Episode 949: Hoover's Sign
Episode description
Contributor: Travis Barlock, MD
Educational Pearls:
What is Hoover’s sign used to identify?
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This physical exam maneuver differentiates between organic vs. functional (previously known as psychogenic) leg weakness.
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Organic causes include disease processes such as stroke, MS, spinal cord compression, guillain-barre, ALS, and sciatica, among others
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In Functional Neurologic Disorder, the dysfunction is in brain signaling, and treatment relies on more of a psychiatric approach
How is Hoover's Sign performed?
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Place your hand under the heel of the unaffected leg and ask the patient to attempt to lift the paralyzed leg.
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If the paralysis is due to an organic cause, then you should feel the unaffected leg push down.
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This is due to the crossed-extensor reflex mechanism, an unconscious motor control function mediated by the corticospinal tract.
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If you don’t feel the opposite heel push down, that is a positive Hoover’s Sign.
How sensitive/specific is it?
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An unblinded cohort study in patients with suspected stroke found a sensitivity of 63% and a specificity of 100%
Fun Fact
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There’s also a pulmonary Hoover’s sign, named after the same doctor, Charles Franklin Hoover, which refers to paradoxical inward movement of the lower ribs during inspiration due to diaphragmatic flattening in COPD.
References
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McWhirter L, Stone J, Sandercock P, Whiteley W. Hoover's sign for the diagnosis of functional weakness: a prospective unblinded cohort study in patients with suspected stroke. J Psychosom Res. 2011 Dec;71(6):384-6. doi: 10.1016/j.jpsychores.2011.09.003. Epub 2011 Oct 6. PMID: 22118379.
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Stone J, Aybek S. Functional limb weakness and paralysis. Handb Clin Neurol. 2016;139:213-228. doi: 10.1016/B978-0-12-801772-2.00018-7. PMID: 27719840.
Summarized by Jeffrey Olson, MS3 | Edited by Jorge Chalit, OMS3
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