title: The utility of somatosensory evoked potential monitoring during cervical spine surgery: how often does it prompt intervention and affect outcome?
abstract: METHODS
  Retrospective review of the results of somatosensory evoked potentials (SSEP) performed in cervical spine surgery.
  
  
  OBJECTIVE
  To evaluate the utility of spinal cord monitoring during cervical spine surgery in a single surgeon's practice, based on how often it prompted an intraoperative intervention.
  
  
  BACKGROUND
  Intraoperative monitoring during cervical spine surgery is not a universally accepted standard of care. This is due in part to the paucity of literature regarding the impact of monitoring on patient management or outcome.
  
  
  METHODS
  SSEP for tibial, median, and ulnar nerves were monitored in 809 consecutive cervical spine operations performed by a single surgeon. The average patient age was 52 years (range, 2 to 88 years), with 472 males and 339 females. Cases were screened for significant degradation or loss of SSEP data. Specific attention was paid to 1) what interventions were performed in response to the SSEP degradation with subsequent improvement, and 2) whether SSEP changes corresponded with postoperative neurological deficits.
  
  
  RESULTS
  Seventeen of 809 patients (2.1%) had SSEP degradation that met warning criteria and therefore prompted intervention. Release of shoulder tape (8) or traction (4) most often resulted in SSEP improvement. Failure of SSEP data to return to within acceptable limits of baseline was associated with neurological deficit (p=0.04). Two patients awoke with new postoperative neurological deficits, which resolved in 6 hours and 2 months respectively. Patients with ossification of the posterior longitudinal ligament (OPLL) were at seven-fold greater risk of intraoperative SSEP degradation.
  
  
  CONCLUSIONS
  SSEP monitoring in this surgical population proved sensitive to perioperative factors which may increase the risk of postoperative neurologic deficit, and probably prevented neurological deficits in 15 of 809 patients (1.9%). Improvement in data following intervention appears to correlate well with unchanged neurologic status. Experience with intraoperative monitoring in this patient series has led to incorporation of these techniques as a standard of care in cervical spine surgeries performed by this surgeon.
authors.affiliation: Rockford Orthopedic Associates, Rockford, Illinois, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Roh
authors.forename: Tracy J
authors.initials: TJ
authors.lastname: Wilson-Holden
authors.forename: Anne M
authors.initials: AM
authors.lastname: Padberg
authors.forename: Jong-Beom
authors.initials: JB
authors.lastname: Park
authors.forename: K
authors.initials: K
authors.lastname: Daniel Riew
references.citation: J Spinal Disord. 1996 Dec;9(6):485-93
references.pmid: 8976488
references.citation: J Spinal Disord. 1994 Aug;7(4):277-84
references.pmid: 7949695
references.citation: J Neurosurg. 1996 Oct;85(4):566-73
references.pmid: 8814157
references.citation: J Spinal Disord. 2000 Apr;13(2):178-82
references.pmid: 10780696
references.citation: Spine (Phila Pa 1976). 1993 May;18(6):737-47
references.pmid: 8516704
references.citation: Spine (Phila Pa 1976). 1996 Mar 1;21(5):589-94
references.pmid: 8852314
references.citation: J Spinal Disord. 1997 Aug;10(4):299-303
references.pmid: 9278914
references.citation: Spine (Phila Pa 1976). 1999 Aug 1;24(15):1593-8
references.pmid: 10457580