Taking The Guess Work Out Of Predicting Pain Relief For Patients With Back Pain And Sciatica

Main Category: Back Pain
Also Included In: Pain / Anesthetics
Article Date: 06 Oct 2009 - 0:00 PDT

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Patients suffering from back pain, sciatica, or a herniated disc, sometimes find relief with epidural steroid injections (ESI). Recent research has found that needle electromyography (EMG) can reliably predict, among other factors, the patient's potential pain relief from these injections.

A prospective study was conducted at the North Texas Veterans Administration Medical Center in Dallas, TX to determine whether needle EMG findings could predict pain relief in patients who had sciatica and underwent ESI. Eighty-eight subjects were found to meet the following criteria for lumbar radiculopathy: symptoms of leg pain, abnormal lumbar magnetic resonance imaging, and positive physical examination findings. Each subject then underwent needle EMG examination of the back and lower extremities. The needle EMG tracings were then reviewed by two blinded experts, both certified by the American Board of Electrodiagnostic Medicine. Membrane instability was the criterion for abnormality because this is the most clear-cut indicator of abnormality in lumbar radiculopathy. Motor unit analysis was not performed. All patients received interlaminar lumbar ESI. The patients underwent a focused examination and completed a pain rating visual analog scale (VAS), pain drawing, and disability questionnaire.

Of 80 patients completing the study, 25 had normal needle EMG results, 42 had a clear-cut abnormal needle EMG indicating a radiculopathy, and 13 results indicated a possible radiculopathy. Multiple regression analysis showed that positive EMG was an independent predictor of long-term pain response to ESI, measured as a drop in the VAS score of 1.68 (p < 0.001), but that it was not an independent predictor of short- term pain response. Age, disability status, and alcohol use also were independent predictors of pain response at 6 months.

"The subjects with abnormal needle EMG showed improvement with ESI that lasted up to 6 months, versus those that had a negative needle EMG," according to Dr. Samuel M. Bierner, lead researcher on the project. "Needle EMG results were not the only indicator, but with the other clinical information, this procedure can be a very useful and reliable diagnostic test for physicians in the evaluation of lumbar radiculopathy and serves as an independent predictor of long-term pain relief after lumbar ESI," stated Bierner.

The complete findings and results of this study are being presented at the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) 56th Annual Meeting in San Diego, California, at the Manchester Grand Hyatt, October 7-10, 2009. With over 5000 members, the AANEM is the world's largest organization dedicated to advancing neuromuscular, musculoskeletal, and electrodiagnostic medicine.

Source
American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM)