A 70-year-old semiretired janitor with a history of hypertension had a sudden onset of nausea, vomiting, and unsteadiness. She was taken to the ER, where her exam was notable for slurred speech with slowed tongue movements, dysmetria on finger-to-nose testing on the left, dysmetria on heel-to-shin testing on the left and left dysdiadochokinesia (inability to perform rapid alternating movements). Upon attempting to stand, she fell to the left, even when she kept his eyes open. The remainder of the exam was unremarkable. a. On the basis of the signs and symptoms, where is the lesion? b. What is the most likely cause?

(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.

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