Diastematomyelia (Split Cord Malformation)

Overview

Diastematomyelia, also known as split cord malformation, is a rare condition present from birth in which the spinal cord is divided into two halves over part of its length. The two halves are often separated by a spur made of bone, cartilage, or fibrous tissue that projects from the spine. This is a type of spinal cord malformation that develops during early fetal growth.

The split itself, and especially the dividing spur, can tether the spinal cord and prevent it from moving freely, leading to stretching and nerve injury much like tethered cord syndrome. Diastematomyelia frequently occurs alongside other spinal abnormalities, including spina bifida and tethered cord. Symptoms can appear in childhood as a child grows, or sometimes later in life. Treatment, when needed, is usually surgical and aims to remove the dividing spur and release the cord.

Symptoms

Some people have few or no symptoms, while others develop neurological problems, often as they grow. Possible features include:

• Back pain and, in children, changes in walking or balance
• Leg weakness, numbness, or differences in size or strength between the two legs
• Foot deformities, such as a high arch or differences between the feet
• Curvature of the spine (scoliosis)
• Bladder and bowel problems
• Skin markings over the lower back, such as a tuft of hair, dimple, birthmark, or fatty lump, which can be a visible clue

Because the condition can tether the cord, symptoms may progress over time, which is why ongoing evaluation is important once it is identified.

Causes

Diastematomyelia results from abnormal development of the spinal cord during early pregnancy, when the structures forming the cord do not come together normally. Key points include:

• Developmental malformation: The spinal cord forms in two parts separated by a dividing spur.
• Association with neural tube defects: It often occurs with spina bifida and other spinal abnormalities.
• Tethering element: The spur and surrounding tissue can anchor the cord, contributing to symptoms.

The exact reason the malformation occurs is usually not known, and like other neural tube and spinal abnormalities, it is thought to involve a combination of genetic and environmental factors during early development.

Risk Factors

• The presence of other neural tube defects such as spina bifida
• A family history of spinal abnormalities or neural tube defects
• Low folic acid intake during early pregnancy, a general risk factor for neural tube defects
• Other associated congenital spinal conditions

Diagnosis

Diagnosis relies on imaging and neurological assessment:

• MRI: The most useful test, showing the split cord, the dividing spur, and any associated tethering or other spinal abnormalities.
• CT scan: Helpful for detailing a bony spur and the surrounding vertebrae.
• X-rays: May reveal associated spinal abnormalities or scoliosis.
• Neurological examination: Testing strength, sensation, reflexes, and bladder function.

Skin markings over the lower back in an infant or child may prompt imaging that reveals the condition. Specialists evaluate the findings to plan care.

Treatment

Treatment depends on whether the condition is causing symptoms or is likely to:

• Surgery: When there are symptoms or progression, a neurosurgeon removes the dividing spur and releases the tethered cord to prevent further nerve damage.
• Observation: Some people without symptoms may be monitored, with decisions made by specialists based on the individual situation.
• Supportive care: Physical therapy, bladder management, and treatment of scoliosis or foot problems as needed.
• Follow-up: Ongoing monitoring, especially in growing children, since symptoms can develop or progress.

Surgery aims to stop progression and protect function; the degree of improvement depends on how much nerve damage was present beforehand.

Prevention

Diastematomyelia itself usually cannot be prevented, but related measures may help:

• Taking folic acid before and during early pregnancy lowers the risk of neural tube defects, which are linked to spinal cord malformations
• Attending recommended prenatal care
• Having any unusual skin markings over a child's lower back evaluated by a doctor
• Seeking early assessment of new neurological, walking, or bladder problems so treatment can be timely

When to See a Doctor

See a doctor if you or your child have progressive leg weakness, numbness, back or leg pain, walking changes, scoliosis, or new bladder or bowel problems, particularly with a known spinal abnormality or skin markings over the lower spine. Seek prompt medical care for:

• New or rapidly worsening leg weakness or numbness
• Sudden loss of bladder or bowel control
• Numbness in the groin or inner thighs

These can indicate significant spinal cord involvement that needs urgent evaluation. Skin findings over a baby's lower back should always be assessed by a doctor.

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS).
2. American Association of Neurological Surgeons (AANS).
3. MedlinePlus, U.S. National Library of Medicine.
4. Genetic and Rare Diseases Information Center (GARD).