Why is hydrocephalus often associated with spina bifida?

Hydrocephalus is frequently associated with spina bifida because both conditions are linked to the abnormal development of the neural tube during early embryonic life.12

The neural tube is the precursor to the central nervous system, and its failure to close properly results in various congenital defects. In cases of severe spina bifida, such as meningomyelocele, the structural malformations often disrupt the normal pathways for the circulation and drainage of cerebrospinal fluid (CSF).123

When these passages are partially or completely blocked, CSF accumulates within the brain ventricles, leading to hydrocephalus. Because the same developmental failure that prevents the closure of the vertebral column can also affect the flow of fluid throughout the developing nervous system, infants born with serious forms of spina bifida commonly present with hydrocephalus as well.312