Diastematomyelia is a rare congenital condition affecting the spinal cord, characterized by a longitudinal division of the cord. This developmental anomaly can occur at any level of the spine, though it is more frequently observed in the lower thoracic or upper lumbar regions. While present from birth, its manifestations can vary widely and may not become apparent until later in childhood or even adulthood.
Understanding Diastematomyelia
Diastematomyelia involves a sagittal division of the spinal cord, creating two hemicords. This splitting is caused by the presence of a septum—a bar of tissue—within the spinal canal. The condition is a type of split cord malformation (SCM) and originates during the third and fourth weeks of gestation due to abnormal development of the neuroenteric canal, leading to the formation of two notochords instead of one.
There are two primary types of diastematomyelia. Type I is characterized by two hemicords, each encased in its own dural sac, separated by a rigid midline bony or cartilaginous spur. In contrast, Type II involves two hemicords contained within a single dural sac, with a non-rigid fibrous or fibrovascular septum dividing them. Type I is associated with more pronounced symptoms due to the rigid nature of the dividing spur, while Type II may be less severe or asymptomatic.
Recognizing the Symptoms
The signs and symptoms of diastematomyelia can manifest at various ages, though diagnosis occurs during childhood. Neurological symptoms may include weakness in the legs, numbness, and issues with bladder or bowel control. Patients might also experience low back pain, muscle atrophy, and asymmetric reflexes. These neurological problems stem from the spinal cord being stretched or “tethered” by the dividing septum, which limits its normal movement within the spinal column.
Orthopedic manifestations include scoliosis, a sideways curvature of the spine, seen in over half of affected individuals. Foot deformities, such as clubfoot or cavus foot, and gait abnormalities can also be present. Dermatological signs are also common and can indicate an underlying spinal anomaly. These include hairy patches (hypertrichosis), dimples, or hemangiomas (reddish birthmarks) on the back, often located over the affected spinal area.
Diagnosis and Treatment Pathways
Diagnosing diastematomyelia involves a combination of examinations and advanced imaging. A physical examination may reveal external skin abnormalities or orthopedic deformities. Prenatal ultrasound can sometimes detect the condition during the third trimester of pregnancy. For a more definitive diagnosis, Magnetic Resonance Imaging (MRI) is the preferred imaging method, providing detailed views of the spinal cord, the dividing septum, and any associated abnormalities like hydromyelia or tethered cord syndrome. Computed Tomography (CT) scans are useful for delineating bony structures, such as an osseous spur, if present.
Treatment for diastematomyelia involves surgical intervention, especially for symptomatic individuals or those with progressive neurological deficits. The main goal of surgery is to remove the dividing septum, whether it is bony or fibrous, and to untether the spinal cord, which releases it from abnormal attachments and allows for improved movement. This procedure aims to prevent further neurological deterioration and can sometimes lead to modest clinical improvement. Asymptomatic patients may be monitored closely, with surgery considered if symptoms develop or worsen.
Long-Term Outlook
The long-term outlook for individuals with diastematomyelia is influenced by early diagnosis and appropriate management. Early surgical intervention, particularly before the onset of significant neurological deficits, can help prevent progressive damage to the spinal cord. While surgery aims to prevent further deterioration, complete neurological recovery may not always occur, especially if symptoms were already established.
Ongoing monitoring is necessary to track any changes in neurological function or the progression of associated conditions like scoliosis. Some individuals may benefit from continued physical therapy to address musculoskeletal issues and maintain mobility. The risk of developing neurological deficits can increase with age due to the continued strain on the spinal cord, emphasizing the need for vigilance.