Abstract
Introduction: Functional movement disorders (FMD) refer to a group of movement disorders that present with clinical characteristics incongruent to those due to established pathophysiologic processes, as for example in the case of neurodegeneration or lesions. The aim of this study was to assess clinical features that contribute to the specific phenotypic presentations and disease course of FMD.Methods: The study consisted of 100 patients with FMD treated at Clinic for Neurology, Clinical Center of Serbia, who were longitudinally observed. Comprehensive clinical and psychiatric assessment was performed at the baseline, when initial FMD phenotype was defined. Follow-up assessment of phenotypic pattern over the time and clinical course was done after 3.2 ± 2.5 years at average.Results: We showed that 48% of FMD patients were prone to changes of phenotypic pattern during the disease course. Dystonia had tendency to remains as single and unchanged phenotype over the time (68.2%), while patients initially presented with Tremor, Gait disorder, Parkinsonism and Mixed phenotype were more susceptible to developing additional symptoms (62.5, 50, and 100%, respectively). Higher levels of somatoform experiences (p = 0.033, Exp(B) = 1.082) and higher motor severity (p = 0.040, Exp(B) = 1.082) at baseline assessment were associated with an increased likelihood of further enriching of FMD phenotype with additional functional symptoms. Also, these patients more frequently reported pain, and had higher scores on majority of applied psychiatric scales, together with more frequent presence of major depressive disorder.Conclusion: Results from this prospective study suggested tendency for progression and enrichment of functional symptoms in FMD patients over time. Besides functional core symptoms, other key psychological and physical features (like pain or multiple somatisations) were quite relevant for chronicity and significant dysability of FMD patients.
Highlights
Functional movement disorders (FMD) refer to a group of movement disorders that present with clinical characteristics incongruent to those due to established pathophysiologic processes, as for example in the case of neurodegeneration or lesions
According to DSM-5 criteria, the most commonly established psychiatric diagnoses were major depressive disorder (MDD), both in the form of single (23%) or recurrent episodes (22%), followed by dysthymia diagnosed in 10% of patients
The main finding of our prospective study of 100 FMD patients is that 48% of patients are prone to changes of phenotypic pattern during the disease course
Summary
Functional movement disorders (FMD) refer to a group of movement disorders that present with clinical characteristics incongruent to those due to established pathophysiologic processes, as for example in the case of neurodegeneration or lesions. Functional movement disorders (FMD) refer to a group of disorders that includes tremor, dystonia, myoclonus, parkinsonism, speech, and gait disturbances, and other movement disorders that are incongruent with established clinical patterns due to different pathophysiologic processes, as for example in the case of lesions [1]. Additional physical features (such as pain, fatigue, bladder, or bowel problems, etc), as well as psychiatric comorbidities, are usually associated with FND/FMD and can have significant impact on outcome [4]. The unpredictability of such disorders is further reflected through the highly variable prognosis of different FND [5]. A combination of wide variety of neurological and psychiatric symptoms are likely to contribute to disability and reduced quality of life in patients with FMD/FND [4], even being comparable to those of patients with Parkinson’s disease [5]
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