Answer:
(a) The lesion is on the left side of the cerebellum (ipsilateral)
(b) The most likely cause is the occlusion of the cerebellar arteries by a thrombus
Explanation:
The cerebellum is primarily involved in the maintenance of posture and balance, muscle tone and voluntary muscle activity.
Dysmetria, dysdiadochokinesia, intention tremor and dysarthria (slurred speech due to ataxia of the laryngeal muscles) are classic cerebellar signs.
Cerebellar lesions may give rise to a hemispheric syndrome, vermis syndrome, etc. which are usually ipsilateral (side affected is same as lesion).
Since the janitor is 70 years old and hypertensive, these are factors that could have predisposed him to thrombus formation (clotting) within his blood vessels. The thrombus formed could have embolized to occlude the cerebellar arteries, leading to inadequate blood supply and in turn, cerebellar dysfunction.