A Gait Paradigm Reveals Different Patterns of Abnormal Cerebellar Motor Learning in Primary Focal Dystonias

Abstract

Accumulating evidence points to a role of the cerebellum in the pathophysiology of primary dystonia. The aim of this study was to investigate whether the abnormalities of cerebellar motor learning in primary dystonia are solely detectable in more pure forms of cerebellum-dependent associative motor learning paradigms, or whether these are also present in other motor learning paradigms that rely heavily on the cerebellum but in addition require a more widespread sensorimotor network. Twenty-six patients with various forms of focal dystonia and 10 age-matched healthy controls participated in a motor learning paradigm on a split-belt treadmill. By using reflective markers, three-dimensional kinematics were recorded using a 6-camera motion analysis system. Adaptation walking parameters were analyzed offline, comparing the different dystonia groups and healthy controls. Patients with blepharospasm and writer's cramp were significantly impaired on various adaptation walking parameters. Whereas results of cervical dystonia patients did not differ from healthy controls in terms of adaptation walking parameters, differences in parameters of normal gait were found. We have here demonstrated abnormal sensorimotor adaptation with the split-belt paradigm in patients with blepharospasm and writer's cramp. This reinforces the current concept of cerebellar dysfunction in primary dystonia, and that this extends beyond more pure forms of cerebellum-dependent associative motor learning paradigms. However, the finding of normal adaptation in cervical dystonia patients indicates that the pattern of cerebellar dysfunction may be slightly different for the various forms of primary focal dystonia, suggesting that actual cerebellar pathology may not be a primary driving force in dystonia.

Effects of cerebellar theta-burst stimulation on arm and neck movement kinematics in patients with focal dystonia

“…This hypothesis is supported by a number of recent studies based on various neurophysiological techniques, in which the cerebellum was found not to be affected in CD. For example, it has been recently reported that CD patients did not differ from HS in the adaptation of the walking parameter, including speed, step width, step length symmetry and swing/stance ratio (Hoffland et al, 2014). Using a visuomotor task, Sadnicka et al (2014) tested the hypothesis that cerebellar abnormalities in CD patients would translate into motor adaptation deficits.…”

Dissecting the Links Between Cerebellum and Dystonia

“…A new study [12] extends the investigation of the role of the cerebellum in primary dystonia beyond the more pure forms of cerebellum-dependent associative motor learning, such as eye-blink classical conditioning, to motor adaptation paradigms. Within traditional motor adaptation paradigms, adaptive learning is assessed by the degree of the after-effect observed during a de-adaptation task and the amount of savings upon a second exposure to the adaptation task (i.e., a readaptation task).…”

Combined focal myoclonus and dystonia secondary to a cerebellar hemorrhage: a case report

“…However, there are suggestions that abnormal cerebellar learning and functional interactions between cerebellar and basal ganglia circuits may play a role [8, 9]. …”