Motor amplitudes may predict electromyography-confirmed radiculopathy in patients referred for radiating limb pain

Radiculopathy is diagnosed by needle electromyography, with nerve conduction studies excluding alternative diagnoses.

In patients referred for electrodiagnostic evaluation of radiating limb pain, we compared ulnar motor amplitudes between those with and without electromyographically confirmed C8 radiculopathy, as well as fibular motor amplitudes between those with and without electromyographically confirmed L5 radiculopathy.

Patients with electromyographically confirmed C8 or L5 radiculopathy demonstrated decreased ulnar or fibular motor amplitudes, respectively, as compared to patients without radiculopathy. Receiver operating characteristic curves demonstrated good diagnostic accuracy, with areas under the curve of 0.85 and 0.82, respectively. Optimal cut-offs for electromyographically confirmed C8 and L5 radiculopathies were 10.2 mV and 3.6 mV, respectively, with associated sensitivities/specificities of 0.86/0.74 and 0.92/0.60.

Ulnar and fibular motor amplitudes may have clinical utility in assessing the likelihood of patients demonstrating electromyographically confirmed C8 and L5 radiculopathies with active denervation. The findings may be particularly useful in patients intolerant of needle electromyography. Muscle Nerve 59:561-561, 2019.