Journal of Postgraduate Medicine
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CLINICAL SIGN
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Year : 2013  |  Volume : 59  |  Issue : 3  |  Page : 216-217  

Hoover's sign

R Sekerci, L Sarikcioglu 
 Department of Anatomy, Akdeniz University Faculty of Medicine, Antalya, Turkey

Correspondence Address:
L Sarikcioglu
Department of Anatomy, Akdeniz University Faculty of Medicine, Antalya
Turkey




How to cite this article:
Sekerci R, Sarikcioglu L. Hoover's sign.J Postgrad Med 2013;59:216-217


How to cite this URL:
Sekerci R, Sarikcioglu L. Hoover's sign. J Postgrad Med [serial online] 2013 [cited 2020 Mar 29 ];59:216-217
Available from: http://www.jpgmonline.com/text.asp?2013/59/3/216/118041


Full Text

 Historical Background



Weakness that is clinically inconsistent with any recognized neurological disease is a common problem for Neurologists. Although it has been considered to have a physical cause, a loss or disturbance of normal function may be attributed to a psychological cause. Neurologists use physical challenges to elicit motor behaviors or sensory reports discrepant with patterns seen in genuine neurologic diseases. [1] Several terms such as "non-physiological," "nonorganic," "functional" or "hysterical" have been employed by neurologists to label findings that imply a voluntary or nonsensical component. [1]

Dr. Charles Franklin Hoover (1865-1927) is remembered primarily for his contributions in distinguishing "organic" weakness from "functional" (i.e., psychogenic) weakness of the lower extremities. [2] In 1908, Hoover published an article in journal of the American medical association in which he described his sign for testing this functional weakness. [3] He described it as follows: "If a normal person, lying on a couch in the dorsal position, be asked to lift the right foot off the couch with the leg extended, the left heel will be observed to dig into the couch as the right leg and thigh are elevated. If you place your hand under the Achilles tendon of the left side and sense the muscular resistance offered by the left leg you will observe that the left heel is pressed onto the couch with the same force, which is exhibited in lifting the right leg off the couch. In other words, the left heel is employed to fix a point of opposition against the couch during the effort to lift the right leg. This will always occur if the healthy person makes a free and uninhibited effort to lift the right leg." [3] Not long after Hoover's publication, Philip Zenner was able to confirm Hoover's findings in the same journal. [4]

Charles Franklin Hoover was an outstanding scientist of his time and was born in 1865 in Miamisburg, Ohio. He graduated from Harvard University in 1892. [5] Like some wealthy American students of his era, he spent 5 years in fashionable academic centers in Europe. He worked under Edmond von Neusser (1852-1912) at the University of Vienna and Friedrich Kraus (1858-1936) at the University of Strasbourg. At one time, he also spent time in Paris at the Clinic of Pierre Marie before returning to Cleveland. He was appointed the 1 st full-time Professor of Medicine at Western Reserve University serving from 1925 until his death in 1927. [2]

 Anatomy and Physiology



Hoover's sign is based on associated movements in the opposite leg. When a person flexes his/her own hip, the contralateral hip is extended [Figure 1]. [6] It is assumed that this is a result of the "crossed extension-reflex" described by Sherrington. [4],[7] The reflex is active in normal walking and can also be demonstrated even in decerebrate animals. [4],[7] Walking is more complicated than it looks, but does rely on this basic response. The pathway for this reflex involves excitatory spinal interneurons, which conveys signals to multiple levels of the spinal cord before producing an antagonistic contraction in the opposite limb. [8]{Figure 1}

Classical textbooks explain the "crossed extension-reflex" by a noxious stimulation; however, changing the body position may also contribute to afferent arm of this reflex. A noxious stimulation activates pain fibers and the generated impulses are conveyed to the spinal cord through afferents, which send collaterals through the anterior commissure of the spinal cord that make multisynaptic connections with alpha motor neurons that innervate contralateral flexor and extensor muscles. This neuronal circuitry of the flexion and crossed extension reflexes permits extension on the limb contralateral to the site of noxious stimulation and the withdrawal (flexion) of the limb ipsilateral to it. [9] In other words as seen in the Hoover's sign, such synapse pattern to motor neuron enables to stabilize the contralateral side of the body (for instance, preparing the opposite leg to support the entire body weight when the other foot has lifted off the couch) to maintain balance of body in the frame of a synergist activity. [8] Although it looks very simple actions, these synergic actions are more complicated actions than those described by Sherrington.

 False Positives



Reasons for false positives of Hoover's sign are (i) pain in the affected hip, (ii) patient with organic disease may try to convince the examiner that he/she is ill. Patient's concentration on flexing his/her healthy hip when testing in voluntary extension of the weak hip may produce false negative result. [6] It should be kept in mind that Hoover's test does not differentiate functional or hysterical problems from malingering or simulated weakness. Some patients may have a combination of organic and functional weakness. [6]

 Validity and Quantification Efforts



Although Hoover's test is an easy test to perform, quantifications efforts have also been studied in the literature. A significant difference was discovered in maximal involuntary/voluntary force ratio between the "paretic" limbs in "non-organic" patients when compared with control subjects and/or "organic"patients. [10] Sonoo [11] compared sensitivity and specificity of the Hoover's test with his new sign, abductor sign, in a small sample of pseudohemiparetic patients. He reported his test as 100% accurate. [6] Recently, sensitivity and specificity of Hoovers sign was studied by McWhirter et al. [12] on 337 patients with suspected stroke, 124 of whom presented with leg weakness. They reported that sensitivity of Hoover's sign for a diagnosis of functional weakness in those who presented with leg weakness was 63% and specificity was 100%. Arieff et al. [13] examined several patients with functional weakness using electromyography and a set of bathroom scales to quantify the heel pressure during contralateral leg raising. Although, there are some quantification efforts we think that busy clinicians could not perform such quantification methods in this very easy test.

 Hoover's Sign in the Arms



In 1908, Dr. Charles Franklin Hoover had also observed a similar sign in the arm, but not consistently. He commented that the phenomenon of "complementary opposition" is also present in the movements of the shoulder. He described this fact as follows: "When the upper extremity is involved this sign is sometimes demonstrable on the normal arm, but another times it is wanting." Ziv et al. [10] investigated arm movements with a computerized quantitative method and found similar results to those in the lower limb. They questioned its usage into the clinical practice.

 Hoover's Sign in Daily Practice



Most clinicians, including neurologists, remember Hoover's sign as of value in ruling out only organic weakness; however, this sign can also be used as positive objective evidence in diagnosing mild cases of hemiparesis or weakness in the lower extremity. [13]

Hoover's sign is an easy sign to learn and use in clinical practice. It can be repeated and does not rely on skilled examination. Although Hoover's sign is a reliable indication of unilateral psychogenic weakness of the lower extremities, it can also be used to demonstrate to the patient their own potential for recovery. [6]

 Acknowledgement



The authors would like to thank Akdeniz University Research Fund for the financial support.

References

1Greiffenstein MF. Motor, sensory, and perceptual-motor pseudoabnormalities. In: Larrabee GJ, editor. Assessment of Malingered Neuropsychological Deficits. Oxford: Oxford University Press; 2007. p. 105.
2Caplan LR. Charles Franklin Hoover (1865-1927). J Neurol 2004;251:118-9.
3Hoover CF. A new sign for the detection of malingering and functional paresis of the lower extremities. JAMA 1908;LI: 746-7.
4Koehler PJ, Okun MS. Important observations prior to the description of the Hoover sign. Neurology 2004;63:1693-7.
5Shams T, Ashraf F, DeGeorgia M. Charles Franklin Hoover and the Hoover Sign. Neurology 2012;78:P04.006.
6Stone J, Zeman A, Sharpe M. Functional weakness and sensory disturbance. J Neurol Neurosurg Psychiatry 2002;73:241-5.
7Sherrington CS. Flexion-reflex of the limb, crossed extension-reflex, and reflex stepping and standing. J Physiol 1910;40:28-121.
8Williams PL, Warick R, Dyson M, Bannister LH. Gray's Anatomy. Edinburgh: Churchill Livingstone; 1989. p. 1035-42.
9Noback CR, Strominger NL, Demarest RJ, Ruggiero DA. The Human Nervous System: Structure and Function. New Jersey: Humana Press Inc; 2005.
10Ziv I, Djaldetti R, Zoldan Y, Avraham M, Melamed E. Diagnosis of "non-organic" limb paresis by a novel objective motor assessment: The quantitative Hoover's test. J Neurol 1998;245:797-802.
11Sonoo M. Abductor sign: A reliable new sign to detect unilateral non-organic paresis of the lower limb. J Neurol Neurosurg Psychiatry 2004;75:121-5.
12McWhirter 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;71:384-6.
13Arieff AJ, Týgay EL, Kurtz JF, Larmon WA. The Hoover sign. An objective-sign of pain and/or weakness in the back or lower extremities. Arch Neurol 1961;5:673-8.

 
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