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

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.