title: A prospective, masked 18-month minimum follow-up on neurophysiologic changes in persons with spinal stenosis, low back pain, and no symptoms.
abstract: OBJECTIVE
  To describe neurophysiologic changes over time in persons with and without spinal complaints and to assess whether paraspinal denervation predicts change in stenosis on magnetic resonance imaging (MRI) and clinical course.
  
  
  METHODS
  Prospective, controlled, masked trial.
  
  
  METHODS
  University spine program.
  
  
  METHODS
  Persons aged 55 to 80 years, screened for polyneuropathy and determined on clinical examination to have spinal stenosis, mechanical low back pain, or no spinal symptoms.
  
  
  METHODS
  A comprehensive codified history was obtained and subjects underwent physical examination, ambulation testing, masked electrodiagnostic testing including paraspinal mapping, and MRI, repeated at greater than 18 months. This study presents detailed technical information and additional analyses not reported previously.
  
  
  METHODS
  Change in electrodiagnostic findings. Among persons with clinical stenosis, relationship of change in paraspinal mapping scores to MRI findings and clinical changes.
  
  
  RESULTS
  Of 149 initial subjects, 83 (79.3% of eligible subjects) repeated testing at 20 (+/-2 SDs) months. No significant change in limb muscle spontaneous activity or motor unit pathology was noted in any group. In 23 persons with initial diagnosis of stenosis, paraspinal mapping electromyography related to change in diagnosis over time (analysis of variance F = 3.77, P = .037), but not to most initial magnetic resonance imaging measurements or to change in spinal canal diameter.
  
  
  CONCLUSIONS
  Clinical spinal stenosis is neurophysiologically stable in most persons. Paraspinal electromyographic changes reflect large changes in clinical course, but neither neurophysiologic nor clinical changes relate to change in spinal geometry over 20 months.
authors.affiliation: Department of Physical Medicine and Rehabilitation, The University of Michigan, Ann Arbor, MI 48108, USA. andyhaig@umich.edu
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Haig
authors.forename: Karen S J
authors.initials: KS
authors.lastname: Yamakawa
authors.forename: Christopher
authors.initials: C
authors.lastname: Parres
authors.forename: Anthony
authors.initials: A
authors.lastname: Chiodo
authors.forename: Henry
authors.initials: H
authors.lastname: Tong
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004576:Electromyography; D005500:Follow-Up Studies; D006801:Humans; D017116:Low Back Pain / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D010147:Pain Measurement; D011446:Prospective Studies; D013130:Spinal Stenosis / Q000150:complications / Q000473:pathology* / Q000503:physiopathology*; D013997:Time Factors