Case description:

This is a 40 year old left-handed male with history of metastatic nonseminomatous germ cell tumor treated 8 years ago. Treatment included surgical resection of bifrontal metastatic lesions followed by whole brain radiation therapy (WBRT) to a total dose of 30 Gy. He suffered residual impairment of cognitive and executive functions and mild right hemiparesis. Sequelae included infrequent focal epileptic seizures involving right arm and face with few episodes of secondary generalization. Seizures were fairly controlled with a single AED and he remained seizure free for the last 3 years. He presented with new onset left sided headache and subsequently developed global aphasia, flaccid left-sided hemiplegia, and had a generalized seizure. Extensive workup ruled out vascular, infectious and neoplastic etiologies. MRI showed leptomeningeal enhancement involving the entire left hemisphere  compelling for a diagnosis of SMART syndrome based on imaging findings and clinical history. He gradually returned to  clinical baseline over the following 10 days. Follow-up MRI revealed resolution of cortical enhancement on MRI.

SMART syndrome is a rare complication of cranial irradiation. Pathophysiology has been speculated to be a result of a process driven by cerebral hyperexcitability with impaired autoregulatory mechanisms and endothelial damage as a consequence of remote radiation. Clinico-radiological features are challenging and typically include reversible episodic unilateral neurological dysfunction, headache and sometimes seizures in association with transient cortical gadolinium enhancement. Differential diagnoses includes: tumor recurrence, leptomeningeal carcinomatosis, infection, vascular disorders, hemiplegic migraine, posterior reversible encephalopathy (PRES) and post-ictal MRI changes. Duration of symptoms varies from hours to several weeks. Most reported cases had full clinical and radiological recovery with symptomatic management.