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Distal versus proximal arm tremor in multiple sclerosis assessed by visually guided tracking tasks
1University Laboratory of Physiology, Oxford, UK. xuguang.liu@physiol.ox.ac.uk
Journal of Neurology, Neurosurgery, and Psychiatry
|January 14, 1999
Summary
Action tremor (AT) in multiple sclerosis patients was analyzed using tracking tasks. Most patients exhibited distal AT, differentiating it from proximal tremor, suggesting corticocerebellocortical pathway involvement.
Area of Science:
- Neuroscience
- Neurology
- Biomedical Engineering
Background:
- Multiple sclerosis (MS) can cause action tremor (AT), affecting patient quality of life.
- Differentiating tremor origin (proximal vs. distal) is crucial for understanding MS pathophysiology.
Purpose of the Study:
- To compare AT during manual tracking in normal subjects and MS patients (with and without tremor).
- To distinguish between distal and proximal arm tremor in MS patients.
Main Methods:
- Subjects performed visually guided ramp tracking (wrist) and whole arm circle tracking (shoulder).
- Action tremor was quantified using the standard deviation of tracking velocity.
- The ratio of wrist to arm tremor was calculated to differentiate distal from proximal involvement.
Main Results:
- AT in MS patients showed a dominant frequency of 4-5 Hz during wrist tracking.
- The wrist:arm tremor ratio was significantly higher in the MS-tremor group.
- Most tested arms (8/12) displayed tremor predominantly at the distal joint.
Conclusions:
- Two distinct tracking tasks effectively differentiate proximal and distal AT in MS.
- The majority of AT in MS patients was distal, not proximal.
- Conduction block in corticocerebellocortical pathways may cause this distal tremor.