MON-LB45 Posterior Hypothalamic Involvement on Pre-Operative Magnetic Resonance Imaging as a Predictor for Hypothalamic Obesity in Craniopharyngiomas

Craniopharyngioma (CP) is a rare embryonic tumor of the sellar and parasellar region with benign histology (World Health Organization grade I) thought to arise from embryonic remnants of Rathke’s pouch. Despite its high survival rates, this tumor can lead to severe morbidity secondary to destruction of adjacent structures. Hypothalamus (HT) is a brain region that has a central role in regulating body weight through a complex mechanism involving central and peripheral signaling pathways. Destruction of its distinctive nuclei induces hyperphagia, hyperinsulinemia and weight gain. Seventy-five patients with CP who underwent first surgical resection in a single center by the same neurosurgeon between February 2005 and March 2019 were screened; those who have had prior radiation, were aged below 18 years, or did not have follow up body mass index (BMI) after surgery were excluded. Ultimately, this study included 45 patients with a mean age 50.5 years, 73.3% women. Pre and post-operative MRI were independently reviewed by three neuroradiologists to determine involvement of the hypothalamic regions: anterior, anterior and posterior, or no hypothalamic involvement. Body mass index were recorded pre operatively and subsequently after TSS up to 24 months post operation. Association between hypothalamic region involvement and BMI as well as endocrine function were examined. Posterior hypothalamic involvement seen in pre operative MRI (N=28) was significantly associated with higher BMI at 3-6 month, 7-12 month, and 13-24 month follow up (p < 0.05) in comparison to involvement of anterior hypothalamic alone or no hypothalamic involvement. Similarly, posterior hypothalamic involvement in the pre and post-operative MRI was significantly associated with development of diabetes insipidus (DI) (p < 0.05) compared to anterior or no hypothalamic involvement. There was no association between pre-operative BMI and hypothalamic involvement. Although the weight gain was accelerated after surgery, there was no association between post operative MRI and ensuing BMI, suggesting that the damage of the hypothalamic nuclei was done by the CP rather than surgical procedure. Conclusion: Assessment of hypothalamic involvement by anterior and posterior regions on pre operative MRI can be helpful in predicting development of obesity in patients with CP.