Split spinal cord malformation

Alternate names

Diastematomyelia; SSCM; Diplomyelia; Pseudodiplomyelia; Dimyelia; Split cord malformation; SCM type 1; Split cord malformation type 1

Definition

Split spinal cord malformation (SSCM) is a rare form of spinal dysraphism in which a person is born with splitting, or duplication, of the spinal cord. It may be characterized by complete or incomplete division of the spinal cord, resulting in two 'hemicords.'

Cause

SSCM is thought to be caused by abnormal formation of the notochord and neural tube (which ultimately form the brain and spinal cord) very early in embryonic development.

Inheritance

• Most cases of split spinal cord malformation (SSCM) appear to be isolated (occurring in one person in a family).
• To our knowledge, only 4 reports in the medical literature describe familial cases of SSCM.
• All reports of familial cases describe affected siblings, and all have been female.
• We are not aware of any reports describing an affected parent and child.
• Due to the rarity of reports of SSCM, there may be limited data to determine if, and how, SSCM may be inherited.
• In one report, the authors suggested it may be inherited in an X-linked dominant manner, or it may be a multifactorial condition (caused by a combination of genetic and environmental factors) with female sex preference.
• People with spinal dysraphism with a significant spinal defect reportedly show an increased incidence of open neural tube defects (ONTDs) in their children. The risk is thought to be similar to that for open spina bifida, which is about 4%.
• However, because no genetic cause of SSCM has been identified and there is no clear inheritance pattern, we cannot estimate the exact chance that a person will have a child with SSCM.
• A parent with a severe form spinal dysraphism is encouraged to speak with their prenatal care provider regarding the option of prenatal testing for ONTDs.

Types

There are two types of SSCM.

• In type I, each hemicord has a full protective covering (thecal sac) and they are separated by a bony structure, forming a double spinal canal.
• In type II, the two hemicords are surrounded by one thecal sac and there is a single spinal canal.

Onset

SSCM is present from birth, it may become apparent at any age and is more common in women than in men.

Signs and symptoms

• Some people may not have symptoms, while others may have a tethered cord and/or various other spinal abnormalities.
• Symptoms vary and may include back pain, bladder dysfunction, and leg pain or weakness.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Diastomatomyelia

30%-79% of people have these symptoms

• Generalized hirsutism(Excessive hairiness over body)
• Scoliosis

Treatment

Treatment may include surgery for release of a tethered cord, and/or physical therapy for neurologic problems or pain.

NIH genetic and rare disease info

• NIH info on Split spinal cord malformation

Split spinal cord malformation is a rare disease.