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The Accuracy of the Physical Examination for the Diagnosis of Midlumbar and Low Lumbar Nerve Root Impingement

Suri, Pradeep, MD*,†,‡,§; Rainville, James, MD*,‡; Katz, Jeffrey N., MD, MS; Jouve, Cristin, MD*,‡; Hartigan, Carol, MD*,‡; Limke, Janet, MD*,‡; Pena, Enrique, MD*; Li, Ling, MPH*; Swaim, Bryan, MS*; Hunter, David J., MBBS, PhD*

doi: 10.1097/BRS.0b013e3181c953cc
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Study Design. Cross-sectional study with prospective recruitment.

Objective. To determine the accuracy of the physical examination for the diagnosis of midlumbar nerve root impingement (L2, L3, or L4), low lumbar nerve root impingement (L5 or S1) and level-specific lumbar nerve root impingement on magnetic resonance imaging, using individual tests and combinations of tests.

Summary of Background Data. The sensitivity and specificity of the physical examination for the localization of nerve root impingement has not been previously studied.

Methods. Sensitivities, specificities, and likelihood ratios (LRs) were calculated for the ability of individual tests and test combinations to predict the presence or absence of nerve root impingement at midlumbar, low lumbar, and specific nerve root levels.

Results. LRs ≥5.0 indicate moderate to large changes from pre-test probability of nerve root impingement to post-test probability. For the diagnosis of midlumbar impingement, the femoral stretch test (FST), crossed FST, medial ankle pinprick sensation, and patellar reflex testing demonstrated LRs ≥5.0 (LR ∞). LRs ≥5.0 were observed with the combinations of FST and either patellar reflex testing (LR 7.0; 95% confidence interval [CI] 2.3–21) or the sit-to-stand test (LR ∞). For the diagnosis of low lumbar impingement, the Achilles reflex test demonstrated an LR ≥5.0 (LR 7.1; 95% CI 0.96–53); test combinations did not increase LRs. For the diagnosis of level-specific impingement, LRs ≥5.0 were observed for anterior thigh sensation at L2 (LR 13; 95% CI 1.8–87); FST at L3 (LR 5.7; 95% CI 2.3–4.4); patellar reflex testing (LR 7.7; 95% CI 1.7–35), medial ankle sensation (LR ∞), or crossed FST (LR 13; 95% CI 1.8–87) at L4; and hip abductor strength at L5 (LR 11; 95% CI 1.3–84). Test combinations increased LRs for level-specific root impingement at the L4 level only.

Conclusion. Individual physical examination tests may provide clinical information that substantially alters the likelihood that midlumbar impingement, low lumbar impingement, or level-specific impingement is present. Test combinations improve diagnostic accuracy for midlum-bar impingement.

We conducted a study of the accuracy of the physical examination for the diagnosis of nerve root impingement on magnetic resonance imaging. Individual physical examination tests may provide information which substantially alters the likelihood that nerve root impingement is present. Test combinations improve accuracy for midlumbar impingement.

*Division of Research, New England Baptist Hospital, Boston, MA

Spaulding Rehabilitation Hospital, Boston, MA

Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA

§VA Boston Healthcare System, Boston, MA

Division of Rheumatology, Immunology and Allergy, Department of Medicine and Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.

Address correspondence and reprint requests to Pradeep Suri, MD, Division of Research, New England Baptist Hospital, 125 Parker Hill Ave Boston, MA 02130; E-mail: psuri@caregroup.harvard.edu

Acknowledgment date: August 21, 2009. First revision date: October 20, 2009. Second revision date: October 27, 2009. Acceptance date: November 3, 2009.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Funds were received to support this work from NIH. 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. Supported by the Rehabilitation Medicine Scientist Training Program (RMSTP) and the National Institutes of Health grant K12 HD 01097 (to P.S.), and, in part, by the grant NIH/NIAMS K24 AR 02123 (to J.N.K.).

© 2011 Lippincott Williams & Wilkins, Inc.