Bilateral perisylvian polymicrogyria
(BPP) is a rare neurological disorder that may be apparent at birth, infancy, or later during childhood. It is characterized mainly by partial paralysis of muscles on both sides of the face, tongue, jaws, and throat; difficulties in speaking, chewing, and swallowing (dysphagia); and/or seizures (epilepsy). In most cases, mild to severe intellectual disability is also present. While the exact cause of BPP is not fully understood, this condition is thought to be due to improper development of the outer surface of the brain (cerebral cortex) during embryonic growth. In most cases, BPP appears to occur sporadically (non-inherited) for unknown reasons in a person with no family history of the disorder. However, there are reports of a few families in which more than one member has BPP. Environmental causes of the disorder can include exposure to cytomegalovirus (CMV) during pregnancy. Treatment usually focuses on the specific symptoms that are present in each individual and may include anticonvulsant drugs to help prevent, reduce, or control epilepsy associated with the condition. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.