Correlation between low triggered electromyographic thresholds and lumbar pedicle screw malposition : Analysis of 4857 screws

A retrospective analysis of 1078 spinal surgical procedures with lumbar pedicle screw placement at a single institution. Based on previously established normative values, triggered electromyographic stimulation (TrgEMG) was re-examined to evaluate its efficacy in determining screw malposition. Thres...

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Bibliographic Details
Published in:Spine (Philadelphia, Pa. 1976) Pa. 1976), 2007-11, Vol.32 (24), p.2673-2678
Main Authors: RAYNOR, Barry L, LENKE, Lawrence G, BRIDWELL, Keith H, TAYLOR, Brett A, PADBERG, Anne M
Format: Article
Language:English
Subjects:
Action Potentials
Adolescent
Adult
Aged
Aged, 80 and over
Bayes Theorem
Biological and medical sciences
Bone Screws
Cerebrospinal fluid. Meninges. Spinal cord
Child
Diseases of the osteoarticular system
Diseases of the spine
Electrodiagnosis. Electric activity recording
Electromyography - standards
False Negative Reactions
False Positive Reactions
Female
Humans
Investigative techniques, diagnostic techniques (general aspects)
Lumbar Vertebrae - surgery
Male
Medical sciences
Middle Aged
Monitoring, Intraoperative - standards
Muscle, Skeletal - innervation
Nervous system
Nervous system (semeiology, syndromes)
Neurology
Reproducibility of Results
Retrospective Studies
Sacrum - surgery
Spinal Fusion - instrumentation
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Summary:A retrospective analysis of 1078 spinal surgical procedures with lumbar pedicle screw placement at a single institution. Based on previously established normative values, triggered electromyographic stimulation (TrgEMG) was re-examined to evaluate its efficacy in determining screw malposition. Threshold values for confirmation of intraosseous placement of pedicle screws with EMG stimulation is controversial. TrgEMG threshold values for 4857 pedicle screws placed from L2 to S1 from 1996 to 2005 were analyzed. An ascending method of constant current stimulation was applied to each pedicle screw to obtain a compound muscle action potential (CMAP) from lower extremity myotomes. Previously determined threshold value normative data from a published clinical series of 233 screws were as follows: 0 to 4 mA, high likelihood of pedicle wall breach; 4 to 8 mA, possible pedicle wall breach; >8 mA, no pedicle wall defect. A total of 7.74% (376 of 4857) of all screws tested had threshold values
ISSN:0362-2436
1528-1159
DOI:10.1097/BRS.0b013e31815a524f