Cervical radiculopathy: discrepancy or concordance between electromyography and magnetic resonance imaging?

In the screening of patients with cervical radiculopathy, a relatively common finding is the discrepancy between normal needle electromyography (EMG) and abnormal MRI, or vice versa. We carried out a retrospective study to assess the relationship between needle EMG and MRI findings in the preoperative evaluation of patients with cervical radiculopathy. The records of 147 patients were reviewed; 58 patients (M = 32, F = 26; age 53 ± 9) were included in the study. Needle EMG examination was abnormal in 28 patients. MRI abnormalities were found in all 58 patients, showing degenerative changes not affecting the nerve root in 15 and foraminal stenosis affecting the nerve root in 43; in the latter, needle EMG was abnormal in 28 patients and normal in the remainder. Concordance between EMG and MRI level of abnormality was found in 71% of patients with non-dermatomal symptom distribution. Concordance between clinical level, EMG and MRI abnormality was found in 50% of patients with C5, in 70% with C6 and in 67% with C7 symptom distribution. When EMG and MRI level of abnormality was discordant, the EMG abnormalities corresponded to the clinical level of symptom distribution. The results of our retrospective study reveal that in the majority of cases of cervical radiculopathy, EMG and MRI level of abnormalities are concordant. When there is discordance between EMG and MRI findings, the EMG helps in the guidance of patient selection for surgical intervention because it provides evidence of nerve root lesion and offers a dynamic tool in the follow-up evaluation.