Impairment of rapid repetitive finger movements and visual reaction time in patients with essential tremor

The question whether patients with essential tremor (ET) have slowed movements as part of their clinical manifestations is still a matter of controversy. We analyzed basic motor function in patients with ET and in healthy matched controls.

We studied 61 patients with ET and 122 age- and sex-matched controls. Evaluation included four timed tests (pronation-supination, finger tapping and movement between two points, all with both hands, and walking test); and three tests performed on a personal computer (speed for pressing repetitively a key - frequency, visual reaction time and movement time, all with both hands).

Essential tremor patients showed higher mean values for right and left finger tapping, left movement between two points; and with right and left frequency and reaction time. In the logistic regression study, ET patients showed significantly higher values than controls for right and left finger tapping; mean, SD, maximum and rank values of right and left frequency; and mean, SD, minimum, maximum and rank values of right and left visual reaction time. Tremor severity was not correlated with the altered values.

Patients with ET showed impaired motor performance, at least in some tasks, such as rapid repetitive finger movements (finger tapping and frequency) and visual reaction time (impairment was not related with tremor severity). This probably means that patients with ET have some degree of bradykinesia.