Lauryn Cooper, Marc Kent
Background
Intervertebral disc herniation (IVDH) is rare in cats, with most cases involving extradural compression. Reports of intramedullary disc extrusion exist, but intradural-extramedullary (ID-EM) disc extrusion has not previously been documented in this species. Differentiating lesion location relative to the meninges on MRI is often challenging, and findings may mimic neoplasia.
Methods
A 10-year-old spayed female domestic shorthair cat presented with a 6-week history of abnormal tail carriage, tail pain, and constipation. Neurological examination indicated lower motor neuron tail paresis. MRI showed a contrast-enhancing mass over the lumbosacral disc space, presumed to be extradural. The cat underwent lumbosacral laminectomy and durotomy. Surgical samples were examined histopathologically.
Results
Surgery revealed white, firm material within the subarachnoid space compressing the cauda equina. Histopathology confirmed the material was degenerated intervertebral disc tissue. Postoperatively, the cat’s tail function, pain, and constipation resolved fully, with complete recovery reported at follow-up.
Limitations
MRI failed to distinguish between intradural-extramedullary and extradural location, leading to diagnostic uncertainty preoperatively. The decision for surgery was influenced by the presumed extradural nature of the lesion and its favorable prognosis compared to suspected neoplasia.
Conclusions
This is the first reported case of intradural-extramedullary intervertebral disc extrusion in a cat. Although MRI can misclassify such lesions, exploratory surgery provided both a definitive diagnosis and successful treatment. Clinicians should consider ID-EM disc extrusion as a differential in feline spinal lesions, particularly when imaging findings are equivocal.
On sequential (a–c, from cranial to caudal) postcontrast T1-weighted images acquired using the Dixon fat saturation technique, the mass (arrow) appeared as a slightly right-sided epidural lesion that displayed strong, homogeneous contrast enhancement
How did we do?
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