Imaging wise characterized by hemi atrophy as in this case on right side.
Atrophy is progressive, may be associated with cortical gliosis.
Rasmussen Encephalitis, a chronic progressive encephalitis results in severe, intractable epilepsy.
Seizures typically are focal motor type, begin abruptly in previously normal children. Follows by motor function deterioration with hemi paresis or hemiplegia, progressive cognitive decline
Proposed hypothesis is autoimmunity associated with persistent viral infection.
Refractory to medical treatment.
Surgical treatment is functional hemispherectomy.
Imaging wise DDs:
1. Peri natal hemispheric infarction (Dyke Davidoff Masson syndrome)
characterized by hemi atrophy with an associated compensatory ipsilateral bony calvarial thickening, hyper pneumatisation of paranasal sinuses, elevation of petrous ridge.
2. Sequel of previous Encephalitis
in which case atrophy is non progressive, pt clinically will not show worsening , respond well to medications, history of previous hospitalization for encephalitis if any.