Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy

OBJECTIVE: This study aimed to investigate the reliability and diagnostic accuracy of typical dermatomes and myotomes for determining the pathologic level in surgically verified patients with cervical radiculopathy. METHODS: Patients who underwent single-level surgery due to cervical radiculopathy with at least a 60% reduction in preoperative symptoms or recovery of muscle power after surgery were included. The observed clinical symptoms (pain, paresthesia, motor weakness) were compared to those of typical cervical dermatomes and myotomes. RESULTS: Among the 227 patients reviewed, 142 (62.6%) had a standard dermatomal pattern, and 74 of 110 (67.3%) had a standard myotomal pattern. The myotome of C5/6 radiculopathy showed much more variance than those of other cervical segments. Among the patients with severe motor weakness (muscle strength ≤ grade 3 or obvious muscle atrophy), all those with involvement of root C5, C7, and C8 showed a typical pattern (C4/5: 13 of 13 patients, C6/7: 5 of 5 patients, C7/T1: 3 of 3 patients), while only 2 of the 6 patients (33.3%) with severe motor weakness caused by C5/6 radiculopathy fit the typical pattern. CONCLUSION: Among various symptoms, cervical myotome is of great value in determining the pathological level. However, it should be noted that there is high variability in human dermatomes and myotomes, especially for motor weakness due to C6 root compression, which is more variable than others.