P2-22. Cervical myotomal chart inferred from MRI-confirmed single root lesions

Myotomal chart is an important basis of clinical as well as electromyographic evaluations. The aim of this study is to determine C5, C6, and C7-innervated muscles using EMG conducted on patients with MRI-confirmed single root lesions. We retrospectively reviewed EMG records of 15 patients with MRI-confirmed isolated C5, C6, or C7 radiculopathy. EMG abnormalities were judged primarily based on the presence of moderate or greater amount of denervation potentials. Four patients had C5, 5 had C6, and 6 had C7 radiculopathies, respectively. For C5 radiculopathy cases, 3/3 of explored Deltoid (Del), 1/3 of Biceps brachii (BB), 0/4 of Pronator teres (PT) were abnormal. For C6 cases, 4/5 of PT, 3/5 of ECRB, 2/4 of ECRL, 1/5 of BB, 0/2 of Del and 0/4 of Flexor carpi radialis (FCR) muscles were abnormal. For C7 cases, 6/6 of FCR, 5/6 of Triceps brachii (TB), 2/5 of ECRB, 1/6 of Extensor digitorum communis (EDC), 0/6 of PT, 0/3 of Flexor carpi ulnaris (FCU) muscles were abnormal. In conclusion, this study added some evidence to the myotomal innervation of the upper-limb muscles. Del, PT, and FCR muscles were mainly innervated by C5, C6, and C7 roots, respectively.