Table 1.

Summary table for Subependymal Heterotopia associated with other brain anomalies (SEH)

Etiology	The causes of SEH associated with other brain anomalies are often unknown. However, there are a number of identified genetic causes of SEH, such as a mutation of the filamin 1 or of the ARFGEF2 gene.
Incidence	The exact incidence is unknown.
Gender ratio	Both the sporadic and the genetic form of SEH are found primarily in females, as affected males have much more severe phenotypes, with a high incidence of spontaneous abortion. However, associated cerebral malformations are found in both males and females.
Age predilection	Congenital malformations. Females with isolated SEH usually come to medical attention with the onset of epilepsy, usually in the second decade of life. Male patients and the ones with SEH associated with other brain anomalies often did not survive infancy.
Risk factors	Unknown. However, familial cases of SEH have been recognized.
Treatment	Only epilepsy associated with subependymal nodular heterotopia could be treated by surgery.
Prognosis	Patients, mostly females, with isolated SEH develop epilepsy during the second decade of life. In patients with SEH associated with cerebral malformations there is an elevated perinatal and childhood mortality rate.
Imaging findings	MRI SEH: Multiple nodular depositions located just beneath and abutted the ependymal lining of the occipital horns of the lateral ventricles. The nodules present low signal intensity, similar to that of the gray matter, on T2-weighted sequences.