Abstract 13: Use of electromyography to predict functional outcome after epidural spinal injections for lumbar radiculopathy.

Abstract

Objective: To determine if electromyographic diagnostic evaluation can predict functional outcome in patients undergoing lumbar spinal injections. Design: Retrospective study of functional outcome in patients undergoing lumbar interforaminal epidural spinal injections (ESIs) after electromyographic testing. Setting: Clinic. Participants: 39 subjects with low back pain with radicular symptoms into the lower extremity were evaluated for functional improvement after electromyography and ESI. Interventions: Fluoroscopic guidance of interforaminal ESI in the lumbar region was performed where positive clinical or electromyographic levels were suspected. Main Outcome Measures: Oswestry Disability Index (ODI) and Verbal Rating Scale (VRS) for current pain severity. Results: Electromyography diagnosed 18 patients with a radiculopathy; 21 had a normal or negative examination. Patients were followed postinjection on average for 10.8±3.9 weeks. Pretreatment ODI scores ± SD did not differ significantly between groups showing positive radiculopathy (72.3±12.7) or negative electromyographic findings (65.9±18.6) ( P>.05). There was significantly greater improvement of ODI rating for electromyography positive radiculopathy (7.11±9.5) compared with negative electromyography (3.2±17.4) ( P<.05). Positive radiculopathy subjects complained of more pain as measured on the VRS before ESI (8.1±1.0) than subjects with negative electromyographic findings (7.3±0.8) ( P>.05). The VRS mean improvement did not differ significantly between the positive electromyography group (1.8±1.2) and the negative electromyography group (1.2±1.2) ( P>.05). Conclusions: Subjects undergoing interforaminal ESI, who had a positive radiculopathy by electromyography prior to injection, showed significant improvement in functional outcome as measured by the ODI but not as measured by current pain intensity on the VRS. This study showed the importance and diagnostic value of electromyography for radiculopathy evaluation prior to spinal procedures and the difficulty of pain evaluation outcome by using the VRS.