Comparison of Preoperative Quantitative Magnetic Resonance Imaging and Clinical Assessment of Deep Pain Perception as Prognostic Tools for Early Recovery of Motor Function in Paraplegic Dogs with Intervertebral Disk Herniations

Abstract

BackgroundPrognostic tools to predict early postoperative motor function recovery (MFR) after thoracolumbar intervertebral disk herniation (IVDH) in paraplegic dogs represent an opportunity to timely implement novel therapies that could shorten recovery times and diminish permanent neurological dysfunctions.HypothesisFractional anisotropy (FA) values obtained using diffusion tensor imaging have a higher prognostic value than a lesion extension ratio in T2‐weighted images (T2W‐LER) and clinical assessment of deep pain perception (DPP) for MFR.AnimalsThirty‐five paraplegic dogs with diagnosis of acute or subacute thoracolumbar IVDH.MethodsProspective, descriptive observational study. At admission, absence or presence of DPP, T2W‐LER, and FA values was evaluated. MFR was assessed within 4 weeks after decompressive surgery. Values of T2W‐LER and FA of dogs with and without MFR were compared using t‐tests. All 3 methods were evaluated for their sensitivity and specificity as a prognostic factor.ResultsNo differences were found between groups regarding T2W‐LER. FA values differed statistically when measured caudally of lesion epicenter being higher in dogs without MFR compared to dogs with MFR (P = .023). Logistic regression analysis revealed significance in FA values measured caudally of the lesion epicenter (P = .033, area under the curve = 0.72). Using a cutoff value of FA = 0.660, the technique had a sensitivity of 80% and a specificity of 55%. Evaluation of DPP had a sensitivity of 73.3% and specificity of 75% (P = .007).Conclusions and Clinical ImportanceEvaluation of DPP showed a similar sensitivity and a better specificity predicting early MFR than quantitative magnetic resonance imaging.

Magnetic resonance imaging features of dogs with incomplete recovery after acute, severe spinal cord injury

“…The MRI appearance of acute myelopathies in dogs has been documented with various qualitative and quantitative features. 2 , 3 , 5 , 6 , 8 – 17 Among these, the presence and dimensions of intramedullary hyperintensity on T2W images and length of cord compression have been associated with outcome for dogs suffering from acute intervertebral disc herniation. 6 , 10 , 13 , 18 The maximal cross-sectional area of intramedullary hyperintensity on T2W images has been associated with outcome in acute, non-compressive nucleus pulposus extrusion.…”

Transcranial magnetic motor evoked potentials and magnetic resonance imaging findings in paraplegic dogs with recovery of motor function

“…This measurement was performed separately to account for possible overlapping of hyperintensities and regions of spinal cord compression. The length of L2 was used to calculate standardized T2‐weighted hyperintensity length ratio (T2WLR), spinal cord compression length ratio (CLR), and T2 weighted‐lesion extension ratio (T2W‐LER), as described before (Figure ) . The same observers performed all measurements on initial and follow‐up MRI examinations and had access to a list of patient IDs, being blinded to neurological status throughout the study at the time of performing MRI measurements.…”

“…19 (T2W-LER), as described before ( Figure 2). 25,33,34,42 The same observers performed all measurements on initial and follow-up MRI examinations and had access to a list of patient IDs, being blinded to neurological status throughout the study at the time of performing MRI measurements.…”

The role of diffusion tensor imaging as an objective tool for the assessment of motor function recovery after paraplegia in a naturally-occurring large animal model of spinal cord injury

“…DTI metrics measured during the pre-operative time point were previously reported [ 34 , 39 ]. DTI values from the follow up examination, statistical analysis, and results described in this study have been independently calculated and have not been previously reported.…”

“…As patient management may represent a restraining factor limiting the time for MRI scans in acute traumatic SCI, the interest for using DTI in the spinal cord of dogs as a large animal model for traumatic SCI has been increasingly growing [ 34 – 38 ]. We recently characterized acute and chronic stages of severe SCI and evaluated the prognostic value of DTI for predicting early MFR [ 34 , 39 ]. However, description of DTI metrics during MFR may represent a useful tool for objective in vivo evaluation of the spinal cord parenchyma during clinical trials.…”