Split cord malformation type I

Split cord malformation type I (SCM type I), also known as diastematomyelia type I, is a rare congenital spinal dysraphism in which the spinal cord is divided into two hemicords by a rigid osseocartilaginous (bony or cartilaginous) septum or spur. Each hemicord is contained within its own separate dural tube. This distinguishes it from type II split cord malformation, where the two hemicords share a single dural sac and are separated by a fibrous septum. The condition results from a developmental defect during embryogenesis, likely related to abnormal formation of the notochord and persistence of an accessory neurenteric canal. Split cord malformation type I primarily affects the nervous system and musculoskeletal system. The bony septum tethers the spinal cord, leading to progressive neurological deterioration as the child grows. Key clinical features include lower limb weakness or asymmetry, foot deformities (such as clubfoot), gait abnormalities, back pain, scoliosis, and neurogenic bladder or bowel dysfunction. Cutaneous stigmata overlying the affected spinal segment — such as a hairy patch (hypertrichosis), dimple, lipoma, or hemangioma — are frequently present and may serve as early diagnostic clues. Symptoms may present in infancy or childhood but can occasionally remain undiagnosed until adulthood if neurological deficits are mild. Diagnosis is typically confirmed through MRI of the spine, often supplemented by CT scanning to visualize the bony septum. Treatment is surgical and involves removal of the osseocartilaginous septum and untethering of the spinal cord to prevent further neurological deterioration. Early surgical intervention generally yields better outcomes, particularly in preserving neurological and urological function. Postoperative monitoring is important, as re-tethering can occur. There is no cure for existing neurological damage, and rehabilitation including physiotherapy and management of bladder dysfunction may be necessary as part of long-term care.

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