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Psychogenic Movement Disorders
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19
Psychogenic Movement Disorders
Introduction
A common problem in neurology is the existence of disorders that cause neurologic symptoms, but do not have an identifiable neurologic basis. Many different terms have been used to describe these disorders, including “hysterical, functional, conversion disorder, and psychogenic.”1 These terms reflect the concept that an organic basis will not be found for the symptoms or that a psychiatric disorder is the primary substrate from which the atypical symptoms blossom. The concept of hysteria has been present in Western medicine for over 2000 years. Briquet in the 1850s and Charcot in the 1880s are generally recognized for their early work on disorders on the border between neurology and psychiatry and guiding them into modern medicine.2 The term conversion was first used by Breuer and Freud to describe the transformation of unresolved psychologic conflicts and unassimilated emotions into physical manifestations.2 Conversion disorders fall under the broader heading of somatoform disorders in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision.3 Diagnostic criteria for conversion disorder involve symptoms affecting voluntary motor or sensory functions suggesting a neurologic condition that are judged to be caused by psychological factors. These symptoms cause impaired function, are not intentionally produced, and cannot be explained after a thorough medical evaluation.3
Epidemiology The first U.S. description of conversion disorder in children consisted of 98 cases.4 Despite continued study, few data exist to estimate the population prevalence of conversion disorder in children in the United States. Prevalence of conversion disorder among children has been estimated at 2 to 4 per 100,000.5 Conversion disorder is a relatively common reason for presentation to movement disorders clinics. Among adults, estimates vary from 2% to 9% of patients.6,7 242
Common psychogenic movement disorders (PMDs) include dystonia, tremor, myoclonus, tics, hemiballismus, chorea, parkinsonism, and gait disorders. Although there are few data on these disorders in children, it has been estimated that 2% to 4% of children treated at movement disorder clinics have a PMD.8–10 Conversion disorder has been reported in children as young as 4 years, but most often occurs during the peripubertal years.2,7 For PMDs in children, the average age of onset is 12 to 14 years, with a range of 7 to 18 years.8–10 No children under age 7 years were reported in those three series. PMDs affect girls more than boys in a 3:1 to 4:1 ratio.8–10 One report indicated a 1:1 ratio of boys to girls in children 12 years of age or younger.9
Clinical Features of Psychogenic Movement Disorders In adults, the nondominant side of the body is more commonly affected, leading to theories of symptom origins in the right cerebral hemisphere.2 However, in children the dominant extremities are more likely to be involved. It has been speculated that this difference may be due to incomplete hemispheric lateralization in children.11 Regardless of underlying mechanism, the preferential involvement of the dominant extremities is a consistent finding in children with PMDs.9,10 The typical course of conversion symptoms in children is for the symptoms to resolve within 3 months from the time of diagnosis.12 The great majority of children have complete resolution of symptoms and recurrence of symptoms appears to be rare.13,14 Outcome of PMDs specifically has not been studied; long-term outcome is good in the majority of cases,10,15 but may be less good than for childhood conversion disorders more generally.10 However, these reports from specialty clinics may reflect an ascertainment bias. It is often possible to identify a specific precipitant for the conversion symptoms in children.13 In a study of 47 Israeli children with conversion disorder,
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Chapter 19 Psychogenic Movement Disorders
a specific reason for the conversion was discovered in 40.16 Among children with PMD, antecedent history of physical or emotional stressors is common, being reported in 53% to 69% of cases.9,10,15 Children with PMD commonly have coexisting impairment of mood, especially anxiety, depressed mood, or irritability,9,10 and “perfectionistic” tendencies are common.9,13
Pathophysiology There is emerging evidence that conversion disorders have a basis in altered brain function. One of the first studies to demonstrate this was a single-photon emission computed tomography (SPECT) study showing decreased regional cerebral blood flow in the thalamus and basal ganglia contralateral to psychogenic sensorimotor deficits in adults.17 An important finding of that study was that the contralateral basal ganglia and thalamic hypoactivation resolved after recovery. In adult subjects with conversion hemiparesis, cerebral blood flow responses in a motor imagery task were abnormally increased in the ventromedial prefrontal cortex and superior temporal cortex despite normal task performance.18 These studies and several other small studies using electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), positron emission tomography (PET), or SPECT have suggested that conversion disorders are associated with abnormal modulation of motor and sensory representations by affective or stress-related factors.19 To date, physiologic or imaging studies have directly investigated PMDs and no studies have included children. Nonetheless, these data can be taken as strong evidence for a neurobiologic basis for conversion disorders including PMDs.
Diagnosis At first glance, some organic movement disorders may appear to be psychogenic in origin. Historically, many physicians believed that Tourette syndrome and task-specific focal dystonias, such as writer’s cramp, were “hysterical.” Some movements related to organic movement disorders can be suppressed, including tics, tardive dyskinesia, parkinsonian rest tremor, and some choreas. Hemiballismus, brought on by brain injury or stroke, can begin precipitously and follow a static or diminishing course. Organic paroxysmal dyskinesias, by definition, occur and remit abruptly, and may be misdiagnosed as psychogenic. Rapid-onset dystonia parkinsonism may have abrupt onset and reach a stable severe plateau within days.20 Psychiatric dysfunction may be the initial presentation for diseases containing abnormal movements, such as Huntington’s disease and Wilson’s disease.
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BOX 19-1 Useful Clues for Diagnosing Psychogenic Movement Disorders in Children Historical Clues 1. Abrupt onset 2. Static course 3. Spontaneous remission or inconsistency over time 4. Remission when the child is not aware of being observed 5. Presence of secondary gain Clinical Clues 1. Inconsistent character of the movement (amplitude, frequency, distribution, selective disability) 2. Paroxysmal movement disorder 3. Movements increase with attention to the movement, or decrease with distraction 4. Ability to trigger or relieve the abnormal movements with unusual or nonphysiologic interventions (e.g., body trigger points) 5. False weakness or sensory findings 6. Deliberate slowness of movements 7. Entrainment 8. Functional disability out of proportion to examination findings Therapeutic Responses 1. Unresponsiveness to appropriate medications 2. Response to placebos 3. Remission with psychotherapy
Certain features appear to be consistent across the range of patients with PMD7,21 (Box 19-1). These clues to making the diagnosis of a PMD may be present in the history, in the physical examination, or in therapeutic trials. Although suggestive of a PMD, presence of these features alone does not confirm the diagnosis. Some of these features may be present in organic movement disorders, so care and further evidence is required for diagnosis.7 A thorough medical history including family history, physical examination, and in some cases diagnostic testing is necessary to arrive at a confirmed diagnosis of a psychogenic movement disorder. Conversion disorders and organic neurologic disease can coexist, most commonly in chronic relapsing diseases such as epilepsy. However, fewer than 10% of children diagnosed with conversion disorder have a preexisting physical disease.16 In adults, once a diagnosis of a functional, non-organic neurological disorder is made, new organic diagnoses rarely emerge, even when symptoms persist. A recent study in over 1000 adults judged by neurologists as having symptoms “unexplained by organic disease” found fewer than 1% had acquired a new organic disease diagnosis 18 months later.35
244 Section 5 Selected secondary movement disorders
Diagnostic Criteria for Psychogenic Movement Disorders Many physicians are reluctant to make the diagnosis of a conversion disorder. This also appears to be true of PMDs. The average time from onset of symptoms to diagnosis has been reported to range from several days to as long as 21 years.9,10,15 Accurate diagnosis is crucial since children may undergo invasive testing and surgical procedures before diagnosis. In one series, 22% of children underwent unnecessary surgery before accurate diagnosis for symptoms related to the PMD.9 Fahn and Williams22 have described criteria to categorize the degree of diagnostic uncertainty with regard to dystonia, but this classification system can be applied to all psychogenic disorders. Among the assumptions underlying these criteria is that spontaneous remission of dystonia of organic etiology is uncommon. In other movement disorders, such as chorea, tremor, or ataxia, spontaneous remission can occur, making diagnosis of a PMD by the following criteria less secure. These criteria have not been validated in children nor are they necessarily useful in clinical practice.
Documented PMD This most stringent category requires that the abnormal movement be persistently relieved through psychotherapy with or without psychotropic medications. Adjunctive therapies include use of placebos and psychologic suggestion; however, placebo response has not been studied in children and placebo trials may not be reliable. Definitive diagnosis can also be made if psychiatric intervention is refused or nontherapeutic, but the patient is noted to have symptomatic improvement when unaware of observation.
Clinically Established PMD This category requires inconsistency of symptoms over time or incongruence with the classic clinical presentation of an organic movement disorder. It should be noted that some organic movement disorders have fluctuation of symptom severity over time (e.g., Sydenham chorea) and others, such as tic disorders, have a changing phenotype over time. Thus additional evidence in the form of other physical signs that are definitely psychogenic, multiple somatizations, or obvious psychiatric disturbance is necessary for this diagnosis.
Probable PMD This category is defined as movements that are inconsistent or incongruent with a classic organic movement
disorder, but without the additional evidence required for clinically established PMD.
Possible PMD This least stringent category consists of abnormal movements that are consistent with the classic definition of an organic movement disorder, but that are accompanied by an obvious psychiatric disturbance. It must be remembered that psychiatric symptoms commonly accompany some organic movement disorders, such as Sydenham chorea, Huntington’s disease, Wilson’s disease, and Tourette syndrome. In other cases, psychiatric symptoms may be secondary to having a prominent or disabling illness. Thus this category has limited usefulness.
Aids in Diagnosing Psychogenic Movement Disorders Testing beyond the scope of the neurologic examination can occasionally be helpful in supporting a diagnosis of PMDs. Suggestion and placebo challenge have been used by physicians to obtain a clearer picture of a patient’s symptoms, and can help distinguish organic from psychogenic disease. Placebos, including intravenous (IV) injections and mild skin irritants, are controversial because of the possibility of disturbing the trust implicit in the doctor-patient relationship. They are even more controversial in young children because of informed consent concerns. However, in select circumstances they may play a role in diagnosis and treatment when used in a supportive environment as part of a comprehensive treatment plan and when the use of placebo is fully disclosed in the course of the evaluation.22 Diagnosis of certain PMDs may be aided by electrophysiologic studies although many movement disorder specialists with access to neurophysiological studies rarely use them.36 Differentiation of psychogenic jerks from myoclonus or tics may be done through electromyography (EMG). EMG bursts less than 70 ms in duration are most likely organic in nature. Longer bursts with a well-organized triphasic pattern of activation of opposing muscle groups may represent psychogenic or volitional movements. Combined application of EEG and EMG provides a more sensitive test. The poststimulus latency of reflex or stimulus-sensitive myoclonus can be examined. Latencies greater than 100 ms from the stimulus to the onset of movement suggest that the movement is voluntary.23 Tremor occurring at different frequencies in different muscle groups usually indicates an organic etiology.
Chapter 19 Psychogenic Movement Disorders
Frequency variability can be seen in psychogenic tremor, but there is enough overlap between organic and nonorganic tremor frequency variation to prevent diagnosis based on frequency variability alone.24,25 Simultaneous activity in agonists and antagonists has been associated with psychogenic tremor. Tremors faster than 11 Hz are likely beyond the upper frequency limit of voluntary tremor, and are likely of organic etiology.23 Entrainment of tremor with voluntary rapid alternative movements of different frequencies supports the diagnosis of psychogenic tremor.
Specific Movement Disorder Types in Psychogenic Movement Disorders The most commonly reported movement disorders among children with PMD are tremor (26% to 65%), dystonia (34% to 47%), myoclonus (4% to 37%), and gait disorders (13% to 30%).8–10 In two series, tics were reported as a common manifestation of PMD.15,37 These relative proportions are comparable to what has been reported in adults with PMDs.26,27
Tremor In a report of 24 adolescent and adult patients with clinically established or documented psychogenic tremor, subjects ranged in age from 15 to 78 years with 15 women and 9 men.28 Variability in tremor characteristics (e.g., tremor direction) was seen in greater than 90% of patients and variable tremor amplitude and frequency was observed in all patients. Unusual characteristics of these tremors included abrupt onset, bilateral involvement, distractibility, and a nonprogressive course with fluctuating severity.25 These psychogenic tremors often consisted of resting, postural, and kinetic components and were associated with selective, but not task-specific, disabilities. Neurologic examination often revealed other inconsistencies, and drug treatment was usually ineffective. Children with psychogenic tremor may be more likely to be diagnosed with a PMD based on clinical grounds and without extensive laboratory or imaging investigations.9
Dystonia Fahn and Williams22 defined the features of psychogenic dystonia in 39 patients, who were mostly female, had symptoms lasting between 1 month and 15 years, and ranged in age between 8 and 56 years old. Eightyfive percent of these patients had movements that were incongruous or inconsistent with those of dystonia, but most had other clues including false weakness, pain, and multiple somatizations.7 Occurring mostly
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in young women, these disorders occurred as painful dystonias inconsistent with established organic dystonias and had associated nonanatomic sensory changes and false weakness.29 As noted, organic dystonia can be misdiagnosed as psychogenic. Misdiagnosis is most likely due to the varied presentation and protean findings in dystonia. Clinical features that may appear psychogenic but are organic include varied movements (writhing, jerking, spasms, and tremors), spontaneous remission, task-specificity or action induction, normal neurologic examination, relief through geste antagoniste (sensory trick), worsening with increased stress and relief by relaxation, and paroxysmal appearance or diurnal variation.22 In addition, dystonias of sudden onset and remission can occur with medication ingestion, particularly dopamine blocking agents such as phenothiazines.
Myoclonus In a report of 18 cases of psychogenic myoclonus, movements were predominantly segmental in character, occurred at rest, and were often exacerbated by voluntary movement. The psychogenic nature of these cases was suggested by “the inconsistent character of the movements, associated psychiatric symptomatology, reduction in myoclonus with distraction, exacerbation and relief with placebo and suggestion, spontaneous periods of remission, acute onset and sudden resolution, and evidence of underlying psychopathology.”30
Treatment and Outcome For patients with mild symptoms, a clear diagnosis given in a non-judgmental manner, in a way that makes sense, and reassurance may be sufficient.36,38 As for more significant symptoms, a multi-discplinary approach with an ongoing alliance between the neurologist and the patient is an important component of the treatment process. Insight into the psychologic roots of the conversion disorder may necessitate the involvement of a psychiatrist or psychologist.31 Some patients, their families, or other physicians may be resistant to the idea of a psychiatric or psychologic consultation. In that case, it is often helpful to emphasize the neurobiology of the disorder. It may be helpful to recommend that evaluation of the disorder should occur from different specialties simultaneously.22 Identification of the precipitating stressor, which may include psychological conflict, environmental stress, or trauma, and perpetuating factors is essential to guide treatment strategy.32 Physical therapy and positive reinforcement to psychotherapy appear to reduce or abolish symptoms
246 Section 5 Selected secondary movement disorders
in many cases. As discussed earlier, placebo testing may have a role in both diagnosis and treatment of symptoms, but it must be used in a supportive setting. Anxiolytics and antidepressant medications may prove useful if mood disorders appear to be playing a primary role in the etiology of the abnormal movements.1 Biofeedback via EMG may be useful in some cases.32 Characteristics of patients with better prognosis include “acute onset, short duration of symptoms, healthy premorbid functioning, absence of coexisting organic psychopathology, and presence of an identifiable stressor.”1 Symptom duration of less than 2 weeks was strongly correlated with a good outcome in psychogenic disorders.6 Of patients who had symptomatic improvement while in the hospital, 96% had good long-term outcome.33 Conversion symptoms following mechanical trauma may have a better prognosis than those arising from severe emotional trauma. It has been postulated that mechanical trauma may provoke a simple shock reaction, whereas emotional trauma is more likely to elicit psychological defenses.34
Conclusion Psychogenic movement disorders are an important form of conversion disorder that may cause substantial morbidity and are associated with a risk of unnecessary procedures. Their incidence in movement disorder clinics has gradually been increasing as neurologists recognize typical movement disorders and refer the more atypical disorders, many of which are PMDs, to specialists. They may be difficult to distinguish from organic neurologic conditions, but with a careful history and neurologic examination in addition to knowledge of diagnostic clues, a firm diagnosis can be made. The diagnosis should not be based on merely excluding organic causes, but on specific diagnostic criteria. There have been relatively few series of children with psychogenic movements, but those that do exist are relatively consistent across studies. Clearly, differences between adults and children with PMDs exist; however, many elements are similar. Treatment of conversion disorders, such as PMDs, often requires a multifaceted approach, including behavioral, psychological, physical, and pharmacologic therapies. Children with acute onset and short duration of disease appear to have the best prognosis for recovery. Acceptance of the diagnosis by the child and family is probably important. An ongoing relationship with the neurologist is important.
REFERENCES 1. Marjama J, Troster A, Koller W: Psychogenic movement disorders, Neurol Clin 13:283–297, 1995. 2. Putnam F: Conversion symptoms. In Joseph A, Young R, editors: Movement disorders in neurology and neuropsychiatry, Boston, 1992, Blackwell Scientific. 3. American Psychiatric Association: Diagnostic and statistical manual of mental disorders, Washington, DC, 2000, American Psychiatric Association. 4. Sheffield HB: A contribution to the study of hysteria in childhood as it occurs in the United States of America, N Y State J Med 68:412–436, 1898. 5. Kozlowska K, Nunn KP, Rose D, et al: Conversion disorder in Australian pediatric practice, J Am Acad Child Adolesc Psychiatry 46:68–75, 2007. 6. Lempert T, Dietrich M, Huppert D, Brandt T: Psychogenic disorders in neurology: frequency and clinical spectrum, Acta Neurol Scand 82:335–340, 1990. 7. Williams D, Ford B, Fahn S: Phenomenology and psychopathology related to psychogenic movement disorders, Adv Neurol 65:231–257, 1995. 8. Fernandez-Alvarez E: Movement disorders of functional origin (psychogenic) in children, Rev Neurol 40(Suppl 1):S75–S77, 2005. 9. Ferrara J, Jankovic J: Psychogenic movement disorders in children, Mov Disord 23:1875–1881, 2008. 10. Schwingenschuh P, Pont-Sunyer C, Surtees R, et al: Psychogenic movement disorders in children: a report of 15 cases and a review of the literature, Mov Disord 23:1882–1888, 2008. 11. Regan J, LaBarbera J: Lateralization of conversion symptoms in children and adolescents, Am J Psychiatr 141:1279–1280, 1984. 12. Fritz G, Fritsch S, Hagino O: Somatoform disorders in children and adolescents: a review in the past 10 years, J Am Acad Child Adolesc Psychiatry 36:1329–1338, 1997. 13. Grattan-Smith P, Fairley M, Procopis P: Clinical features of conversion disorder, Arch Dis Child 63:408–414, 1988. 14. Turgay A: Treatment outcome for children and adole scents with conversion disorder, Can J Psychiatry 35: 585–589, 1990. 15. Ahmed MA, Martinez A, Yee A, et al: Psychogenic and organic movement disorders in children, Dev Med Child Neurol 50:300–304, 2008. 16. Zeharia A, Mukamel M, Carel C, et al: Conversion reaction: management by the paediatrician, Eur J Pediatr 158:160–164, 1999. 17. Vuilleumier P, Chicherio C, Assal F, et al: Functional neuroanatomical correlates of hysterical sensorimotor loss, Brain 124:1077–1090, 2001. 18. de Lange FP, Roelofs K, Toni I: Increased self-monitoring during imagined movements in conversion paralysis, Neuropsychologia 45:2051–2058, 2007. 19. Vuilleumier P: Hysterical conversion and brain function, Prog Brain Res 150:309–329, 2005.
Chapter 19 Psychogenic Movement Disorders
20. Brashear A, Dobyns WB, de Carvalho Aguiar P, et al: The phenotypic spectrum of rapid-onset dystonia-parkinsonism (RDP) and mutations in the ATP1A3 gene, Brain 130:828–835, 2007. 21. Schrag A, Lang AE: Psychogenic movement disorders, Curr Opin Neurol 18:399–404, 2005. 22. Fahn S, Williams D: Psychogenic dystonia, Adv Neurol 50:431–455, 1988. 23. Brown P, Thompson P: Electrophysiological aids to the diagnosis of psychogenic jerks, spasms, and tremor, Mov Disord 16:595–599, 2001. 24. McAuley JH, Rothwell JC, Marsden CD, Findley LJ: Electrophysiological aids in distinguishing organic from psychogenic tremor, Neurology 50:1882–1884, 1998. 25. Kenney C, Diamond A, Mejia N, et al: Distinguishing psychogenic and essential tremor, J Neurol Sci 263: 94–99, 2007. 26. Factor S, Podskalny G, Molho E: Psychogenic movement disorders: frequency, clinical profile, and characteristics, J Neurol Neurosurg Psychiatry 59:406–412, 1995. 27. Thomas M, Vuong KD, Jankovic J: Long-term prognosis of patients with psychogenic movement disorders, Parkinsonism Relat Disord 12:382–387, 2006. 28. Koller W, Lang AE, Vetere-Overfield B, et al: Psychogenic tremors, Neurology 39:1094–1099, 1989. 29. Lang AE: Psychogenic dystonia: a review of 18 cases, Can J Neurol Sci 22:136–143, 1995. 30. Monday K, Jankovic J: Psychogenic myoclonus, Neurology 43:349–352, 1993. 31. Jankovic J, Cloninger CR, Fahn S, et al: Therapeutic approaches to psychogenic movement disorders.
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In Hallett M, et al: Psychogenic movement disorders: neurology and neuropsychiatry, Philadelphia, 2006, AAN Enterprises and Lippincott Williams & Wilkins. 32. Ford C: Conversion disorder and somatoform disorder not otherwise specified. In Gabbard G, editor: Treatment of psychiatric disorders, Washington, DC, 1984, American Psychiatric Publishing. 33. Couprie W, Wijdicks EFM, Roojmans HGM, vanGijn J: Outcome in conversion disorder: a follow up study, J Neurol Neurosurg Psychiatry 58:750–752, 1995. 34. Krull F, Schifferdecker M: Inpatient treatment of conversion disorder: a clinical investigation of outcome, Psychother Psychosom 53:161–165, 1990. 35. Stone J, Carson A, Duncan R, et al: Symptoms ‘unexplained by organic disease’ in 1144 new neurology out-patients: how often does the diagnosis change at follow-up?, Brain EPUB 2009. 36. Espay AJ, Goldenhar LM, Voon V, et al: Opinions and clinical practices related to diagnosing and managing patients with psychogenic movement disorders: An international survey of movement disorder society members, Mov Disord 24:1366–1374, 2009. 37. Gilbert DL, Isaacs KM: Phenomenology and clinical characteristics of pediatric patients diagnosed with a psychogenic movement disorder. Presented at the Second International Conference on Psychogenic Movement Disorders and Other Conversion Disorders, Washington DC, April 245:2–4, 2009. 38. Stone J, Carson A, Sharpe M: Functional symptoms in neurology: management, J Neurol Neurosurg Psychiatry Mar 2005; 76 Suppl 1:i13-21.
19
Psychogenic Movement Disorders
Introduction
A common problem in neurology is the existence of disorders that cause neurologic symptoms, but do not have an identifiable neurologic basis. Many different terms have been used to describe these disorders, including “hysterical, functional, conversion disorder, and psychogenic.”1 These terms reflect the concept that an organic basis will not be found for the symptoms or that a psychiatric disorder is the primary substrate from which the atypical symptoms blossom. The concept of hysteria has been present in Western medicine for over 2000 years. Briquet in the 1850s and Charcot in the 1880s are generally recognized for their early work on disorders on the border between neurology and psychiatry and guiding them into modern medicine.2 The term conversion was first used by Breuer and Freud to describe the transformation of unresolved psychologic conflicts and unassimilated emotions into physical manifestations.2 Conversion disorders fall under the broader heading of somatoform disorders in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision.3 Diagnostic criteria for conversion disorder involve symptoms affecting voluntary motor or sensory functions suggesting a neurologic condition that are judged to be caused by psychological factors. These symptoms cause impaired function, are not intentionally produced, and cannot be explained after a thorough medical evaluation.3
Epidemiology The first U.S. description of conversion disorder in children consisted of 98 cases.4 Despite continued study, few data exist to estimate the population prevalence of conversion disorder in children in the United States. Prevalence of conversion disorder among children has been estimated at 2 to 4 per 100,000.5 Conversion disorder is a relatively common reason for presentation to movement disorders clinics. Among adults, estimates vary from 2% to 9% of patients.6,7 242
Common psychogenic movement disorders (PMDs) include dystonia, tremor, myoclonus, tics, hemiballismus, chorea, parkinsonism, and gait disorders. Although there are few data on these disorders in children, it has been estimated that 2% to 4% of children treated at movement disorder clinics have a PMD.8–10 Conversion disorder has been reported in children as young as 4 years, but most often occurs during the peripubertal years.2,7 For PMDs in children, the average age of onset is 12 to 14 years, with a range of 7 to 18 years.8–10 No children under age 7 years were reported in those three series. PMDs affect girls more than boys in a 3:1 to 4:1 ratio.8–10 One report indicated a 1:1 ratio of boys to girls in children 12 years of age or younger.9
Clinical Features of Psychogenic Movement Disorders In adults, the nondominant side of the body is more commonly affected, leading to theories of symptom origins in the right cerebral hemisphere.2 However, in children the dominant extremities are more likely to be involved. It has been speculated that this difference may be due to incomplete hemispheric lateralization in children.11 Regardless of underlying mechanism, the preferential involvement of the dominant extremities is a consistent finding in children with PMDs.9,10 The typical course of conversion symptoms in children is for the symptoms to resolve within 3 months from the time of diagnosis.12 The great majority of children have complete resolution of symptoms and recurrence of symptoms appears to be rare.13,14 Outcome of PMDs specifically has not been studied; long-term outcome is good in the majority of cases,10,15 but may be less good than for childhood conversion disorders more generally.10 However, these reports from specialty clinics may reflect an ascertainment bias. It is often possible to identify a specific precipitant for the conversion symptoms in children.13 In a study of 47 Israeli children with conversion disorder,
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Chapter 19 Psychogenic Movement Disorders
a specific reason for the conversion was discovered in 40.16 Among children with PMD, antecedent history of physical or emotional stressors is common, being reported in 53% to 69% of cases.9,10,15 Children with PMD commonly have coexisting impairment of mood, especially anxiety, depressed mood, or irritability,9,10 and “perfectionistic” tendencies are common.9,13
Pathophysiology There is emerging evidence that conversion disorders have a basis in altered brain function. One of the first studies to demonstrate this was a single-photon emission computed tomography (SPECT) study showing decreased regional cerebral blood flow in the thalamus and basal ganglia contralateral to psychogenic sensorimotor deficits in adults.17 An important finding of that study was that the contralateral basal ganglia and thalamic hypoactivation resolved after recovery. In adult subjects with conversion hemiparesis, cerebral blood flow responses in a motor imagery task were abnormally increased in the ventromedial prefrontal cortex and superior temporal cortex despite normal task performance.18 These studies and several other small studies using electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), positron emission tomography (PET), or SPECT have suggested that conversion disorders are associated with abnormal modulation of motor and sensory representations by affective or stress-related factors.19 To date, physiologic or imaging studies have directly investigated PMDs and no studies have included children. Nonetheless, these data can be taken as strong evidence for a neurobiologic basis for conversion disorders including PMDs.
Diagnosis At first glance, some organic movement disorders may appear to be psychogenic in origin. Historically, many physicians believed that Tourette syndrome and task-specific focal dystonias, such as writer’s cramp, were “hysterical.” Some movements related to organic movement disorders can be suppressed, including tics, tardive dyskinesia, parkinsonian rest tremor, and some choreas. Hemiballismus, brought on by brain injury or stroke, can begin precipitously and follow a static or diminishing course. Organic paroxysmal dyskinesias, by definition, occur and remit abruptly, and may be misdiagnosed as psychogenic. Rapid-onset dystonia parkinsonism may have abrupt onset and reach a stable severe plateau within days.20 Psychiatric dysfunction may be the initial presentation for diseases containing abnormal movements, such as Huntington’s disease and Wilson’s disease.
243
BOX 19-1 Useful Clues for Diagnosing Psychogenic Movement Disorders in Children Historical Clues 1. Abrupt onset 2. Static course 3. Spontaneous remission or inconsistency over time 4. Remission when the child is not aware of being observed 5. Presence of secondary gain Clinical Clues 1. Inconsistent character of the movement (amplitude, frequency, distribution, selective disability) 2. Paroxysmal movement disorder 3. Movements increase with attention to the movement, or decrease with distraction 4. Ability to trigger or relieve the abnormal movements with unusual or nonphysiologic interventions (e.g., body trigger points) 5. False weakness or sensory findings 6. Deliberate slowness of movements 7. Entrainment 8. Functional disability out of proportion to examination findings Therapeutic Responses 1. Unresponsiveness to appropriate medications 2. Response to placebos 3. Remission with psychotherapy
Certain features appear to be consistent across the range of patients with PMD7,21 (Box 19-1). These clues to making the diagnosis of a PMD may be present in the history, in the physical examination, or in therapeutic trials. Although suggestive of a PMD, presence of these features alone does not confirm the diagnosis. Some of these features may be present in organic movement disorders, so care and further evidence is required for diagnosis.7 A thorough medical history including family history, physical examination, and in some cases diagnostic testing is necessary to arrive at a confirmed diagnosis of a psychogenic movement disorder. Conversion disorders and organic neurologic disease can coexist, most commonly in chronic relapsing diseases such as epilepsy. However, fewer than 10% of children diagnosed with conversion disorder have a preexisting physical disease.16 In adults, once a diagnosis of a functional, non-organic neurological disorder is made, new organic diagnoses rarely emerge, even when symptoms persist. A recent study in over 1000 adults judged by neurologists as having symptoms “unexplained by organic disease” found fewer than 1% had acquired a new organic disease diagnosis 18 months later.35
244 Section 5 Selected secondary movement disorders
Diagnostic Criteria for Psychogenic Movement Disorders Many physicians are reluctant to make the diagnosis of a conversion disorder. This also appears to be true of PMDs. The average time from onset of symptoms to diagnosis has been reported to range from several days to as long as 21 years.9,10,15 Accurate diagnosis is crucial since children may undergo invasive testing and surgical procedures before diagnosis. In one series, 22% of children underwent unnecessary surgery before accurate diagnosis for symptoms related to the PMD.9 Fahn and Williams22 have described criteria to categorize the degree of diagnostic uncertainty with regard to dystonia, but this classification system can be applied to all psychogenic disorders. Among the assumptions underlying these criteria is that spontaneous remission of dystonia of organic etiology is uncommon. In other movement disorders, such as chorea, tremor, or ataxia, spontaneous remission can occur, making diagnosis of a PMD by the following criteria less secure. These criteria have not been validated in children nor are they necessarily useful in clinical practice.
Documented PMD This most stringent category requires that the abnormal movement be persistently relieved through psychotherapy with or without psychotropic medications. Adjunctive therapies include use of placebos and psychologic suggestion; however, placebo response has not been studied in children and placebo trials may not be reliable. Definitive diagnosis can also be made if psychiatric intervention is refused or nontherapeutic, but the patient is noted to have symptomatic improvement when unaware of observation.
Clinically Established PMD This category requires inconsistency of symptoms over time or incongruence with the classic clinical presentation of an organic movement disorder. It should be noted that some organic movement disorders have fluctuation of symptom severity over time (e.g., Sydenham chorea) and others, such as tic disorders, have a changing phenotype over time. Thus additional evidence in the form of other physical signs that are definitely psychogenic, multiple somatizations, or obvious psychiatric disturbance is necessary for this diagnosis.
Probable PMD This category is defined as movements that are inconsistent or incongruent with a classic organic movement
disorder, but without the additional evidence required for clinically established PMD.
Possible PMD This least stringent category consists of abnormal movements that are consistent with the classic definition of an organic movement disorder, but that are accompanied by an obvious psychiatric disturbance. It must be remembered that psychiatric symptoms commonly accompany some organic movement disorders, such as Sydenham chorea, Huntington’s disease, Wilson’s disease, and Tourette syndrome. In other cases, psychiatric symptoms may be secondary to having a prominent or disabling illness. Thus this category has limited usefulness.
Aids in Diagnosing Psychogenic Movement Disorders Testing beyond the scope of the neurologic examination can occasionally be helpful in supporting a diagnosis of PMDs. Suggestion and placebo challenge have been used by physicians to obtain a clearer picture of a patient’s symptoms, and can help distinguish organic from psychogenic disease. Placebos, including intravenous (IV) injections and mild skin irritants, are controversial because of the possibility of disturbing the trust implicit in the doctor-patient relationship. They are even more controversial in young children because of informed consent concerns. However, in select circumstances they may play a role in diagnosis and treatment when used in a supportive environment as part of a comprehensive treatment plan and when the use of placebo is fully disclosed in the course of the evaluation.22 Diagnosis of certain PMDs may be aided by electrophysiologic studies although many movement disorder specialists with access to neurophysiological studies rarely use them.36 Differentiation of psychogenic jerks from myoclonus or tics may be done through electromyography (EMG). EMG bursts less than 70 ms in duration are most likely organic in nature. Longer bursts with a well-organized triphasic pattern of activation of opposing muscle groups may represent psychogenic or volitional movements. Combined application of EEG and EMG provides a more sensitive test. The poststimulus latency of reflex or stimulus-sensitive myoclonus can be examined. Latencies greater than 100 ms from the stimulus to the onset of movement suggest that the movement is voluntary.23 Tremor occurring at different frequencies in different muscle groups usually indicates an organic etiology.
Chapter 19 Psychogenic Movement Disorders
Frequency variability can be seen in psychogenic tremor, but there is enough overlap between organic and nonorganic tremor frequency variation to prevent diagnosis based on frequency variability alone.24,25 Simultaneous activity in agonists and antagonists has been associated with psychogenic tremor. Tremors faster than 11 Hz are likely beyond the upper frequency limit of voluntary tremor, and are likely of organic etiology.23 Entrainment of tremor with voluntary rapid alternative movements of different frequencies supports the diagnosis of psychogenic tremor.
Specific Movement Disorder Types in Psychogenic Movement Disorders The most commonly reported movement disorders among children with PMD are tremor (26% to 65%), dystonia (34% to 47%), myoclonus (4% to 37%), and gait disorders (13% to 30%).8–10 In two series, tics were reported as a common manifestation of PMD.15,37 These relative proportions are comparable to what has been reported in adults with PMDs.26,27
Tremor In a report of 24 adolescent and adult patients with clinically established or documented psychogenic tremor, subjects ranged in age from 15 to 78 years with 15 women and 9 men.28 Variability in tremor characteristics (e.g., tremor direction) was seen in greater than 90% of patients and variable tremor amplitude and frequency was observed in all patients. Unusual characteristics of these tremors included abrupt onset, bilateral involvement, distractibility, and a nonprogressive course with fluctuating severity.25 These psychogenic tremors often consisted of resting, postural, and kinetic components and were associated with selective, but not task-specific, disabilities. Neurologic examination often revealed other inconsistencies, and drug treatment was usually ineffective. Children with psychogenic tremor may be more likely to be diagnosed with a PMD based on clinical grounds and without extensive laboratory or imaging investigations.9
Dystonia Fahn and Williams22 defined the features of psychogenic dystonia in 39 patients, who were mostly female, had symptoms lasting between 1 month and 15 years, and ranged in age between 8 and 56 years old. Eightyfive percent of these patients had movements that were incongruous or inconsistent with those of dystonia, but most had other clues including false weakness, pain, and multiple somatizations.7 Occurring mostly
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in young women, these disorders occurred as painful dystonias inconsistent with established organic dystonias and had associated nonanatomic sensory changes and false weakness.29 As noted, organic dystonia can be misdiagnosed as psychogenic. Misdiagnosis is most likely due to the varied presentation and protean findings in dystonia. Clinical features that may appear psychogenic but are organic include varied movements (writhing, jerking, spasms, and tremors), spontaneous remission, task-specificity or action induction, normal neurologic examination, relief through geste antagoniste (sensory trick), worsening with increased stress and relief by relaxation, and paroxysmal appearance or diurnal variation.22 In addition, dystonias of sudden onset and remission can occur with medication ingestion, particularly dopamine blocking agents such as phenothiazines.
Myoclonus In a report of 18 cases of psychogenic myoclonus, movements were predominantly segmental in character, occurred at rest, and were often exacerbated by voluntary movement. The psychogenic nature of these cases was suggested by “the inconsistent character of the movements, associated psychiatric symptomatology, reduction in myoclonus with distraction, exacerbation and relief with placebo and suggestion, spontaneous periods of remission, acute onset and sudden resolution, and evidence of underlying psychopathology.”30
Treatment and Outcome For patients with mild symptoms, a clear diagnosis given in a non-judgmental manner, in a way that makes sense, and reassurance may be sufficient.36,38 As for more significant symptoms, a multi-discplinary approach with an ongoing alliance between the neurologist and the patient is an important component of the treatment process. Insight into the psychologic roots of the conversion disorder may necessitate the involvement of a psychiatrist or psychologist.31 Some patients, their families, or other physicians may be resistant to the idea of a psychiatric or psychologic consultation. In that case, it is often helpful to emphasize the neurobiology of the disorder. It may be helpful to recommend that evaluation of the disorder should occur from different specialties simultaneously.22 Identification of the precipitating stressor, which may include psychological conflict, environmental stress, or trauma, and perpetuating factors is essential to guide treatment strategy.32 Physical therapy and positive reinforcement to psychotherapy appear to reduce or abolish symptoms
246 Section 5 Selected secondary movement disorders
in many cases. As discussed earlier, placebo testing may have a role in both diagnosis and treatment of symptoms, but it must be used in a supportive setting. Anxiolytics and antidepressant medications may prove useful if mood disorders appear to be playing a primary role in the etiology of the abnormal movements.1 Biofeedback via EMG may be useful in some cases.32 Characteristics of patients with better prognosis include “acute onset, short duration of symptoms, healthy premorbid functioning, absence of coexisting organic psychopathology, and presence of an identifiable stressor.”1 Symptom duration of less than 2 weeks was strongly correlated with a good outcome in psychogenic disorders.6 Of patients who had symptomatic improvement while in the hospital, 96% had good long-term outcome.33 Conversion symptoms following mechanical trauma may have a better prognosis than those arising from severe emotional trauma. It has been postulated that mechanical trauma may provoke a simple shock reaction, whereas emotional trauma is more likely to elicit psychological defenses.34
Conclusion Psychogenic movement disorders are an important form of conversion disorder that may cause substantial morbidity and are associated with a risk of unnecessary procedures. Their incidence in movement disorder clinics has gradually been increasing as neurologists recognize typical movement disorders and refer the more atypical disorders, many of which are PMDs, to specialists. They may be difficult to distinguish from organic neurologic conditions, but with a careful history and neurologic examination in addition to knowledge of diagnostic clues, a firm diagnosis can be made. The diagnosis should not be based on merely excluding organic causes, but on specific diagnostic criteria. There have been relatively few series of children with psychogenic movements, but those that do exist are relatively consistent across studies. Clearly, differences between adults and children with PMDs exist; however, many elements are similar. Treatment of conversion disorders, such as PMDs, often requires a multifaceted approach, including behavioral, psychological, physical, and pharmacologic therapies. Children with acute onset and short duration of disease appear to have the best prognosis for recovery. Acceptance of the diagnosis by the child and family is probably important. An ongoing relationship with the neurologist is important.
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