Objective: If essential tremor (ET) is the most common movement disorder in adults, its pathophysiology remains poorly understood and few data are available as for the existence of gait disorders in this affection. ET could include various phenotypes, and the patients presenting head tremor (HT) associated to upper limb tremor (ULT) could represent a phenotypical ET sub-group. Our objective was to characterize these various phenotypes, by comparing the locomotor performances and the data of anatomical and metabolic cerebral imagery, of patients with HT to those of patients having an isolated ULT.

Methods: 54 patients’ gait (30 HT) was analyzed by a multiparametric system of motor analysis, as well as the density of grey matter of the cerebral cortex in voxel-based morphometry, and the cerebral metabolism with 18-FDG PET in these two sub-groups of patients.

Results: Compared with controls, ET patients have a reduction of gait velocity; HT group do not have a difference of natural gait velocity compared to ULT group. In inter-group comparison, two cerebral areas present an increase in density of grey matter (rights cerebellar hemisphere and Brodmann Area 6) and four areas present an increase in the cerebral metabolism (rights posterior cerebellar lobe, BA6, post central gyrus, paracentral lobule) in HT sub-group compared to the ULT.

Conclusions: Using a quantitative approach, this study provides evidence of gait impairment in ET. The existence of morphological and metabolic cerebral differences between HT and ULT sub-groups suggests that the HT would belong to a different phenotypical sub-group within a heterogeneous affection.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/phenotypes-in-essential-tremor-gait-analysis-and-imaging-study/