Abstracts

Rationale: Epileptic canines are gaining validity as a translational One Health model of human epilepsy, with similarities in pathophysiology, physical manifestation, and treatment modalities, but several key unknowns. With minimal veterinary use of clinical electroencephalography (EEG), electrographic seizure descriptions are sparse with poorly characterized epileptogenic pattern morphology. The spike-wave complex is the EEG hallmark for seizure detection, analysis, and epilepsy diagnosis. Misinterpretation of spikes on the EEG is a common reason for misdiagnosis and inaccuracy in research. In human epileptology, a spike is a sharply contoured negative deflection of cortical origin lasting less than 70ms, where the duration of the spike’s first half (FHS) is less than the second half (SHS) (Blume and Lemieux, Electroenceph and Clin Neurophys69: 508-515, 1988), largely unconfirmed in veterinary medicine.Our objective was to compare the duration and morphology of canine and human spikes. Methods: Archived cases meeting our inclusion criteria were retrieved from three institutions (Figure 1). Visual inspection selected those spikes with clear negative deflections from, and returns to, baseline. Combined ictal and interictal spike duration and morphology were compared between the two species. Spike durations were measured using a linear regression equation and curve of best fit (Figure 2), and the FHS to SHS duration ratios ascertained. Results: Seventeen canines and nine humans were included. Average canine spike duration was 37.21ms with confidence interval (CI): 30.83-44.91ms, and averaged case values ranged 17.46-83.09ms. Human spike duration average was 100.21ms (CI: 77.39-129.76ms), and case averages ranged 61.56-194.42ms. Human and canine mean spike durations were significantly different (p<0.0001). Canine (c) and human (h) spike morphology means were FHSc =17.4ms (CI: 13.97-21.69ms), FHSh=37.9ms (CI: 28.03-51.27ms), SHSc=18.99ms (CI: 15.81-22.81ms), SHSh=61.13ms (CI: 47.52-78.63ms). Tukey pairwise comparison: FHSc:SHSc (p=0.172, post-hoc, p=0.506), p<0.0001 for FHSh:SHSh, FHSc:FHSh and SHSc:SHSh. Conclusions: Canine spikes showed significantly different duration and morphology from human spikes, appearing faster and more symmetric. Notably, visual selection of human spikes found few with duration less than 70ms. Thus, algorithms for human seizure (spike) detection and analysis used in canine EEG need validation. This canine spike morphology clarification will improve confidence in accurate spike detection and contribute towards validation of this translational model for human epilepsy research. Funding: University of Guelph Undergraduate Research Assistantship.