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

Abstract

BackgroundTranscranial magnetic motor evoked potentials (TMMEP) are associated with severity of clinical signs and magnetic resonance imaging (MRI) findings in dogs with spinal cord disease.HypothesisThat in initially paraplegic dogs with thoracolumbar intervertebral disc herniation (IVDH), MRI findings before surgery and TMMEPs obtained after decompressive surgery are associated with long‐term neurological status and correlate with each other.AnimalsSeventeen client‐owned paraplegic dogs with acute thoracolumbar IVDH.MethodsProspective observational study. TMMEPs were obtained from pelvic limbs and MRI (3T) of the spinal cord was performed at initial clinical presentation. Follow‐up studies were performed ≤ 2 days after reappearance of motor function and 3 months later. Ratios of compression length, intramedullary hyperintensities' length (T2‐weighted hyperintensity length ratio [T2WLR]), and lesion extension (T2‐weighted‐lesion extension ratio) in relation to the length of the 2nd lumbar vertebral body were calculated.ResultsTMMEPs could be elicited in 10/17 (59%) dogs at 1st and in 16/17 (94%) dogs at 2nd follow‐up. Comparison of TMMEPs of 1st and 2nd follow‐up showed significantly increased amplitudes (median from 0.19 to 0.45 mV) and decreased latencies (from 69.38 to 40.26 ms; P = .01 and .001, respectively). At 2nd follow‐up latencies were significantly associated with ambulatory status (P = .024). T2WLR obtained before surgery correlated with latencies at 2nd follow‐up (P = .04).ConclusionsTMMEP reflect motor function recovery after severe spinal cord injury.

Prognostic Factors in Canine Acute Intervertebral Disc Disease

“…There has been interest in the utility of repeated TMMEP evaluation in dogs that were paraplegic at presentation. Dogs that show recovery of pain perception and motor function recover TMMEPs, leading to the suggestion that this tool can be used to complement assessment of recovery (96). Two groups have evaluated the presence and latency of TMMEPs in dogs that do not regain deep pain perception, and reached different conclusions with one group finding an association between TMMEP presence and recovery or walking, and the other failing to find this association (97,98).…”