ARRS Case of the Week

MUSCULOSKELETAL IMAGING: Spine

Case Author: Brian D. Petersen, MD, University of Colorado

History

58-year-old woman with 1 year of numbness, burning pain described as 8 of 10, and tingling involving both feet and radiating to mid calf bilaterally; examination showed hyperreflexia, bilateral upgoing Babinski sign, and sustained clonus of the right ankle.

Imaging Findings

Sagittal T2-weighted MR image (A) of the lumbar spine shows a low-lying conus (arrow) at L4–L5 and hypoplastic L4 and L5 vertebral bodies. Sagittal T1-weighted MR image (B) shows tissue of linear high T1 signal intensity (arrows) in the sacral canal and fusion of the spinous processes (star). Representative axial T2-weighted MR images from superior to inferior show a small syrinx (arrow, C), focal short-segment splitting of the spinal cord (arrows, D) with distal rejoining (not pictured). Inferior most image (E) shows a small focus of chemical shift artifact (arrow) corresponding to the thin high-signal-intensity structure in B.

Diagnosis

Diastematomyelia, Pang type 2 with tethered cord related to fatty filum

MSK insights delivered straight to your headphones 
AJR Podcasts feature authors of select AJR articles discussing how they performed their studies and how the results have changed their practices.

Teaching Points

Diastematomyelia is sagittal division of the spinal cord into two distinct hemicords. Cords can be divided by a fibrous or bony septum. CT can supplement MRI, and the findings define or exclude a bony septum.

Pang type 1 diastematomyelia has separate dural sacs with an osseous or fibrous spur. Pang type 2 has a single dural sac. Diastematomyelia is asymptomatic unless the cord is tethered; 75% of diastematomyelia cases have a tethered cord.

In 91% of cases of diastematomyelia, the hemicords reunite distally into a single filum terminale; 50% of cases of diastematomyelia have an associated syrinx (as in this case).

In 85% of cases, diastematomyelia is associated with spinal anomalies at the level of the cord division.

Intersegmental laminar fusion is pathognomonic of diastematomyelia.

Suggested Readings

Barkovich AJ. Pediatric neuroimaging, 4th ed. Philadelphia, PA: Lippincott, 2005

Ross JS, Brant-Zawadski M, Moore KR, Crim J, Chen MZ, Katzman GL. Diagnostic imaging: spine. Salt Lake City, UT: Amirsys, 2007:1–56

This page is updated with new content weekly. It was last updated on March 19, 2019.