Evaluation of the Correlation of Magnetic Resonance Imaging and Electrodiagnostic Findings in Chronic Low Backache Patients

Background: Low back pain (LBP) is one of the most common medical complaints and leading cause of workforce loss in many countries. Magnetic resonance imaging (MRI) is a highly sensitive method for the detection of lesions in the spine because of its excellent imaging of anatomical detail. However, MRI does not provide information about physiological nerve function and has relatively low specificity. Electrodiagnostic (EDX) study, including needle electromyography (EMG), is a specific test to assess the physiological functions of nerve roots or peripheral nerves. The aim of the present study was to correlate the electrophysiological and MRI findings in chronic low backache patients.

Materials and methods: Fifty patients (26 males and 24 females) with mean age 33.54 ± 8.33 years with a history of LBP of minimum 3 consecutive months were evaluated with MRI and EDX (bilateral nerve conduction study of three nerves [tibial, peroneal, and sural nerve] and bilateral EMG of three muscles [paraspinal, tibialis anterior, vastus medialis]) studies.

Results: Twenty-seven patients showed disc involvement on MRI and 23 MRI were normal. Mean conduction velocity was mildly decreased in tibial and sural nerves in all the patients either with normal MRI or disc involvement on MRI. In disc involvement conduction velocity, decrease was more as compared to normal MRI. About 39% patients with normal MRI and 78% patients with disc involvement showed abnormal EMG. This data represented statistically significant association of EDX study with MRI (P < 0.05).

Conclusions: In patients with LBP, EDX studies are significantly more correlated with clinical data than MRI. Therefore, EMG may be a useful diagnostic tool to establish management protocols and prevent unnecessary interventions. EDX gives a better representation of physiological status of nerve and muscle, a supra added benefit which MRI lacks. However, MRI gives better visualization of anatomic parameters and structural details which may or may not be associated with chronic LBP.