Psychogenic Dystonia and Reflex Sympathetic Dystrophy

Anette Schrag

ABSTRACT

Dystonia was for many years misdiagnosed as a psychogenic condition, leading to inappropriate management strategies in a considerable number of patients. As a result, many neurologists are currently reluctant to make a diagnosis of psychogenic dystonia (PD), and this condition is now probably underrecognized. This is particularly so as dystonia largely remains a clinical diagnosis, and as unusual presentations can make the differentiation of neurologic disorders from PD very difficult. PD is typically classified as a secondary dystonia, but routine investigations are usually normal. Specialized neurophysiologic investigations show abnormalities in groups of patients with neurologic dystonia, but due to their insufficient sensitivity and specificity, these tests are not useful in the diagnosis of individual patients. However, in PD, careful psychiatric assessment and neurologic examination often reveal previous somatizations, psychiatric comorbidity, psychological stressors, and nonorganic signs. Furthermore, features of inconsistency over time or during examination, or of incongruency with typical presentations of dystonia (which should be judged by a neurologist with experience in movement disorders) are suggestive of this diagnosis, and allow PD to be diagnosed using defined criteria. Controversial patients are those with dystonia developing within days of a peripheral injury. Such dystonia is often fixed and may be associated with features of complex regional pain syndrome (CRPS) type I. Fixed dystonic postures are a common manifestation of PD and, although they can be seen following brain lesions, they are not seen in idiopathic dystonia. Controversy exists whether this syndrome of posttraumatic dystonia is due to abnormal cortical reorganization from a peripheral injury—akin to amputation stump movements—or whether at least a large proportion of these patients suffer from a psychogenic movement disorder, as suggested by the high proportion of nonorganic signs and associated clinical and psychiatric features.

INTRODUCTION

Although idiopathic torsion dystonia was considered an organic condition in its first descriptions (1,2), only in the last decades has it been universally considered a neurologic rather than a psychiatric disorder (3,4). Dystonias were, therefore, for many years attributed to psychological causes, resulting in unnecessary and unhelpful treatment strategies and considerable psychological consequences for sufferers and their families. As a result of this long history of misdiagnosis, there has been considerable reluctance among neurologists and psychiatrists in making a diagnosis of PD. However, the pendulum has perhaps swung the opposite way, and PD is now often underdiagnosed.

Overall, PD is a rare cause of dystonia and represents only approximately 5% of patients with dystonia, but among psychogenic movement disorders, dystonia accounts for approximately 20% to 50% of cases (5). While the term “psychogenic” is somewhat controversial, implying a psychological causation which cannot always be demonstrated, the term “psychogenic” contrasting with “organic” has been used in the literature to distinguish such patients from those with neurologic disorders. For the purpose of this chapter, I will refer to this perhaps overly simplified classification, which will be discussed elsewhere in this book.

DIAGNOSIS

Diagnostic Difficulties

The above diagnostic uncertainties reflect the considerable difficulties in making a diagnosis of PD. The definition of dystonia is not particularly helpful in making this diagnosis as it is descriptive, defining dystonia as “abnormal muscle contractions, often holding a body part in an abnormal position, that may be repetitive or tremulous” (6). This definition clearly encompasses PD as the cause for the abnormal muscle contraction. There is a plethora of conditions that can cause dystonia, and these have been classified by Fahn and others (6). The primary dystonias are those with no identifiable cause, and are often due to a genetic abnormality; dystonia-plus includes dystonias associated with other neurologic abnormalities such as myoclonus or parkinsonism; the heredodegenerative dystonias are heredodegenerative conditions in which dystonia may be part of the presentation; and secondary dystonia is due to a known symptomatic cause such as lesions in the basal ganglia. PD is classified in this last category.

There are a number of factors that contribute to the difficulties in differentiating psychogenic from other types of dystonia. The diagnosis relies almost entirely on clinical history, examination, and clinical judgment. There is no biologic marker or pathognomonic sign that in isolation allows an unequivocal diagnosis of PD, and, conversely, with the exception of a few available genetic tests for some types of dystonia, there is no biologic marker for primary dystonia. Even for secondary dystonia, a cause cannot always be found, and in at least two thirds of patients with organic dystonia, investigations are normal. It is true that an organic condition causing secondary dystonia must always be excluded by appropriate investigations, but the diagnosis of dystonia in the majority of cases remains a clinical one.

In addition, organic dystonia and PD both have a wide and overlapping spectrum of presentations, which often includes bizarre and unusual presentations that may appear inconsistent and be unique to individual patients. The differentiation of these conditions based on clinical features thus requires extensive experience with the wide spectrum of presentations of dystonia.

Finally, organic dystonia and PD can occur together, and a PD may have developed on top of an organic condition. Although this co-occurrence is probably not quite as frequent as the co-occurrence of epileptic and nonepileptic attacks [which is estimated to be up to 25% (7)], functional overlay in an underlying organic condition is always a possibility.

Despite these caveats, a diagnosis of PD is possible and can be made when (a) appropriate investigations have been negative, and (b) positive findings allow a diagnosis based on standardized diagnostic criteria (see below).

Clinical Clues

Characteristics of Dystonia

The characteristics of dystonia contribute to the confusion between organic dystonia and PD. Dystonia is often bizarre and may appear inconsistent, as it may be mild or absent at rest, worsen or only be present with action, and respond to sensory tricks (e.g., improvement of torticollis when the chin is touched—geste antogoniste); it may also only be apparent when specific actions are performed, for example, when walking forward but not when walking backward, when walking but not when running, when writing but not when using a knife and fork, or when playing an instrument but not during other actions involving the same muscles. However, primary dystonia, which is the main area of diagnostic difficulty, has characteristic patterns that help in the differentiation of primary dystonia from PD: whilst only some actions may trigger the dystonia, these actions will reliably do so; the pattern of abnormality is consistent over time with little change in its distribution and phenotype (although it may progress and spread); and the distribution and progression of primary dystonia is characteristic at different age groups. Thus, while childhoodonset primary dystonia typically starts in the lower limbs and slowly spreads to other body parts, primary dystonia with onset in adulthood does not usually affect the legs first, and typically remains restricted to the craniocervical region or the upper limbs. In addition, the onset of dystonia is usually gradual, and progression is slow over several months or years; there is not usually pain (with the exception of cervical dystonia, which can be painful), and it is typically mobile (and often absent at rest) and remains so until very late stages of advanced disease.

The most helpful features in making a diagnosis of PD are those that do not fit with these recognized patterns of
primary dystonia, and are therefore incongruent with primary dystonia. Positive features for a PD thus include dystonic postures that start abruptly and progress rapidly to severe disability, often with a fixed dystonic posture without return to the neutral position at rest from the beginning. There may be marked fluctuations with exacerbations and (almost) complete remissions, which are rare in primary dystonia. The presentation may have been inconsistent over time, with a complete change in the nature of the abnormal movement or the development of other psychogenic movement disorders. Onset in the leg in an adult also suggests a PD once a symptomatic cause has been excluded, and so does a lack of sensory tricks and the presence of severe pain. However, none of these features are specific for PD. They can also occur in other secondary dystonias, and other secondary causes, such as a basal ganglia lesion, must be excluded before a diagnosis of PD is made.

Additional Medical History

The past medical history may also be revealing. Episodes of a different movement disorder in the same limb or another limb may have occurred with complete or partial remissions. There may also be a history of nonepileptic seizures or of other somatizations, putting the current presentation in the context of a wider somatoform illness. Previous somatizations may include other “functional” syndromes, such as fibromyalgia, atypical chest pain, irritable bowel syndromes (8), or other medically unexplained symptoms which may have resulted in a number of investigations and treatments, including operations (9). For example, inflammation may not have been found in an appendectomy performed for severe abdominal pain, or an episode of unexplained prolonged fatigue may have occurred previously. While patients with somatoform illness often report a number of previous diagnoses or complaints, the somatoform nature often only becomes apparent when patients or their general practitioners are specifically asked about the outcome of investigations (10).

The history may also be informative in other respects. It may reveal abnormal illness behavior, for example, noncompliance with treatment, “splitting” behavior among the health professionals involved in a patient’s care, or “doctor-shopping.” Litigation or a compensation claim may represent a maintaining factor, or there may be obvious secondary gain. There may have been an obvious psychological stressor before the onset of the PD, suggesting a diagnosis of conversion disorder, or psychological trauma in the past history. However, this type of information may be misleading as psychological conflicts are common in the population, and the coincidence between past psychological trauma and the presentation may be spurious.

Examination

The physical examination concentrates on four aspects.

Absence of “hard” neurologic signs. Most neurologists would be reluctant to make a diagnosis of a PD in the presence of “hard” neurologic signs. However, as mentioned above, psychogenic overlay may exist comorbidly with an underlying organic illness. This may occur for a variety of reasons, including the patient’s wish to demonstrate the extent of his or her ailments (e.g. patients with Parkinson disease referred for stereotactic surgery) (Anthony Lang, personal communication in October 2003), or when patients have had previous experiences with doctors who were unconvinced of the seriousness of the problem. In addition, secondary physical changes may have occurred following a longstanding PD with prolonged immobilization, including wasting, trophic changes, or even osteoporosis. Furthermore, pseudoneurologic signs are not uncommon, including pseudoclonus, abnormal reflexes in a rigidly held limb, or pseudobabinski (often as a delayed, prolonged plantar extension), which can mislead the examiner. Although the interpretation of such findings is difficult, the recognition of the possibility of a pseudoneurologic sign facilitates the recognition of a psychogenic disorder.
The presence of other nonorganic signs and findings, such as nonorganic weakness, nonanatomical sensory loss, resistance to passive movements, bouts of whole-body shaking, or an excessive startle response. There may be extreme slowness, which, unlike bradykinesia, is not fatiguing and without a decrement in the amplitude of the movement. There may be consistent past-pointing in an otherwise normal (sometimes excessively slow) finger-nose test, and other tasks may simply not be completed (e.g., stopping two inches early in the finger-nose test). The most useful sign is probably the Hoover sign, which has been shown to quantitatively differentiate organic and nonorganic weakness (11) (see Chapter 13). However, caveats apply to all nonorganic signs. For example, give-way weakness may be seen if the movement causes pain, and sensory disturbance not following a nerve or radicular distribution is common in Parkinson disease and often predates the onset of motor symptoms. In addition, classical signs such as midline splitting, splitting of vibration sense, and la belle indifférence have poor specificity and are therefore of limited value in assessing these patients (12). There may also be a discrepancy between objective signs and disability (e.g., patients with mild unilateral weakness who are bed- or wheelchair-bound or, conversely, patients with no use of both arms who manage at home on their own). Similarly, there may be a
discrepancy between subjectively reported symptoms and investigations that exclude a pathophysiologic correlate (e.g., normal sensory evoked potentials in a patient reporting total loss of sensation in a limb).
Features of a psychogenic movement disorder. There are a number of specific, positive features which suggest the diagnosis of a psychogenic movement disorder, including PD (see Chapter 13). These include fluctuations during the examination, particularly an increase of the dystonia with attention and suggestion, and a decrease with distraction; a changing pattern of frequency, amplitude, or pattern; the ability to trigger movements with unusual or nonphysiologic interventions (e.g., trigger points on the body, passive movements of another limb); and the character of the dystonia may be incongruous with the presentation of an organic dystonia. The last is an important criterion in differentiating psychogenic and organic dystonia, but requires considerable experience with the presentation of dystonia, and it is therefore generally agreed that this diagnosis should only be made by a neurologist with experience in these disorders. The most reliable feature allowing a confident diagnosis of a PD (or other psychogenic movement disorder), however, is a marked and persistent improvement with psychotherapy, placebo, or suggestion. It is important that this response is significant and sustained, as placebo effects are wellrecognized to improve movement disorders transiently up to 30% (13).
Scars from multiple operations or self-inflicted injuries. The physical examination may reveal multiple scars from multiple previous operations, which may be due to previous abnormal illness behavior or somatization, or self-inflicted injury, suggesting an underlying psychiatric disturbance.

Psychiatric Assessment

There are few studies assessing psychiatric aspects specifically in PD. However, psychiatric aspects of psychogenic movement disorders, which are discussed in detail elsewhere in this book, also apply to PD. In brief, “psychogenic movement disorders” summarize, from a neurologic point of view, a mixture of conversion disorders, somatoform disorders, factitious disorders, and malingering. While many patients with PD report an entirely normal mental state (and are often reluctant to see a psychiatrist), psychiatric assessment can provide useful information and potentially allow underlying psychological causes to be addressed. In particular, concurrent psychiatric comorbidity, which most commonly comprises depression, anxiety disorders, and personality disorders (5,14, 15, 16), may be diagnosed (and treated); previous episodes of psychiatric illness, behavioral abnormalities, and self-harm may be revealed; psychological stressors as precipitating or maintaining factors identified and addressed, or a history of psychological trauma, including childhood sexual, physical, or emotional abuse, uncovered. Whilst these features may support a diagnosis of a psychogenic problem, none of them is specific for this and may be coincidental. Nevertheless, addressing these issues may improve patients’ overall quality of life and lead to improvement of the physical presentation of a PD in a proportion of patients.

The differing characteristics of psychogenic and primary dystonia in the past medical history, history of dystonia, physical examination, and response to treatment are listed in Table 8.1, modified from Lang (17).

Diagnostic Criteria for PD

None of the features listed above is specific for PD. Not only does psychiatric comorbidity, a history of psychological stressors, or childhood abuse occur in a high proportion of people with neurologic illness or the general population, but psychogenic signs may occur in organic illness, and single episodes of somatization occur in a high proportion of people without reaching the diagnostic criteria for somatization disorder (18). However, some of these features of PD and psychogenic movement disorders in general are more suggestive of this diagnosis than are others, and the presence of several of these features increases the likelihood of this diagnosis. Based on these features, the diagnostic classification of psychogenic movement disorders, which reflects the degree of diagnostic certainty of this diagnosis, was modified for PD (19) (Table 8.2).

COURSE OF ILLNESS

As mentioned above, many patients with PD have a history of previous somatizations or other psychogenic movement disorders, which may have remitted spontaneously or with treatment. There may also have been paroxysmal exacerbations and remissions, but in others no fluctuations occur and the disorder remains stable over years. The prognosis is generally poor, with the majority of patients suffering long-term disability. However, outcome varies considerably, and while the PD remains stable in most patients, some develop other psychogenic movement disorders, replace the dystonia with a mental disorder, or experience complete remission of symptoms (14,17,20).

Investigations

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