spina bifida occulta
A mild form of spina bifida where the vertebral arches fail to fuse completely but the spinal cord and meninges remain intact beneath normal skin.
Full Definition
Spina bifida occulta is the mildest form of neural tube defect, characterized by incomplete closure of one or more vertebral arches, most commonly at the L5 or S1 level. Unlike other forms of spina bifida, the spinal cord and meninges are not exposed, and the overlying skin is typically intact, though there may be subtle surface markers such as a dimple, tuft of hair, or lipoma. Most cases are asymptomatic and discovered incidentally on imaging studies. However, some children may develop tethered cord syndrome if there are associated abnormalities such as a thickened filum terminale or lipomyelomeningocele. The term 'occulta' means hidden, reflecting that this condition is often not visible externally.
Usage
Usage note: Distinguish from spina bifida cystica (open forms) which involve protrusion of neural elements. 'Occulta' should not be capitalized when used as an adjective.
In Context
- "The MRI revealed spina bifida occulta at L5 with an associated dermal sinus tract." — Radiology report
- "Most children with spina bifida occulta have no symptoms and require no treatment." — Patient education material