Objective: (1) To examine if gait timing control is impaired in ET patients compared with age-matched controls. (2) To examine whether timing impairments are related to clinical measures of disease severity (i.e., kinetic tremor score, intention tremor score, cranial tremor score).

Background: Essential tremor (ET) is a common movement disorder characterized by kinetic, postural and intention tremors. ET also leads to gait and balance impairments that increase the risk of falls. Mounting evidence suggests an underlying dysfunction of the cerebellum or cerebellar system. Cerebellar dysfunction is thought to result in impairments in timing control of movements. While a small number of recent studies report impairments in timing control of finger movements in ET, timing control of gait has not been examined to date.

Methods: One-hundred-fifty-five ET patients and sixty age-matched controls were administered a comprehensive neurological assessment and gait analysis. Subjects walked at a criterion step frequency (cadence) with a metronome (timing production) and walking at a criterion step frequency after the metronome was turned off (timing reproduction). Primary outcomes were cadence error and cadence variability. Between group differences were analyzed using general linear model procedures. Association between gait and tremor severity (kinetic tremor score, intention tremor score, cranial tremor score) were analyzed with independent linear regression analysis.

Results: Cadence was lower in ET patients than controls (p < 0.03), whereas step time was similar for ET patients and controls. Cadence error and cadence variability were not different in ET patients compared with controls. Cranial tremor score was significantly associated with cadence (timing production condition, p=0.003 and timing reproduction condition, p=0.0001) and cadence error (timing production condition, p=0.01). Kinetic tremor and intention tremor scores were not associated with gait measures.

Conclusions: ET patients did not demonstrate impairments in timing control of gait. Cerebellar dysfunction has been shown to cause selective impairments in timing of discrete movements (such as finger tapping) but not continuous movements (such as circle drawing). Our results support the hypothesis that the cerebellum may be important for timing control of discrete rather than continuous movements.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/timing-control-of-gait-in-essential-tremor-patients-vs-age-matched-controls/