, Stanmore, Middlesex, UK. atsirikos@hotmail.com
Aderinto
Joseph
J
Tucker
Stewart K
SK
Noordeen
Hilali H
HH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws / Q000009:adverse effects; D015984:Causality; D002648:Child; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013116:Spinal Cord / Q000503:physiopathology; D013119:Spinal Cord Injuries / Q000209:etiology / Q000517:prevention & control* / Q000601:surgery; D016103:Spinal Fractures / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome