Cervical radiculopathies: comparison of surgical and EMG localization of single-root lesions

To identify the various electrodiagnostic (EDX) patterns of C-5, C-6, C-7, and C-8 cervical radiculopathy, we compared 50 cases of surgically proven solitary-root lesions with their preoperative EDX patterns. We excluded patients with polyradiculopathy, myelopathy, and previous surgery. We classified EDX studies as abnormal only by the needle electrode examination, and only by the demonstration of fibrillation potentials (either the positive sharp wave or the biphasic spike form). Seven patients (14%) had C-5 radiculopathy, nine (18%) had C-6, 28 (56%) C-7, and six (12%) C-8. With C-5, C-7, and C-8 radiculopathies, changes were relatively stereotyped, with involvement of the spinati,deltoid, biceps, and brachioradialis with C-5; the pronator teres, flexor carpi radialis, triceps, and anconeus with C-7; and the first dorsal interosseous, abductor digiti minimi, abductor pollicis brevis, flexor pollicis longus, and extensor indicis proprius with C-8. The root lesion with the most variable presentation was C-6--in half the patients, the findings were similar to C-5 radiculopathies, except that the pronator teres tended to be involved, whereas in the other half, the findings were identical to those with C-7 radiculopathies.