Adam M. Conley, M.D.
Shokei Yamada, M.D.
Editor in Chief
Neural tube defects are due to improper closure of the neural tube during the first 3–4weeks of fetal development. Neural tube defects produce a wide range of congenital defects of the CNS from anencephaly to spina bifida. Spina bifida results from the failure of the posterior vertebral arches to fuse in the midline, producing a congenital absence of spinous processes and lamina. Spina bifida occulta is the most common and mildest form, occurring in up to 1/1000 live births with malformed posterior elements at one or more vertebrae. Spina bifida occulta is distinct from spina bifida cystica, including myelomeningoceles and meningoceles, which involve a protrusion of meninges with or without neural tissues through the vertebral defect, respectively.
- History and physical examination key: No exposure of the meninges or neural elements is seen on physical examination. The history is benign, given that tethered spinal cords are often asymptomatic when occurring alone. A MRI will be helpful in defining the anatomy.
- Variable symptoms: When a spina bifida occulta is associated with a tethered cord, fibrolipoma of the filum, lipomyelomeningocele, split cord malformation, or dermal sinus symptoms will vary from none to those either associated with dysfunction of the spina cord or from a consequence in the alteration of the local anatomy.
- Clinical manifestations due to traction or compression: Symptoms that do arise are from traction of the spinal cord or mass compression effects, resulting in neurological, urological, and musculoskeletal abnormalities.