Diagnosis and therapy of functional tremor a systematic review illustrated by a case report

Predictive Processing and the Pathophysiology of Functional Neurological Disorder

The contemporary neuroscience understanding of the brain as an active inference organ supports that our conscious experiences, including sensorimotor perceptions, depend on the integration of probabilistic predictions with incoming sensory input across hierarchically organized levels. As in other systems, these complex processes are prone to error under certain circumstances, which may lead to alterations in their outcomes (i.e., variations in sensations and movements). Such variations are an important aspect of functional neurological disorder, a complex disorder at the interface of brain-mind-body interactions. Thus, predictive processing frameworks offer fundamental mechanistic insights into the pathophysiology of functional neurological disorder. In recent years, many of the aspects relevant to the neurobiology of functional neurological disorder - e.g., aberrant motor and sensory processes, symptom expectation, self-agency, and illness beliefs, as well as interoception, allostasis, and emotion - have been investigated through the lens of predictive processing frameworks. Here, we provide an overview of the current state of research on predictive processing and the pathophysiology of functional neurological disorder.

Investigation of Phase Shifts Using AUC Diagrams: Application to Differential Diagnosis of Parkinson's Disease and Essential Tremor

This study was motivated by the well-known problem of the differential diagnosis of Parkinson's disease and essential tremor using the phase shift between the tremor signals in the antagonist muscles of patients. Different phase shifts are typical for different diseases; however, it remains unclear how this parameter can be used for clinical diagnosis. Neurophysiological papers have reported different estimations of the accuracy of this parameter, which varies from insufficient to 100%. To address this issue, we developed special types of area under the ROC curve (AUC) diagrams and used them to analyze the phase shift. Different phase estimations, including the Hilbert instantaneous phase and the cross-wavelet spectrum mean phase, were applied. The results of the investigation of the clinical data revealed several regularities with opposite directions in the phase shift of the electromyographic signals in patients with Parkinson's disease and essential tremor. The detected regularities provide insights into the contradictory results reported in the literature. Moreover, the developed AUC diagrams show the potential for the investigation of neurodegenerative diseases related to the hyperkinetic movements of the extremities and the creation of high-accuracy methods of clinical diagnosis.

The use of rhythmic auditory stimulation for functional gait disorder: A case report

BACKGROUND: Functional gait disorders (FGD) are a common and disabling condition. Consensus-based rehabilitation techniques for treating FGD and other functional neurological disorder presentations at large utilize a variety of therapeutic strategies, including distraction, novel approaches to movement, entrainment, stress/hypervigilance modulation, and psychotherapy. CASE REPORT: Here we present a case of a 24-year-old woman with a complex history of anxiety, depression, left frontal astrocytoma, postural orthostatic tachycardia syndrome (POTS) and FGD. During a multidisciplinary inpatient rehabilitation stay for FGD, the patient underwent rhythmic auditory stimulation (RAS) delivered by a neurologic music therapist in conjunction with physical therapy, occupational therapy, and psychotherapy. RESULTS: The RAS intervention appeared to play a significant role in symptom resolution for this patient. Improvement in the patient’s truncal displacement, foot dragging, and well as overall gait speed occurred following serial RAS trials performed over a single treatment session. Benefits persisted immediately following the intervention and upon subsequent reassessment. Although at four-year follow-up the patient’s FGD symptoms remained resolved, fatigue continued to limit her ambulatory capacity and overall endurance. CONCLUSION: RAS represents a unique therapeutic approach for treating FGD, complementary to existing consensus-based rehabilitation recommendations, and may warrant further consideration by the field.