Posterior Circulation Stroke

Key considerations: Basilar artery occlusion (locked-in syndrome, high mortality), Cerebellar infarct with edema (obstructive hydrocephalus), Vertebral artery dissection

Cannot miss

Basilar artery occlusion (locked-in syndrome, high mortality)
Cerebellar infarct with edema (obstructive hydrocephalus)
Vertebral artery dissection

Likely diagnoses

Basilar artery occlusion
Cerebellar infarction
Lateral medullary syndrome (Wallenberg)
Posterior cerebral artery stroke

Red flags

Sudden onset vertigo + ataxia + vomiting
Diplopia
Dysphagia
Dysarthria
Crossed deficits (ipsilateral face + contralateral body)
Decreased consciousness

Workup

history: Onset time (for thrombolytic window), vascular risk factors, recent neck manipulation or trauma; exam: HINTS exam (Head Impulse/Nystagmus/Test of Skew), cerebellar signs, cranial nerve exam, crossed motor/sensory findings; labs: CBC, BMP, coags, glucose, troponin, lipid panel, HbA1c; imaging: NCCT head (rule out hemorrhage — less sensitive for posterior fossa); CT angiography head and neck (basilar occlusion, vertebral dissection); MRI/DWI (gold standard for posterior fossa infarcts); bedside: NIHSS (often underestimates posterior stroke), HINTS exam, swallow assessment

Management

immediate: tPA if within window (same criteria as anterior circulation); Basilar artery occlusion: thrombectomy up to 24 hours; general: Cerebellar infarct: neurosurgery consult for suboccipital craniectomy if edema/herniation risk; Antiplatelet therapy if no thrombolytics; BP management per stroke protocol; Dysphagia screening before oral intake

Disposition

admit: Stroke unit, ICU if basilar occlusion or cerebellar edema; discharge: Never acutely for posterior circulation stroke; consults: Neurology, neurointerventional if thrombectomy candidate, neurosurgery if cerebellar edema

Clinical pearls

HINTS exam: normal head impulse test + direction-changing nystagmus = central cause until proven otherwise
NIHSS often underestimates posterior circulation stroke severity — a low NIHSS does not rule out basilar occlusion
Cerebellar infarction can cause progressive edema leading to brainstem compression 2-4 days after stroke — close monitoring mandatory

Source and review

AHA/ASA Stroke Guidelines 2019, ATTENTION Trial 2022. Last reviewed: 2024-11-01