A Case of Functional Dystonia with Associated Functional Neurological Symptoms: Diagnostic and Therapeutic Challenges

Functional dystonia: A case-control study and risk prediction algorithm

OBJECTIVE

Functional dystonia (FD) is a disabling and diagnostically challenging functional movement disorder (FMD). We sought to identify historical predictors of FD vs. other primary dystonias (ODs) and develop a practical prediction algorithm to guide neurologists.

METHODS

1475 consecutive new patient medical records were reviewed at an adult/pediatric tertiary-referral dystonia clinic from 2005 to 2017. Ninety-nine met criteria for clinically established FD (85 adults and 14 pediatric), paired with 99 age/dystonia distribution-matched OD. Univariate and multivariate regression analyses were performed to identify predictors of FD and disability. We formed a prediction algorithm, assessed using the area under the receiver operating curve (AUC).

RESULTS

Multivariate logistic regression analysis investigating independent predictors of FD (P < 0.001) followed by development of a prediction algorithm showed that the most robust predictors included abrupt onset, spontaneous resolution/recurrence, pain, cognitive complaints, being on or pursuing disability, lifetime mood/anxiety disorder, comorbid functional somatic disorders, and having ≥3 medication allergies. The prediction algorithm had utility for both adult and pediatric FD, with excellent sensitivity/specificity (89%/92%) and an area under the curve (AUC) 0.95 (0.92-0.98). Greater disability (modified Rankin Scale) independently correlated with a number of functional examination features, unemployment/not attending school, number of medication allergies, and younger age of presentation. FD patients were high health-care utilizers and were more frequently prescribed opiates/opioids and benzodiazepines (P < 0.003).

INTERPRETATION

This case-control study provides an algorithm to guide clinicians in gauging their index of suspicion for a FD, with diagnostic confirmation subsequently informed by neurological examination. While this algorithm requires prospective validation, health-care utilization data underscore the importance and need for more research in FD.

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.

Outpatient Physical Therapy for Functional Neurological Disorder: A Preliminary Feasibility and Naturalistic Outcome Study in a U.S. Cohort

OBJECTIVE

Despite promising research and consensus recommendations on the important therapeutic role of physical therapy for motor functional neurological disorder (FND), little is known about the feasibility and potential efficacy of implementing physical therapy for this population in a U.S.-based outpatient program. Given health care system differences internationally, this is an important gap in the literature.

METHODS

In this retrospective cohort study, the authors investigated the relationship between treatment adherence and clinical outcome in a hospital-based outpatient physical therapy clinical program. Medical records of 50 consecutive patients with motor FND referred from an FND clinical program were reviewed. The physical therapy intervention included a 1-hour initial assessment and the development of individualized treatment plans guided by published consensus recommendations. Statistical analyses included nonparametric, univariate screening tests followed by multivariate regression analyses.

RESULTS

In univariate analyses, there was a statistically significant positive correlation between the number of sessions attended and clinical improvement. This relationship held when adjusting for demographic variables, concurrent psychogenic nonepileptic seizures, and other major neurological comorbidities. In a post hoc analysis of the subset of individuals with available gait speed data, posttreatment 10-meter gait speed times improved compared with baseline measurements. Baseline neuropsychiatric factors did not correlate with clinical improvement.

CONCLUSIONS

This preliminary, retrospective cohort study demonstrated that treatment adherence to a U.S.-based outpatient physical therapy program was associated with clinical improvement. Prospective observational and randomized controlled trials are needed to further optimize physical therapy for patients with functional motor symptoms in the outpatient setting.