Stroke-like migraine attacks after radiation therapy (SMART) syndrome is a rare delayed entity after brain irradiation consisting of recurrent headaches, seizures, or focal neurological deficits accompanied by T2 hyperintensity and cortical enhancement. The pathophysiology is not well understood although multiple mechanisms have been proposed. We describe a case of SMART syndrome with hyperperfusion supporting impaired vascular reactivity as a potential mechanism.

56-year-old male with history of multiple meningiomas involving the craniocervical junction, temporal parietal, and clinoidal regions treated with partial resection followed by focal 54Gy radiation to the left temporal-occipital lobes presented 14 years later with acute onset non-fluent aphasia, visual field deficit, and was initially treated for stroke. However, brain magnetic resonance imaging (MRI) showed no diffusion restriction but mild parieto-occipital T2 hyperintensity without enhancement. Electroencephalogram showed unchanged focal slowing in the left temporal region. He had no evidence of infection with only mild protein elevation in the cerebrospinal fluid. Perfusion MRI 5 days later showed hyperperfusion in the left parieto-occipital, temporal, and inferior frontal gyri. Clinical symptoms improved over 2 months and on further history, he reported a similar incident five years earlier that also spontaneously resolved after 5-7 days. Patient was diagnosed with SMART syndrome given radiation history, clinical presentation, eventual recovery, and negative workup for alternative etiologies.

This case illustrates a classic presentation of SMART syndrome lacking hallmark MRI findings of cortical enhancement. Given diverse presentation and imaging findings, SMART syndrome should remain on the differential in setting of atypical radiographic features. Various mechanisms including impaired vascular reactivity, neuronal dysfunction, and disruption of blood-brain-barrier have been theorized. Parenchymal hyperperfusion demonstrated by this case may support impaired vascular reactivity; however, future studies with larger sample size would be helpful for additional delineation.