But what causes this randomization? The lesions in TLE patients result in cell loss, which might cause a reduction of the number of connected edges [38], as has been described in brain tumor patients [19]. Apart from cell loss, mossy fiber sprouting is a hallmark of seizure-induced sclerosis in TLE. Dyhrfjeld-Johnsen and others used a model with cell loss and sprouting to simulate network changes in TLE patients [39]. The value of L/Lrandom = 1,19 found in the Dyhrfjeld-Johnsen study at baseline (without a sclerotic process) was the same as the average path length found in our study. When looking at progression of sclerosis, we see that one of their simulation models, based on mossy fiber sprouting, also has a pattern similar to ours. In this model, L/Lrandom remains stable while C/Crandom becomes more random with increasing sclerosis. Mossy fiber sprouting might therefore explain our findings of a more random network with increased epilepsy duration.
