Presumptive intramedullary intervertebral disc extrusion in 12 cats: clinical presentation, MRI findings, treatment and outcome

Abstract

ObjectivesThis study aimed to describe the clinical characteristics, MRI findings, treatment and outcome in cats presumptively diagnosed with intramedullary intervertebral disc extrusions.MethodsA retrospective review was conducted of medical records and MRI data from cats presumptively diagnosed with intramedullary intervertebral disc extrusions. Long-term outcome (⩾6 months) was assessed through medical records, questionnaires completed by the owners or both.ResultsA total of 12 cats met the inclusion criteria. All presented with peracute or acute clinical signs, with nine having confirmed (n = 3) or possible (n = 6) external trauma based on history, physical examination or MRI findings. Seven cats were ambulatory and five were non-ambulatory. Eight cats presented with urinary incontinence; none exhibited faecal incontinence. Neuroanatomical localisation included the T3-L3 (n = 7) and L4-S3 (n = 5) spinal cord segments. MRI showed an intramedullary intervertebral disc extrusion at the following sites: T12-T13 (n = 1), T13-L1 (n = 1), L1-L2 (n = 2), L2-L3 (n = 2), L4-L5 (n = 3) and L5-L6 (n = 3). All cats underwent treatment and were discharged after a median hospitalisation time of 4 days (range 3-14). All non-ambulatory cats with available follow-up information (4/5) regained ambulation by the time of the short-term (<6 weeks) or long-term (⩾6 months) assessment. Moreover, all cats either retained or regained urinary continence by the time of discharge, the short-term (<6 weeks) or the long-term (⩾6 months) assessment. Overall, nine cats achieved a successful outcome and were considered functional pets at the short-term (<6 weeks) and/or long-term (⩾6 months) follow-up. Two cats were lost to follow-up, and one cat had perceived persistent generalised discomfort.Conclusions and relevanceMost cats presumptively diagnosed with an intramedullary intervertebral disc extrusion showed a favourable outcome with treatment in this study. This condition should be considered in cats presenting with peracute or acute signs of T3-L3 or L4-S3 spinal cord dysfunction, especially if there is a history or indication of trauma.

Keywords: Intramedullary intervertebral disc extrusion; MRI; intervertebral disc disease; non-compressive nucleus pulposus extrusion.

Figure 1

(a) Sagittal T2-weighted image of the thoracolumbar vertebral column, (b) transverse T2-weighted image at the level of the T13–L1 intervertebral disc space, and (c) transverse T2-weighted image at the level of the L2 vertebral body of a domestic shorthair cat aged 3 years 5 months. (a) A linear hypointense tract extends from the T13–L1 intervertebral disc into the spinal cord parenchyma, surrounded by an ill-defined hyperintense area (arrow). The T13–L1 nucleus pulposus shows a reduced volume compared with the adjacent discs. (b) Right-sided intramedullary changes are evident at the level of the T13–L1 intervertebral disc (arrow), with no apparent extraneous material in the epidural space. (c) A relatively well-demarcated hyperintensity within the epaxial musculature at the level of the L2 vertebral body, suggestive of epaxial muscle contusion or oedema (not haemorrhage, based on excluded T2*-weighted gradient-recall echo images), was considered potentially indicative of external trauma or secondary to the extrusion (arrow)