Characteristics of two distinct clinical phenotypes of functional (psychogenic) dystonia: follow-up study.

BACKGROUND: The fixed dystonia phenotype was originally established as a prototype of functional dystonia. Nevertheless, in recent reports different functional dystonia phenotypes have been recognized with dystonic movement comprising phasic instead of tonic contraction. OBJECTIVES: To examine clinical characteristic in all patients with dystonia who fulfilled the criteria for functional movement disorders irrespective of phenotype in an attempt to determine parameters of clinical presentations that might impact the disease progression pattern and outcome. METHODS: Patients presented with dystonia features incompatible with organic disease without other features required for the diagnosis of functional movement disorders were analyzed and prospectively followed-up. The two-step cluster analysis was performed to obtain the subgroups of dystonia phenotypes. RESULTS: The two-step cluster analysis extracted two subgroup of patients. Patients of the first cluster (68.8%) presented with "mobile" dystonia (84.9%), of cranial/neck/trunk localization (90.9%), fluctuated clinical course (69.7%), with frequent additional movement or other functional neurological disorders (63.6%) during follow-up. In the second cluster (31.2%) all of the patients presented with "fixed" dystonia of extremities, and the clinical course was characterized by either the disease progression (60%), or continuous without improvement (26.7%), and rare occurrence of additional functional neurological disorders (13.3%). CONCLUSION: In terms of clinical and demographic features as well as pattern of disease progression there are two clinical phenotypes in patients with functional dystonia. Distinctive features of incongruence and inconstancy are characteristic for "mobile" functional dystonia subgroup of patients.

Is there a specific psychiatric background or personality profile in functional dystonia?

OBJECTIVE: The aim of this cross-sectional study was to identify if there was a specific difference between patients with functional dystonia (DysF) and those with adult-onset, isolated idiopathic ("primary") dystonia (DysP) in terms of psychiatric disorders, psychological stressor, dissociation correlates, and personality traits. METHODS: Thirty-nine clinically definite DysF and 30 DysP patients matched by age, gender and dystonia distribution underwent psychiatric interview based on DSM-5 criteria and additional testings for global cognitive and psychiatric functions (Mini-Mental State Examination, Hamilton Depression and Hamilton Anxiety Rating Scale, Apathy Scale, Somatoform Dissociation Questionnaire-20, Dissociative Experiences Scale II, and the five-dimensional Revised Neuroticism-Extroversion-Openness Personality Inventory). RESULTS: Almost half of our DysF patients had prior psychiatric treatment, which was significantly more frequent when compared to DysP. Patients with DysF in comparison to DysP also had considerably more frequent preceding stress, higher apathy, dissociative and somatoform scores, as well as significantly higher rate of la belle indifférence sign. This sign, stress before dystonia and prior psychiatric disorder independently predicted having DysF. Some of psychiatric disorders (i.e. substance-related disorders, schizophrenia, adjustment disorder, borderline personality disorder, post-traumatic stress disorder, psychotic depression, delusional disorder) were exclusively present among DysF patients. DysF compared to DysP patients had lower scores for both extroversion and openness to experiences. CONCLUSION: Our data found different pattern of psychiatric comorbidity and personality traits between DysF and DysP patients, including a higher prevalence of psychological stressor and dissociative correlates, indicating at least a partial role of psychological mechanisms in the pathogenesis of DysF.