Diastematomyelia: Splitting of the Spinal Cord

What Is Diastematomyelia?

Diastematomyelia is a congenital condition where a part of the spinal cord splits. It is also known as split cord malformation, in which there is a longitudinal separation of the spinal cord. This usually occurs at the level of upper lumbar vertebrae and occurs in the presence of a bony, cartilaginous, or fibrous septum in the central part of the spinal canal, which splits complete or incomplete longitudinal (sagittal) portions of the spinal cord into two hemicords. Diastematomyelia is most commonly seen in the female gender. Moreover, split cord malformations are hereditary and account for five percent of all congenital spinal faults.

How Does Diastematomyelia Occur?

Diastematomyelia is believed to happen during the developmental stage of the fetus, which usually occurs during the gastrulation phase (third week of human development) due to abnormal movement and division of precursor cells. This causes the spinal cord and the nerve roots in the spinal cord to split into two columns. The split may be found at any level, but usually, it is found in the lower thoracic or upper lumbar regions. The thoracic region runs from the base of the neck down to the abdomen, and the lumbar region is the lower part of the back. This condition also leads to slow spinal cord growth by restricting the upward migration of neural elements, leading to progressive neurologic defects in the lower limbs.

What Are the Types of Diastematomyelia?

Split cord malformations are usually classified into two types according to the presence of a dividing septum and a single or dual dural sac. The types include:

Type I (Classic Diastematomyelia) - This type is generally symptomatic and is represented by -

• Duplicated dural sac.

• Vertebral abnormalities include butterfly vertebrae, hemivertebrae, a fusion of laminae of adjacent levels, and spina bifida.

• Midline spur (osseous or osseocartilaginous).

• Skin pigmentation.

• Hemangioma (benign vascular tumor derived from blood vessels).

• Hypertrichosis (hair patch).

Type II - This type is milder than type I and does not have the same characteristics as type I. Some of the features seen in this type include -

• Single dural sac.

• Cord separated or incomplete.

• Hydromyelia (abnormal widening of the central canal of the spinal cord) may be present.

• Spina bifida (deformity of the spinal cord).

Moreover, there are multiple anomalies associated with diastematomyelia which include:

1. Cutaneous Manifestations:

• Telangiectasias (presence of dilated small blood vessels on the skin or mucous membranes).

• Hemangiomas (benign vascular tumors derived from a blood vessel).

• Lipomas (fatty tumors located below the skin).

• Atrophic skin (decreased thickness of the dermis).

• Pigmented nevi (non-cancerous growths on the skin that usually are flesh-colored, brown, or black).

• Hypertrichosis (excessive hair growth on the body).

2. Vertebral Anomalies:

• Congenital scoliosis (abnormal curvature of the spine).

• Kyphosis (forward rounding of the upper back).

• Spina bifida (abnormal development of the spine).

• Hemivertebra (only one side of vertebrae is fully developed).

3. Muscular-skeletal Anomalies:

• Muscular atrophy.

• Deformity of the foot.

4. Urologic Anomalies:

• Loss of bowel and bladder control.

What Are the Symptoms of Diastematomyelia?

There are multiple symptoms associated with diastematomyelia. However, patients with type II diastematomyelia may have no symptoms (asymptomatic). Some of the symptoms may include:

• Weakness in legs.

• Lower back pain.

• Scoliosis (abnormal lateral curvature of the spine).

• Incontinence of bladder and bowel.

In patients with diastematomyelia, some of the following anomalies may also be seen which include:

• Meningocele (a birth defect in which the baby's spinal cord fails to develop properly).

• A neuromeric cyst (rare lesion of the spinal axis).

• Dermoid cyst (masses present at birth under the skin).

• Clubfoot (foot abnormalities usually present at birth).

• Spinal cord lipoma (intraspinal mass of adipose tissue contiguous with the adjacent spinal cord).

• Hemangioma (a benign vascular tumor from blood vessel cell types) overlying the spine.

What Is the Diagnosis of Diastematomyelia?

In adult patients, diastematomyelia is distinctive and can be easily viewed with the help of modern imaging tools. The common location of the lesion is between the first and third lumbar vertebrae. These malformations can be easily seen via X-rays. However, MRI (magnetic resonance imaging) is usually the first choice of test for screening and diagnosing spinal malformations.

Though it gives a satisfactory analysis of the deformities, it also has some limitations in providing detailed bone anatomy. Therefore, CT (computed tomography) is another option that can be used instead of MRI, as it provides demonstrated detailed anatomy of bones and pathological anatomy of the affected areas of the spinal cord. About 50 percent of spinal cord malformations are found in the lower cord area and 25 percent in the upper areas of the spinal cord. In X-ray, some of the following malformations can be seen which include:

• Multilevel spina bifida.

• Associated scoliosis (abnormal curvature of the spine).

• Anterior posterior vertebral body narrowing.

The MRI (magnetic resonance imaging) diagnostic tool is best used in cases of children to detect split cord malformations, show hydromyelia (abnormal widening of the central canal of the spinal cord) if it is present, and also detect multiple associated anomalies.

How Is Diastematomyelia Treated?

In cases where diastematomyelia is asymptomatic, there is no need for treatment. However, these types of patients should have regular neurological checkups to avoid any complications, and if any symptoms appear, they should immediately report them to the healthcare provider.

In cases where the patient experiences symptoms, the treatment plan mainly depends on the severity of the symptoms and how to manage them. The physiotherapist recommends specific physical exercises if any deformity is present, such as scoliosis.

Surgery: In some cases, surgery may be required. Surgery is usually required in patients with neurological signs and symptoms or a history of progressive neurological representations associated with this abnormality. The surgery in diastematomyelia includes decompression surgery of neural elements and removing bony spurs. The surgery can be performed with or without resection and fixing the reoccurring Dural sacs.

Conclusion

Diastematomyelia is a rare defect of the spinal cord that is mostly seen in the female population. It is a congenital condition and is primarily diagnosed in the prenatal stage. Multiple defects are associated with this condition, so a proper diagnosis must be made to confirm it. The treatment usually depends on managing the symptoms associated with it. This condition is very rare, and it can be managed easily with an early diagnosis.