Teaching Case

A 65-year-old woman with a CT performed for thyroid cancer and assessment of its extension.

Axial CT image of the spine at D11 level shows a bony bar that creates two distinct spinal canals, an incidental finding that corresponds with diastematomyelia (Fig. 1, 2 and 3).
Associated scoliosis is also detected (Fig. 4).

Background: Diastematomyelia, also known as a split cord malformation, refers to a type of spinal dysraphism (spina bifida occulta) when there is a longitudinal split in the spinal cord. Diastematomyelia usually occurs between 9th thoracic and 1st sacral levels of the spinal column [1].
Spinal cord malformations are divided into two types according to presence of a dividing septum and single vs dual dural sac [1].
Type I: duplicated dural sac, with common midline spur (osseous or fibrous) and usually symptomatic.
Type II: single dural sac containing both hemicords; impairment less marked.
However, in our case, due to the absence of an MRI, we cannot determine the type of diastematomyelia (but it is likely to be a type II because of the absence of symptomatology).
Imaging Perspective: CT is able to better image many of the features seen on plain films and in addition may demonstrate the bony septum, but MRI is the modality of choice for assessing children with split cord malformations. As well as being able to elegantly demonstrate the cord and presence of hydromyelia (if present), it can also assess for the presence of the numerous associated anomalies [1].
The best diagnostic clue is a fibrous or osseous spur splits spinal cord into 2 hemicords.
Diastematomyelia has been associated with other neural tube defects, spinal dysraphisms and scoliosis (like in our case). While patients are often initially asymptomatic, they may present due to visceral malformations, myelomeningoceles, lipomas, Chiari malformations, tethered spinal cords, and other vertebral anomalies. Skin abnormalities such as hypertrichosis are also common [3]. Syringomyelia is rarely a concurrent abnormality [2].


Outcome: Asymptomatic patients with diastematomyelia do not require treatment (like in our case). However, if the patient has symptoms related to the abnormality, they can be treated surgically. Treatment in these patients includes surgery to remove bony spur and reconstruct the dura around the two separated cords [4].