Discover the intriguing method of Hoover's Sign, a physical exam techique that distinguishes between organic and functional leg weakness. Learn how it works and its impressive diagnostic sensitivity and specificity. Delve into the fascinating world of neurological disorders and the role of brain signaling in functional neurologic dysfunction. Plus, explore a fun fact about the pulmonary Hoover’s Sign related to COPD, adding depth to your understanding of these critical assessments in medical practice.
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Hoover's Sign Differentiates Weakness
Hoover's sign differentiates organic versus functional leg weakness using a simple physical exam maneuver.
You feel the unaffected leg push down if the weakness is organic, demonstrating the crossed-extensor reflex.
volunteer_activism ADVICE
Use and Communicate Hoover's Sign
If you don't feel the opposite heel push down, this is a positive Hoover's sign indicating functional weakness.
Document it clearly and communicate findings to the team, patient, and family for appropriate management.
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This physical exam maneuver differentiates between organic vs. functional (previously known as psychogenic) leg weakness.
Organic causes include disease processes such as stroke, MS, spinal cord compression, guillain-barre, ALS, and sciatica, among others
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?
Place your hand under the heel of the unaffected leg and ask the patient to attempt to lift the paralyzed leg.
If the paralysis is due to an organic cause, then you should feel the unaffected leg push down.
This is due to the crossed-extensor reflex mechanism, an unconscious motor control function mediated by the corticospinal tract.
If you don't feel the opposite heel push down, that is a positive Hoover's Sign.
How sensitive/specific is it?
An unblinded cohort study in patients with suspected stroke found a sensitivity of 63% and a specificity of 100%
Fun Fact
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
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.
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
Emergency Medical Minute