Spurious neurological signs and symptoms in children

Physicians are usually trained in tertiary care settings, which attract patients with unusual and rare diagnoses. As the focus of training programs has appropriately shifted to meet the educational needs of trainees, attending faculty have tried to ensure that their residents and fellows are exposed to the most remarkable patients. This has resulted in physicians who are extremely knowledgeable about rare and unusual cases, but have had less exposure to the more mundane disorders that comprise the majority of patients. This sometimes results in a diagnostic approach that is dependent on the use of extensive tests to exclude rare diagnoses before physicians conclude that the diagnosis is either commonplace or nonorganic. The approach to symptoms that are nonorganic may be particularly difficult, and frequently results in unnecessary and expensive investigations. Undertaking tests can also be counterproductive because they may indicate to the patient and family that you suspect some underlying pathology. The subsequent failure of the tests to find ‘the answer’ might undermine the family's confidence in your reassurance. In the present commentary, we review some clinical skills that have been neglected and ‘nearly forgotten’, but are often helpful in reaching the appropriate diagnosis for patients with neurological symptoms that do not have an organic basis. We focus on gait disorders, paralysis, sensory disturbances and visual impairment because these are the most typical functional neurological disorders. The terminology used when dealing with patients whose symptoms are not caused by disease has been controversial. The term ‘hysteria’ is often regarded as pejorative and has fallen out of favour. Other suggested terms have included functional illness, psychosomatic illness, nondisease, persistent somatization, nonorganic disease and pseudoneurological illness. Alternative terms used are conversion disorder, malingering and fictitious, feigned or simulated illness. Whatever term is used, it is essential to make an early diagnosis and to devise a plan that ensures the patient's return to well-being (1). The history of functional disorders is often striking and dramatic, with symptoms that usually appear suddenly and are often maximal at their onset. The details of the history, however, may be vague and inconsistent. The patients, who are usually older than 10 years of age, are often prone to suggestion during both the history and the physical examination. La belle indifference, or apparent indifference to symptoms, is unreliable as a sign of a nonorganic disorder in children. During your assessment, it is essential to spend time with the child and parents separately because aspects of the history may only be divulged in private. Your history and examination must always respect the child's dignity, but it is critical to make the parents aware that your findings can only be explained by a functional disorder. It may be helpful to demonstrate the pertinent findings to the parents after you have explained your diagnosis and the nature of their child's findings. It is also critical to remember that children with nonorganic symptoms often choose their complaint based on genuine symptoms and experiences in their own lives, or in those of close family members or friends. For example, children experiencing nonepileptic seizures often also have epilepsy, and those with hysterical blindness may have refractive errors. Functional gait disorders are common nonorganic complaints. The gait is often bizarre and lurching. The child may feign weakness by walking with the hips and knees partially flexed, which requires considerable strength. In contrast, children with true leg weakness are more likely to hyperextend the knees (termed back-knee). Alternatively, they may drag their feet along the ground as they shuffle forward – a gait that is not found among children with organic disorders. Patients with functional gait disorders may also tend to push the involved leg. In contrast, patients with genuine gait disorders usually drag their weak or spastic leg. When patients with a functional disorder do drag the leg, they tend to do so in an exaggerated way, as though they are ‘dragging a cannon ball behind them’. Ask yourself whether the child's gait resembles any of the gait disorders you have seen. Does the patient have a Trendelenburg gait associated with proximal weakness, the high-stepping gait of distal weakness that is seen with neuropathies, or the spastic gait seen with hemiplegia, diplegia or quadriplegia? Is the gait ataxic, which is usually associated with a wide-based stance? In contrast, the pseudoataxic gait is usually characterized by a stance in which the feet are maintained close together; the child may demonstrate impressive athletic abilities as he walks with a stumbling gait while crossing one leg over the other in successive steps without falling. When patients do fall, they ensure that there is a physician or parent available to catch them, or that they will fall on a soft object. Try to mimic the gait; if this is challenging, suspect a functional disorder. If you do suspect a functional gait disorder, the following techniques may be helpful in confirming your suspicion and in convincing the parents of your conclusions: By holding the patient's hand, you can dictate the speed of walking. Vary the speed. A patient with a functional disorder will have difficulty maintaining the motor programming needed for their faulty gait. While walking with the patient, ask them to undertake an age-appropriate cognitively challenging task. Because maintaining a functional gait disorder requires concentration, the gait will vary while the competing task is being performed. For patients who need support to walk, vary the amount of support given. Distract the child with conversation and, as you move from the patient's right to left side, briefly remove all support. With the patient supine, test the same muscle groups that appear abnormal while walking. In functional disorders, there is usually a discrepancy between the leg movements while supine and walking. Ask the patient to undertake different tasks with the same limb. Walking on the toes and heels will often change the functional gait pattern. Similarly, duck-walking (with the knees and hips flexed as far as possible) will frequently expose the neurological inconsistencies of the gait. Children with functional gait disorders are usually better able to propel themselves backwards and forwards in a swivel chair with wheels (2). In contrast, patients with true gait disorders perform equally well (or badly) when walking or in a chair. If the gait appears spastic, expect associated neurological findings such as hyper-reflexia or extensor plantar responses. Pseudoparalysis, or the diminished ability to move a limb, usually involves the legs, and is not associated with urinary or bowel dysfunction. The weakness usually fluctuates over time and is not consistent with the anatomical distribution expected from a neurological lesion. The patient may move the affected limb during sleep, in response to noxious stimuli, during ‘automatic’ behaviours (eg, dressing) or when covertly observed. Watch how easily the patient is able to roll over and move in bed. Look for expected objective findings such as atrophy, hyper-reflexia or extensor plantar responses. Helpful techniques in exposing functional paralysis include the following: In functional disorders, the weak limb(s) maintain their position transiently after support is removed. Thus, when the weak leg is lifted from the bed, it may hover briefly after you suddenly move your hand away. The amount of weakness is inconsistent and the strength varies with the resistance offered in your examination. For example, patients may only be able to lift the leg three inches off the bed, irrespective of the amount of resistance you provide. Hoover's sign relies on the principle of synergistic contraction. With the patient supine, hold your hand under the heel of the ‘good’ leg and ask the patient to raise the ‘paralyzed’ leg off the bed. In true paralysis, there will be involuntary downward pressure from the ‘good’ leg. If there is no downward pressure, the patient is not trying to raise the bad leg and the diagnosis is functional weakness. For patients with apparent complete paralysis of a leg, the Spinal Injuries Center test may be helpful (3). In the test, the patient lies supine and you passively flex the knees with the feet remaining on the examining table. When you gently release the knee, those with feigned paralysis may maintain their position, while the leg of those with real paralysis will fall laterally. Normally, there is a ‘rebound’ movement of a limb when the resistance you provide is suddenly removed. This also occurs in weak limbs but is often absent in those with pseudoweakness. For patients who present with wrist drop, ask them to make a fist. In those with pseudoparalysis, the wrist will extend involuntarily. For patients experiencing hand weakness, ask them to grip your fingers. As you quickly pull fingers free, those with hysterical weakness usually briefly tighten their grip. If the whole arm is reportedly paralyzed and spurious findings are suspected, hold the arm above the supine patient's head and suddenly release it. In pseudoparalysis, the arm will fall but will move to avoid hitting the face. While the patient is standing, abduct the arm and observe how quickly it falls as you let go. In children with functional weakness, the arm will fall either faster than can be explained by gravity or will hover briefly before falling. Ask the patient if they can imagine touching their nose with the good hand and then with the paralyzed hand. If they cannot imagine using the ‘bad’ hand, the diagnosis is functional. Test the patient's strength simultaneously in both arms as quickly as possible moving distally from the shoulders. It is difficult for the patient to ‘plan’ their response and the good side may also appear weak during some tests such as finger strength. While standing behind the patient with the paralyzed arm that is hanging limply at their side, shake the child's shoulders back and forth. In true paralysis, the arm will flail back and forth. If the ‘paralyzed’ arm remains tightly held against the body, it has normal strength and tone. Paediatric patients may present with either positive (eg, tingling) or negative (eg, loss of feeling) sensory complaints. Symptoms seldom follow the distribution of either dermatomes or peripheral nerves. The patient with functional sensory loss often presents with a distal loss of sensation, which is asymmetrical in the two limbs. In contrast, the glove and stocking sensory loss in diffuse neuropathies, such as Charcot-Marie-Tooth disease, is relatively symmetrical. Pseudosensory symptoms tend to follow a sharply demarcated distribution, which often conforms to the individual's concept of anatomy and is demarcated at joints, skin creases or in the midline. Midline demarcation only occurs in patients experiencing functional sensory loss due to the paramedian sparing caused by the interdigitation of the peripheral nerves across the midline. Patients may have a flagrantly bizarre distribution of sensory loss (eg, from the elbow to the wrist, with sparing of the hand). Functional sensory loss tends to involve all modalities together, with a sharp marginal junction with the area that has intact sensation. In patients with genuine sensory loss, there is an area of reduced sensation between the normal and abnormal areas, with the different modalities dropping out at slightly different levels. Always examine sensation with the patient's eyes closed. The following techniques may be helpful: Ask the patient to say “yes” when you touch them and “no” when you do not. Many children with functional sensory disorders will report “no” for stimuli within the ‘affected’ area. For patients who report sensory loss, ask them to say “yes” when they perceive the stimulus as you successively touch their skin starting within the area of reduced sensation and moving toward the area of intact sensation. If you vary the starting point and the speed at which you move the stimulus, and ‘zigzag’ your way across the limb, the patient will have difficulty reporting a consistent area of sensory loss. By marking the skin to define reported areas of sensory loss, parents can see the variability and inconsistency. With the arms extended, ask the patient to put their index finger on the tip of their nose or, if supine, to put their heel on the opposite knee. With the eyes closed, these tasks depend on intact proprioception. Test sensation with the hands clasped and crossed. Patients with functional sensory deficits of the hand and forearm have difficulty identifying right from left in this position. Test vibration over a bone that crosses the area of sensory loss. Because bone conducts vibration, an inability to perceive the vibration in the area of reduced sensation confirms a nonorganic diagnosis. For example, if there is reported loss of sensation on the left side of the forehead, patients who are unable to feel the vibration from a tuning fork placed just left of the midline on the forehead but who can feel it just to the right of the midline, have a functional disease. Draw figures (such as a number or a circle) on the patient's skin, with part of the figure extending into the area with sensory loss. Patients with functional disorders will usually identify the figure, even though crucial parts were drawn in the area of ‘no sensation’. Retest thermal sensation during sleep by placing a cold object on the forehead or limb. Complete blindness, or ‘bilateral amaurosis’, of sudden onset with preserved pupillary reactions is almost always psychogenic. Sudden, bilateral, occipital lesions should be considered but are extremely rare. Children with feigned blindness do not hurt or injure themselves; surreptitious observation of the child will often reveal normal visual abilities. When patients present with diplopia, the differential diagnosis varies from potentially very significant conditions (such as brain tumours inducing sixth nerve palsies) to hysteria. The following strategies are particularly useful in demonstrating the functional basis of visual complaints. Perform the optokinetic nystagmus test. Hold a striped cloth (preferably) or a 12-inch ruler in front of the child's eyes, and move it from one side to the other. The normal response, which requires fixation on the target, consists of smooth pursuit of the eyes in the direction that the stripe is moving. As the stripe moves beyond the limit of gaze, the eyes rapidly return to midline to focus on the next stripe or target. If optokinetic nystagmus is present, the child is able to see. The absence of optokinetic nystagmus may reflect visual loss, inattention or the purposeful avoidance of near fixation. For children who complain of monocular blindness, ask them to read a page with small print while you hold a pencil vertically between the patient and the page. Those with true monocular blindness will be unable to read some words, while those with hysterical symptoms will be able to read ‘around’ the pencil. Visual fields are normally cone shaped. They expand as the distance from the patient increases. In patients with functional disease, the visual field restriction remains constant despite the examiner's distance from the subject. Test the near visual fields through confrontation and then repeat the examination after taking three to four steps backward. Patients with functional tunnel vision will not have the expected enlargement of the visual field. Despite the reported severe concentric limitation in vision, children with functional disorders usually demonstrate no associated disability with walking and seldom, if ever, trip over obstacles. Ask the patient to demonstrate how they see the two images of a pen by providing them with two pens. First, hold a pen in the vertical orientation and ask the child to demonstrate what he/she sees. Most children with functional diplopia will demonstrate that they see the two images side-by-side and parallel to each other. Next, hold the pen horizontally; most children with functional diplopia will demonstrate that they now see the images in a horizontal direction but still exactly parallel. In real diplopia, the images will be parallel in only one direction. Children who have functional diplopia may still see double when one eye is closed or occluded. Monocular diplopia is exceedingly rare and occurs only with significant ocular disease such as corneal distortion. Children with disease-based ptosis usually try to compensate for the ptosis by raising their eyebrows. In contrast, those with functional ptosis usually lower the eyebrows to achieve the ptosis. The suspicion of functional illness should not be based on an array of normal tests but, rather, on the elucidation of signs and symptoms that are exclusively consistent with a nonorganic etiology. The techniques outlined in the presnt commentary are among the more useful clinical tools to help reach the appropriate diagnosis for patients with neurological symptoms that do not have an organic basis.

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