pachygyria

Pachygyria is a congenital brain malformation resulting from abnormal neuronal migration during fetal development. It is characterized by broad, thickened gyri and shallow sulci, producing a simplified and less densely folded cerebral cortex. Pachygyria is part of the lissencephaly spectrum, lying between agyria (complete absence of gyri) and more typical gyral patterns, and can be bilateral, unilateral, or asymmetric.

Causes and genetics are diverse. Most cases are present at birth or in early infancy and arise from disruptions in neuronal migration during the first and second trimesters of gestation. Genetic factors are implicated in many instances, with mutations in genes such as LIS1 (PAFAH1B1), DCX, ARX, and TUBA1A reported in association with pachygyria or related migrational disorders. Non-genetic factors during pregnancy may also contribute in some cases. The condition can occur as an isolated finding or as part of a broader neurodevelopmental syndrome.

Clinical features vary with the extent and distribution of the cortical malformation. Seizures are common in infancy and childhood, and developmental delay or intellectual impairment is typical. Hypotonia in early life may progress to spasticity. Other neurologic signs depend on regional involvement and may include motor or speech delays and microcephaly.

Diagnosis is primarily radiologic. Brain MRI reveals thickened, broad gyri with shallow sulci and reduced cortical complexity, often with bilateral involvement. MRI helps distinguish pachygyria from other migrational disorders such as agyria and polymicrogyria and guides prognosis and management.

Management is multidisciplinary and supportive. Treatments focus on seizure control, physical and occupational therapy, and educational and developmental support. Prognosis varies with the severity and distribution of the cortical malformation; bilateral, extensive involvement generally portends a poorer outcome.