Intraoperative transabdominal MEPs: four case reports

David W. Allison, Miranda K. Hayworth, Remi Nader, Melodie Ballman, Derrick Sun, Rony Ninan, Edward Southern

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Four recent cases utilizing transabdominal motor-evoked potentials (TaMEPs) are presented as illustrative of the monitoring technique during lumbosacral fusion, sciatic nerve tumor resection, cauda equina tumor resection, and lumbar decompression. Case 1: In a high-grade lumbosacral spondylolisthesis revision fusion, both transcranial motor-evoked potentials (TcMEPs) and TaMEPs detected a transient focal loss of left tibialis anterior response in conjunction with L5 nerve root decompression. Case 2: In a sciatic nerve tumor resection, TcMEPs responses were lost but TaMEPs remained unchanged, the patient was neurologically intact postoperatively. Case 3: TaMEPs were acquired during an L1-L3 intradural extramedullary cauda equina tumor resection utilizing a unique TaMEP stimulation electrode. Case 4: TaMEPs were successfully acquired with little anesthetic fade utilizing an anesthetic regimen of 1.1 MAC Sevoflurane during a lumbar decompression. While the first two cases present TaMEPs and TcMEPs side-by-side, demonstrating TaMEPs correlating to TcMEPs (Case 1) or a more accurate reflection of patient outcome (Case 2), no inference regarding the accuracy of TaMEPs to monitor nerve elements during cauda equina surgery (Cases 3) or the lumbar decompression presented in Case 4 should be made as these are demonstrations of technique, not utility.

Original languageEnglish (US)
Pages (from-to)689-698
Number of pages10
JournalJournal of Clinical Monitoring and Computing
Issue number2
StatePublished - Apr 2023


  • IONM
  • Lumbosacral
  • TaMEP
  • TcMEP
  • Transabdominal motor evoked potential

ASJC Scopus subject areas

  • Health Informatics
  • Critical Care and Intensive Care Medicine
  • Anesthesiology and Pain Medicine


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