Frequently accompanied by hydrocephalus and mental retardation

• A congenital defect of the central nervous system in which a sac containing part of the spinal cord and its meninges protrude through a gap in the vertebral column

WordNet Word definitions in WordNet
n. a congenital defect of the central nervous system in which a sac containing part of the spinal cord and its meninges protrude through a gap in the vertebral column; frequently accompanied by hydrocephalus and mental retardation

Wiktionary Word definitions in Wiktionary
n. (context pathology English) A form of spina bifida characterized by protrusion of the spinal meninges