Minim Invasive Neurosurg 2005; 48(5): 273-277
DOI: 10.1055/s-2005-915594
Original Article
© Georg Thieme Verlag Stuttgart · New York

Verification of Nerve Root Decompression during Minimally-Invasive Lumbar Microdiskectomy: A Practical Application of Surgeon-Driven Evoked EMG

D.  D.  Limbrick Jr. 1 , N.  M.  Wright
  • 1Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
Further Information

Publication History

Publication Date:
01 December 2005 (online)

Abstract

Lumbar microendoscopic diskectomy (MED) has gained widespread acceptance as an alternative to conventional open microdiskectomy due to several potential advantages, including reductions in postoperative pain and recovery time. However, constraints in visualization and working space present technical difficulties in the verification of nerve root decompression and the identification of sequestered disc fragments. This study was undertaken to investigate whether a surgeon-driven, evoked EMG paradigm could be used for intraoperative verification of nerve root decompression within the technical and mechanical confines of lumbar MED. Twenty-two patients underwent intraoperative EMG stimulation threshold recordings during lumbar microendoscopic diskectomy. In this series, the EMG threshold recorded directly from the nerve root immediately prior to diskectomy was 8.6 ± 4.4 mA. Following decompression, the threshold was 4.2 ± 2.1 mA. The difference in pre- and post-decompression EMG stimulation threshold, 4.4 ± 4.0 mA, was statistically significant (p < 0.001). In two of the 22 cases (9.1 %), the EMG threshold was initially unchanged following diskectomy, and further exploration revealed sequestered disc fragments. After removal of these fragments, an appropriate decrease in the EMG threshold was observed. The results from this study suggest that surgeon-driven, evoked EMG threshold testing may provide a simple, effective adjunct to lumbar microendoscopic diskectomy for intraoperative verification of nerve root decompression.

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David D. Limbrick Jr.,M. D., Ph. D. 

Department of Neurological Surgery · Washington University School of Medicine

660 South Euclid Ave.

St. Louis, MO 63110

USA ·

Phone: +1-314-362-3577

Fax: +1-314-362-2107

Email: limbrickd@yahoo.com

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