Ventral intraspinal cysts associated with the intervertebral disc: magnetic resonance imaging observations in seven dogs

Abstract

Objective: To report clinical and diagnostic imaging features, and outcome after surgical treatment of ventral intraspinal cysts in dogs.

Study design: Retrospective study.

Animals: Dogs (n=7) with ventral intraspinal cysts.

Methods: Clinical signs, magnetic resonance imaging (MRI) findings and surgical findings of 7 dogs and histologic findings (1 dog) with intraspinal cysts associated with the intervertebral disc were reviewed.

Results: Ventral intraspinal cyst is characterized by: (1) clinical signs indistinguishable from those of typical disc herniation; (2) an extradural, round to oval, mass lesion with low T1 and high T2 signal intensity on MRI, compatible with a liquid-containing cyst; (3) cyst is in close proximity to the intervertebral disc; and (4) MRI signs of disc degeneration. Although the exact cause is unknown, underlying minor disc injury may predispose to cyst formation.

Conclusion: Intraspinal cysts have clinical signs identical to those of disc herniation. Given the close proximity of the cyst to the corresponding disc and the similarity of MRI findings to discal cysts in humans, we propose the term "canine discal cyst" to describe this observation.

Clinical relevance: Discal cysts should be considered in the differential choices for cystic extradural compressing lesions.