Reversible diffusion weighted imaging hyperintensities during the acute phase of ischemic stroke in pediatric moyamoya disease: a case report.

Background: Moyamoya disease is one of the primary causes of pediatric ischemic stroke, especially in East Asia. Areas of high signal intensity on diffusion weighted imaging (DWI) with decreased apparent diffusion coefficient (ADC) values usually point to irreversible ischemic damage. Reversibility of these DWI hyperintensities during the acute phase of ischemic stroke in pediatric moyamoya disease has not previously been reported.

Case Report: A 3-year-old girl was admitted to our emergency department due to sudden onset speech impairment and right hemiplegia. Computed tomography (CT) revealed a multilobal low-density area in the left cerebral hemisphere. The area was hyperintense on DWI with decreased ADC values. Magnetic resonance (MR) angiography revealed stenosis of the bilateral internal carotid artery bifurcations and their branches. Acute cerebral infarction due to moyamoya disease was diagnosed. MR images taken 4 days later showed resolution of most of the DWI hyperintensity areas. The initial decline in the ADC of the reversible DWI hyperintensities was less severe compared to the irreversible lesion. Within several days after onset, the patient became ambulatory although the follow-up MR fluid attenuated inversion recovery (FLAIR) images taken 2 weeks after onset revealed thinning of the corresponding cortical gyri.

Conclusion: These findings indicate that a wide area of DWI hyperintensity during the acute phase of ischemic stroke can be reversed by appropriate treatment in pediatric moyamoya disease. To the best of our knowledge, this is the first report of reversible DWI hyperintensities over a wide cortical area during the acute phase of ischemic stroke in pediatric moyamoya disease.