A 65-year-old female with history of migraines and bipolar disorder presented with four days of gait imbalance, dysarthria, intermittent dizziness, nausea, mild difficulty with vision and memory impairment. On presentation, neurological exam revealed right-sided sensory deficits, homonymous hemianopsia, mild dysarthria, and unsteady gait. Initial labs including sedimentation rate and C-reactive protein were unremarkable.

Computed tomography head (CTH) imaging revealed bilateral cerebellar and left parieto-occipital infarcts. CT angiogram head and neck was concerning for dissection of bilateral vertebral artery V4 segments, along with subtle irregularities in bilateral posterior cerebral arteries (PCA). Magnetic resonance imaging (MRI) brain confirmed bilateral cerebellar and occipital lobe infarcts. Vessel wall MRI revealed abnormal vessel wall enhancement and concentric thickening in the bilateral vertebral arteries. Cerebral angiogram demonstrated concern for vasculitis given severe bilateral vertebral artery stenosis, internal carotid artery stenosis, and superficial temporal artery irregularities. The patient started on IV Methylprednisolone 1000 mg daily for five days with prednisone taper. Subsequently, temporal artery biopsy was performed, confirming evidence of GCA. Treatment was then escalated to Actemra and Cellcept given worsening symptoms.

This case highlights an atypical GCA presentation with posterior circulation strokes, as GCA typically affects the middle cerebral artery (MCA), followed by anterior (ACA) and posterior cerebral arteries (PCA), with less than 15% of cases involving the vertebrobasilar system. This case also illustrates the utility of vessel wall MRI brain to characterize vessel enhancement when assessing response to therapies or guiding potential biopsy locations.