Dyke-Davidoff-Masson syndrome is a rare entity characterized by hemi cerebral atrophy/hypoplasia secondary to brain insult in fetal or early childhood period along with ipsilateral compensatory osseous hypertrophy and contralateral hemiparesis. The etiopathogenesis could be either vascular insult during intrauterine life resulting in hypoplasia of a cerebral hemisphere or acquired causes like trauma, infection, vascular abnormalities and intracranial hemorrhage in the perinatal period or shortly thereafter causing hemi cerebral atrophy

The diagnosis is based on the typical radiological features on CT and MRI scans which include cerebral hemiatrophy with dilated ipsilateral lateral ventricle. Also there is thickening of calvarium with enlargement of frontal, ethmoid and sphenoid sinuses and elevation of greater wing of sphenoid and petrous ridge.

The differential diagnoses are chronic Rasmussen encephalitis (chronic, progressive inflammation of brain of uncertain etiology) and sturge weber syndrome. However, Rasmussen encephalitis doesn’t show calvarial changes and sturge-weber syndrome additionally shows enhancing pial angiomas and cortical calcifications