SMART syndrome (stroke - like migraine attacks after radiation therapy)

SMART syndrome (stroke-like migraine attacks after radiation therapy)

• SMART syndrome involves transient, reversible neurological dysfunction which may include migrainous headache, at times preceded by aura, prolonged hemispheric neurological impairment and sometimes seizure activity
  • presumed to be a delayed complication of whole-brain irradiation wherein patients have recurrent attacks of complex neurologic signs and symptoms, often including headache and seizures that start many years after radiation therapy and demonstrate characteristic imaging findings
  • may or may not have an antecedent history of migraine headaches or seizures
  • attacks are typically subacute in onset and involve stroke-like deficits such as homonymous hemianopsia, hemiplegia, aphasia, and/or seizures
    
    
• pathophysiology of the SMART syndrome is poorly understood
  • development of the SMART syndrome has been related to a radiation dose of at least 50 Gy
  • specific vulnerability of the parieto-occipital cortex for radiation or chemotherapy may explain why the imaging findings are preferentially observed in this region
  • since radiation may preferentially damage endothelial cells, the SMART syndrome might be a reversible radiation vasculopathy comparable with posterior reversible encephalopathy syndrome (PRES)
  • an alternative hypothesis is that postradiation neuronal dysfunction is the underlying mechanism, such as in migraine or epilepsy, with impairment of the trigeminovascular system or a lowered threshold for cortical spreading depression
    
    
• neuroimaging studies of patients with SMART syndrome typically show focal gyral thickening of the affected cortex and gyriform contrast enhancement
  • MR imaging findings that correlate with these clinical manifestations include unilaterally increased T2 signal within temporal, parietal, or occipital cortices and an exuberant, thick, gyral cortical gray matter enhancement that disappears as symptoms resolve
  • MR imaging findings do not respect vascular borders
    

Reference:

• Kerklaan JP et al. SMART syndrome: a late reversible complication after radiation therapy for brain tumours. Neurol (2011) 258:1098-1104
• Black DF et al. Stroke-like migraine attacks after radiation therapy (SMART) syndrome is not always completely reversible: a case series.AJNR Am J Neuroradiol. 2013 Dec;34(12):2298-303