Abstract
BackgroundHippocampal necrosis in cats has been reported to be associated with epileptic seizures. Magnetic resonance imaging (MRI) features of temporal lobe (TL) abnormalities in epileptic cats have been described but MR images from epileptic and non-epileptic individuals have not yet been systematically compared. TL abnormalities are highly variable in shape, size and signal, and therefore may lead to varying evaluations by different specialists. The aim of this study was to investigate whether there were differences in the appearance of the TL between epileptic and non-epileptic cats, and whether there were any relationships between TL abnormalities and seizure semiologies or other clinical findings. We also investigated interobserver agreement among three specialists.MethodsThe MR images of 46 cats were reviewed independently by three observers, who were blinded to patient data, examination findings and the review of the other observers. Images were evaluated using a multiparametric scoring system developed for this study. Mann–Whitney U-tests and chi-square were used to analyse the differences between observers’ evaluations. The kappa coefficient (k) and Fleiss’ kappa coefficient were used to quantify interobserver agreement.ResultsThe overall interobserver agreement was moderate to good (k =0.405 to 0.615). The MR scores between epileptic and non-epileptic cats did not differ significantly. However, there was a significant difference between the MR scores of epileptic cats with and without orofacial involvement according to all three observers. Likewise, MR scores of cats with cluster seizures were higher than those of cats without clusters.ConclusionCats presenting with recurrent epileptic seizures with orofacial involvement are more likely to have hippocampal pathologies, which suggests that TL abnormalities are not merely unspecific epileptic findings, but are associated with a certain type of epilepsy. TL signal alterations are more likely to be detected on FLAIR sequences. In contrast to severe changes in the TL which were described similarly among specialists, mild TL abnormalities may be difficult to interpret, thus leading to different assessments among observers.
Highlights
Hippocampal necrosis in cats has been reported to be associated with epileptic seizures
Over the past two decades, several case reports on feline hippocampal necrosis (HN) have been published in Europe, Asia, and the United States [1,2,3,4,5,6,7,8,9], indicating that necrosis of the hippocampus and piriform lobe associated with the appearance of epileptic seizures in feline patients is a worldwide phenomenon
Temporal lobe epilepsy with hippocampal sclerosis is well researched in human medicine, and there is strong evidence that temporal lobe epilepsy (TLE) with HS may be common in cats
Summary
Hippocampal necrosis in cats has been reported to be associated with epileptic seizures. There has not been a systematic comparison of MR images of TLs in healthy and epileptic cats, and little is known about the accuracy of this diagnostic modality or the potential subjectivity of the observers’ assessments It remains unclear whether changes in the hippocampal size and signal are always associated with the occurrence of epileptic seizures or whether they can be present in nonepileptic patients. The aims of this retrospective, multi-observer study were to examine whether there was a difference in the TL signal between epileptic and non-epileptic cats and whether an abnormal MR signal was related to seizure semiology or other clinical findings in epileptic patients. We expected good agreement among specialists in identifying signal alterations, and that fluid-attenuated inversion recovery (FLAIR) sequences would be superior to other MR sequences in detecting variations in TL signal intensity
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