In neurology, diastematomyelia (occasionally diastomyelia) is a congenital disorder in which a part of the spinal cord is split, usually at the level of the upper lumbar vertebra in the longitudinal (sagittal) direction.

[1][additional citation(s) needed] The signs and symptoms of diastematomyelia may appear at any time of life, although the diagnosis is usually made in childhood.

Cutaneous lesions (or stigmata), such as a hairy patch, dimple, Hemangioma, subcutaneous mass, Lipoma or Teratoma over the affected area of the spine is found in more than half of cases.

In children, symptoms may include the "stigmata" mentioned above and/or foot and spinal deformities; weakness in the legs; low back pain; scoliosis; and incontinence.

In adulthood, the signs and symptoms often include progressive sensory and motor problems and loss of bowel and bladder control.

Tethered spinal cord syndrome appears to be the result of improper growth of the neural tube during fetal development, and is closely linked to spina bifida.

In most of the symptomatic patients, the spinal cord is split into halves by a bony spicule or fibrous band, each half being surrounded by a dural sac.

Other conditions, such as intramedullary tumors, tethered cord, dermoids, lipoma, syringomyelia, hydromyelia and Arnold–Chiari malformations have been described in medical literature, but they are exceptionally rare.

Occasionally, however, the cleft will extend unusually low and the cord will end with two separate coni medullarae and two fila terminale ("Diplomyelia").

Combined myelographic and post-myelographic CT scan is the most effective diagnostic tool in demonstrating the detailed bone, intradural and extradural pathological anatomy of the affected and adjacent spinal canal levels and of the bony spur.

The surgical procedure required for the effective treatment of diastematomyelia includes decompression (surgery) of neural elements and removal of bony spur.