Bilateral polymicrogyria

Bilateral polymicrogyria (BPP) is a brain malformation characterized by an excessive number of abnormally small folds (gyri) on the surface of the brain (cerebral cortex) affecting both hemispheres. This condition results from abnormal cortical development during fetal brain formation, typically between the 17th and 26th weeks of gestation. The bilateral distribution distinguishes it from unilateral forms and can present in several topographic patterns, including bilateral frontal polymicrogyria, bilateral frontoparietal polymicrogyria, bilateral perisylvian polymicrogyria (the most common form), bilateral parasagittal parieto-occipital polymicrogyria, and bilateral generalized polymicrogyria. The clinical presentation varies depending on the extent and location of the cortical malformation. Common features include epilepsy (often refractory to medication), intellectual disability of variable severity, motor impairment including spastic quadriparesis or diplegia, speech and language difficulties, and feeding problems. Bilateral perisylvian polymicrogyria classically presents with pseudobulbar palsy, characterized by difficulties with tongue movement, swallowing, and speech (dysarthria), along with seizures and cognitive impairment. Some patients may also exhibit microcephaly or mild ventriculomegaly on brain imaging. Bilateral polymicrogyria can arise from genetic causes (including mutations in genes such as GPR56/ADGRG1, TUBB2B, PAX6, EOMES/TBR2, and others), chromosomal abnormalities (such as 22q11.2 deletion), or acquired prenatal insults including congenital cytomegalovirus (CMV) infection, placental insufficiency, or hypoxic-ischemic events. Diagnosis is established through brain MRI. There is no cure for bilateral polymicrogyria; treatment is supportive and symptomatic. Management typically involves antiepileptic medications for seizure control, physical and occupational therapy for motor difficulties, speech-language therapy, and special educational support. In cases of drug-resistant epilepsy, surgical evaluation may be considered, though bilateral involvement often limits surgical options.

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