The purpose of this study was to retrospectively evaluate the cognitive and 
electroclinical characteristics of right cerebral hemiatrophy 
(Dyke-Davidoff-Masson syndrome [DDMS]). Cognitive assessments with a particular 
emphasis on visuospatial functions, electroclinical features, and neuroimaging 
characteristics were analyzed for five patients with a clinically and 
neuroradiologically confirmed diagnosis of right-sided DDMS. Intelligence tests 
revealed mental retardation in all but one. Neuropsychological assessments 
demonstrated consistent impairments in tasks that have a spatial component 
(spatial processing and orientation discrimination), whereas attention, 
executive functions and verbal memory domains were variably impaired. 
Electroclinically, the main seizure types were simple partial motor, complex 
partial, and secondarily generalized seizures. Interictal EEG delineated lower 
amplitudes and slow background activity in the affected hemisphere. Overall, the 
cognitive performance of patients with DDMS encompasses a broad spectrum of 
impairments affecting multiple domains. Our findings support the concept that 
dorsal visual pathways responsible for spatial processing may be lateralized to 
the right hemisphere.