P 63 Does the Anna Karenina principle apply to vestibular migraine and Meniere's disease?

Introduction: To date it is unclear how Meniere’s disease (MD) and vestibular migraine (VM), which often appear in clinically similar attacks, differ from healthy controls (HC) in functional brain connectivity (measured by fcMRI), especially during the interictal phase. The central functional connectivity feature of VM and MD might be “disorganization” relative to HC, due to unpredictable attacks that cannot be compensated for. This “Anna Karenina principle” states that all HCs are very alike while all patients are very dissimilar from each other and the HCs. Here we examined the distribution parameters of functional connectivity between HC, VM and MD to elucidate the state of disorganization in the interictal phase. Methods: 93 patients (42 VM, 51 MD) and 50 HCs underwent fMRI while resting in a 3T MRI (Siemens). Resting-state fMRI connectivity measures were extracted via dual regression and normalized in mean and standard deviation relative to HCs. Robust distribution parameters for all voxels in the grey matter were compared between groups. Results: Distribution parameters were compact for HCs, while those of VM and MD patient groups were significantly more dispersed, i.e., disorganized (Figure 1), permutation test with 10000 permutations. In Figure 1 the bulk of values for the HCs were marked by black outline and superimposed onto the values for the MD and VM groups. Conclusion: Resting-state functional connectivity measures imply disorganized interactions between patients relative to HCs, even in the interictal phase. VM and MD patients are very different in functional connectivity, suggesting that the Anna Karenina principle might apply to these patients. References 1) Dieterich et.al. J Neurol (2016); 2) Liu & Xu, Behav Neurol (2016); 3) Tabet & Saliba, J Clin Med Res (2017) Figure 1. Distribution parameters per voxel relative to healthy control (HC) group. Values for healthy controls (HC) were marked with a black line and superimposed on Meniere disease (MD) and vestibular migraine (VM) group data. Color of dots indicates the median relative to the HC group (blue to yellow). The data of the healthy controls was normalized to mean of 0 and standard deviation 1, and these parameters were used to normalize the MD and VM patients, i.e., everything is presented in the scale of the HC group such that parameters can be compared visually.