Believing is perceiving: mismatch between self-report and actigraphy in psychogenic tremor

Abstract

We assessed the duration and severity of tremor in a real-life ambulatory setting in patients with psychogenic and organic tremor by actigraphy, and compared this with self-reports of tremor over the same period. Ten participants with psychogenic tremor and eight with organic tremor, diagnosed using standardized clinical criteria, were studied. In an explicit design, participants were asked to wear a small actigraph capable of continuously monitoring tremor duration and intensity for 5 days while keeping a diary of their estimates of tremor duration during the same period. Eight patients with psychogenic tremor and all patients with organic tremor completed the study. Psychogenic patients reported significantly more of the waking day with tremor compared with patients with organic tremor (83.5 ± 14.0% of the waking day versus 58.0 ± 19.0% of the waking day; P < 0.01), despite having almost no tremor recorded by actigraphy (3.9 ± 3.7% of the waking day versus 24.8 ± 7.7% of the waking day; P = 0.001). Patients with organic tremor reported 28% more tremor than actigraphy recordings, whereas patients with psychogenic tremor reported 65% more tremor than actigraphy. These data demonstrate that patients with psychogenic tremor fail to accurately perceive that they do not have tremor most of the day. The explicit study design we employed does not support the hypothesis that these patients are malingering. We discuss how these data can be understood within models of active inference in the brain to provide a neurobiological framework for understanding the mechanism of psychogenic tremor.

Functional Neuroanatomy and Neurophysiology of Functional Neurological Disorders (Conversion Disorder)

“…110 The subjective experience of tremor has also been shown to differ from organic movement disorders. Pareés et al 131 showed that patients with PMD (N=8) reported more subjective tremor in the waking day compared with those with organic tremor, despite having very little tremor recorded by objective actigraphy. The authors suggest that the subjective experience might be reflective of the patient's expectation.…”

Functional symptoms in neurology: mimics and chameleons

“…An important study of actigraphy in functional tremor showed that even patients who know they are being monitored are hopeless at guessing how bad their symptoms are. In this study, the 10 patients with functional tremor thought, on average, that their symptoms were present 83% of the time, when in fact they were only present 4% of the time (compared with 58% reported vs 24% observed in organic tremor) 34. In other words, the patients with functional tremor in this study probably only had the symptom when they thought about it, but this gives the illusion of the symptom being there all the time.…”

Functional neurological disorders: mechanisms and treatment

“…They showed that patients with functional neurological disorders performed particularly poorly in tasks that were highly predictable, as these situations allow a switch to an ''attentive self-focused action-monitoring mode''. The idea that attention plays a major role in the presence of symptoms was illustrated by the finding that patients reported having functional tremor 83.5 % of the day, while the tremor was only registered 3.9 % of the day by actigraphy [50] (Fig. 2).…”