Hoovers Sign (Neurological)
Purpose[edit | edit source]
The purpose of the test is to differentiate between leg paresis that has no definitive neurological pathology (non-organic) to that which has a definite, identifiable cause (organic). This test was first described by Dr. Charles Franklin Hoover in 1908 as a bedside test to identify functional weakness in the lower extremities and is 1 of 2 tests ascribed to him, the other being Hoover's Sign (Pulmonary). In the course of using the Hoover sign routinely for physical and neurological examinations, it was also found to be invaluable in the detection of low back pain, sciatica, sciatic neuritis, or lumbosacral radiculitis, such as protruded lumbar intervertebral disk.
Technique[edit | edit source]
Hoover's sign is a motor sign. It is based on the principle of crossed extensor reflex - when one hip is flexed, the contralateral hip is extended eg. if a person in supine is asked to lift the right leg with knee extended, the left heel will be observed to dig into the plinth.
Hoover's sign examines the inconsistency between automatic hip extension vs voluntary hip extension - hip extension in a patient with unilateral functional weakness is weak when tested directly, but briefly returns to normal when triggered by contralateral hip flexion. The following steps are carried out to elicit Hoover's sign.
- The patient is placed in a supine/recumbent position.
- The examiner places his/her hand under the patient's heels.
- The patient is then instructed to press the heels down onto the examiner's hands.
- The examiner is expected to feel pressure on the non-paretic limb.
- The patient is then asked to raise his/her non-paretic limb against downward resistance applied by the therapist.
- No pressure is expected to be felt under the paretic leg that is on the table.
The Hoover's sign is positive when pressure is felt under the paretic leg when the non-paretic leg is raised and no pressure is felt in the non-paretic leg when the paretic leg is being raised.
Discussion[edit | edit source]
It should be noted that apraxia, a common neurological deficit, could also explain the failure to voluntarily extend the hip.
Limitations of Hoover's sign[edit | edit source]
False-positive results can occur in the following conditions
- Pain in the affected hip may produce greater weakness on direct, compared with indirect testing which may be due to pain rather than weakness.
- Patients with organic disease may be trying to "help" or "convince" the examiner that they are ill.
- Cortical neglect can cause a positive Hoover's sign. With the help of functional neuroimaging studies, it has been shown that subjects with conversion disorder usually have functional impairment in striatothalamocortical circuits, which control sensorimotor function and voluntary motor behavior. Similar sub-cortical premotor circuits are also involved in unilateral motor neglect after organic brain damage, in which voluntary limb use may fail despite preserved muscle strength and intact primary sensorimotor pathways.
- False positivity may sometimes occur as a direct result of organic brain disease, for example, multiple sclerosis.
False-negative results can occur in the following conditions
1. If applied to patients with bilateral symptoms.
2. The patient may not be concentrating on flexing their sound hip when the examiner is testing the involuntary extension of the weak hip.
Hoover's sign in the arms[edit | edit source]
Hoover described a similar phenomenon of "complementary opposition" in the arms. In a patient with functional weakness, flexion of an outstretched arm against resistance produces involuntary extension of the other arm. In another method to detect functional weakness of the upper limb, on testing shoulder adduction in one limb, the contralateral side will also adduct in patients with functional paresis of the upper limb, while it will remain stable in organic weakness.
Contralateral Knee Sign[edit | edit source]
The contralateral knee sign is a new test proposed as an extension of Hoover's sign, based on the same principles governing it: the crossed extensor reflex. This test aims to unveil functional paralysis of knee extension by testing for automatic knee extension.
Validity and Specificity[edit | edit source]
Hoover's sign was moderately sensitive and very specific for a diagnosis of functional weakness. McWhirter et al evaluated Hoover's sign as a part of the diagnostic work-up in patients presenting with suspected stroke. Authors found moderate sensitivity (63%) and high specificity (100%) of Hoover's sign for a diagnosis of functional weakness.
References[edit | edit source]
- Koehler, P.J., Okun, M.S. (2004). Important observations prior to the description of the Hoover sign. Historical Neurology. 63: 1693-1697.
- Larner, A.J. (2001). A Dictionary of Neurological Signs. Springer.
- 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.
- Shams T, Ashraf F, DeGeorgia M. Charles Franklin Hoover and the Hoover Sign (P04. 006). Neurology Apr 2012 78:1
- 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.
- 1. Koehler PJ, Okun MS. Important observations prior to the description of the Hoover sign. Neurology. 2004;63(9):1693–7.
- 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.
- 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.
- Kaufman, D.M. (2007). Clinical neurology for psychiatrists: 6th edition. Elsevier Health Sciences. p. 20.
- online video, http://www.youtube.com/watch?v=F4Fk_ZzCX6A, last accessed 6/2/2009
- Clinically Relevant Technologies, http://www.youtube.com/watch?v=QqQuPL36loM, last accessed May 2011
- Ercoli T, Stone J. False Positive Hoover's Sign in Apraxia. Movement disorders clinical practice (Hoboken, NJ). 2020;7(5):567–8.
- 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.
- 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.
- 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.