Psychogenic Movement Disorders

Efficacy of a 5-day, intensive, multidisciplinary, outpatient physical and occupational therapy protocol in the treatment of functional movement disorders: A retrospective study

BACKGROUND

The use of rehabilitation services has been shown to be beneficial for patients with functional movement disorders (FMD). However, there is great variability in the type of rehabilitation services utilized. In the present study we aimed at determining the efficacy of an intense outpatient physical rehabilitation program as a treatment modality for patients with FMD.

METHODS

Eighteen participants underwent treatment in a specialized outpatient rehabilitation program utilizing a multidisciplinary approach for the treatment of FMD. Participants completed a series of tests on day one and day five of the program.

RESULTS

Results indicated statistically significant improvements in all but one motor and gait outcomes in patients with functional movement disorders treated with physical rehabilitation.

CONCLUSION

These results provide support for the continued use of physical and occupational therapy for functional movement disorder patients. Further research is needed to fully validate these findings and there remains a need for further study into multidisciplinary approaches that may be even more efficacious.

Increased Incidence of Functional (Psychogenic) Movement Disorders in Children and Adults Amid the COVID-19 Pandemic: A Cross-sectional Study

BACKGROUND AND OBJECTIVES

Functional (psychogenic) movement disorders (FMDs) are conditions in which affected patients develop abnormal movements that are incongruous with known, organic, movement disorders, often associated with psychological stressors.

METHODS

In this case series, electronic medical records of all patients who presented to our adult and pediatric tertiary care movement disorders clinics between March 1 and October 30, 2020, and during the same period in 2019 were reviewed. All patients diagnosed with functional (psychogenic) movement disorder were included if they satisfied diagnostic criteria.

RESULTS

Among 550 new patients referred for evaluation at our tertiary care movement disorders centers, 45 (8.2%) received a diagnosis of FMD; 75.6% were female, in comparison to the prior year during which time 665 new patients were evaluated and 5.1% were diagnosed with FMD. This represents a 60.1% increase (90.1% in pediatric cohort, 50.9% in adult cohort) in new patients diagnosed with FMD during the COVID-19 pandemic.

CONCLUSIONS

Within our patient population, there has been increased incidence of FMDs in the setting of the COVID-19 pandemic, possibly reflecting increased psychological and other stressors during this period.

Psychedelic-assisted therapy for functional neurological disorders: A theoretical framework and review of prior reports

Functional neurological disorders (FNDs), which are sometimes also referred to as psychogenic neurological disorders or conversion disorder, are common disabling neuropsychiatric disorders with limited treatment options. FNDs can present with sensory and/or motor symptoms, and, though they may mimic other neurological conditions, they are thought to occur via mechanisms other than those related to identifiable structural neuropathology and, in many cases, appear to be triggered and sustained by recognizable psychological factors. There is intriguing preliminary evidence to support the use of psychedelic‐assisted therapy in a growing number of psychiatric illnesses, including FNDs. We review the theoretical arguments for and against exploring psychedelic‐assisted therapy as a treatment for FNDs. We also provide an in‐depth discussion of prior published cases detailing the use of psychedelics for psychosomatic conditions, analyzing therapeutic outcomes from a contemporary neuroscientific vantage as informed by several recent neuroimaging studies on psychedelics and FNDs.

Functional Dystonia: Differentiation From Primary Dystonia and Multidisciplinary Treatments

Dystonia is a common movement disorder, involving sustained muscle contractions, often resulting in twisting and repetitive movements and abnormal postures. Dystonia may be primary, as the sole feature (isolated) or in combination with other movement disorders (combined dystonia), or as one feature of another neurological process (secondary dystonia). The current hypothesis is that dystonia is a disorder of distributed brain networks, including the basal ganglia, cerebellum, thalamus and the cortex resulting in abnormal neural motor programs. In comparison, functional dystonia (FD) may resemble other forms of dystonia (OD) but has a different pathophysiology, as a subtype of functional movement disorders (FMD). FD is the second most common FMD and amongst the most diagnostically challenging FMD subtypes. Therefore, distinguishing between FD and OD is important, as the management of these disorders is distinct. There are also different pathophysiological underpinnings in FD, with for example evidence of involvement of the right temporoparietal junction in functional movement disorders that is believed to serve as a general comparator of internal predictions/motor intentions with actual motor events resulting in disturbances in self-agency. In this article, we present a comprehensive review across the spectrum of FD, including oromandibular and vocal forms and discuss the history, clinical clues, evidence for adjunctive "laboratory-based" testing, pathophysiological research and prognosis data. We also provide the approach used at the Massachusetts General Hospital Dystonia Center toward the diagnosis, management and treatment of FD. A multidisciplinary approach, including neurology, psychiatry, physical, occupational therapy and speech therapy, and cognitive behavioral psychotherapy approaches are frequently required; pharmacological approaches, including possible targeted use of botulinum toxin injections and inpatient programs are considerations in some patients. Early diagnosis and treatment may help prevent unnecessary investigations and procedures, while facilitating the appropriate management of these highly complex patients, which may help to mitigate frequently poor clinical outcomes.

Complex dystonias: an update on diagnosis and care

Complex dystonias are defined as dystonias that are accompanied by neurologic or systemic manifestations beyond movement disorders. Many syndromes or diseases can present with complex dystonia, either as the cardinal sign or as part of a multi-systemic manifestation. Complex dystonia often gradually develops in the disease course, but can also be present from the outset. If available, the diagnostic workup, disease-specific treatment, and management of patients with complex dystonias require a multi-disciplinary approach. This article summarizes current knowledge on complex dystonias with a particular view of recent developments with respect to advances in diagnosis and management, including causative treatments.

Psychosocial interventions for conversion and dissociative disorders in adults

BACKGROUND

Conversion and dissociative disorders are conditions where people experience unusual neurological symptoms or changes in awareness or identity. However, symptoms and clinical signs cannot be explained by a neurological disease or other medical condition. Instead, a psychological stressor or trauma is often present. The symptoms are real and can cause significant distress or problems with functioning in everyday life for the people experiencing them.

OBJECTIVES

To assess the beneficial and harmful effects of psychosocial interventions of conversion and dissociative disorders in adults.

SEARCH METHODS

We conducted database searches between 16 July and 16 August 2019. We searched Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and eight other databases, together with reference checking, citation searching and contact with study authors to identify additional studies.  SELECTION CRITERIA: We included all randomised controlled trials that compared psychosocial interventions for conversion and dissociative disorders with standard care, wait list or other interventions (pharmaceutical, somatic or psychosocial).  DATA COLLECTION AND ANALYSIS: We selected, quality assessed and extracted data from the identified studies. Two review authors independently performed all tasks. We used standard Cochrane methodology. For continuous data, we calculated mean differences (MD) and standardised mean differences (SMD) with 95% confidence interval (CI). For dichotomous outcomes, we calculated risk ratio (RR) with 95% CI. We assessed and downgraded the evidence according to the GRADE system for risk of bias, imprecision, indirectness, inconsistency and publication bias.

MAIN RESULTS

We included 17 studies (16 with parallel-group designs and one with a cross-over design), with 894 participants aged 18 to 80 years (female:male ratio 3:1).  The data were separated into 12 comparisons based on the different interventions and comparators. Studies were pooled into the same comparison when identical interventions and comparisons were evaluated. The certainty of the evidence was downgraded as a consequence of potential risk of bias, as many of the studies had unclear or inadequate allocation concealment. Further downgrading was performed due to imprecision, few participants and inconsistency. There were 12 comparisons for the primary outcome of reduction in physical signs. Inpatient paradoxical intention therapy compared with outpatient diazepam: inpatient paradoxical intention therapy did not reduce conversive symptoms compared with outpatient diazepam at the end of treatment (RR 1.44, 95% CI 0.91 to 2.28; 1 study, 30 participants; P = 0.12; very low-quality evidence). Inpatient treatment programme plus hypnosis compared with inpatient treatment programme: inpatient treatment programme plus hypnosis did not reduce severity of impairment compared with inpatient treatment programme at the end of treatment (MD -0.49 (negative value better), 95% CI -1.28 to 0.30; 1 study, 45 participants; P = 0.23; very low-quality evidence). Outpatient hypnosis compared with wait list: outpatient hypnosis might reduce severity of impairment compared with wait list at the end of treatment (MD 2.10 (higher value better), 95% CI 1.34 to 2.86; 1 study, 49 participants; P < 0.00001; low-quality evidence). Behavioural therapy plus routine clinical care compared with routine clinical care: behavioural therapy plus routine clinical care might reduce the number of weekly seizures compared with routine clinical care alone at the end of treatment (MD -21.40 (negative value better), 95% CI -27.88 to -14.92; 1 study, 18 participants; P < 0.00001; very low-quality evidence). Cognitive behavioural therapy (CBT) compared with standard medical care: CBT did not reduce monthly seizure frequency compared to standard medical care at end of treatment (RR 1.56, 95% CI 0.39 to 6.19; 1 study, 16 participants; P = 0.53; very low-quality evidence). CBT did not reduce physical signs compared to standard medical care at the end of treatment (MD -4.75 (negative value better), 95% CI -18.73 to 9.23; 1 study, 61 participants; P = 0.51; low-quality evidence). CBT did not reduce seizure freedom compared to standard medical care at end of treatment (RR 2.33, 95% CI 0.30 to 17.88; 1 trial, 16 participants; P = 0.41; very low-quality evidence). Psychoeducational follow-up programmes compared with treatment as usual (TAU): no study measured reduction in physical signs at end of treatment. Specialised CBT-based physiotherapy inpatient programme compared with wait list: no study measured reduction in physical signs at end of treatment. Specialised CBT-based physiotherapy outpatient intervention compared with TAU: no study measured reduction in physical signs at end of treatment. Brief psychotherapeutic intervention (psychodynamic interpersonal treatment approach) compared with standard care: brief psychotherapeutic interventions did not reduce conversion symptoms compared to standard care at end of treatment (RR 0.12, 95% CI 0.01 to 2.00; 1 study, 19 participants; P = 0.14; very low-quality evidence). CBT plus adjunctive physical activity (APA) compared with CBT alone: CBT plus APA did not reduce overall physical impacts compared to CBT alone at end of treatment (MD 5.60 (negative value better), 95% CI -15.48 to 26.68; 1 study, 21 participants; P = 0.60; very low-quality evidence). Hypnosis compared to diazepam: hypnosis did not reduce symptoms compared to diazepam at end of treatment (RR 0.69, 95% CI 0.39 to 1.24; 1 study, 40 participants; P = 0.22; very low-quality evidence). Outpatient motivational interviewing (MI) and mindfulness-based psychotherapy compared with psychotherapy alone: psychotherapy preceded by MI might decrease seizure frequency compared with psychotherapy alone at end of treatment (MD 41.40 (negative value better), 95% CI 4.92 to 77.88; 1 study, 54 participants; P = 0.03; very low-quality evidence). The effect on the secondary outcomes was reported in 16/17  studies. None of the studies reported results on adverse effects. In the studies reporting on level of functioning and quality of life at end of treatment the effects ranged from small to no effect.

AUTHORS' CONCLUSIONS

The results of the meta-analysis and reporting of single studies suggest there is lack of evidence regarding the effects of any psychosocial intervention on conversion and dissociative disorders in adults. It is not possible to draw any conclusions about potential benefits or harms from the included studies.

Psychogenic (Functional) Movement Disorders

PURPOSE OF REVIEW

This article reviews a practical approach to psychogenic movement disorders to help neurologists identify and manage this complex group of disorders.

RECENT FINDINGS

Psychogenic movement disorders, also referred to as functional movement disorders, describe a group of disorders that includes tremor, dystonia, myoclonus, parkinsonism, speech and gait disturbances, and other movement disorders that are incongruent with patterns of pathophysiologic (organic) disease. The diagnosis is based on positive clinical features that include variability, inconsistency, suggestibility, distractibility, suppressibility, and other supporting information. While psychogenic movement disorders are often associated with psychological and physical stressors, the underlying pathophysiology is not fully understood. Although insight-oriented behavioral and pharmacologic therapies are helpful, a multidisciplinary approach led by a neurologist, but also including psychiatrists and physical, occupational, and speech therapists, is needed for optimal outcomes.

SUMMARY

The diagnosis of psychogenic movement disorders is based on clinical features identified on neurologic examination, and neurophysiologic and imaging studies can provide supporting information.

Acute cerebellar ataxia: differential diagnosis and clinical approach

Cerebellar ataxia is a common finding in neurological practice and has a wide variety of causes, ranging from the chronic and slowly-progressive cerebellar degenerations to the acute cerebellar lesions due to infarction, edema and hemorrhage, configuring a true neurological emergency. Acute cerebellar ataxia is a syndrome that occurs in less than 72 hours, in previously healthy subjects. Acute ataxia usually results in hospitalization and extensive laboratory investigation. Clinicians are often faced with decisions on the extent and timing of the initial screening tests, particularly to detect treatable causes. The main group of diseases that may cause acute ataxias discussed in this article are: stroke, infectious, toxic, immune-mediated, paraneoplastic, vitamin deficiency, structural lesions and metabolic diseases. This review focuses on the etiologic and diagnostic considerations for acute ataxia.

Functional gait disorders, clinical phenomenology, and classification

BACKGROUND

Functional gait disorders (FGDs) are relatively common in patients presenting for evaluation of a functional movement disorder (FMD). The diagnosis and classification of FGDs is complex because patients may have a primary FGD or a FMD interfering with gait.

METHODS

We performed a detailed evaluation of clinical information and video recordings of gait in patients diagnosed with FMDs.

RESULTS

We studied a total of 153 patients with FMDs, 68% females, with a mean age at onset of 36.4 years. A primary FGD was observed in 39.2% of patients; among these patients, 13 (8.5%) had an isolated FGD (a gait disorder without other FMDs). FMDs presented in 34% of patients with otherwise normal gait. Tremor was the most common FMD appearing during gait, but dystonia was the most common FMD interfering with gait. Patients with FGD had a higher frequency of slow-hesitant gait, astasia-abasia, bouncing, wide-based gait and scissoring compared with patients with FMDs occurring during gait. Bouncing gait with knee buckling was more frequently observed in patients with isolated FGD (P = 0.017). Patients with FGDs had a trend for higher frequency of wheelchair dependency (P = 0.073) than those with FMDs interfering with gait.

CONCLUSIONS

Abnormal gait may be observed as a primary FGD or in patients with other FMDs appearing during gait; both conditions are common and may cause disability.

Case Report on Fear of Falling Syndrome: A Debilitating but Curable Gait Disorder

Patient: Male, 70

Final Diagnosis: Fear of falling syndrome

Symptoms: Inability to get up from a chair and ambulate independently

Medication: —

Clinical Procedure: Lumbar puncture

Specialty: Neurology

Functional movement disorders in neurogeriatric inpatients : Underdiagnosed, often comorbid to neurodegenerative disorders and treatable

BACKGROUND

The proportion of patients with functional movement disorders (FMD) is particularly high in neurology clinics. Treatment options have not been consistently developed, not well evaluated and not validated. This article presents the preliminary data on the prevalence and treatment response of patients with FMD who were treated within the framework of an early rehabilitative geriatric complex treatment at a university hospital for neurology.

METHODS

From July 2017 to November 2018 the prevalence, demographic and clinical parameters, and response to treatment of FMD patients were documented and compared to non-FMD patients treated at the neurogeriatric ward of the University Hospital Schleswig-Holstein, in Kiel. Clinical endpoints were the Short Physical Performance Battery (SPPB) for mobility and the Barthel index for instrumented activity of daily life (iADL).

RESULTS

The prevalence of FMD was 11% (19/175) and predominantly observed in women (74%). Of the FMD patients nine also had a diagnosis of either idiopathic Parkinson's disease (N = 7), dementia with Lewy bodies (N = 1) or progressive supranuclear palsy (N = 1). At admission, neither the SPPB nor the iADL differed significantly between FMD and non-FMD patients. The treatment response was comparable between the groups: SPPB change was +0.3±1.8 (mean, standard deviation) in FMD and +0.4±1.9 in non-FMD patients (p = 0.83). The iADL change was +19±15 in FMD and +18±17 in non-FMD (p = 0.83).

CONCLUSION

The prevalence of FMD was unexpectedly high in the neurogeriatric ward of a German university hospital. There were comparable impairments and responses to multidisciplinary treatment in mobility and iADL between FMD and non-FMD geriatric patients, suggesting that specific and informed treatment provided by a multidisciplinary geriatric team is effective in geriatric FMD patients. Further studies of this underdiagnosed disorder in older age are warranted.

Pathogenesis and pathophysiology of functional (psychogenic) movement disorders

Functional movement disorders (FMDs), known over time as "hysteria", "dissociative", "conversion", "somatoform", "non-organic" and "psychogenic" disorders, are characterized by having a voluntary quality, being modifiable by attention and distraction but perceived by the patient as involuntary. Although a high prevalence of depression and anxiety is observed in these patients, a definitive role of psychiatric disorders in FMDs has not been proven, and many patients do not endorse such manifestations. Stressful events, social influences and minor trauma may precede the onset of FMDs, but their pathogenic mechanisms are unclear. Patients with FMDs have several abnormalities in their neurobiology including strengthened connectivity between the limbic and motor networks. Additionally, there is altered top-down regulation of motor activities and increased activation of areas implicated in self-awareness, self-monitoring, and active motor inhibition such as the cingulate and insular cortex. Decreased activation of the supplementary motor area (SMA) and pre-SMA, implicated in motor control and preparation, is another finding. The sense of agency defined as the feeling of controlling external events through one's own action also seems to be impaired in individuals with FMDs. Correlating with this is a loss of intentional binding, a subjective time compression between intentional action and its sensory consequences. Organic and functional dystonia may be difficult to differentiate since they share diverse neurophysiological features including decreased cortical inhibition, and similar local field potentials in the globus pallidus and thalamus; although increased cortical plasticity is observed only in patients with organic dystonia. Advances in the pathogenesis and pathophysiology of FMDs may be helpful to understand the nature of these disorders and plan further treatment strategies.

Familial paroxysmal kinesigenic dyskinesia is associated with mutations in the KCNA1 gene

Paroxysmal kinesigenic dyskinesia (PKD) is a heterogeneous movement disorder characterized by recurrent dyskinesia attacks triggered by sudden movement. PRRT2 has been identified as the first causative gene of PKD. However, it is only responsible for approximately half of affected individuals, indicating that other loci are most likely involved in the etiology of this disorder. To explore the underlying causative gene of PRRT2-negative PKD, we used a combination strategy including linkage analysis, whole-exome sequencing and copy number variations analysis to detect the genetic variants within a family with PKD. We identified a linkage locus on chromosome 12 (12p13.32-12p12.3) and detected a novel heterozygous mutation c.956 T>G (p.319 L>R) in the potassium voltage-gated channel subfamily A member 1, KCNA1. Whole-exome sequencing in another 58 Chinese patients with PKD who lacked mutations in PRRT2 revealed another novel mutation in the KCNA1 gene [c.765 C>A (p.255 N>K)] within another family. Biochemical analysis revealed that the L319R mutant accelerated protein degradation via the proteasome pathway and disrupted membrane expression of the Kv1.1 channel. Electrophysiological examinations in transfected HEK293 cells showed that both the L319R and N255K mutants resulted in reduced potassium currents and respective altered gating properties, with a dominant negative effect on the Kv1.1 wild-type channel. Our study suggests that these mutations in KCNA1 cause the Kv1.1 channel dysfunction, which leads to familial PKD. The current study further extended the genotypic spectrum of this disorder, indicating that Kv1.1 channel dysfunction maybe one of the underlying defects in PKD.

[Clinical and cognitive aspects of functional (psychogenic) tremor]

Functional (psychogenic) tremor is the most common functional movement disorder. Characteristic clinical features, so called red flags, can help to make the clinical distinction of this type from other tremor disorders. The most common features include the variability of frequency and amplitude. Clinical examination should include different types of distraction including motor or cognitive tasks or testing the influence of suggestibility on tremor amplitude, frequency or direction. Patients often report sudden onset and remissions that may last for months or even years. In some cases, the tremor is only present in highly specific situations. Although functional tremor shares characteristics with voluntary actions, patients experience their abnormal movements as involuntary. Recent experimental approaches have revealed an impairment in sense of agency. The diagnosis can be supported by neurophysiological measurements including accelerometry, which achieved a sensitivity of 89.5% and a specificity of 95.9% in a validated test battery, thus providing a useful additional diagnostic tool. Psychotherapeutic treatment is indicated in patients with and without evident psychological symptoms. A specific physiotherapeutic approach for functional tremor is re-trainment.

Research Priorities in Limb and Task-Specific Dystonias

Dystonia, which causes intermittent or sustained abnormal postures and movements, can present in a focal or a generalized manner. In the limbs, focal dystonia can occur in either the upper or lower limbs and may be task-specific causing abnormal motor performance for only a specific task, such as in writer’s cramp, runner’s dystonia, or musician’s dystonia. Focal limb dystonia can be non-task-specific and may, in some circumstances, be associated with parkinsonian disorders. The true prevalence of focal limb dystonia is not known and is likely currently underestimated, leaving a knowledge gap and an opportunity for future research. The pathophysiology of focal limb dystonia shares some commonalities with other dystonias with a loss of inhibition in the central nervous system and a loss of the normal regulation of plasticity, called homeostatic plasticity. Functional imaging studies revealed abnormalities in several anatomical networks that involve the cortex, basal ganglia, and cerebellum. Further studies should focus on distinguishing cause from effect in both physiology and imaging studies to permit focus on most relevant biological correlates of dystonia. There is no specific therapy for the treatment of limb dystonia given the variability in presentation, but off-label botulinum toxin therapy is often applied to focal limb and task-specific dystonia. Various rehabilitation techniques have been applied and rehabilitation interventions may improve outcomes, but small sample size and lack of direct comparisons between methods to evaluate comparative efficacy limit conclusions. Finally, non-invasive and invasive therapeutic modalities have been explored in small studies with design limitations that do not yet clearly provide direction for larger clinical trials that could support new clinical therapies. Given these gaps in our clinical, pathophysiologic, and therapeutic knowledge, we have identified priorities for future research including: the development of diagnostic criteria for limb dystonia, more precise phenotypic characterization and innovative clinical trial design that considers clinical heterogeneity, and limited available number of participants.

Psychodynamic Psychotherapy for Functional (Psychogenic) Movement Disorders

OBJECTIVE

As the literature for the treatment of functional (psychogenic) movement disorders (FMD) is sparse, we assessed clinical outcomes in patients with FMD who underwent treatment with psychodynamic psychotherapy (PDP).

METHODS

A retrospective analysis of the data of patients with FMD who were referred for PDP from 2008-2014 at Emory University Medical Center was performed.

RESULTS

Thirty patients were included, mean age at presentation was 50 years (SD 13.9) and majority were female (27/30). Most common movement disorder was involuntary shaking/jerky movements (50%) and tremor (43%). Mean duration of symptoms was 3.2 years and mean number of PDP visits was 4.9. PDP lead to good outcomes in 10, modest in 8, and poor in 9. Three patients lost to follow up. Mean duration of symptoms between two groups (good vs. poor) was not statistically significant (p = 0.11), mean number of PDP visits showed a trend towards significance (p = 0.053). In all cases of good outcomes precipitants of the movement disorder were identified and a majority (60%) was receptive of the diagnosis and had good insight.

CONCLUSION

PDP lead to improvement in 60% of the patients which is encouraging as the treatment is challenging. This study supports heterogeneous causes of FMD including varied roles of past/recent events and demonstrates importance of psychological approaches such as PDP. Treatment with PDP should be considered in some patients with FMD but predicting who will respond remains a challenge. Further long term prospective studies with large sample size and placebo control are needed.

Recent Advances in Understanding and Managing Tourette Syndrome

Tourette syndrome (TS) is a neurologic and behavioral disorder consisting of motor and phonic tics with onset in childhood or adolescence. The severity of tics can range from barely perceptible to severely impairing due to social embarrassment, discomfort, self-injury, and interference with daily functioning and school or work performance. In addition to tics, most patients with TS have a variety of behavioral comorbidities, including attention deficit hyperactivity disorder and obsessive-compulsive disorder. Studies evaluating the pathophysiology of tics have pointed towards dysfunction of the cortico-striato-thalamo-cortical circuit, but the mechanism of this hyperkinetic movement disorder is not well understood. Treatment of TS is multidisciplinary, typically involving behavioral therapy, oral medications, and botulinum toxin injections. Deep brain stimulation may be considered for “malignant” TS that is refractory to conventional therapy. In this review, we will highlight recent developments in the understanding and management strategies of TS.

Psychogenic (functional) parkinsonism

Psychogenic parkinsonism (PP), although often quite disabling, is one of the least commonly reported subtypes of psychogenic movement disorders. There are certain features that help distinguish PP from idiopathic Parkinson's disease, such as abrupt onset, early disability, bilateral shaking and slowness, nondecremental slowness when performing repetitive movements, voluntary resistance against passive movement without cogwheel rigidity, distractibility, "give-way" weakness, stuttering speech, bizarre gait, and a variety of behavioral symptoms. While the diagnosis of PP is clinical, functional imaging evaluating the integrity of nigrostriatal pathways can help distinguish PP from other types of parkinsonism. PP can coexist in patients with organic parkinsonism, adding to the challenge of making a diagnosis of PP. Being cognizant of the clinical signs of psychogenic movement disorders, including PP, will lead to earlier diagnosis and hopefully improved outcomes.

Functional eye movement disorders

Functional (psychogenic) eye movement disorders are perhaps less established in the medical literature than other types of functional movement disorders. Patients may present with ocular symptoms (e.g., blurred vision or oscillopsia) or functional eye movements may be identified during the formal examination of the eyes in patients with other functional disorders. Convergence spasm is the most common functional eye movement disorder, but functional gaze limitation, functional eye oscillations (also termed "voluntary nystagmus"), and functional convergence paralysis may be underreported. This chapter reviews the different types of functional eye movement abnormalities and provides a practical framework for their diagnosis and management.

Functional (psychogenic) movement disorders - Clinical presentations

Functional or psychogenic movement disorders are common and disabling, and sometime difficult to diagnose. The history and physical exam can give positive features that will support the diagnosis, which should not be based solely on exclusion. Some clues in the history are sudden onset, intermittent time course, variability of manifestation over time, childhood trauma, history of other somatic symptom and secondary gain. Anxiety and depression are common, but not necessarily more than the general population. On examination, distraction and suggestibility may be present. There are specific signs that should be looked for with different types of movements. For example, with tremor, change in frequency over time and entrainment are common features. With myoclonus, the movements might be complex in type with long latencies to stimulus induced jerks. Gait disorders show good balance despite claims to the contrary. Functional dystonia still remains a challenging diagnosis in many circumstances, although fixed dystonia is one sign more likely to be functional.

Clinical and scientific perspectives on movement disorders: Stanley Fahn's contributions

Dr. Stanley Fahn, the H. Houston Merritt Professor of Neurology and Director Emeritus of the Center for Parkinson's Disease and Other Movement Disorders at Columbia University, one of the founders of the field of movement disorders, was the first president of the Movement Disorders Society (subsequently renamed as the International Parkinson and Movement Disorder Society). Together with his friend and colleague, Professor David Marsden, he also served as the first co-editor of the journal Movement Disorders. By emphasizing phenomenology as the key element in differentiating various hypokinetic and hyperkinetic movement disorders, Dr. Fahn drew attention to the clinical history and the power of observation in the diagnosis of movement disorders. Dr. Fahn had major influence on the development of classifications and assessments of various movement disorders and in organizing various research groups such as the Parkinson Study Group. As the founder and president of the World Parkinson Coalition and an organizer of the initial three World Parkinson Congresses, he has demonstrated his long-standing commitment to the cause of including patients as partners. The primary goal and objective of this invited review is to highlight some of Dr. Fahn's most impactful scientific and clinical contributions to the understanding and treatment of Parkinson's disease, dystonia, and other movement disorders.