This chapter discusses the case of a 27-year-old male who was admitted to the hospital with right arm numbness. It presents the clinical history, examination, follow-up, diagnosis, and the results of the procedures performed on the patient. Physical examination showed a fixed left pupil and a Babinski response bilaterally. The diagnosis was hypersomnia with paroxysmal sleep associated with acute bilateral paramedian thalamic infarction, classified as hypersomnia of central origin. The thalamus has numerous connections with other areas of the brain as well, and these are thought to be important in the integration of cerebral, cerebellar and brainstem activity. The differential diagnosis includes the "top of the basilar artery" syndrome, where infarctions tend also to involve the territories supplied by the superior cerebellar and posterior cerebral arteries, and the occlusion of multiple vascular territories or other pathological conditions such as vasculitis or infectious disease.