Which clinical picture suggests a posterior circulation stroke?

• A. Sudden onset vertigo, ataxia, nystagmus, dysarthria, and cross-symptoms or ipsilateral limb ataxia.
• B. Hemiparesis and aphasia.
• C. Vision loss with optic disc pallor.
• D. Facial droop and arm weakness.

Answer: (A)

Posterior circulation strokes involve the brainstem and cerebellum, so the presenting picture centers on vestibulocerebellar and bulbar signs. Sudden vertigo with gait ataxia or limb ataxia, along with nystagmus and dysarthria, points to dysfunction in the vestibular nuclei, cerebellar pathways, and cranial nerve nuclei found in the brainstem. The presence of cross-symptoms or an ipsilateral limb ataxia reflects brainstem localization, where cranial nerve findings on one side accompany motor or sensory deficits on the opposite side.

The other descriptions fit different vascular territories. Hemiparesis with aphasia usually localizes to the anterior circulation (eg, MCA territory) affecting cortical speech and motor areas. Vision loss with optic disc pallor suggests optic nerve or chronic optic neuropathy rather than an acute brainstem/cerebellar syndrome. Facial droop with arm weakness more often reflects cortical or subcortical involvement of the anterior circulation rather than posterior circulation.