Investigation of hippocampal and subfield volumes in migraine patients without aura

In this study, we aimed to examine the volumes of the hippocampus and its subfields in patients with migraine without aura and to evaluate potential structural changes associated with migraine. The study included 125 migraine patients (mean age: 32.86±10.25 years; 63 females, 62 males) and 125 healthy controls (mean age: 33.71±10.95 years; 64 females, 61 males), matched for age and sex. T1-weighted magnetic resonance images of all participants were analyzed using the open-access VolBrain software, and hippocampal segmentation was performed based on the Winterburn atlas. The results revealed that the right (migraine: 2.35±0.298 cm³; control: 2.26±0.354 cm³; p=0.03) and left (migraine: 2.27±0.285 cm³; control: 2.19±0.353 cm³; p=0.05) hippocampal volumes were significantly larger in the migraine group compared to the healthy controls. In the evaluation of subfields, the volumes of right CA4-GD (Cornu Ammonis 4–Gyrus Dentatus), SR-SL-SM (Stratum Radiatum–Stratum Lacunosum–Stratum Moleculare), and subiculum were found to be significantly higher in the migraine group (0.58±0.08; 0.43±0.06; 0.26±0.04) than in the control group (0.55±0.10; 0.41±0.07; 0.24±0.05) (p<0.05). On the left side, the subiculum volume was also significantly larger in the migraine group (0.28±0.04) compared to controls (0.26±0.05) (p<0.001). In sex-based analyses, male migraine patients showed significantly larger volumes in the right hippocampus (2.46±0.29), CA4-GD (0.60±0.09), SR-SL-SM (0.45±0.06), and subiculum (0.27±0.04) compared to male controls (2.33±0.40; 0.56±0.12; 0.43±0.08; 0.24±0.05), whereas in females, only the left subiculum was significantly larger in the migraine group (0.27±0.04) than in controls (0.29±0.04) (p<0.05). When evaluating the relationship between headache frequency/duration and hippocampal volumes, significant differences were observed in the volumes of the left hippocampus, left CA1, and left SR-SL-SM regions as headache frequency increased (p<0.05). Additionally, in terms of headache duration, a significant difference was detected only in the asymmetry index of the right CA4-GD subfield (p=0.01). These findings suggest that the duration of migraine pain may lead to structural changes in the hippocampus and its subfields. In conclusion, significant structural differences were identified in the hippocampus and its subfields in migraine patients compared to healthy individuals. These differences were more pronounced in male migraine patients and appeared to be associated with headache frequency. Our findings indicate that the hippocampus may play a role in the neuroanatomical processes of migraine and highlight the need for a more detailed investigation of this region in future studies. We believe our results will contribute to the growing body of literature on the neuroanatomical basis of migraine.