Assessment of forearm pronation strength in C6 and C7 radiculopathies

Consecutive case series of patients with C6 and C7 radiculopathies.

To explore the clinical utility and reliability of manual muscle testing of forearm pronation strength in C6 and C7 radiculopathies.

EMG evidence of denervation of the pronator teres was the most common finding in C6 radiculopathies, and frequently present in C7 radiculopathies. Clinical evaluation of the pronator teres through manual muscle testing of forearm pronation has never been explored; therefore, its clinical utility is unknown as compared with the muscle groups that are traditionally evaluated.

Fifty-five subjects with diagnostic imaging evidence of either C6 (n = 25) or C7 (n = 30) cervical root compression and clinical symptoms consistent with cervical radiculopathy were recruited for this study. These subjects underwent manual muscle testing of forearm pronation, wrist extension, elbow flexion, and elbow extension. The frequency of impaired strength was recorded and compared for C6 and C7 radiculopathies. A second examiner evaluated each subject, with his or her findings compared with the first examiner only for the determination of interrater reliability.

In C6 radiculopathy subjects, forearm pronation weakness was present in 72%, was twice as common as wrist extension weakness, was present in all cases where elbow flexion or wrist extension weakness was noted, and was found in all but 2 subjects where elbow extension weakness was present. In C7 radiculopathy subjects, forearm pronation weakness accompanies elbow extension weakness in 23% of subjects and was the only weakness in 10% of subjects. Manual muscle testing demonstrated adequate interrater reliability.

Forearm pronation weakness is the most frequent motor finding in C6 radiculopathies and may be noted is some cases of C7 nerve root compression.