Temporal lobe epilepsy (TLE) is a specific form of epilepsy that has specific pathology. As you might imagine, the pathology is found in the temporal lobe and consists of given cellular degeneration, loss of neurons and sprouting of mossy fibers (what a great term for a fiber). Clinically, TLE often shows facial automatisms (focal seizures) and is commonly drug resistant. As a result, patients with TLE may under go radiation or surgical intervention to manage their epilepsy. A group from the University of Wisconsin Neurology service recently investigated a cohort of 7 dogs with clinical seizures suggestive of TLE to determine if the same pathology was represented in dogs.
Materials and Methods
Seven dogs with focal facial seizures who were euthanized due to progressive disease were included.
Key neuropathologic findings
· No significant hilar neuron loss was identified in any dog. Cell counts fell within a relatively narrow range, and no hippocampus showed neuron numbers >2 SD below the group mean.
· No hippocampal asymmetry was detected in neuronal counts between left and right hippocampi.
· Mossy fiber sprouting was mild in all dogs (median score ~1.1/5), with no cases showing extensive sprouting typical of TLE.
· No asymmetry in mossy fiber sprouting was found between hippocampi.
· Overall, none of the dogs met human neuropathologic criteria for TLE, despite having focal seizure semiology.
What does this mean?
These findings indicate that focal seizures in dogs with idiopathic epilepsy are not necessarily associated with TLE-like hippocampal pathology, contrasting with humans. The mild hippocampal changes observed may reflect seizure-related or age-related alterations rather than a distinct epileptogenic lesion. Importantly, previously reported MRI hippocampal asymmetry in some epileptic dogs may be a consequence of focal seizure activity, not evidence of true TLE. This data does not support pursuit of radiation therapy or surgery in dogs with resistant epilepsy, however there may be specific individual differences that warrant considering these treatments on a case-by-case basis.
I thought this article was worth discussing even though the results were negative. Maybe because the results were negative? We always think we could or should be doing more for some pets who are suffering from refractory seizures – and we should keep trying – but this study did not support similarities between human TLE and canine focal seizures. Therefore, without similar pathology, we cannot pursue similar treatments.
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Reference: https://avmajournals.avma.org/view/journals/ajvr/aop/ajvr.25.07.0260/ajvr.25.07.0260.xml