What are the symptoms? CBPS patients have weakness of the face, throat, tongue and the chewing process, with lack of speech or slurred speech and drooling. Most have learning impairments (see entry Learning Disability), behaviour problems and epilepsy. Arthrogryposis (fixed deformity of the ankle joints) has been described in some patients. Seizures usually begin between the ages of four to 12 years and are poorly controlled in about 60 per cent of patients. The most frequent seizure types are atypical absences, tonic or atonic drop attacks and tonic-clonic seizures, sometimes occurring as Lennox-Gastaut syndrome. A minority of patients have partial seizures. What are the causes? Consistent familial recurrence has been reported only for bilateral perisylvian polymicrogyria, which is sporadic in the great majority of patients. In some families, children with similar problems with and without MRI abnormalities have been observed. A genetic basis is also possible for unilateral polymicrogyria, at least in some cases. Bilateral perisylvian polymicrogyria has been reported in children born from identical twin pregnancies that were complicated by twin-twin transfusion syndrome. How is it diagnosed? This is primarily an MRI diagnosis by may need careful examination to be sure if polymicrogyria are present. How is it treated? Seizures are treated in the usual fashion but there are often difficulties in their management. In addition these children very commonly have cognitive delay, attention deficit hyperactive disorder, autism spectrum condition, depression and anxiety and should be screened and treated for these. Inheritance patterns and prenatal diagnosis Inheritance patternsSeveral families with multiple affected members have been reported with possible autosomal recessive, dominant and X-linked recessive inheritance. These families have been linked to the Xq28 chromosomal region but the causative gene is not known at present. Prenatal diagnosisPrenatal diagnosis using fetal ultrasound or magnetic resonance imaging may be particularly difficult as the regions of the brain that are involved in this malformation may not have reached their final folding until birth. Is there support? Information and support in the UK for congenital bilateral perisylvian syndrome is provided by the Worster-Drought Syndrome Support Group (see entry Worster-Drought syndrome).