Responses to mechanical stimulation of the upper limb in painful cervical radiculopathy.

Clinical and electromyographic (EMG) responses to non-noxious mechanical stimuli were studied in four patients with painful cervical radiculopathy, and in two control subjects. In the symptomatic arm(s), palpation over one or more nerve trunks was painful and accompanied by EMG activity, whereas palpation of adjacent soft tissues was painless and unaccompanied by EMG activity. Electromyographic activity was widespread in three patients when myotatic reflexes were elicited in the symptomatic arm(s). In asymptomatic arms of patients and controls, EMG responses to the myotatic reflexes were more localised. Allodynic nerve trunks in cervical radiculopathy appear to be afferent correlates of central sensitisation; the accompanying EMG activity may represent a motor correlate of this same process.