Hoover's sign (leg paresis)
Involuntary extension of the "normal" leg occurs when flexing the contralateral leg against resistance. To perform the test, the examiner should hold their hand under the "normal" limb's heel and ask the patient to flex the contralateral hip against resistance (while the patient is supine, ask them to keep the weak leg straight while raising it). If the patient is making an honest effort, then you should feel the "normal" limb's heel extending (pushing down) against your hand as the patient tries to flex (raise) the "weak" leg's hip. This would indicate an organic cause of the paresis. If you do not feel the "normal" leg's heel pushing down as the patient flexes the "weak" limb's hip, then this likely indicates a non-organic cause of paresis, such as malingering or conversion disorder. Examples of how to do the test are readily available on youtube.com.
Strong hip muscles can make the test difficult to interpret.
Efforts have been made to use the theory behind the sign to report a quantitative result.
- "George Crile, Charles Hoover and John Phillips".
- Koehler PJ, Okun MS (November 2004). "Important observations prior to the description of the Hoover sign". Neurology 63 (9): 1693–7. doi:10.1212/01.wnl.0000142977.21104.94. PMID 15534257.
- Stone, Keith (2011). CURRENT Diagnosis & Treatment Emergency Medicine, 7e. McGraw-Hill Companies, Inc.
- Sonoo M (January 2004). "Abductor sign: a reliable new sign to detect unilateral non-organic paresis of the lower limb". J. Neurol. Neurosurg. Psychiatr. 75 (1): 121–5. PMC 1757483. PMID 14707320.
- Ziv I, Djaldetti R, Zoldan Y, Avraham M, Melamed E (December 1998). "Diagnosis of "non-organic" limb paresis by a novel objective motor assessment: the quantitative Hoover's test". J. Neurol. 245 (12): 797–802. doi:10.1007/s004150050289. PMID 9840352.