title: Intraoperative somatosensory evoked potential monitoring during anterior cervical discectomy and fusion in nonmyelopathic patients--a review of 1,039 cases.
abstract: BACKGROUND
  Intraoperative somatosensory evoked potential (SSEP) monitoring has been shown to reduce the incidence of new postoperative neurological deficits in scoliosis surgery. However, its usefulness during cervical spine surgery remains a subject of debate.
  
  
  OBJECTIVE
  To determine the utility of intraoperative SSEP monitoring in a specific patient population (those with cervical radiculopathy in the absence of myelopathy) who underwent anterior cervical discectomy and fusion (ACDF) surgery.
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  A total of 1,039 nonmyelopathic patients who underwent single or multilevel ACDF surgery. The control group (462 patients) did not have intraoperative SSEP monitoring, whereas the monitored group (577 patients) had continuous intraoperative SSEP monitoring performed.
  
  
  METHODS
  A new postoperative neurological deficit.
  
  
  METHODS
  SSEP tracings were reviewed for all 577 patients in the monitored group and all significant signal changes were noted. Medical records were reviewed for all 1,039 patients to determine if any new neurological deficits developed in the immediate postoperative period.
  
  
  RESULTS
  None of the patients in the control group had any new postoperative neurological deficits. In the monitored group there were six instances of transient SSEP changes (1 due to suspected carotid artery compression; 5 thought to be due to transient hypotension) which resolved with the appropriate intraoperative intervention (repositioning of retractors; raising the arterial blood pressure). Upon waking up from anesthesia, one patient in the monitored group had a new neurological deficit (partial central cord syndrome) despite normal intraoperative SSEP signals.
  
  
  CONCLUSIONS
  ACDF appears to be a safe surgical procedure with a low incidence of iatrogenic neurological injury. Transient SSEP signal changes, which improved with intraoperative interventions, were not associated with new postoperative neurological deficits. An intraoperative neurological deficit is possible despite normal SSEP signals.
authors.affiliation: Department of Orthopedic Surgery, University of Pittsburgh, 3741 Fifth Avenue, Suite 1010, Pittsburgh, PA 15213, USA.
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Smith
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Balzer
authors.forename: Mustafa H
authors.initials: MH
authors.lastname: Khan
authors.forename: Rick A
authors.initials: RA
authors.lastname: Davis
authors.forename: Donald
authors.initials: D
authors.lastname: Crammond
authors.forename: William C
authors.initials: WC
authors.lastname: Welch
authors.forename: Peter
authors.initials: P
authors.lastname: Gerszten
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Sclabassi
authors.forename: James D
authors.initials: JD
authors.lastname: Kang
authors.forename: William F
authors.initials: WF
authors.lastname: Donaldson
mesh_terms: D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000601:surgery*; D017586:Diskectomy; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006801:Humans; D007049:Iatrogenic Disease / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011183:Postoperative Complications / Q000517:prevention & control; D011843:Radiculopathy / Q000175:diagnosis / Q000503:physiopathology / Q000517:prevention & control*; D012189:Retrospective Studies; D013123:Spinal Fusion