title: Dynamic somatosensory evoked potentials to determine electrophysiological effects on the spinal cord during cervical spine extension: clinical article.
abstract: OBJECTIVE
  The goal of this prospective study was to investigate somatosensory evoked potentials (SSEPs) during dynamic motion of the cervical spine and to evaluate the efficacy of analyzing dynamic SSEPs for predicting dynamic effects on the spinal cord in patients with cervical spondylotic myelopathy (CSM).
  
  
  METHODS
  In total, 40 human subjects (20 CSM patients and 20 healthy volunteers as a control group) were examined prospectively using dynamic SSEPs with median nerve stimulation. The CSM patients showed cervical myelopathy due to cervical cord compression at the C4-5 segment. The SSEPs were examined with the cervical spine in a neutral position and at a 20° extension for 10 and 20 minutes. Changes in the N20 latency and amplitude were determined and analyzed. The authors defined the changes in the N20 latency and N20 amplitude between the neutral and extension positions of the cervical spine as percent latency and amplitude, respectively.
  
  
  RESULTS
  In the CSM patients, SSEPs tended to deteriorate after cervical spine extension, and a statistically significant deterioration of the N20 amplitude after the extension was observed. Moreover, the percent latency and amplitude progressively increased during cervical spine extension in these patients. In the healthy controls, SSEPs tended to deteriorate with cervical spine extension, but these changes did not result in statistically significant differences. Moreover, in this group the percent latency and amplitude were almost identical during the extension. When the CSM patients and the healthy controls were compared, a significant difference in the percent amplitude was observed between the 2 groups during the cervical spine extension.
  
  
  CONCLUSIONS
  This study suggests the potential of dynamic SSEPs as a useful neurophysiological technique to detect the effect of dynamic factors on the pathogenesis of CSM.
authors.affiliation: Department of Orthopedic Surgery, Spinal Injuries Center, Iizuka, Japan. uchiro1968@mac.com
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Morishita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Maeda
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ueta
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Naito
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Shiba
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000503:physiopathology*; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods; D055724:Electrophysiological Phenomena / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013117:Spinal Cord Compression / Q000209:etiology / Q000503:physiopathology*; D055009:Spondylosis / Q000150:complications / Q000503:physiopathology*; D055815:Young Adult