Analysis of action tremor and impaired control of movement velocity in multiple sclerosis during visually guided wrist-tracking tasks

Research output: Contribution to journalArticlepeer-review


  • R. Xuguang Liu
  • Tipu Z. Aziz
  • Jackie A. Palace
  • Patrick N. Haggard
  • John F. Stein

Colleges, School and Institutes

External organisations

  • University of Oxford
  • Department of Neurosurgery
  • Radcliffe Infirmary
  • UCL


We investigated the relationship between action tremor (AT) and impaired control of movement velocity (MV) in visually guided tracking tasks, in normal subjects and in patients with multiple sclerosis (MS) with or without motor deficits. The effects of withdrawing visual feedback of either the target or the cursor were then investigated. Visually cued simple reaction times (SRTs) were also measured. The effects of thalamotomy on motor performance in these tasks were evaluated in seven patients. In the MS patients with tremor, there was no correlation between AT and impairment in control of MV, but the latter was highly correlated with an increased delay in SRT. Withdrawal of visually guiding cues increased the error significantly in MV, but reduced AT by ~ 30% in magnitude. Frequency analysis indicated that the AT had two components: (a) non-visual-dependent, oscillatory movements, mainly at 4 Hz; and (2) visual-dependent, repetitive movements, with significant power at 1-2 Hz. Thalamotomy significantly reduced AT but hardly improved accuracy in MV. These results suggest that visual feedback of a spatial mismatch signal may provoke a visually dependent repetitive movement contributing to AT. Conduction delays along either the cortico-cerebello-cortical or the proprioceptive pathways and impaired working memory caused by MS may be responsible for the movement disorders in these patients.


Original languageEnglish
Pages (from-to)992-999
Number of pages8
JournalMovement Disorders
Issue number6
Publication statusPublished - 2 Dec 1997


  • Movement velocity, Multiple sclerosis, Tracking, wrist, Tremor, Visual guidance

ASJC Scopus subject areas