title: The value of intraoperative neurophysiological monitoring in tethered cord surgery.
abstract: OBJECTIVE
  The value of intraoperative neurophysiological monitoring (IONM) with surgical detethering in dysraphic patients has been questioned. A retrospective analysis of our series of 65 patients is presented with special focus on technical set-up and outcome.
  
  
  METHODS
  All patients were diagnosed with a tethered cord (TC) due to spinal dysraphism. A high-risk group (HRG) was determined consisting of 40 patients with a lipomyelomeningocele and/or a split cord malformation sometimes in combination with a tight filum terminale. The surgical procedure was a detethering operation in all cases performed by a single surgeon during a 9-year period (1999-2008). A standard set-up of IONM was used in all patients consisting of motor-evoked potentials (MEP) evoked by transcranial electrical stimulation (TES) and electrical nerve root stimulation. In young patients, conditioning stimulation was applied in order to improve absent or weak MEPs.
  
  
  RESULTS
  IONM responses could be obtained in all patients. Postoperative deterioration of symptoms was found in two patients of whom one patient belonged to the HRG. Mean maximal follow-up of all 65 patients was 4.6 years (median 4.1 years). Long-term deterioration of symptoms was found in 6 of 65 patients with a mean follow-up of 5 years (median 5.3 years).
  
  
  CONCLUSIONS
  The use of IONM is feasible in all TC patients. The identification of functional nervous structures and continuous guarding of the integrity of sacral motor roots by IONM may contribute to the safety of surgical detethering.
authors.affiliation: Department of Neurosurgery, University Medical Centre Groningen, The Netherlands. e.w.hoving@nchir.umcg.nl
authors.forename: Eelco W
authors.initials: EW
authors.lastname: Hoving
authors.forename: Esther
authors.initials: E
authors.lastname: Haitsma
authors.forename: Charlotte M C
authors.initials: CM
authors.lastname: Oude Ophuis
authors.forename: Henricus L
authors.initials: HL
authors.lastname: Journée
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009436:Neural Tube Defects / Q000503:physiopathology / Q000601:surgery*; D012189:Retrospective Studies; D016896:Treatment Outcome