A Prospective, Masked 18-Month Minimum Follow-up On Neurophysiologic Changes In Persons with Spinal Stenosis, Low Back Pain, and No Symptoms

ObjectivesTo 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.DesignProspective, controlled, masked trial.SettingUniversity spine program.ParticipantsPersons 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.InterventionsA 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.Main Outcome MeasurementsChange in electrodiagnostic findings. Among persons with clinical stenosis, relationship of change in paraspinal mapping scores to MRI findings and clinical changes.ResultsOf 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.ConclusionsClinical 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.