Genetics Northern California


Limited dorsal myeloschisis

A defect of primary neurulation resulting from incomplete fusion of the posterior neural tube. A slender stalk of neural tissue extends through the nuchal fascia into the myelomeningocele sac.

Lipomyelomeningocele, lipomeningocele

A spinal cord lipoma associated with an underlying spina bifida lesion. Often, the fatty tissue of the lipoma extends into the spinal canal, and may press on the spinal cord, resulting in progressive neurological deterioration.


A protrusion of the meninges, without brain or spinal cord, through a defect in the spine or skull. The defect is covered with skin. If occurring on the spine, there is often a bulge in the midline of the back where the abnormality is located. Although there is frequently less nerve damage initially, complications can occur later from tethering of the spinal cord.


Most serious and most common form of spina bifida. The skin, muscle, and bone over the opening in the spinal column fail to close properly. The spinal cord and meninges (fibrous protective sheath/covering) protrude through an opening on the back into a sac. Most infants born with myelomeningocele will have significant spinal cord dysfunction.

Spina bifida occultaLiterally “hidden” spina bifida. Most often involves a bony defect of the spinal column only and is discovered incidentally during a routine x-ray. Sometimes accompanied by external signs, such as a tuft of hair or discolored area on the back. Some forms of spina bifida occulta may involve the spinal cord, and require surgery (such as release of tethered spinal cord). Such as lipomyelomeningocele, lipomeningocele, split cord malformations, thickened or fatty filum terminale, and some dermal sinus tracts.