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The Sensitivity and Specificity of Electrodiagnostic Testing for the Clinical Syndrome of Lumbar Spinal Stenosis

Haig, Andrew J. MD*†; Tong, Henry C. MD, MS*; Yamakawa, Karen S. J. MS*; Quint, Douglas J. MD; Hoff, Julian T. MD§; Chiodo, Anthony MD*; Miner, Jennifer A. MBA*; Choksi, Vaishali R. MD; Geisser, Michael E. PhD*

doi: 10.1097/01.brs.0000188400.11490.5f
Diagnostics

Study Design. Prospective, masked, double controlled diagnostic trial.

Objectives. To determine the sensitivity and specificity of electrodiagnostic consultation (EDX) for the clinical syndrome of lumbar spinal stenosis.

Summary of Background Data. EDX has been used for more than 50 years to diagnose spinal disorders but has not met the new standards of evidence-based medicine.

Methods. A total of 150 subjects (asymptomatic volunteers and patients with MRIs suggesting back pain or spinal stenosis; 55–80 years of age) underwent physiatrist history and physical examination, MRI, and review of this data by a neurosurgeon, with each clinician masked to any outside information, leading to a unanimous consensus on diagnosis in 55. After masked EDX testing, 7 subjects with undiagnosed neuromuscular disease were discovered. EDX findings were related to “clinical gold standard” diagnoses in 48 persons.

Results. Paraspinal mapping EMG score of >4 had 100% specificity and 30% sensitivity for stenosis compared with either the back pain or asymptomatic groups (each, P < 0.04). A composite limb and paraspinal fibrillation score had a sensitivity of 47.8% and specificity of 87.5% (P = 0.008), and H-wave sensitivity was 36.4, specificity 91.3 (P = 0.026) for stenosis versus all controls.

Conclusions. This first masked study in the 60-year history of needle electromyography also introduces anatomically validated needle placement, quantified and reproducible examination of the paraspinal muscles, and dual control populations to EDX research in spinal disorders. EDX has statistically significant, clinically meaningful specificity for spinal stenosis and detects neuromuscular diseases that may masquerade as stenosis.

This first successfully blinded study in electrodiagnostic (EDX) history shows that EDX test components have excellent sensitivity and specificity in separating patients with a consensus clinical diagnosis of spinal stenosis from those with back pain and asymptomatic volunteers, and detect neuromuscular disorders that masquerade as stenosis.

From the Departments of *Physical Medicine and Rehabilitation, †Orthopedic Surgery, ‡Radiology, and §Neurosurgery, University of Michigan Spine Program, Ann Arbor, MI. Study examiners and staff included April M. Fetzer, DO, Marcus J. Harris, BS, Julian T. Hoff, MD, Janis Huff, Richard W. Kendall, DO, Allan Rowley, MD, Matthew J. Smith, MD, André Taylor, MD, and John A Yarjanian, MD.

Acknowledgment date: October 18, 2004. First revision date: May 10, 2005. Acceptance date: August 2, 2005.

This is a publication of the Spine Program of the University of Michigan, which is funded by the United States Department of Health and Human Services, National Institutes of Health under Grant No. 5 R01 NS41855-02.

The opinions contained in this publication are those of the grantee and do not necessarily reflect those of the United States Department of Health and Human Services.

The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.

Federal funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Andrew J. Haig, MD, Department of Physical Medicine and Rehabilitation, University of Michigan, 325 E. Eisenhower, Ann Arbor, MI 48108; E-mail: andyhaig@umich.edu

© 2005 Lippincott Williams & Wilkins, Inc.