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Unilateral tremors is associated with cerebellar or thalamic stroke
. As per your description, I would attribute left sided uncontrolled shaking to right thalamic or left cerebellar strokes. However if a recent scan (done after he developed the shaking) were normal, then I do not think any serious organic condition causing the shaking.
On other thoughts, I also would like to examine him to rule out tremors on the right side, just to make sure we do not miss out bilateral symptoms wherein we need to consider other causes.
Currently, since MRI
and blood reports are normal, there is no major reasons to worry. Discuss with your neurologist
Hope this answers your query.