Resting state functional MRI reveals abnormal network connectivity in orthostatic tremor

Abstract

Very little is known about the pathogenesis of orthostatic tremor (OT). We have observed that OT patients might have deficits in specific aspects of neuropsychological function, particularly those thought to rely on the integrity of the prefrontal cortex, which suggests a possible involvement of frontocerebellar circuits. We examined whether resting-state functional magnetic resonance imaging (fMRI) might provide further insights into the pathogenesis on OT. Resting-state fMRI data in 13 OT patients (11 women and 2 men) and 13 matched healthy controls were analyzed using independent component analysis, in combination with a “dual-regression” technique, to identify group differences in several resting-state networks (RSNs). All participants also underwent neuropsychological testing during the same session. Relative to healthy controls, OT patients showed increased connectivity in RSNs involved in cognitive processes (default mode network [DMN] and frontoparietal networks), and decreased connectivity in the cerebellum and sensorimotor networks. Changes in network integrity were associated not only with duration (DMN and medial visual network), but also with cognitive function. Moreover, in at least 2 networks (DMN and medial visual network), increased connectivity was associated with worse performance on different cognitive domains (attention, executive function, visuospatial ability, visual memory, and language). In this exploratory study, we observed selective impairments of RSNs in OT patients. This and other future resting-state fMRI studies might provide a novel method to understand the pathophysiological mechanisms of motor and nonmotor features of OT.

Lessons I have learned from my patients: everyday life with primary orthostatic tremor

“…Many of our POT patients had anxiety as part of the emotional burden [3]. Moreover, fatigue, depression and social avoidance reported our patient are in line with the higher scores for somatic concerns, anxiety related disorders, depression and antisocial features described in a recent case control study including 16 POT patients [5, 6]. …”

Orthostatic Tremor and Orthostatic Myoclonus: Weight-bearing Hyperkinetic Disorders: A Systematic Review, New Insights, and Unresolved Questions

“…However, in the recent study by Gallea et al,55 fMRI connectivity between the cerebellum and SMA was abnormally increased in OT patients, and correlated positively with tremor severity. These findings contrast with the decreased connectivity reported by Benito-Leon 61. Gallea et al55 also performed open-label, repetitive cerebellar transcranial magnetic stimulation (TMS) in nine patients; tremor severity and functional connectivity between the lateral cerebellum and SMA were reduced 55.…”

“…A functional MRI (fMRI) study assessed resting state network connectivity in 13 OT patients and 13 matched healthy controls 61. Compared with controls, OT patients had reduced connectivity in cerebellum and sensorimotor networks, which correlated with longer duration of OT.…”

Diffusion tensor imaging in orthostatic tremor: a tract‐based spatial statistics study

“…In line with this, OT patients might suffer deficits in cognitive and neuropsychiatric areas, especially those thought to involve the integrity of the prefrontal cortex, which, in turn, also suggests changes of limbic cortico‐striato‐thalamo‐cortical loops . On the other hand, in one resting state functional magnetic resonance imaging (MRI) study, changes in connectivity in particular resting‐state networks was detected . More specifically, OT patients showed increased connectivity in resting‐state networks involved in cognitive processes (e.g., default mode network and frontoparietal networks) and decreased connectivity in the cerebellum and sensorimotor networks .…”

“…On the other hand, in one resting state functional magnetic resonance imaging (MRI) study, changes in connectivity in particular resting‐state networks was detected . More specifically, OT patients showed increased connectivity in resting‐state networks involved in cognitive processes (e.g., default mode network and frontoparietal networks) and decreased connectivity in the cerebellum and sensorimotor networks . To date, there have been few studies.…”