Old Right MCA Perinatal Infarct with Wallerian Degeneration

6-month-old male with a sibling who suffered a left middle cerebral artery perinatal infarct, an MRI was performed for evaluation of left upper extremity weakness and clumsiness. There is a chronic right MCA territory infarct with associated encephalomalacia and ex vacuo dilatation of the right lateral ventricle. No acute infarct on the diffusion weighted images, and no ischemic penumbra on the arterial spin labeled perfusion maps. Axial sections more inferiorly through the brainstem demonstrate prominent asymmetric volume loss within the belly of the pons on the right and right ventral medulla. The findings are compatible with sequelae of Wallerian degeneration. The color-coded fractional anisotropic maps confirm the asymmetric volume loss within the corticospinal tract on the right. Perinatal ischemic stroke has an estimated incidence of 1:2,300 live births, and most cases initially present with seizures. Infarcts results in long term neurologic morbidity including cerebral palsy, epilepsy, focal neurologic deficits and cognitive impairment. Etiologies include coagulopathies, emboli, infection and underlying vasculopathy.