Abstract
BackgroundProgressive myelomalacia (PMM) is a usually fatal complication of acute intervertebral disc extrusion (IVDE) in dogs but its risk factors are poorly understood. The objective of this retrospective case-control study was to identify risk factors for PMM by comparing dogs with complete sensorimotor loss following IVDE that did and did not develop the disease after surgery. We also investigated whether any risk factors for PMM influenced return of ambulation. Medical records of client-owned dogs with paraplegia and loss of pain perception that underwent surgery for IVDE from 1998 to 2016, were reviewed. Dogs were categorized as PMM yes or no based on clinical progression or histopathology. Walking outcome at 6 months was established. Signalment, onset and duration of signs (categorized), steroids, non-steroidal anti-inflammatory drugs (yes or no), site of IVDE (lumbar intumescence or thoracolumbar) and longitudinal extent of IVDE were retrieved and their associations with PMM and walking outcome were examined using logistic regression.ResultsOne hundred and ninety seven dogs were included, 45 with and 152 without PMM. A 6-month-outcome was available in 178 dogs (all 45 PMM dogs and 133 control dogs); 86 recovered walking (all in the control group). Disc extrusions at the lumbar intumescence were associated with PMM (p = 0.01, OR: 3.02, CI: 1.3–7.2). Surgery performed more than 12 h after loss of ambulation was associated with PMM (OR = 3.4; CI = 1.1–10.5, p = 0.03 for 12-24 h and OR = 4.6; CI = 1.3–16.6, p = 0.02 for the > 24 h categories when compared with the ≤12 h category). Treatment with corticosteroids was negatively associated with PMM (OR: 3.1; CI: 1.3–7.6, p = 0.01). The only variable to affect walking outcome was longitudinal extent of IVDE (OR = 2.6; CI = 1.3–5.3, p = 0.006).ConclusionDogs with lumbar intumescence IVDE are at increased risk of PMM. Timing of surgery and corticosteroid use warrant further investigations. PMM and recovery of walking are influenced by different factors.
Highlights
Progressive myelomalacia (PMM) is a usually fatal complication of acute intervertebral disc extrusion (IVDE) in dogs but its risk factors are poorly understood
The only factor shown to have an influence on long term outcome was the longitudinal extent of the disc herniation (p = 0.006) with dogs with an extensive disc herniation being less likely to walk at 6 months than dogs with a focal herniation (OR = 2.6; Confidence intervals (CI) = 1.3–5.3). In this exploratory, retrospective study we evaluated the factors associated with development of PMM and recovery of walking in 197 dogs with surgically treated thoracolumbar intervertebral disc extrusion (TL IVDE)
A disc herniation at the level of the lumbar intumescence was significantly associated with the development of this condition and use of corticosteroids and prompt surgical decompression might be protective
Summary
Progressive myelomalacia (PMM) is a usually fatal complication of acute intervertebral disc extrusion (IVDE) in dogs but its risk factors are poorly understood. The objective of this retrospective case-control study was to identify risk factors for PMM by comparing dogs with complete sensorimotor loss following IVDE that did and did not develop the disease after surgery. Progressive myelomalacia (PMM) is one of the most sinister complications associated with thoracolumbar intervertebral disc extrusion (TL IVDE) [1, 2] In this condition, there is progressive ascending and/or descending hemorrhagic necrosis of the cord following acute, severe thoracolumbar spinal cord injury (SCI) due to acute IVDE [2]. Most dogs develop signs consistent with PMM within 48 h of presentation but the majority progress and are euthanized within 3 days after onset of signs, a delayed progression can be observed [5]
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