Genetics Northern California

Glossary

TermDescription
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.
Split cord malformation (diastematomyelia, diplomyelia)

The spinal cord (the bundle of nerves found in the spine) is split in two, usually by a piece of bone or cartilage. Split cord malformation (SCM) does not occur in isolation and is always connected with other abnormalities of the spine, particularly tethered cord. It can present as a simple splitting of the cord housed in a single dural sac with a nonrigid median septum (Type II SCM) or as double dural sacs with an osseous or osseocartilaginous midline septum (Type I SCM). It occurs more commonly in females than males, and mostly in the lumbar or lower thoracic region.