Electromyographic study to predict functional outcome of transforaminal epidural steroid injection in lumbosacral radiculopathy

Abstract

ContextEpidural steriod injections (ESIs) are commonly used for managment of lumbosacral radiculopathy (LSR). Predicting outcomes after ESIs could be another valuable application of needle electromyography (EMG) in these patients.AimThe aim was to determine if EMG study can predict the functional outcome of transforaminal ESIs in patients with LSR.Materials and methodsThe study included 20 patients with clinical diagnosis of LSR. Peripheral nerve conduction study, late responses, somatomsensory evoked potentials, and needle EMG were performed in both lower limbs followed by transforaminal ESI under fluoroscopic guidance. The functional outcome was evaluated using visual analog scale for pain and Oswestry disability index (ODI) that were performed before and after injections.ResultsThere were statistically significant decrease in pain severity (visual analog scale; P=0.022) and in ODI (improvement in functional score; P=0.029) after injection in patients with symptom duration less than 3 months compared with patients with longer duration of symptoms. In patients with negative EMG findings, there was a significantly greater reduction in pain severity (P<0.01) and ODI score (P<0.01) after injection compared with patients with positive findings. Regression analysis showed that negative needle EMG findings were significant predictors of pain reduction (P=0.001) and functional improvement (P=0.002) in patients with LSR after ESI.ConclusionThis study supports the notion that EMG studies can be used for prediction of functional outcome in patients with LSR performing transforaminal ESI.