Ischemic stroke in a 6 month old infant! What's behind?

A 6-month-old infant was admitted to the Emergency Department due to prostration and focal seizures for the last 3 days. On admission he was hypotonic, had right side eye deviation and later developed left sided hemiparesis. Cranial CT showed an extensive heterogeneously hypodense lesional area involving the entire right cerebral hemisphere. (Figure 1) The electroencephalogram showed right temporal epileptic activity suggesting focal status epilepticus. Brain MRI revealed an extensive ischemic stroke in the right hemisphere involving the internal carotid artery (ICA) and posterior cerebral artery territories, as well as a small contralateral infarction in the middle cerebral artery/barrier territory. MR angiography showed a bilateral pre-obliterative stenosis of the distal ICA and proximal segments of the anterior and middle cerebral arteries with lenticulostriate branch hypertrophy. (Figure 2) The genetic study revealed a heterozygous variant in the RNF213 gene.
After revascularization surgery a partial focal deficit recovery was observed, with remnant moderate psychomotor development delay.

Figure 1. Cranial CT showed an extensive heterogeneously hypodense lesional area involving the entire right cerebral hemisphere.


Figure 2 MR angiography showed a bilateral pre-obliterative stenosis of the distal ICA and proximal segments of the anterior and middle cerebral arteries.


What is the diagnosis?