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

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

Patients with cervical cord syrinxes may show abnormalities in median nerve SEPs, indicating a lesion in the upper cervical cord, with relative sparing of lower-limb SEPs. Wagner et al monitored median nerve SEPs intraoperatively in 28 patients with cervical or cervicothoracic syringomyelia. [52] Analysis was focused on SEP components: N13 (spinal cord), P14 (brain stem), and N20 (cortex).

N13 was absent in about 87% of patients because of a combined effect of syringomyelia and general anesthesia, and it did not recover. [52] P14 showed a significant intraoperative latency increase in 2 patients; this was irreversible in 1 patient who had a postoperative worsening of sensory function. N20 showed no significant alterations. Pure motor deficits after surgery were not predicted by SEP monitoring.

Thus, intraoperative P14 recordings helped to identify, and thereby prevent, injury to the dorsal columns, whereas N13 recording did not contribute to the intraoperative monitoring of spinal cord function in syringomyelia. [52]


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