Mechanical quantitative sensory testing in cavalier King Charles spaniels with and without syringomyelia

Abstract

Background: Syringomyelia (SM) is a debilitating condition in the cavalier King Charles spaniel (CKCS) that results in neuropathic pain and diminished quality of life. Von Frey aesthesiometry (VFA) is a method of mechanical quantitative sensory testing that provides an objective sensory threshold (ST) value and can be used to quantify neuropathic pain (NP) and monitor response to therapy. The utility of VFA has been previously established in client-owned dogs with acute spinal cord injury but the technique has not been evaluated in dogs with SM. The goal of this study was to evaluate ST, as determined by VFA, in dogs with and without SM, to assess the utility of VFA in quantifying NP in SMaffected dogs. We hypothesized the SM-affected CKCS would have lower ST values, consistent with hyperesthesia, when compared to control CKCS. Additionally, we hypothesized that ST values in SM-affected dogs would be inversely correlated with syrinx size on MRI and with owner-derived clinical sign scores. Results: ST values for the thoracic and pelvic limbs differed significantly between the SM-affected and control CKCS (p = 0.027; p = 0.0396 respectively). Median ST value (range) for the thoracic limbs was 184.1 g (120.9-552) for control dogs, and 139.9 g (52.6-250.9) for SM-affected dogs. The median ST value (range) for the pelvic limbs was 164.9 g (100.8-260.3) in control dogs and 129.8 g (57.95-168.4) in SM-affected dogs. The ST values in SM-affected dogs did not correlate with syrinx height on MRI (r = 0.314; p = 0.137). Owner-reported clinical sign scores showed an inverse correlation with pelvic limb ST values, where dogs with lower ST values (hyperesthesia) were reported by their owners to display more frequent and severe clinical signs (r = − 0.657; p = 0.022). Conclusion: ST values were lower in SM-affected CKCS compared to control dogs, suggesting the presence of neuropathic pain. Dogs with lower ST pelvic limb values were perceived by their owners to have more severe clinical signs classically associated with SM. Our results suggest that VFA might offer quantitative assessment of neuropathic pain in SM-affected dogs and could be useful for monitoring response to therapy in future clinical studies.

Longitudinal assessment of syringomyelia in Pomeranians

“…Therefore, we elected to include only T1W-based measurements in this study. SM measurements are often recorded absolutely (e.g., a syrinx diameter of 2.2 mm), or dogs are classified in groups with specific measurement categories (e.g., <1.0 mm, 1.0-1.9 mm, et cetera), or dogs are classified as having SM or not based on size (e.g., >2 mm) (6,7,14,19,(22)(23)(24)(25)(26)(27)(28)(29). Few studies provided relative syrinx sizes (e.g., syrinx height: C3 vertebral depth or the spinal cord itself) (9, 13,19).…”

Phenotypic characterization of Pomeranians with or without Chiari-like malformation and syringomyelia

“…What is or is not associated with pain in animals, is therefore always a subjective interpretation. Studies on quantitative assessments of SM-related neuropathic pain have yielded conflicting results ( 27 – 29 ). Taking this into account, including whether or not signs of pain where provoked vs. spontaneous seemed to be an interesting differentiation to investigate in our study population.…”

Diffusion Tensor Imaging in Syringomyelia Secondary to Chiari Malformation in Cavalier King Charles Spaniel—A Preliminary Study

“…Fractional anisotropy is a parameter considered to be a marker of fibre tract integrity while an increase in ADC values suggests a demyelinating process [ 21 , 22 , 24 , 26 , 27 ]. In agreement with our hypothesis, changes in both DTI parameters confirmed disturbed integrity and organization of the spinal cord in SM-symptomatic dogs.…”

“…It is a non-invasive MRI technique which is more sensitive to microstructural changes than conventional MR images and is able to show abnormalities within the spinal cord which are not visible on standard structural MR images. It measures microstructural characteristics of water diffusion within the nervous tissue [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Diffusion tensor imaging is a method that has been increasingly used in the assessment of myelopathies, such as syringomyelia, and degenerative myelopathy or traumatic spinal injuries [ 19 ].…”