PMON330 The Relationship between Pituitary Volume and Chiari Malformation in Growth Hormone Deficiency and Idiopathic Short Stature

Patients with a small posterior cranial fossa may present with cerebellar tonsillar herniation through the foramen magnum, known as Chiari malformation (CM). The relationship between CM, pituitary volume (PV), and growth hormone deficiency (GHD) has not yet been explored and is the subject of this abstract. This study seeks to compare the differences in PV in short patients with CM with a diagnosis of either GHD or idiopathic short stature (ISS), to normal controls (NCs). The database of a Peds Endo Center between 2013-21 was queried for patients with CM and who had undergone MRI evaluation. Patients were separated into 4 groups: CM and GHD, CM and ISS, GHD without CM, and ISS without CM. These groups’ PV results were compared with NCs who we previously reported. The ages of short patients with CM (n=29) were compared to the ages of NCs (n=170); no significant difference was found (p = 0.12). The MN and MD PV for patients with GHD alone were 230.8 ± 89.64 and 217.62mm3, respectively. The MN and MD PV for patients with GHD and CM (n=23) were 246.55 ± 128.0 and 200.5mm3, respectively. The MN and MD PV for CM and ISS (n=6) were 671.54 ± 350.25 and 619.55mm3, respectively. The MN and MD PV for NCs were 364.0 ± 145.2 and 346.0mm3, respectively. The PV of patients with GHD alone were compared to the PV of patients with both GHD and CM; there was no significant difference found (p=1.0). Next, the PV of patients with GHD alone were compared to the PV of patients with both ISS and CM which showed that patients with GHD alone had significantly smaller PV compared to patients with both ISS and CM (p<0.05). Lastly, we compared the PV of patients with both GHD and CM versus patients with both ISS and CM, which showed that patients with both GHD and CM had significantly smaller PVs compared to patients with both ISS and CM (p<0.05). The PV of short patients with CM (n=29) were compared to the PV of NCs (n=170) and there was no significant difference found (p = 0.58). Our study demonstrates that PV is smaller in patients with GHD regardless of whether they have CM or not. We speculate that CM appears to be a radiological finding with no significant impact on PV, whereas GHD appears to have a significant impact on PV. Therefore we speculate the small PV exhibited in patients with CM and GHD appear to be related to GHD. A larger sample size will be needed to further elaborate on this concept. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.