Youth with essential tremor differ from age-matched controls in multiple aspects of visually-guided reaching movements

This is the authors' abstract. We don't add key points for this paper.

OBJECTIVE: Essential tremor (ET) likely includes deficits outside tremor, though this is under-examined in youth. We tested the hypothesis that reaching movements in youth with ET are characterized by greater incoordination. METHODS: Fifteen youth with ET (ages 11 to 17) recruited from the Calgary Tourette and Pediatric Movement Disorders Clinic completed a visually-guided reaching task using the Kinarm Exoskeleton Lab. Performance in several kinematic parameters was compared with age-matched controls. RESULTS: Youth with ET differed from controls in multiple parameters. In the dominant arm, the initial portion of reaching movements was slower and smaller-amplitude, with longer reaction time and greater posture speed at movement end when the hand should be at rest. In the non-dominant arm, those with ET differed from controls in a larger number of parameters. All but three with ET were impaired in at least one task parameter, scoring outside age-predicted norms. CONCLUSION: Our study supports the notion of ET as a disorder with abnormalities beyond tremor, and that motoric abnormalities are demonstrable in youth with ET. SIGNIFICANCE: This is the first study showing youth with ET differ from age-matched controls in multiple aspects of reaching movements, including initial trajectory control, movement smoothness, overall trajectory, and endpoint control.