E4923. Smarting Under Radiation Insult: SMART Syndrome - A Case Based Review
  1. Muhammad Shaheer Sherani; University of Virginia
  2. Tanvir Rizvi; University of Virginia
Gyriform enhancement refers to contrast enhancement along the cerebral gyri. The differential diagnosis of gyriform enhancement includes vascular, infectious, and neoplastic etiologies. One such vascular etiology is stroke-like migraine attacks after radiation therapy (SMART) syndrome, a complication that can be seen after external beam radiation therapy. The syndrome, postulated to be due to both vascular and neuronal dysfunction, presents with prolonged but reversible neurological episodes, such as seizures and vision changes.

Educational Goals / Teaching Points
A series of five institutional cases is presented, demonstrating the characteristics of the syndrome. The current knowledge of SMART syndrome is discussed, including pathophysiology, epidemiology, symptomatology, treatment, and prognosis. MRI findings of SMART syndrome, as well as their prognostic utility, are described.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The epidemiological range in SMART syndrome is very broad. The syndrome is slightly male predominant, with symptoms presenting over 5 years after radiation therapy in the cases assessed (age range: 35–78 years). In all cases, the initial pathology was a primary brain tumor. All patients presented with seizures, with two cases also presenting with stroke-like symptoms (facial droop, aphasia). In the literature, SMART syndrome usually occurs in cases where the initial pathology was in posterior structures, but two of the reviewed cases had pathology within the frontal lobe. Key imaging features on gadolinium contrast-enhanced MRI include gyriform enhancement on T1 postcontrast sequences, hypointense signal on T1 precontrast sequences, hyperintense signal on T2/flair sequences, and occasional minor diffusion restriction and susceptibility. There also must be no persistence or recurrence of the prior intracranial neoplasm. SMART syndrome is generally self-limiting. All patients reviewed recovered within 12 weeks of the onset of symptoms. Imaging abnormalities subsided by 8 weeks. Per literature, steroids, calcium channel blockers, and antiepileptics are the current treatment options, although these were not necessary for resolution in the reviewed cases. Corticosteroid therapy and younger age are positive prognostic factors. Subcortical white matter edema, diffusion restriction, and increased relative cerebral blood volume are negative prognostic factors. These findings were not seen in the reviewed cases, fitting with the general positive outcomes in the reviewed cases.

In conclusion, SMART syndrome must be on the differential in patients presenting with acute neurological symptoms who have had even a very remote history of intracranial radiation. MRI with and without gadolinium contrast is essential and sensitive in assessment. The exhibit presents a set of cases showing the diversity in presentation of SMART syndrome and reviews the current consensus on the management of this rare but impactful disease.