What is the role of somatosensory evoked potentials (SEPs) in the workup of spondylosis?

Updated: Oct 25, 2019
  • Author: Andrew B Evans, MD; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Berthier et al evaluated the effects of spondylosis on SEP to ascertain its potential role in the preoperative assessment of cervical myelopathy in patients with MRI abnormalities and clinical findings of either segmental spinal cord or dorsal column dysfunction; using median and tibial nerve SEP, they found no clear correlation between the severity of MRI abnormalities and that of clinical presentation or SEP abnormalities. [53]

In this study, some patients with MRI evidence of cervical cord impingement or intramedullary T2 hyperintensity showed normal SEPs, whereas 8 of 13 patients without evidence of cord narrowing or T2 signal abnormality showed abnormal SEPs. [53] This discrepancy suggests that MRI and SEPs may evaluate different aspects of the disease process.

On the basis of this study, the SEP does not appear to be a good measure of anatomic deficit; however, spinal cord dysfunction detected by SEP may be present in patients with an unremarkable MRI image. SEP recording may therefore be useful in the preoperative assessment of symptomatic patients without MRI evidence of cervical cord compression.

Lyczak et al reported abnormal SEPs in 56% of patients with cervical myelopathy. [54] The tibial nerve SEPs were used, and abnormal central conduction times were observed. A significant reduction of the abnormalities occurred after the operation. Abnormal SEPs before the procedure correlated with the severity of myelopathy, and improvement in SEPs after the procedure correlated strongly with clinical improvement.


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