J Vet Sci.  2020 Jul;21(4):e52. 10.4142/jvs.2020.21.e52.

Preliminary study of presumptive intradural-intramedullary intervertebral disc extrusion in 20 dogs

• Kim J
• Kim H
• Hwang J
• Eom K

• KMID: 2504882
• DOI: http://doi.org/10.4142/jvs.2020.21.e52

Abstract

Background
Intradural-intramedullary intervertebral disc extrusion (IIVDE) is a rare condition of intervertebral disc disease. However, the diagnosis of IIVDE is challenging because the prognosis and imaging characteristics are poorly characterized.
Objectives
We aimed to describe the clinical and imaging characteristics of tentatively diagnosed IIVDE in dogs to assess the prognostic utility of neurological grade and magnetic resonance imaging (MRI) findings.
Methods
Twenty dogs were included in this retrospective cohort study.
Results
Nonchondrodystrophic breeds (n = 16) were more predisposed than chondrodystrophic breeds. Most dogs showed acute onset of clinical signs. Neurological examination at admission showed predominant non-ambulatory paraparesis (n = 9); paresis (n = 16) was confirmed more frequently than paralysis (n = 4). Follow-up neurological examination results were only available for 11 dogs, ten of whom showed neurological improvement and 8 showed successful outcomes at 1 month. The characteristic MRI findings include thoracic vertebra (T)2 hyperintense, T1 hypointense, intramedullary linear tracts with reduced disc volume, and cleft of the annulus fibrosus. None of the MRI measurements were significantly correlated with neurological grade at admission. Neurological grade did not differ according to the presence of parenchymal hemorrhage, parenchymal contrast enhancement, and meningeal contrast enhancement. Neurological grades at admission showed a statistical correlation with those observed at the 1-month follow-up (r = 0.814, p = 0.02).
Conclusions
IIVDE is a rare form of disc extrusion commonly experienced after physical activity or trauma and most frequently affects the cranial-cervical and thoracolumbar regions of nonchondrodystrophic dog breeds. Neurological score at admission emerged as a more useful prognostic indicator than MRI findings in dogs with suspected IIVDE.

Keyword

3D dimensional T2-weighted fast spin echo sequence; dog; intradural-intramedullary intervertebral disc extrusion; intervertebral disc disease; magnetic resonance imaging