Significance of Dermatomal Somatosensory Evoked Potentals in the Diagnosis and Evaluation of Efficacy of the Treatment on Herniated Lumbosacral Discs.

Lee, G S; Rha, H K; Ahn, M S; Choi, C R; Song, J U

Original Article

Journal of Korean Neurosurgical Society 1987;16(3): 761-770.

G S Lee, H K Rha, M S Ahn, C R Choi, J U Song

Department of Neurosurgery, St Paul's Hospital, Catholic Medical College, Seoul, Korea.

ABSTRACT

We recorded dermatomaly somatosensory evoked potentials(DSSEPs) in 30 healthy subjects and 50 patients with a herniated lumbosacral disc. DSSEPs normally consists of three negative peaks, N36 N55 N75 and N42 N59 N78 by bilateral stimulation of L5 and S1 dermatome, respectively. In the patient group, both the first & second peak of DSSEPs are often abnormal whereas the third peak tends to remain normal. Of the 20 patients who underwent laminectomy, 17(85%) patients demonstrated positive findings of the lesion corresponding to myelographic finding. However, 19(95%) patients of the 20 surgical cases showed operative findings identical with DSSEPs. Follow-up study with DSSEPs in the patients of 20 surgical cases and 30 cases treated with either RF rhizotomy or physiotherapy resulted in returning to normal waveform from abnormal one. In comparing to other electro-diagnostic test, DSSEPs are more valuable noninvasive diagnostic tool in the evaluation of herniated lumbosacral disc.

Key Words: Herniated lumbosacral disc; Diagnosis; Dermotomal somatosensory evoked potential