ESPE Abstracts

Background/Aim: Sex hormones drive organizational and activational changes in craniofacial structures and various regions of the brain and establish a sexual dimorphism in the re-shaping of the brain and related structures during puberty. Although the evolutionary approach, which accepts the brain and related structures as secondary sex characteristics since they are target organs for sexual selection, increases awareness of the role of sex hormones in sex-specific brain development during the pubertal period, further research is required to improve our understanding of the subject. This study focused on dimensional changes of craniofacial and various structures of the brain in girls with precocious puberty (PP) characterized by the early onset of pubertal development.

Materials and Methods: The study included a total of 120 participants, 87 PP and 37 healthy girls, aged 6-8 years. In all the participants, following variables were measured: craniofacial structures including nasal bone length, anterior nasal spine, transfer nasal diameter, biparietal distance, bitemporal diameter, intermaxillary diameter, head circumference, and limbic structures including inter-uncal distance, pituitary height, right and left hippocampal dimensions using magnetic resonance imaging (MRI). Basal estradiol (E2), basal/stimulated luteinizing hormone (LH), follicle-stimulating hormone (FSH) values, uterus length, and ovarian volumes were evaluated in the girls with PP.

Results: When compared the measurements in the PP and healthy girls, there were significant differences following variables: nasal bone length, nasal transfer diameter, biparietal diameter, pituitary height, transverse and craniocaudal distances for right hippocampus, craniocaudal distance for left hippocampus(<0.001, 0.001, 0.007, 0.013, 0.029, <0.001, <0.001, respectively). In girls with PP, there was no correlation of measurement of the craniofacial/limbic structures with following variables: basal E2 and basal/stimulated LH and FSH, while moderate correlation was found between uterine and nasal bone lengths(r = 432). While moderate and/or strong correlations were found between most of the craniofacial and limbic structures with each other in healthy children, most of these correlations were not found in girls with PP.

Conclusion: This study demonstrated that dimensional changes occur in various structures, including the craniofacial and limbic system in girls with PP, pointing to dimensional changes of potential craniofacial/limbic structures as surrogate markers for regions where functional changes occur in the brain. It also showed that there is no significant relationship between craniofacial/limbic and reproductive structures/dimensional measurements of sex hormones, indicating that further studies are needed to elucidate the relationship between pubertal physical changes and brain development.