Cervical radiculopathies: relationship between symptom duration and spontaneous EMG activity.

The purpose of this multicenter study was to prospectively examine whether denervation in paraspinal muscles (PSM) and in other major proximal and distal muscles is related to symptom duration in cervical radiculopathies (CRs). Information was collected on 93 electrodiagnostically confirmed CRs using standardized history, physical examination, and electromyographic (EMG) screens. Multivariate, maximum-likelihood estimates showed no evidence of correlation between PSM spontaneous activity and symptom duration. Symptom duration was also nonsignificant in eight of the remaining nine upper limb muscles analyzed. We conclude that the probability of spontaneous activity is not related to symptom duration. Clinicians, therefore, should refrain from interpreting electrodiagnostic findings based upon duration of symptoms.