Dyke-Davidoff-Masson syndrome (DDMS) has cerebral hemiatrophy and compensatory 
ipsilateral skull thickening, and is manifested by recurrent seizures and 
hemiparesis. We present one case with typical DDMS, who had a brother suffering 
from epilepsy with mild imaging abnormality relevant to DDMS and similar seizure 
semiology. A 26-year-old man had a history of developmental delay, mental 
retardation, hemiparesis and recurrent seizures. His brother, 23-year-old man 
had also experienced recurrent seizures, but he had no neurological deficits. 
Older brother experienced focal motor seizures with/without secondary 
generalization. Sometimes, he noted an auditory aura. MRI demonstrated the 
hemispheric atrophy with the adjacent bony hypertrophy. The seizures of younger 
brother were mainly of the auditory type and the MRI showed mild hemispheric 
atrophy with hippocampal sclerosis without any bony change. Our sibling cases 
might have a familial predisposition and support the idea that clinical courses 
and radiological findings of DDMS are varied even within one family.