Paraspinal mapping: quantified needle electromyography in lumbar radiculopathy.
In the diagnosis of low back pain, the presence of a high percentage of false positive findings on radiologic imaging studies has lead to a more definitive role for electrodiagnosis as a confirmatory test. The paraspinal muscles are a crucial part of the electrodiagnostic examination for radiculopathy. To date, no technique for paraspinal evaluation has been validated. Based on previously documented anatomical techniques, we have designed a method of paraspinal examination termed "paraspinal mapping" (PM). Electromyographic (EMG) needles are placed in five carefully chosen locations and inserted in multiple directions. Individual scores for these insertions are added to determine a total PM sensitivity score. The first 50 studies using PM were compared to peripheral EMG, imaging studies, and pain drawings. Results indicate that the technique is easy to perform. Sensitivity scores relate well with these tests. In this limited and uncontrolled population, PM had higher sensitivity for abnormalities than either peripheral EMG or imaging studies. Because of the anatomical validity of PM, future studies may show it to be useful in localizing the level of radiculopathy independently from peripheral EMG, and to support clinical findings and imaging studies.