The syndrome of stroke-like migraine
attacks after radiation therapy (SMART) is an extremely rare complication of cerebral irradiation. It is characterized by reversible episodic neurological dysfunction, commonly associated with headaches and occasionally with seizures, occurring years after cranial radiotherapy. Approximately a dozen cases have been reported in adult patients to date.
In 1997, a 48-year-old man underwent resection of a right cerebellar metastasis from renal cell carcinoma, followed by whole-brain irradiation. Two years later he began experiencing recurrent episodes of headache associated with reversible left hemiparesis, dysphasia, visual field defects, and confusion. Over subsequent years these episodes increased in frequency, and in 2009 and 2010 the patient experienced 2 episodes associated with seizures and characterized by severe depression in level of consciousness (GCS 5); the latter of these was particularly prolonged, with neurological recovery requiring almost 6 months. Cortical and leptomeningeal gadolinium enhancement was demonstrated on magnetic resonance imaging during the second episode. Repeated electroencephalography studies did not demonstrate any epileptiform activity, and extensive workup including brain biopsy failed to identify any neoplastic, vascular, or infective pathology. The diagnosis of SMART syndrome
was therefore made.
Reduced level of consciousness of such severity and duration as observed here has not previously been described in SMART syndrome
. This report, however, suggests that an excellent prognosis can be expected even in cases of prolonged unresponsiveness. The pathogenic mechanisms of SMART syndrome
remain unclear, but may involve pathways common to both migraine