title: Characteristics of C6-7 myelopathy: assessment of clinical symptoms and electrophysiological findings.
abstract: METHODS
  This is a single-center retrospective study.
  
  
  OBJECTIVE
  The objective of this study was to study the clinical symptoms and electrophysiological features of C6-7 myelopathy.
  
  
  METHODS
  This study was conducted at the Department of Orthopedic surgery, Yamaguchi University Graduate school of medicine, Japan.
  
  
  METHODS
  A total of 20 patients with cervical compressive myelopathy were determined by spinal cord-evoked potentials or a single level of obvious magnetic resonance imaging (MRI)-documented cervical spinal cord compression. Neurological examinations included manual muscle testing and investigation of deep tendon reflex, including Hoffmann sign, and of sensory disturbance areas. Motor-evoked potentials (MEPs), compound muscle action potentials (CMAPs) and F-wave were recorded from bilateral abductor digit minim and abductor halluces muscles. Central motor conduction time was calculated as follows: MEPs latency-(CMAPs latency+F latency-1)/2 (ms).
  
  
  RESULTS
  Eighteen patients (90%) had negative Hoffmann sign. Eight patients (40%) had no sensory disturbance in the upper limbs and 8 patients (40%) had no muscle weakness in the upper limbs. We determined that patients had cervical myelopathy when their central motor conduction time measured in abductor digit minim was longer than 6.76 ms (+2 s.d.). Using this definition, the sensitivity for myelopathy was 42.8%.
  
  
  CONCLUSIONS
  Patients with C6-7 myelopathy may lack clinical symptoms in their hands and central motor conduction time measured in abductor digit minim tended to be less prolonged, and it only showed symptoms in their lower limbs as gait disturbance. Surgeons should bear in mind the possibility of disorders of caudal C6-7 when they encounter patients with no or few symptoms in their hands and with leg weakness or numbness.
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Funaba
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kanchiku
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Imajo
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Nishida
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Fujimoto
authors.affiliation: Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube city, Japan.
authors.forename: T
authors.identifier: http://orcid.org/0000-0003-1802-3473
authors.initials: T
authors.lastname: Taguchi
mesh_terms: D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology*; D009460:Neurologic Examination; D011930:Reaction Time / Q000502:physiology; D012189:Retrospective Studies; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D055815:Young Adult