Psychogenic movement disorders

Transcription

1 Psychogenic movement disorders Vanessa K Hinson, W Blake Haren Diagnosis and treatment of psychogenic movement disorders are challenging for both neurologists and psychiatrists. Symptoms can mimic the full range of organic abnormal involuntary movements, affect gait and speech, or present as unusual undifferentiated movements. Typical clinical characteristics of these disorders are acute onset, fast progression, movement patterns incongruent with organic movement disorders, distractibility, variability, and simultaneous occurrence of various abnormal movements and dysfunctions. Avoidance of iatrogenic damage by unnecessary invasive tests or inappropriate medication, as well as use of appropriate psychiatric treatments are pivotal steps in the management of these disorders. The few clinical trials specific to psychogenic movement disorders focus on antidepressants and psychotherapy. Presence of a comorbid psychiatric diagnosis of depression or an anxiety disorder is a positive prognostic factor, whereas long-standing symptoms, insidious onset of movements, and a psychiatric diagnosis of hypochondriasis, factitious disorder, or malingering are associated with poor outcome. Introduction Psychogenic movement disorders are substantial diagnostic and management challenges for both neurologists and psychiatrists. The term psychogenic is traditionally used to describe disorders that cannot be attributed to any known structural or neurochemical disease but that result from an underlying psychiatric illness or malingering. The disorders commonly present with various complex movements. Symptoms can mimic the full range of organic abnormal involuntary movements, affect gait and speech, or present as unusual undifferentiated movements that do not fit into a known category. The disorders most commonly fulfil psychiatric criteria for a conversion disorder, a form of somatoform disorder, along with somatisation disorder, hypochondriasis, body dysmorphic disorder, and pain disorder. Psychogenic movement disorders can be disabling and the health-care cost associated with somatoform disorders in general is substantial, amounting to an estimated cost of US$20 billion per year. 1 Many physicians are reluctant to make the diagnosis of psychogenic movement disorder for fear of missing an underlying organic and potentially treatable disorder or because of the general reluctance of the patient to accept the diagnosis. In this review we discuss the epidemiology, diagnosis, and current treatment options for these disorders. Epidemiology Neurological dysfunction of psychogenic origin occurs in 1 9% of all neurological diagnoses, 2,3 depending on the applied clinical definitions and methods for case ascertainment. Abnormal movements are among the most common psychogenic signs, 2,4 and patients with psychogenic movement disorders are estimated to account for 2 3% of those in movement disorder clinics. 5 The mean age at onset described in several case series on these disorders ranges between 37 years and 50 years and women are predominantly affected (range 61 87%). 5 7 There are no data on racial distribution in the published research, but a transcultural comparison between patients with these disorders in Spain and in the USA showed essentially similar demographic and clinical characteristics by ethnic origin. 8 Psychogenic movement disorders usually occur as a single neurological diagnosis, but are associated with organic neurological disorders in 10 15% of patients. 9 More commonly, these disorders are encountered in the context of a second coexisting psychiatric illness. Feinstein and colleagues 10 assessed psychiatric comorbidities in 88 patients with psychogenic movement disorders by use of structured clinical interviews for the fourth edition of the diagnosistic and statistical manual of the American Psychiatric Association (DSM-IV). 11 They reported a coexisting axis I diagnosis (most commonly major depression and anxiety disorders) in addition to the diagnosis of conversion disorder in 38% of patients, and an axis II diagnosis (personality disorder) in 42%. Several risk factors for psychogenic movement disorders have been identified. These include history of sexual abuse or rape, previous surgery or other physical trauma, and major emotionally stressful life events, such as divorce or death of a family member. 3,6,10 Diagnosis Diagnosis of psychogenic movement disorders was typically viewed as a diagnosis of exclusion, 12 but a recent increase in clinical and research interest has led to improved understanding of the clinical characteristics and the role of ancillary testing. As a result, diagnostic criteria have been established that enable clinicians to make a positive diagnosis and a specific treatment plan. In general, these disorders can present with the whole variety of movements seen in movement disorders of organic origin (tremor, dystonia, chorea, bradykinesia, myoclonus, tics, athetosis, ballism, incoordination) and can affect speech and gait. The disorders commonly present with complex movements that affect several body regions. Hinson and colleagues 7 analysed a sample of 88 patients with psychogenic movement disorders at a tertiary referral centre by means of a rating scale designed to reflect the complex clinical signs in these disorders. 7 Action tremor (42%) was the most commonly observed Lancet Neurol 2006; 5: Department of Neurosciences, Murray Center for Research on Parkinson s Disease and Related Disorders, Medical University of South Carolina, Charleston Memorial Hospital, Charleston, SC 29425, USA (V K Hinson MD, W B Haren MD) Correspondence to: Dr Vanessa K Hinson hinsonvk@musc.edu Vol 5 August

2 sign, followed by resting tremor (39%), dystonia (32%), bradykinesia (23%), myoclonus (19%), incoordination resembling cerebellar dysfunction (11%), tics (8%), chorea (7%), athetosis (3%), and ballism (2%). 60% had a gait disorder and 28% had speech dysfunction. Most patients (74%) exhibited two or more signs. The upper hands and arms were most frequently affected, followed by the legs and feet, the neck, trunk, head, face, and shoulders. The mode of onset typifies the clinical presentation of psychogenic movement disorders: symptoms begin abruptly, sometimes in the context of a minor injury or another precipitating event, and maximum symptom severity and disability are reached quickly. 10 Disabilities might be selective and only affect specific functions, such as walking, whereas movement of the extremities is normal when engaged in other motor tasks (rapid alternating movements, strength testing). 5,13 Other signs that implicate psychogenicity are abnormal movements incongruent with an organic movement disorder, deliberate slowness of movement, distractibility, variability, and simultaneous occurrence of various abnormal movements and dysfunctions (eg, tremor associated with myoclonus and gait dysfunction). Movements may resolve when a patient is unaware of being observed and increase when the affected body part is being examined. Distractibility and variability are especially common in psychogenic tremor (80% of cases 14 ) and commonly coexist with entrainment and coactivation signs. 15 Entrainment is tested by having the patient make voluntary movements at a given frequency Panel 1: Clinical characteristics of psychogenic movement disorders Mode of onset Abrupt Precipitating event Fast progression to maximum symptom severity and disability Clinical signs Signs incongruent with organic disease Distractibility and variability Multiple abnormal movements Increased movement with attention to the affected body part Deliberate slowness of movement Entrainment, coactivation Association with false weakness, sensory loss, and pain Unresponsiveness to drugs for organic movement disorders, response to placebo drugs and suggestion Ancillary tests Electromyography based tremor analysis Variable frequency and amplitude, entrainment, coactivation, abnormal response to weight loading Electromyographic analysis of myoclonus Variable and prolonged latencies and duration of myoclonic jerks, variable patterns of muscle recruitment, habituation with the extremity contralateral to the side under assessment. The psychogenic movement will assume the frequency of the contralateral voluntary movement if entrainment is positive. Coactivation is increased muscle tone in the tremulous extremity that is inconsistent during the examination and can be overcome with passive movement. These characteristic features of psychogenic tremors can also be seen in cases of psychogenic parkinsonism, which is a rare syndrome accounting for % of all parkinsonism cases. 5,13 In psychogenic parkinsonism, atypical tremor occurs in conjunction with extremely slow movements that are often accompanied by grimacing, sighing, or whole-body movements when patients do a simple motor task. 16 Common characteristics of organic parkinsonism, such as hypomimia, decreased blink rate, or axial rigidity, are usually absent in psychogenic parkinsonism. 16 Psychogenic dystonia often lacks the typical variability and distractibility of other psychogenic movement disorders and presents with fixed abnormal postures, 17 which are often painful and can manifest in an atypical distribution. Leg involvement, for example, is uncommon in adult-onset organic dystonia, but quite common in psychogenic dystonia. 17,18 Abnormal gait is commonly associated with the abnormal movements of psychogenic movement disorders. Psychogenic gait disorders are characterised by exaggerated effort and slowness, unusual uneconomic postures, convulsive shaking episodes, sudden knee buckling, and near falling. 19,20 The movement disorder is commonly accompanied by other psychogenic neurological symptoms, such as false weakness or sensory findings, or by excessive pain and tenderness. 6,21 Response to placebo drugs and suggestion 22,23 are other important characteristics of these disorders. 24 Placebo administration should be carefully planned and ideally given in a doubleblind fashion with the patient s consent to avoid feelings of deception or mistrust. 6,25 Organic movement disorders, however, can transiently improve with placebo therapy, and a diagnosis of a psychogenic movement disorder should not be made on the basis of the presence of a placebo response alone. 6,26 Typical clinical characteristics of these disorders are summarised in panel 1. In general, a discrepancy between the presenting symptoms and the negative results of multiple neurological investigations (eg, MRI, spinal-fluid analysis, evoked potentials) exists. Nonetheless, ancillary testing might be useful in some difficult-to-diagnose cases to exclude organic movement disorders. 27 Functional neuroimaging with iodine-123-labelled β CIT singlephoton-emission CT and fluorine-18-labelled-dopa PET, for example, has been used in the diagnosis of psychogenic parkinsonism. Factor and co-workers 28 and Booij and colleagues 29 confirmed cases of psychogenic parkinsonism by use of 123 I-β-CIT single-photon-emission CT, which showed no striatonigral degeneration. However, O Sullivan and colleagues 30 and Lang and Vol 5 August 2006

3 co-workers 13 reported cases of suspected psychogenic parkinsonism, but abnormal functional neuroimaging was consistent with organic pathological changes. Additionally, there are several neurophysiological tests that positively reinforce the diagnosis of psychogenic movement disorders. Tremor analysis based on electromyography can identify entrainment and coactivation, 15,31 an increase of tremor amplitude and frequency with weight loading of the tremulous extremity, variability in tremor frequency, and coactivation of antagonist muscles. Electromyographic assessment of psychogenic myoclonus shows an abnormally long and variable latency between the stimulus and the myoclonic jerk, variable patterns of muscle recruitment within each jerk, prolonged duration of myoclonic bursts, as well as significant habituation with repeated stimulation. 32 Psychogenic movement disorders are a diagnostic challenge to the clinician, and diagnosis should be made by an experienced movement-disorders neurologist familiar with the various organic counterparts of the disorders. The underlying psychiatric diagnosis and associated secondary psychiatric disorders might not be obvious and need expert assessment by a psychiatrist in all cases. The DSM IV 11 identifies three pertinent diagnostic categories for these disorders: somatoform disorders, factitious disorders, and malingering. Somatoform disorders encompass conversion disorders (physical symptoms that are brought on by psychological stressors) and somatisation disorders (a multitude of physical, non-organic symptoms). Factitious disorders are associated with symptoms that are intentionally produced with the purpose of achieving some psychological gain, whereas malingering is intentional symptom production for material (eg, financial) gain. The most commonly encountered psychiatric diagnosis for psychogenic movement disorders is conversion disorder, then somatisation disorder, factitious disorder, and malingering. 6 Psychogenic movement disorders are commonly associated with other axis I psychiatric disorders, usually depression and anxiety. Because individual clinical characteristics can be difficult to interpret, Williams and colleagues 6 defined four levels of certainty for the diagnosis of psychogenic movement disorders, which are currently being used in clinical practice and research (panel 2). Treatment An important part of the management of these disorders is the avoidance of iatrogenic damage by unnecessary invasive tests or inappropriate medication, early and precise diagnosis, and the use of the appropriate psychiatric treatment. Since patients acceptance of the diagnosis of psychogenicity is fundamental to treatment success, delivery of the diagnosis becomes a pivotal step. Williams and co-workers 6 have called this the diagnostic debriefing. 6 Ideally involving the patient, the neurologist, and the psychiatrist, this meeting allows the patient to Panel 2: Levels of certainty for diagnosis of psychogenic movement disorders 6 Documented psychogenic movement disorders Movements relieved by psychotherapy, suggestion, or placebo, or spontaneous symptom resolution when the patient feels unobserved Clinically established psychogenic movement disorders Movements incongruent with organic disease or inconsistent symptoms, in addition to the presence of other false neurological signs, multiple somatisations, or a documented psychiatric illness Probable psychogenic movement disorders Movements are incongruent with organic disease or inconsistent, but no other supportive features are present Possible psychogenic movement disorders Suspicion for disorder based on the patient s obvious emotional disturbance alone receive information from the preceding assessment and to begin to understand the diagnosis and their own role in the treatment plan. The specific movement-disorder diagnosis based on the primary abnormal movements (eg, tremor, dystonia, myoclonus) should be disclosed, and the underlying psychiatric disorder clearly discussed in layman s terms. The interaction between body and mind will often be mentioned, as will the good outcome compared with organic neurodegenerative diseases. This debriefing is also a time to remind the patient that the process of treating these disorders is fluid and that the participation of the neurologist will be ongoing. To ensure patients confidence in the treatment plan, agreement between the neurologist and the psychiatrist on diagnosis and management is crucial. Effective communication of the diagnosis to the treating mentalhealth professional is necessary to avoid misperception of movement-disorder symptoms and doubt of the diagnosis on the part of the non-neurological consultant. 33 The psychiatric treatment process will begin with a structured clinical interview according to DSM IV 11 to establish the pertinent diagnostic category for the psychogenic movement disorder (somatoform disorder, factitious disorder, or malingering) and secondary psychiatric illnesses. Eliciting the potential coexisting psychiatric disorders is of great importance given that proper treatment of masked depression can improve physical symptoms. 2 There have been several case reports of treatment for psychogenic movement disorders, but clinical trials specific to these disorders are rare. Voon and co-workers 34 did an open-label trial of antidepressants (either citalopram or paroxetine) in 15 patients who fulfilled Fahn and Willams diagnostic criteria for a documented or clinically established psychogenic movement disorder. Three patients also received concurrent supportive psychotherapy. Eight of ten patients with primary conversion disorder had substantial improvements in both motor and global outcomes (clinical global Vol 5 August

4 impression scale and depression and anxiety rating scales), and seven had a complete remission. The remaining five patients were diagnosed with primary hypochondriasis, somatisation, and probable factitious disorder or malingering and did not improve with the intervention. All the patients with primary conversion disorder had a current or previous anxiety or depression diagnosis, whereas only 40% of the patients within the somatoform group had these diagnoses. Hinson and colleagues 35 recruited ten patients with psychogenic movement disorders for a single-blind clinical trial to receive 12 weeks of treatment with outpatient psychodynamic psychotherapy and use of antidepressants or anxiolytic drugs. Psychotherapy was given once weekly by the same study psychiatrist. This treatment modality falls in the category of brief psychotherapy and is based on psychoanalytic theories. The psychiatrist also gave antidepressant or anxiolytic drugs if indicated depending on comorbid psychiatric diagnosis. The movement disorder was videotaped before and after treatment. Tapes were rated in a random order by a rater unaware of treatment allocation using the psychogenic movement disorder rating scale (PMDRS). 7 All patients were diagnosed with conversion disorder. Psychiatric comorbidities were major depressive disorder (five patients), post-traumatic stress disorder (two patients), personality disorder (two patients), anxiety disorder (one patient), and bipolar disorder (one patient). Nine of ten recruited patients completed the study. Total mean PMDRS and total mean PMDRS function scores improved with psychotherapeutic intervention. There were significant treatment effects in Hamilton depression scores, Beck anxiety scores, and global assessment of function. Several other clinical trials, even though not specifically designed for psychogenic movement disorders but for other forms of conversion or somatoform disorders, are worth mentioning here. An open-label trial of somatisation disorder studied the efficacy of nefazodone in patients with and without comorbid depression and showed improvement in clinical global impression and functioning in 73% of patients. 36 The efficacy of haloperidol compared with sulpiride (a D2 blocking neuroleptic not available in the USA) was assessed in a clinical trial of 18 patients with conversion disorder of the motor type had tried previous medication (tricyclic antidepressants and benzodiazepines) with no success. Patients were randomly assigned to receive either haloperidol or sulpiride for 16 weeks. Objective assessment with the Middlesex Hospital questionnaire and the Hamilton depression and anxiety rating scale showed that in the haloperidol group one patient substantially improved, three partly improved, and two did not improve. Whereas, in the sulpiride group, eight patients remarkably improved, two partly improved, and two did not improve. This study concluded that there seems to be a positive correlation between dopamine blockade, drug-induced plasma prolactin concentrations, and improvement in a patient s conversion symptoms. However, because of the risk for drug-induced movement disorders and general medical side-effects, the use of D2 blocking neuroleptics in this population should be avoided. Moene and colleagues 38 did a randomised controlled clinical trial of treatment for conversion disorder of the motor type with hypnosis. They randomly assigned 48 patients to receive either hypnosis or a control intervention consisting of generic elements of psychotherapy. Outcome measures were a video rating scale for motor conversion symptoms, the symptom checklist-90, and elements of the international classification of impairments, disabilities, and handicaps. Independent of the treatment condition, 65% of patients showed substantial improvement at post-treatment assessment and 84% at 6-month follow-up, which suggests that both psychotherapy and hypnosis have a role in the treatment of conversion disorder. Psychotherapy has been an important treatment modality of conversion disorders, depression, anxiety, and somatoform disorders in general. Cognitive behavioural therapy (CBT) is of value in the management of functional somatic symptoms. The goal of CBT is to reduce symptoms, perceived stress, and disability and to limit the inappropriate use of medical care. 39 A controlled trial of the use of CBT for medically unexplained physical symptoms 40 enrolled 79 patients and randomly assigned them to receive either CBT or optimum medical care. The CBT intervention group had less impairment of sleep, a lower mean intensity of physical symptoms, and a higher recovery rate on follow-up measured with a general health questionnaire and a checklist for somatic symptoms than did the optimum medical care group. Kroenke and coworkers 41 did a meta-analysis of studies of CBT for various somatisation syndromes that showed a definite or possible treatment effect of CBT in 71% of patients. In summary, there are few data derived from controlled clinical trials that could lead to specific treatment guidelines for psychogenic movement disorders. However, a recent round-table discussion among experts led to a publication of treatment strategies based on their cumulative personal experiences. 33 There was consensus a psychiatrist should explore the psychodynamic basis of the individual psychogenic movement disorder and define the underlying and secondary psychiatric disorders. A psychiatrist will then develop a treatment plan addressing the psychiatric pathologies, commonly using a combination of psychotherapy (psychodynamic psychotherapy or CBT), stress management, relaxation techniques, and pharmacological treatment of associated depression and anxiety. Additionally, referral to physical or occupational therapy might help the patient reestablish a healthy pattern of motor function. The ultimate goal of this therapeutic approach is to enable the patient to give up the sick role and return to the previous level of function as quickly as possible (panel 3) Vol 5 August 2006

5 Panel 3: Commonly used treatment strategies Psychotherapy CBT Psychodynamic psychotherapy Stress management and relaxation techniques Biofeedback Yoga Meditation Pharmacotherapy Antidepressants Anxiolytics Rehabilitation Physical therapy Occupational therapy Prognosis The outcome of patients with psychogenic movement disorders is variable, but several factors that affect outcome have been described. In general, outlook for patients with these disorders is better than for those with other somatoform complaints, such as sensory symptoms, weakness, or pain. 2 The presence of a comorbid psychiatric diagnosis of depression or anxiety disorder is a positive prognostic factor for the outcome of conversion disorders in general 37 and also in psychogenic movement disorders. 10 Negative prognostic value has been associated with long-standing symptoms (more than 6 months), 5 insidious onset of movements, 5 and primary psychiatric diagnosis of hypochondriasis, factitious disorder, or malingering. 34 Other common obstacles to treatment success are patients resistance towards the diagnosis of psychogenicity and lack of willingness to engage in psychiatric treatment. 42 However, patients can be motivated successfully to engage in psychiatric treatment when physicians take interest in the condition and deliver an unambiguous diagnosis and a clearly outlined treatment plan. 35 Of 20 consecutively identified patients with psychogenic movement disorders, only one patient did not accept the diagnosis and was opposed to psychiatric treatment. 35 If left untreated, psychogenic movement disorders tend to become chronic, and follow-up data in several series show persistent symptoms in 65 95% of patients, 5,6,10,37 clearly showing the need for effective early intervention strategies and larger, carefully designed clinical trials with long-term follow-up. Conclusion Psychogenic movement disorders are diagnostically and therapeutically challenging to both neurologists and psychiatrists. More research into the underlying mechanisms of these disorders, as well as larger treatment studies, are clearly needed to improve the understanding and management of these complex disorders. Search strategy and selection criteria References for this review were identified by searches of PubMed and MDconsult from 1966 to May 2006, with the terms psychogenic movement disorders, functional movement disorders, conversion disorder, somatoform disorder, and somatization disorder. Articles and book chapters were identified through searches of the authors own files. Abstracts and reports from meetings were also included. Only articles published in English were reviewed. The final reference list was generated on the basis of originality and relevance to the topic. Contributors Both authors contributed to the selection of references and the writing of the review. Conflicts of interest We have no conflicts of interest. References 1 Lipsitt DR. Challenges of somatization: diagnostic, therapeutic and economic. Psychiatr Med 1992; 10: Lempert T, Dieterich M, Huppert D, Brandt T. Psychogenic disorders in neurology: frequency and clinical spectrum. Acta Neurol Scand 1990; 82: Marsden CD. Hysteria a neurologist s view. Psychol Med 1986; 16: Crimlisk H, Bhatia K, Cope C, David A, Marsden D, Ron MA. Slater revisited: 6 year follow up study of patients with medically unexplained motor symptoms. BMJ 1998; 316: Factor S, Podskalny G, Molho E. Psychogenic movement disorders: frequency, clinical profile, and characteristics. J Neurol Neurosurg Psychiatry 1995; 59: Williams DT, Ford B, Fahn S. Phenomenology and psychopathology related to psychogenic movement disorders. Adv Neurol 1995; 65: Hinson VK, Cubo E, Comella C, Leurgans S, Goetz CG. Rating scale for psychogenic movement disorders: scale development and clinimetric testing. Mov Disord 2005; 20: Cubo E, Hinson VK, Goetz CG, et al. Transcultural comparison of psychogenic movement disorders. Mov Disord 2005; 20: Ranawaya R, Riley D, Lang AE. Psychogenic dyskinesias in patients with organic movement disorders. Mov Disord 1990; 5: Feinstein A, Stergiopoulus V, Fine J, Lang AE. Psychiatric outcome in patients with a psychogenic movement disorder: a prospective study. Neuropsychiatry Neuropsychol Behav Neurol 2001; 14: American Psychiatric Association. Diagnostic and statistical manual for mental disorders, 4th edn. Washington, DC, USA: APA; Fahn S, Williams PJ. Psychogenic dystonia. Adv Neurol 1988; 50: Lang AE, Koller WC, Fahn S. Psychogenic parkinsonism. Arch Neurol 1995; 52: Kim YJ, Pakiam ASI, Lang AE. Historical and clinical features of psychogenic tremor: a review of 70 cases. Can J Neurol Sci 1999; 26: Deuschl G, Koester B, Luecking CH, Scheidt C. Diagnostic and pathophysiological aspects of psychogenic tremor. Mov Disord 1998; 13: Morgan JC, Sethi KD. Psychogenic parkinonism. In: Hallett M, Yudofsky SC, Lang AE, et al, eds. Psychogenic movement disorders. Philadelphia, USA: Lippincott Williams & Wilkins, 2006: Schrag A. Psychogenic dystonia and reflex sympathetic dystrophy. In: Hallett M, Yudofsky SC, Lang AE, et al, eds. Psychogenic movement disorders. Philadelphia, USA: Lippincott Williams & Wilkins, 2006: Lang A. Psychogenic dystonia: a review of 18 cases. Can J Neurol Sci 1995; 22: Vol 5 August

6 19 Hayes MW, Graham S, Heldorf P, demoore G, Morris JGL. A video review of the diagnosis of psychogenic gait: appendix and commentary. Mov Disord 1999; 14: Bhatia KP. Psychogenic gait disorders. Adv Neurol 2001; 87: Thomas M, Jankovic J. Psychogenic movement disorders. Diagnosis and management. CNS Drugs 2004; 18: Tan EK. Psychogenic tics: diagnostic value of the placebo test. J Child Neurol 2004; 19: Monday K, Jankovic J. Psychogenic myoclonus. Neurology 1993; 43: Marjama J, Troster AI, Koller WC. Psychogenic movement disorders. Neurol Clin 1995; 13: Kirsch DB, Mink JW. Psychogenic movement disorders in children. Pediatr Neurol 2004; 30: de la Fuente-Fernández R, Schulzer M, Stoessl AJ. Placebo mechanisms and reward circuitry: clues from Parkinson s disease. Biol Psychiatry 2004; 56: Lang AE. General overview of psychogenic movement disorders: epidemiology, diagnosis, and prognosis. In: Hallett M, Yudofsky SC, Lang AE, et al, eds. Psychogenic movement disorders. Philadelphia, USA: Lippincott Williams & Wilkins, 2006: Factor SA, Seibyl J, Innis R, Marek. Psychogenic parkinonism: conformation of diagnosis with β CIT SECT scans. Mov Disord 1998; 13: Booij J, Speelman JD, Horstink MW, Wolters EC. The clinical benefit of imaging dopamine transporters with [ 123 I]FP-CIT SPET in differentiating patients with presynaptic parkinsonism from those with other forms of parkinsonism. Eur J Nucl Med 2001; 28: O Sullivan JD, Costa DC, Lees AJ. Confirming Parkinson s disease with [¹²³I]β-CIT SPECT. Eur J Neurol 1999; 6 (suppl): McAuley J, Rothwell J. Identification of psychogenic, dystonic, and other organic tremors by a coherence entrainment test. Mov Disord 2004; 19: Thompson PD, Colebatch JG, Brown P, Rothwell JC, Obeso JA, Marsden CD. Voluntary stimulus-sensitive jerks and jumps mimicking myoclonus or pathological startle syndromes. Mov Disord 1992; 7: Jankovic J, Cloninger CR, Fahn S, Hallett M, Lang AE, Williams DT. Therapeutic approaches to psychogenic movement disorders. In: Hallett M, Yudofsky SC, Lang AE, et al, eds. Psychogenic movement disorders. Philadelphia, USA: Lippincott Williams & Wilkins, 2006: Voon V, Lang A. Antidepressant outcomes of psychogenic movement disorders. J Clin Psychiatry 2005; 66: Hinson VK, Weinstein S, Bernard B, Leurgans,Goetz CG. Singleblind clinical trial of psychotherapy for treatment of psychogenic movement disorders. Parkinsonism Relat Disord 2006; 12: Menza M, Lauritano M, Allen L, et al. Treatment of somatization disorder with nefazodone: a prospective, open-label study. Ann Clin Psychiatry 2001; 13: Rampello L, Raffaele R, Nicoletti G, LePira, F, Malaguarnera M, Drago F. Hysterical neurosis of the conversion type: therapeutic activity of neuroleptics with different hyperprolactinemic potency. Neuropsychobiology 1996; 33: Moene FC, Spinhoven P, Hoogduin KA, vandyck R. A randomised controlled clinical trial on the additional effect of hypnosis in a comprehensive treatment programme for in-patients with conversion disorder of the motor type. Psychother Psychosom 2002; 71: Sharpe M, Peveler R, Mayou R. The psychological treatment of patients with functional somatic symptoms: a practical guide. J Psychosom Res 1992; 36: Speckens A, van Hemert AM, Spinhoven P, Hawton KE, Bolk JH, Rooijmans HG. Cognitive behavioral therapy for medically unexplained physical symptoms: a randomized controlled trial. BMJ 1995; 311: Kroenke K, Swindle R. Cognitive behavioral therapy for somatization and symptom syndromes: a critical review of controlled clinical trials. Psychother Psychosom 2000; 69: Lazare A. Current concepts in psychiatry: conversion symptoms. N Engl J Med 1981; 305: Vol 5 August 2006