Functional Weakness and Sensory Disturbance J Stone, a Zeman, M Sharpe

J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.73.3.241 on 1 September 2002. Downloaded from 241 PHYSICAL SIGNS Functional weakness and sensory disturbance J Stone, A Zeman, M Sharpe ............................................................................................................................. J Neurol Neurosurg Psychiatry 2002;73:241–245 In the diagnosis of functional weakness and sensory The history of the onset of the symptoms can disturbance, positive physical signs are as important as be particularly helpful. Patients with functional weakness will often describe symptoms sugges- absence of signs of disease. Motor signs, particularly tive of dissociation at the onset—either occurring Hoover’s sign, are more reliable than sensory signs, but in combination with panic, a physical trauma none should be used in isolation and must be (often minor), or spontaneously. In this context, “dissociation” refers to the weakening or loss of interpreted in the overall context of the presentation. It the normal sense of ownership of one’s actions should be borne in mind that a patient may have both a and sensations. Descriptions suggestive of disso- functional and an organic disorder. ciation include: “the leg felt as if it was not connected to me”, “I felt far away”, or “I was in a .......................................................................... place of my own”. ymptoms considered “functional,” “psycho- genic,” “medically unexplained,” or “hysteri- FUNCTIONAL WEAKNESS cal” account for up to one third of new refer- Preliminary observation S The physical assessment of functional weakness rals to neurology outpatient departments. Complaints of weakness or difficulty walking, should begin as the patient gets up from their often in combination with sensory disturbance, chair in the waiting room and end as they are represent a significant subgroup of these symp- leaving the consulting room (or the hospital). The toms. Despite their frequency in clinical practice, primary objective is to look for evidence of incon- descriptions of the diagnosis and management of sistency. It may be particularly helpful to watch the these problems are not easily found in textbooks patient: of neurology. Although elements of the history • Taking their clothes off or putting them on. may be helpful, physical signs are often of crucial • Removing something from a bag and replacing importance in the diagnosis of functional weak- it (for example, a list of medicines). ness. • Walking into the room as compared with walk- In this article, we describe what is known and ing out of the room (and sometimes out of the what is not known about the physical diagnosis of outpatient building). functional weakness, functional gait disturbance, and sensory disturbance. Where evidence is avail- Hoover’s sign able, we have referred to it. Otherwise, we have had to rely on our own clinical and research The test http://jnnp.bmj.com/ experience with these patients. We wish to Hoover’s sign is the most useful test for functional emphasise the importance of the following two weakness and the only one that has been maxims: subjected to scientific study with a neurological control group.23 It is a simple, repeatable test • Look for positive evidence of a functional which does not require skilled surreptitious disorder as well as the absence of signs of observation. The test relies on the principle that organic disease. virtually everyone, whether they have a disease or • Be prepared to make two diagnoses in some not, extends their hip when flexing their contra- on October 1, 2021 by guest. Protected copyright. cases: one of disease and one of varying degrees lateral hip. This finding is thought to be a result of of functional weakness (or functional “over- the crossed extensor reflex, described by lay”). Sherrington,4 which enables normal walking, and is present even in decorticate animals. The test as described by Hoover in 1908 5 can be performed in BEFORE THE PHYSICAL DIAGNOSIS two ways: A careful history is essential. In particular, the presence of multiple symptoms, depression or 1. Hip extension—In patients with functional See end of article for anxiety (particularly panic), or a history of several weakness a discrepancy can be observed between authors’ affiliations previous functional symptoms or surgical opera- their voluntary hip extension (which is often ....................... tions without positive pathology raise the likeli- weak) and their involuntary hip extension when Correspondence to: hood that the primary symptom is functional.1 the opposite hip is being flexed against resistance Dr J Stone, Department of Childhood adverse experience, personality fac- (which is normal). This test is illustrated in fig 1. Clinical Neurosciences, tors, having a model for the illness, a recent life It is important when testing involuntary hip Western General Hospital, extension to ask the patient to concentrate hard Edinburgh EH4 2XU, UK; event, secondary gain (financial and otherwise), [email protected] and illness beliefs may all be relevant to manage- on the good leg. ment, but not enough is known about these 2. Hip flexion—The opposite test, where hip flexion Received 18 April 2002 Accepted 3 May 2002 factors to allow them to be used in making the in the weak leg is tested while the examiner’s ....................... diagnosis. hand is held under the good heel is also described, www.jnnp.com J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.73.3.241 on 1 September 2002. Downloaded from 242 Stone, Zeman, Sharpe Figure 1 Hoover’s sign. (A) Hip extension is weak when tested directly. (B) Hip extension is normal when the patient is asked to flex the opposite hip. although has not been adequately evaluated. In this test the weakness, back pain, or no weakness produced similar absence of downward pressure in the good leg indicates a lack results.3 These studies were not blinded and do not measure of effort transmitted to either leg. the reliability of the test as used in the real world but do pro- Head described an additional variant in which the patient lies vide preliminary support for its use. on their front and is asked to extend their good hip while hip flexion is tested in the weak leg.6 Hoover’s test in the arms? Hoover described a similar phenomenon of “complementary Caveats opposition” in the arms. In this test, flexion against resistance False positives of an arm stretched out in front of the patient can produce • Pain in the affected hip may produce greater weakness on involuntary extension of the other arm. Analysing this direct than on indirect testing as a result of attentional phenomenon, Ziv et al obtained results comparable to those in 2 phenomena (related to pain rather than weakness). the legs. A related test of shoulder adduction is also described based on the principle that often when shoulder adduction is • A patient with organic disease may be trying to “help” you tested on one side, the contralateral side will also adduct.9 http://jnnp.bmj.com/ or “convince” you that they are ill. • There are insufficient data to rule out the possibility that a Collapsing weakness similar phenomenon may sometimes occur as a direct result A common finding in functional weakness is that of “collaps- of organic brain disease, for example multiple sclerosis. ing weakness,” in which a limb collapses from a normal posi- tion with a light touch (or occasionally, even before your hand False negatives has touched the limb). Normal power can often be achieved The patient may not be concentrating sufficiently on flexing transiently with encouragement. The instruction, “At the their good hip when you are testing involuntary extension of count of three, stop me from pushing down . ..” is often help- on October 1, 2021 by guest. Protected copyright. the weak hip. If so, you should find that flexion in the good leg ful in this respect. The intuitive explanation of collapsing is stronger when you remove your hand from under the weak weakness is that the patient simply isn’t trying. While this is leg. sometimes undoubtedly the case, in our experience the The following should also be remembered: performance of most patients with functional weakness • Hoover’s test does not differentiate functional or hysterical seems to get worse the more effort and attention they expend problems from malingering or simulated weakness. on the limb. • Your patient may have a combination of organic and func- The problem with collapsing weakness is that, like Hoover’s tional weakness. Indeed, organic disease is a risk factor for sign, it may also occur for reasons unrelated to functional the development of functional symptoms.78 weakness. These include an inability to understand the instruction, pain in the relevant joint, being generally unwell, Validity and a misguided eagerness of some patients to “help the doc- Hoover’s test has been examined in two controlled studies. In tor” or “convince the doctor,” even though they actually have the first, computer myometry demonstrated a significant dif- organic disease. ference in the “involuntary to voluntary hip extension ratio” in seven patients with non-organic weakness compared with Validity 10 controls with organic weakness.2 An equivalent study using Collapsing or “give-way” weakness has been investigated simple weighing scales where nine subjects with functional neurophysiologically.10–12 Van der Ploeg showed that in weakness were compared with control groups with organic functional weakness the force generated by a limb at the point www.jnnp.com J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.73.3.241 on 1 September 2002. Downloaded from Functional weakness and sensory disturbance 243 Figure 2 Functional monoplegic gait. In both cases the leg is dragged at the hip. External or internal rotation of the hip or ankle inversion/eversion is common. the examiner overcomes the muscle force is unusually high Sternocleidomastoid test when compared with the force generated by normal Recently Diukova et al reported that 24 of 30 patients (80%) 11 resistance.

Load more