Periventricular Heterotopias: Neuroependymal Abnormalities

Periventricular nodular heterotopia (PVNH) is a group of malformation of cortical development characterized by ectopic neuronal nodules, located along the lateral ventricles. Magnetic resonance imaging can identify gray matter nodules located in wall of ventricles, which appear as island having the same signal of gray matter within white matter. The symptomatological spectrum is various, but the most common clinical presentation is with epileptic seizures, often a drug-resistant type. Features as severity, age of presentation, and associated malformations depend on the underlying etiology. From a genetic point of view, FLNA1 and ERMARD are acknowledged to be the main target of mutations that cause PVNH, although recently many other genes have shown a clear pathogenetic involvement. PVNH may manifest as a solitary discovery in brain imaging or present in conjunction with various other brain or systemic abnormalities. The diagnosis of PVNH is mainly carried out with electroneurophysiological and neuroimaging examinations, while the etiological diagnosis is made with genetic investigations. Treatment consists of use of anticonvulsant drugs, but no significant difference exists among them. In addition, frequently, PVNH-related seizures show poor response to drug, leading to requirement for surgical treatment, performed taking advantages from stereotactic ablative techniques that have a meaningful impact on surgical outcome.