The clinical and imaging findings are consistent with the late stage of Rasmussen encephalitis, which is a rare disorder of the central nervous system characterized by chronic encephalitis of one hemisphere of the brain. Although the exact cause of this disorder is not known, viral or post-viral etiology have been postulated.

Differential diagnosis includes Dyke-Davidoff-Masson syndrome, which is less likely in the present case due to absence of compensatory skull vault thickening and ipsilateral falcine displacement.