title: Frequency and severity of carpal tunnel syndrome according to level of cervical radiculopathy: double crush syndrome?
abstract: OBJECTIVE
  The double crush hypothesis (DC) proposes that a proximal lesion along an axon predisposes it to injury at a more distal site along its course through impaired axoplasmic flow. The frequency and severity of carpal tunnel syndrome (CTS) according to the level of cervical radiculopathy were investigated to evaluate the hypothesis of DC.
  
  
  METHODS
  The frequency of CTS was investigated in 277 patients with C6, C7 or C8 radiculopathies and correlation between CTS and radiculopathy level was determined. We also investigated whether the degrees of abnormal sensory responses were more severe in C6, C7 radiculopathies and whether motor responses were more severe in C8 radiculopathy.
  
  
  RESULTS
  Thirty-nine patients were diagnosed with CTS and concomitant cervical radiculopathy at the C6, 7, or C8 root levels. The frequency of coexisting CTS was not statistically different according to the level of radiculopathy. The electrophysiologic results revealed no significant correlation between median sensory parameters and C6, C7 cases, and no relationship was observed between median motor responses and C8 radiculopathy.
  
  
  CONCLUSIONS
  The frequency and electrophysiologic data of CTS analyzed according to cervical radiculopathy level do not support a neurophysiological explanation.
  
  
  CONCLUSIONS
  Based on this study, the DC hypothesis could not be supported.
authors.affiliation: Department of Rehabilitation Medicine, Korea University College of Medicine, 126-1 Anam Dong 5 Ga, Sungbuk Gu, Seoul 136-705, South Korea. hkkwon@korea.ac.kr
authors.forename: Hee-Kyu
authors.initials: HK
authors.lastname: Kwon
authors.forename: Miriam
authors.initials: M
authors.lastname: Hwang
authors.forename: Dae-Won
authors.initials: DW
authors.lastname: Yoon
mesh_terms: D001370:Axonal Transport; D002349:Carpal Tunnel Syndrome / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D004568:Electrodiagnosis; D006801:Humans; D008475:Median Nerve / Q000473:pathology / Q000503:physiopathology; D009046:Motor Neurons / Q000502:physiology; D009431:Neural Conduction; D009475:Neurons, Afferent / Q000502:physiology; D011843:Radiculopathy / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013126:Spinal Nerve Roots / Q000473:pathology / Q000503:physiopathology