Pituitary Deformation in High Altitude Immigrants and the Correlation with Headache：A Preliminary Study.

Abstract Aim: To investigate pituitary gland deformation (PGD) in high altitude (HA) immigrants and determine if a correlation exists between PGD with headache and the ratio of brain volume to total intracranial volume (BV/TIV), and to investigate whether PGD can be used as an objective indicator of headache in HA immigrants.Methods: A total of 34 male HA immigrants and 60 age- and gender-matched sea-level (SL) residents were enrolled in this study. 3D T1 weighted brain MRI scans and headache scales were acquired. HA participants were classified into headache positive (HA[+]) and headache negative (HA[-]) subgroups. PGD was graded visually on mid-sagittal images of the pituitary gland. All continuous variables and categorical variables were compared using Student's t-test or Mann-Whitney test and the χ2 or Fisher exact tests, respectively. Kendall's tau rank correlation coefficient and Spearman’s rho were used to investigate the relationship between PGD and headache or BV/TIV, respectively. Receiver operating characteristic (ROC) analysis was used to evaluate whether PGD can be used as an objective indicator of headache in HA immigrants.Results: A higher proportion of HA participants had PGD (54.8%) than SL residents (23.3%) (p=0.005). The proportion of HA(-) participants with PGD (68.2%) was higher than that of HA(+) participants (22.2%) (p=0.044). PGD was negatively correlated with headache (Kendall's tau=-0.323, p=0.0097) and positively correlated with BV/TIV (r=0.454, p=0.010). The presence of PGD was an indicator of headache in HA immigrants (area under the ROC curve=0.712, p= 0.038, sensitivity=0.778, specificity=0.682). Conclusion: A greater proportion of HA immigrants had PGD, which is an adaptation to chronically altered ICP or compliance. The presence of PGD indicated a restoration of spatial compensatory capacity and compliance of intracranial system, leading to headache relief. PGD is a potential indicator of headache in HA immigrants.