Hypothalamic obesity following craniopharyngioma surgery: What is the role of hypothalamic T2 signal changes in brain MRI?

Abstract Background Despite hypothalamus-sparing surgical techniques, hypothalamic obesity remains common in childhood craniopharyngioma (cCP) survivors. Emerging evidence suggests a role for hypothalamic inflammation (HI) in obesity development. This study aimed to quantitatively assess post-operative T2 signal intensity (SI) changes, suggestive of inflammation and edema, using MRI and investigate its association with clinical outcomes, including BMI changes, over a 1-year period. Methods We retrospectively analyzed 2 cCP cohorts. Diagnostic and post-operative MRIs were evaluated for changes in hypothalamic T2 SI on FLAIR. We assessed clinical and radiological predictors of post-operative T2 SI and examined correlations between ΔT2SI and ΔBMI z-score from pre-operative to 3 months after surgery. A multivariable model was used to evaluate factors influencing BMI z-score change. In a subgroup (n = 40), we compared post-operative T2 SI between patients with and without hypothalamic syndrome at 6 months. Results Both left (P < .001) and right (P < .05) hypothalamic T2 SI increased post-operatively. Higher post-operative T2 SI was associated with increased pre-operative T2 SI, age, less cystic tumors, and higher post-operative Müller grades. ΔT2SI correlated with ΔBMI z-score at 3 months (r = 0.56, 95% CI: 0.29-0.74). ΔT2SI (left) was significantly associated with ΔBMI z-score (β = 1.02, SE = 0.35) after adjusting for baseline variables. Patients with hypothalamic syndrome (n = 17) had higher post-operative T2 SI than those without (n = 23, P < .01). Conclusion Our data suggest that hypothalamic T2 SI increase is associated with the BMI increase and hypothalamic dysfunction after cCP surgery. These insights enhance our understanding of the pathophysiology underlying post-operative hypothalamic obesity and may inform future preventive and therapeutic strategies.