Hoovers Sign

Hoover’s sign is a clinical test used to distinguish functional paresis (without identifiable neurological pathology) from organic paresis (with identifiable neurological cause)¹.

The test was first described by Dr. Charles Franklin Hoover in 1908 as a simple method to identify functional weakness in the lower extremities². It is also used as part of the evaluation in functional neurological disorders (FND), lumbosacral radiculopathy, sciatica, and herniated intervertebral disc³.

Anatomical background

Hoover’s sign is based on the principle of the crossed extension reflex, where flexion of one hip naturally induces extension of the contralateral hip⁴.

Test execution

Patient positionThe patient lies in a supine position on the examination table.

Examiner positionThe examiner places both hands beneath the patient’s heels to detect changes in downward pressure.

Test procedure

1. The patient is instructed to press both heels down against the table.

   • In the case of organic paresis, pressure will still be detected on the affected side.

2. The patient is then asked to lift the non-paretic leg against resistance provided by the examiner.

   • In the case of functional paresis, no pressure will be felt from the paretic heel, as the patient does not generate unconscious counterpressure.

   • If pressure is felt under the paretic heel during this maneuver, the test is positive for functional weakness⁷.

Interpretation of results

• Positive test: Indicates functional weakness – pressure from the paretic heel is observed when the contralateral leg is lifted, but not during direct testing of the paretic side.

• Negative test: Indicates organic paresis – heel pressure on the examination table remains constant.

Discussion and limitations

Although Hoover’s sign is a useful tool, potential sources of error exist:

False positives may occur due to¹²:

• Pain in the affected hip, producing greater weakness on direct testing.

• Patients with organic disease exaggerating weakness to “prove” their condition.

• Cortical neglect, where functional impairment may present despite intact muscle strength.

• Neurological diseases such as multiple sclerosis, which may occasionally produce a positive test.

False negatives may occur if:

• The patient has bilateral symptoms.

• The patient fails to properly activate hip flexion on the healthy side.

Hoover’s sign in the upper extremities

Hoover also described a similar phenomenon in the arms, known as “complementary opposition”¹²:

• During resisted flexion of one arm, a patient with functional paresis will involuntarily extend the opposite arm.

• During resisted shoulder adduction in one arm, a patient with functional paresis of the opposite arm will involuntarily adduct it.

Recent extensions of the test: The “Contralateral Knee Sign”

A more recent variant, the contralateral knee sign, is based on the same principle as Hoover’s sign. It is used to identify functional paresis of knee extension by testing for automatic extension in the contralateral leg¹³.

Diagnostic validity and evidence

• Moderate sensitivity (63%) and high specificity (100%) for functional weakness¹².

• McWhirter et al. found that Hoover’s sign can be useful when functional weakness is suspected following stroke¹².

• Studies show that Hoover’s sign and the hip abduction test are sensitive and specific clinical tools for diagnosing FND¹¹.

Clinical relevance

Hoover’s sign provides clinicians with a simple, bedside tool to differentiate functional from organic paresis. Its strength lies in its high specificity, though its moderate sensitivity means it should be used in combination with other neurological and functional tests.

Conclusion

Hoover’s sign is a simple and reliable test for differentiating functional from organic paresis. It demonstrates high specificity but only moderate sensitivity, and is therefore best applied as part of a comprehensive neurological assessment.

Sources

1. Koehler, P.J., Okun, M.S. (2004). Important observations prior to the description of the Hoover sign.  Historical Neurology. 63: 1693-1697.

2. Larner, A.J. (2001). A Dictionary of Neurological Signs. Springer.

3. Ziv, I., Djaldetti, R., Zoldan, J., Avraham, M., Melamed, E. (1998). Diagnosis of "non-organic" limb paresis by a novel objective motor assessment: The quantitative Hoover's test. Journal of Neurology, 245: 797-802.

4. Shams T, Ashraf F, DeGeorgia M. Charles Franklin Hoover and the Hoover Sign (P04. 006). Neurology Apr 2012 78:1

5. ARIEFF AJ, TIGAY EL, KURTZ JF, LARMON WA. The Hoover Sign: An Objective-Sign of Pain and/or Weakness in the Back or Lower Extremities. Archives of Neurology. 1961 Dec 1;5(6):673-8.

6. 1. Koehler PJ, Okun MS. Important observations prior to the description of the Hoover sign. Neurology. 2004;63(9):1693–7.

7. Hoover CF. A NEW SIGN FOR THE DETECTION OF MALINGERING AND FUNCTIONAL PARESIS OF THE LOWER EXTREMITIES. Journal of the American Medical Association. 1908;LI(9):746–7.  

8. Cock HR, Edwards MJ. Functional neurological disorders: acute presentations and management. Clin Med (Lond). 2018 Oct;18(5):414-417. doi: 10.7861/clinmedicine.18-5-414. PMID: 30287439; PMCID: PMC6334101.

9. Kaufman, D.M. (2007). Clinical neurology for psychiatrists: 6th edition. Elsevier Health Sciences. p. 20.

10. online video, http://www.youtube.com/watch?v=F4Fk_ZzCX6A, last accessed 6/2/2009

11. Clinically Relevant Technologies, http://www.youtube.com/watch?v=QqQuPL36loM, last accessed May 2011

12. Ercoli T, Stone J. False Positive Hoover's Sign in Apraxia. Movement disorders clinical practice (Hoboken, NJ). 2020;7(5):567–8.  

13. Ercoli, T. and Stone, J. . False Positive Hoover’s Sign in Apraxia. Movement Disorders Clinical Practice. 2020;7(5):567–568.

14. Mehndiratta MM, Kumar M, Nayak R, Garg H, Pandey S. Hoover's sign: Clinical relevance in Neurology. Journal of postgraduate medicine. 2014 Jul 1;60(3):297.

15. Brigo F. Contralateral knee sign: an extension of the Hoover's sign to unveil functional paralysis of knee extension. Neurological sciences. 2023;44(9):3351–2.

16. McWhirter, Laura, et al. "Hoover's sign for the diagnosis of functional weakness: a prospective unblinded cohort study in patients with suspected stroke." Journal of psychosomatic research 71.6 (2011): 384-386.