Nodular neuronal heterotopia

Nodular neuronal heterotopia (also known as periventricular nodular heterotopia or subependymal nodular heterotopia) is a brain malformation in which clusters (nodules) of neurons fail to migrate to their proper location in the cerebral cortex during fetal development and instead remain abnormally positioned, most commonly along the walls of the lateral ventricles. This condition results from a disruption in the normal process of neuronal migration, which is critical for the proper formation of the brain's layered cortical structure. The most prominent clinical feature of nodular neuronal heterotopia is epilepsy, which typically begins in adolescence or early adulthood, though onset can be variable. Seizures may be focal or generalized and can sometimes be difficult to control with standard antiepileptic medications. Intellectual ability ranges from normal to mildly impaired, though some individuals may have learning difficulties or developmental delay. Additional features can include reading difficulties (dyslexia) and, in some cases, cardiovascular abnormalities such as patent ductus arteriosus or aortic abnormalities, particularly in the X-linked form caused by mutations in the FLNA gene (filamin A). Some patients may also have coagulopathy or joint hypermobility. The most well-characterized genetic form is X-linked periventricular nodular heterotopia caused by FLNA mutations, which predominantly affects females (affected males often do not survive to birth). Autosomal recessive forms linked to ARFGEF2 mutations and other genetic causes have also been described. Sporadic cases occur as well. Treatment is primarily symptomatic, focusing on seizure management with antiepileptic drugs. In medically refractory epilepsy, surgical evaluation may be considered. Genetic counseling is recommended for affected individuals and their families.

Common questions about Nodular neuronal heterotopia