Atrophy of the pedunculopontine nucleus region in patients with sleep‐predominant seizures: A voxel‐based morphometry study

Summary Non–rapid eye movement (NREM) sleep increases interictal epileptiform discharges and frequency of seizures, whereas REM sleep suppresses them. The pedunculopontine nucleus (PPN), one of the REM sleep–modulating structures, is postulated to have a potent antiepileptogenic role. We asked if patients with sleep‐predominant seizures (SPS) show volume changes in the region of the PPN compared to those with seizures occurring during awake state only (nSPS). The volume of the PPN region was assessed in patients with SPS, those with nSPS, and healthy volunteers, through voxel‐based morphometry and automated, nonbiased region of interest (ROI) analysis of T1 magnetic resonance (MR) images. The volume of PPN region was statistically smaller in patients with SPS (n = 33) than in those with nSPS (n = 40) and healthy controls (n = 30) after controlling for covariates. These results suggest that a structural change in the PPN may be associated with sleep‐predominant timing of seizure occurrence. Our findings might help understand the intervening pathomechanism that lies between the human sleep–wake cycle and epilepsy.