title: Exploration of sensory impairments associated with C6 and C7 radiculopathies.
abstract: BACKGROUND
  Cervical radiculopathy is a common disorder caused by compression of the cervical nerve roots and is characterized by arm pain and altered sensory-motor function. Incongruity in the locations of C6 and C7 dermatomes in competing versions of historical dermatome maps has plagued interpretation of impaired sensation associated with C6 and C7 radiculopathies. Magnetic resonance imaging (MRI) allows accurate identification of the C6 or C7 nerve root compression and therefore makes it possible to explore sensory findings that are associated with compression of specific nerve root.
  
  
  OBJECTIVE
  This study compared the locations of impaired sensation in subjects with cervical radiculopathy from MRI-confirmed C6 and C7 nerve root compression.
  
  
  METHODS
  Case series was used for this study.
  
  
  METHODS
  A total of 122 subjects with symptoms suggestive of cervical radiculopathy were recruited by 11 spine specialist from 5 practice locations. Of these, 30 subjects had MRI-confirmed C6 and 40 subjects C7 radiculopathy.
  
  
  METHODS
  Standardized pinprick sensory examination of the forearm and hand of every subject was performed, and the locations of sensory impairments were recorded.
  
  
  METHODS
  Sensory examination was performed before reviewing MRI results or performing motor or reflex examination. Areas of impaired sensation were recorded on drawings of the palmar and dorsal forearm and hand, and translated using a grid into 36 specific areas for analysis. Chi-square was used to compare frequencies of findings for each grid area for C6 and C7 radiculopathies. Power analysis suggested that a minimum of 27 subjects in each group were needed to detect a 30 percentage point difference in frequency of sensory impairments. Significance was set at ≤.05.
  
  
  RESULTS
  Approximately 80% of subjects had impaired sensation in at least 1 grid area, most often in the distal forearm and hand, and many had findings in multiple areas. There was nearly complete overlap for locations of impaired sensation for C6 and C7 radiculopathy, and the frequencies of impaired sensation differed only in the dorsal aspect of the distal radial forearm where it was twice as common in C6 radiculopathy (p=.02).
  
  
  CONCLUSIONS
  The location of sensory impairments associated with symptomatic C6 and C7 nerve root compression overlap to the extent that caution should be exercised when predicting compression of either the C6 or C7 nerve roots based on locations of impaired sensation. Impaired sensation in the radial aspect of the distal forearm is more common in C6 radiculopathies.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, 02129 USA; New England Baptist Hospital, 125 Parker Hill Avenue, Boston, MA, 02120 USA. Electronic address: jrainvil@nebh.org.
authors.forename: James
authors.initials: J
authors.lastname: Rainville
authors.affiliation: OrthoCarolina Spine Center, Charlotte, NC, 28207 USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Laxer
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, 02129 USA; New England Baptist Hospital, 125 Parker Hill Avenue, Boston, MA, 02120 USA.
authors.forename: John
authors.initials: J
authors.lastname: Keel
authors.affiliation: Seton Medical Center, Austin, TX, 78705 USA.
authors.forename: Enrique
authors.initials: E
authors.lastname: Pena
authors.affiliation: New England Baptist Hospital, 125 Parker Hill Avenue, Boston, MA, 02120 USA; Department of Orthopedic Surgery, Tufts Medical School, Boston, MA, 02111 USA.
authors.forename: David
authors.initials: D
authors.lastname: Kim
authors.affiliation: OrthoCarolina Spine Center, Charlotte, NC, 28207 USA.
authors.forename: R Alden
authors.initials: RA
authors.lastname: Milam
authors.affiliation: New England Baptist Hospital, 125 Parker Hill Avenue, Boston, MA, 02120 USA; Department of Orthopedic Surgery, Tufts Medical School, Boston, MA, 02111 USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Carkner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000473:pathology*; D005260:Female; D006801:Humans; D006987:Hypesthesia / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011843:Radiculopathy / Q000175:diagnosis*; D013126:Spinal Nerve Roots / Q000473:pathology*
keywords: Cervical radiculopathy; Dermatomes; MRI; Physical examination; Sensory testing; Validity