The Value of Somatosensory Evoked Potential Testing for Upper Lumbar Radiculopathy

AAEM Minimonograph 32: The electrodiagnostic examination in patients with radiculopathies

“…Saal and colleagues concluded that dermatomal SEP studies are helpful in evaluating patients with upper-lumbar radiculopathies, but the published report of their experience is difficult to evalu-ate because insufficient details are provided. 97 Their ''gold standard'' for establishing the diagnosis of radiculopathy is not clear, few clinical details are furnished, there is no account of the NEE or the findings obtained thereby, the extent of the anatomic abnormalities detected by imaging studies in individual patients is not stated, and normative SEP data are not provided. Moreover, it is likely that some of the patients studied had spinal stenosis rather than isolated radiculopathies.…”

“…It is also noteworthy that the SEPs were sometimes abnormal when imaging studies showed no abnormality; for uncertain reasons, Saal and colleagues attributed this to a ''chemically mediated radicular syndrome'' as opposed to a false-positive test finding. 97 Aminoff and coworkers compared the diagnostic utility of dermatomal SEPs with more conventional electrophysiologic techniques in 28 patients with clinically unequivocal L5 or S1 compressive root lesions and found that in only 7 (25%) was the final diagnosis confirmed by the SEP findings; the responses were lost or grossly attenuated in 6 patients and prolonged in latency in 1 patient. Although in 2 patients the SEPs were abnormal when other electrophysiologic studies were normal, NEE had the greatest yield, revealing denervation in a myotomal pattern in 21 (75%).…”

Correlation between Dermatomal Somatosensory Evoked Potential, Needle Electromyography and Magnetic Resonance Imaging in Chronic Sensory Lumbosacral Radiculopathies

“…Saal et al used DSEP for upper lumbar radiculopathy. They demonstrated significant correlation for SEP findings with the anatomic abnormalities revealed by computerized tomography, MRI and discogram [18].…”