Structural MRI Differences in the Thalamus, Caudate Nucleus, and Interthalamic Adhesion in Dogs with Idiopathic Epilepsy

Structural changes in the thalamus and basal nuclei (BN) have been documented in magnetic resonance imaging (MRI) studies of human epilepsy. Studies that specifically investigate whether equivalent structural changes exist in dogs with idiopathic epilepsy (IE) are limited. This retrospective study evaluated the morphology of the caudate nucleus and thalamus in dogs with IE (n = 40) compared to a control group (n = 38) using standard MRI studies. Measurements of the interthalamic adhesion (ITA) thickness and area, thalamic area and volume, and caudate nucleus area and volume were made to compare the size and symmetry of these structures between groups. Dogs with IE had a significantly larger ITA thickness (p < 0.0001) and area (p < 0.0001), smaller thalamic area (p < 0.0001) and volume (p < 0.0001), and smaller caudate nucleus volume (p = 0.0126) than controls. There were no significant differences in caudate nucleus area (p = 0.171) and asymmetry index for both thalamus (p = 0.104) and caudate nucleus (p = 0.853) between groups. Our findings indicate that a smaller thalamic and caudate nucleus size is associated with canine IE. However, further research is necessary to determine whether these findings can be generalized to other BN and to investigate the involvement of thalamocortical or BN-thalamocortical circuits in the pathophysiology of IE.