Does cervical radiculopathy have an effect on peripheral nerve conduction studies? An electrophysiological evaluation.

Background: Peripheral nerve neuropathies are more common in patients with cervical radiculopathy (CR) and a proximal lesion along an axon might predispose that nerve to injury at distal sites. To evaluate this hypothesis, the frequency of median nerve neuropathy at the wrist and the frequency of ulnar nerve neuropathy at the elbow were investigated in 80 patients with one-sided CR.

Methods: The symptomatic and asymptomatic extremities were compared for the electrophysiological parameters of ulnar and median nerve conduction studies. The patients were divided into three diagnostic subgroups (C5/C6 radiculopathy, C7 radiculopathy and C8/Th1 radiculopathy), and ulnar nerve conduction studies were compared between symptomatic and asymptomatic extremities in each subgroup.

Results: Although, the median and ulnar nerves are mainly derived from C8/Th1 roots, we did not observe an increased frequency of ulnar nerve involvement at the elbow (3.7% in symptomatic, 2.5% in asymptomatic extremities) while increased median nerve involvement was present at the wrist (27.5% in symptomatic, 12.5% in asymptomatic extremities).

Conclusion: The electrophysiological data and the frequency of ulnar and median nerve neuropathy did not support an etiological association between CR and distal neuropathy.

Significance: the association between CR and peripheral neuropathy is associational rather than causative.