This patient presented in her 40s for assessment of possible metastatic malignancy. An incidental finding of diastematomyelia was made. There was associated fusion anomaly of vertebrae at the thoracolumbar junction. A small syrinx was present above the cord split.
At the level shown, the cord is split into two hemicords, and divided by a fibrous or osseous spur.
Diastematomyelia is associated with congenital spinal deformity in 85%, including segmentation anomalies, laminar fusion, dysraphism, tethered cord, thickened filum terminale, and scoliosis. There is an association with Chiari II malformation.
Diastematomyelia may be classified as type I (two separate dural sacs surround each hemicord) or type II (single dural sac and arachnoid space, no osseus spur).

Reference: Ross JS, et al. Diagnostic Imaging: Spine. Amirsys 2004

Credit: Dr Laughlin Dawes