This paper describes two cases of congenital bilateral perisylvian syndrome (CBPS), a rare disorder of late neuronal migration, which is characterized by language delay, intellectual disorders, epilepsy and bilateral perisylvian polymicrogyria. Pseudobulbar paralysis and orofacial muscles dyspraxia causing drooling and feeding difficulties are common for patients with CBPS. Communicational problems lead to low self-esteem and social maladaptation. Literature data regarding correlation between polymicrogyria topography and speech disorders and articulation impairment severity are presented. The results demonstrate the association of diffuse spreading of bilateral polymicrogyria and more severe speech disorders comparing to mild speech disorders in patients with more local polymicrogyria. Known etiology factors of this syndrome are bilateral cerebral hypoperfusion, brain damage while neuronal migration period, postmigrational vascular insults and gene mutations. Syndrome can be inherited in autosome dominant and X-linked manner. Speech apraxia with normal impressive speech, refractory epileptic seizures and status dysraphicus must be red flags for a physician regarding this syndrome. Overnight video-EEG monitoring and brain MRI confirm a thesis that this syndrome is underdiagnosed in everyday clinical practice.