Objective and subjective movement symptoms in (functional) tremor

Functional movement disorders are among the most prevalent neurological movement disorders. They are characterized by an impairment in explicit movement control, leading to symptoms like tremor and myoclonus. Previously, these disorders were thought to be largely a problem of perception and were of psychogenic origin. Diagnosis of this disorder depended mainly on excluding other forms of neurological movement disorders and treatment concerned addressing potential stressors in patients life.
This research focused mainly on functional tremor, a subtype of functional movement disorders, as this symptom can be studied both subjectively and objectively. Wavelet coherence analysis of electrical muscle activity was shown to aid in the discrimination between functional tremor and other tremor types (i.e. organic tremor types). This adds to the recent tendency to diagnose functional movement disorders using positive criteria.
In a 30-day study period, patients with a functional tremor had a considerable level of objectively measured tremor and they had a similar level of objective tremor symptoms to patients with an organic tremor. Furthermore, the association between subjective and objective tremor symptoms was similar between patients with a functional or organic tremor. Finally, the influence of fluctuations in daily stress on tremor symptoms were similar between patients with a functional or organic tremor.
Concluding, in accordance with other recent literature, this thesis provided evidence against the hypothesis of an exclusive psychological explanation for all FMD symptoms and therefore, this view should be abandoned, both in clinical care as well as in research.