Functional motor disorders: mechanism, prognosis and treatment

Functional motor disorders (FMD) consist of tremor, jerky movements, altered posturing or weakness. They are characterized by specific factors in the history and neurological examination, pointing at their functional nature, like the influence of attention and distraction or incongruency with the anatomy. They are highly prevalent and often significantly impairing. This thesis discusses the pathophysiology, prognosis and treatment of FMD. Part 1 describes that we found many similarities between groups of different functional motor symptoms. Many patients report severe fatigue, which correlates with impaired quality of life and subjective health ratings. This calls for more attention in clinical practice. A comparison between cortical myoclonus and functional jerky movements showed comparable percentages of depressive and anxiety symptoms. Pain is more prevalent in functional jerky movements. Two chapters investigating fMRI in FMS, confirm existing theories on the role of altered attentional processes, perception of body scheme and sense of agency. Part 2 contains a review and a case-control study on the prognosis of FMS. It turns out symptoms did not resolve in a large part of the studied patients and misdiagnosis was low. Part 3 summarized the literature on the treatment on FMD and contains a RCT to the effect of education and self-help on the internet compared to usual care. We did not find differences between groups on clinically relevant outcome measures. Patients did report high satisfaction with the intervention

Functional Jerky Movements

Functional jerky movements (or functional myoclonus) are commonly seen in patients with functional movement disorder. Positive features both from history and clinical examination are important for the diagnosis. However, due to their heterogeneous and paroxysmal nature a home-made video-recording of the jerky movements can be essential to make the diagnose by a movement disorder specialist. Supportive clinical clues include abrupt symptom onset often triggered by a physical event, whereas entrainment and distractibility are supportive signs during physical examination. Localization of the jerky movements, especially proximal localization, is supportive, and can also be helpful in distinguishing functional jerks from tics and myoclonus, which are the most important differential diagnostic considerations. Additional neurophysiological tests include polymyography and electroencephalography-electromyography (EEG-EMG) co-registration in order to demonstrate a readiness potential (RP). Management includes disease education and specialized physical therapy

The prognosis of functional limb weakness, a 14-year case-control study

Reliable data on the prognosis of functional motor disorder are scarce, as existing studies of the prognosis of functional motor disorder are nearly all retrospective, small and uncontrolled. In this study we used a prospectively recruited, controlled cohort design to assess misdiagnosis, mortality and symptomatic and health outcome in patients with functional limb weakness compared to neurological disease and healthy control subjects. We also carried out an exploratory analysis for baseline factors predicting outcome. One hundred and seven patients with functional limb weakness, 46 neurological and 38 healthy control subjects from our previously studied prospective cohort were traced for follow-up after an average of 14 years. Misdiagnosis was determined in a consensus meeting using information from records, patients and their GPs. Numbers and causes of death were collected via death certificates. Outcome of limb weakness, physical and psychiatric symptoms, disability/quality of life and illness perception were recorded with self-rated questionnaires. Outcome measures were compared within and between groups. Seventy-six patients (71%) with functional limb weakness, 31 (67%) neurological and 23 (61%) healthy controls were included in follow-up. Misdiagnosis was found in one patient in the functional limb weakness group (1%) and in one neurological control (2%). Eleven patients with functional limb weakness, eight neurological control subjects and one healthy control subject had died. Weakness had completely remitted in 20% of patients in the functional limb weakness group and in 18% of the neurological controls (P = 0.785) and improved in a larger proportion of functional limb weakness patients (P = 0.011). Outcomes were comparable between patient groups, and worse than the healthy control group. No baseline factors were independent predictors of outcome, although somatization disorder, general health, pain and total symptoms at baseline were univariably correlated to outcome. This study is the largest and longest follow-up study of functional limb weakness. Misdiagnosis in functional limb weakness is rare after long-term follow-up. The disorder is associated with a higher mortality rate than expected, and symptoms are persistent and disabling. It appears difficult to predict outcome based on common baseline variables. These data should help inform clinicians to provide a more realistic outlook of the outcome and emphasize the importance of active and targeted therapy

Electrophysiologic testing aids diagnosis and subtyping of myoclonus

OBJECTIVE: To determine the contribution of electrophysiologic testing in the diagnosis and anatomical classification of myoclonus. METHODS: Participants with a clinical diagnosis of myoclonus were prospectively recruited, each undergoing a videotaped clinical examination and battery of electrophysiologic tests. The diagnosis of myoclonus and its subtype was reviewed after 6 months in the context of the electrophysiologic findings and specialist review of the videotaped clinical examination. RESULTS: Seventy-two patients with myoclonus were recruited. Initial clinical anatomical classification included 25 patients with cortical myoclonus, 7 with subcortical myoclonus, 2 with spinal myoclonus, and 15 with functional myoclonic jerks. In 23 cases, clinical anatomical classification was not possible because of the complexity of the movement disorder. Electrophysiologic testing was completed in 66, with agreement of myoclonus in 60 (91%) and its subtype in 28 (47%) cases. Subsequent clinical review by a movement disorder specialist agreed with the electrophysiologic findings in 52 of 60; in the remaining 8, electrophysiologic testing was inconclusive. CONCLUSIONS: Electrophysiologic testing is an important additional tool in the diagnosis and anatomical classification of myoclonus, also aiding in decision-making regarding therapeutic management. Further development of testing criteria is necessary to optimize its use in clinical practice

Altered Posterior Midline Activity in Patients with Jerky and Tremulous Functional Movement Disorders

Objective: To explore changes in resting-state networks in patients with jerky and tremulous functional movement disorders (JT-FMD). Methods: Resting-state functional magnetic resonance imaging data from seventeen patients with JT-FMD and seventeen age-, sex-, and education-matched healthy controls (HC) were investigated. Independent component analysis was used to examine the central executive network (CEN), salience network, and default mode network (DMN). Frequency distribution of network signal fluctuations and intra- and internetwork functional connectivity were investigated. Symptom severity was measured using the Clinical Global Impression-Severity scale. Beck Depression Inventory and Beck Anxiety Inventory scores were collected tomeasure depression and anxiety in FMD, respectively. Results: Compared with HC, patients with JT-FMD had significantly decreased power of lower range (0.01-0.10 Hz) frequency fluctuations in a precuneus and posterior cingulate cortex component of the DMN and in the dorsal attention network (DAN) component of the CEN (false discovery rate-corrected p < 0.05). No significant group differences were found for intra- and internetwork functional connectivity. In patients with JT-FMD, symptom severity was not significantly correlated with network measures. Depression scores were weakly correlated with intranetwork functional connectivity in the medial prefrontal cortex, while anxiety was not found to be related to network connectivity. Conclusions: Given the changes in the posterodorsal components of the DMN and DAN, we postulate that the JT-FMD-related functional alterations found in these regions could provide support for the concept that particularly attentional dysregulation is a fundamental disturbance in these patients

The efficacy of the modified Atkins diet in North Sea Progressive Myoclonus Epilepsy:an observational prospective open-label study

Background: North Sea Progressive Myoclonus Epilepsy is a rare and severe disorder caused by mutations in the GOSR2 gene. It is clinically characterized by progressive myoclonus, seizures, early-onset ataxia and areflexia. As in other progressive myoclonus epilepsies, the efficacy of antiepileptic drugs is disappointingly limited in North Sea Progressive Myoclonus Epilepsy. The ketogenic diet and the less restrictive modified Atkins diet have been proven to be effective in other drug-resistant epilepsy syndromes, including those with myoclonic seizures. Our aim was to evaluate the efficacy of the modified Atkins diet in patients with North Sea Progressive Myoclonus Epilepsy. Results: Four North Sea Progressive Myoclonus Epilepsy patients (aged 7-20 years) participated in an observational, prospective, open-label study on the efficacy of the modified Atkins diet. Several clinical parameters were assessed at baseline and again after participants had been on the diet for 3 months. The primary outcome measure was healthrelated quality of life, with seizure frequency and blinded rated myoclonus severity as secondary outcome measures. Ketosis was achieved within 2 weeks and all patients completed the 3 months on the modified Atkins diet. The diet was well tolerated by all four patients. Health-related quality of life improved considerably in one patient and showed sustained improvement during long-term follow-up, despite the progressive nature of the disorder. Health-related quality of life remained broadly unchanged in the other three patients and they did not continue the diet. Seizure frequency remained stable and blinded rating of their myoclonus showed improvement, albeit modest, in all patients. Conclusions: This observational, prospective study shows that some North Sea Progressive Myoclonus Epilepsy patients may benefit from the modified Atkins diet with sustained health-related quality of life improvement. Not all our patients continued on the diet, but nonetheless we show that the modified Atkins diet might be considered as a possible treatment in this devastating disorder

The chronnectome as a model for Charcot's 'dynamic lesion' in functional movement disorders

This exploratory study set out to investigate dynamic functional connectivity (dFC) in patients with jerky and tremulous functional movement disorders (JT-FMD). The focus in this work is on dynamic brain states, which represent distinct dFC patterns that reoccur in time and across subjects. Resting-state fMRI data were collected from 17 patients with JT-FMD and 17 healthy controls (HC). Symptom severity was measured using the Clinical Global Impression-Severity scale. Depression and anxiety were measured using the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI), respectively. Independent component analysis was used to extract functional brain components. After computing dFC, dynamic brain states were determined for every subject using k-means clustering. Compared to HC, patients with JT-FMD spent more time in a state that was characterized predominantly by increasing medial prefrontal, and decreasing posterior midline connectivity over time. They also tended to visit this state more frequently. In addition, patients with JT-FMD transitioned significantly more often between different states compared to HC, and incorporated a state with decreasing medial prefrontal, and increasing posterior midline connectivity in their attractor, i.e., the cyclic patterns of state transitions. Altogether, this is the first study that demonstrates altered functional brain network dynamics in JT-FMD that may support concepts of increased self-reflective processes and impaired sense of agency as driving factors in FMD

Functional Disorders in Neurology: Case Studies

Functional, often called psychogenic, disorders are common in neurological practice. We illustrate clinical issues and highlight some recent research findings using six case studies of functional neurological disorders. We discuss dizziness as a functional disorder, describing the relatively new consensus term Persistent Posturo-Perceptual Dizziness (PPPD), axial jerking/myoclonus as a functional movement disorder, functional speech symptoms, post-concussion disorder with functional cognitive symptoms and finally advances in treatment of dissociative seizures and functional motor disorders