Abstract Disclosure: S. Fujio: None. R. Makino: None. J. Sugata: None. T. Hanada: None. R. Hanaya: None. Introduction: In Japan, the restriction on the administration of somapacitan, a long-acting growth hormone (GH) analogue, was lifted in December 2022, allowing the drug to be administered to many patients with severe growth hormone deficiency (sGHD). [Patients and methods] We have 10 patients for whom somapacitan was started as a new drug regime and 26 patients who switched from their daily GH replacement therapy. Among these 36 patients, 21 patients (5 new cases and 16 switched cases) who were followed for more than 6 months after the start of treatment were included in the present study. We compared lipid metabolism, glucose tolerance, liver function, and quality-of-life before and after treatment with somapacitan. [Result] The study population included 12 men and 9 women with a median age of 65 years. Cases included 15 NF-PitNET, 2 Lactotroph PitNET, 2 germ cell tumor, 1 craniopharyngioma, and 1 granuloma. Starting doses of somapacitan were 1.5 mg/week for adults to 60 years of age and 1.0 mg/week for patients aged >60 years. In the switched cases, the median levels of T-chol dropped from 214.5 to 198.5 mg (p<0.05). The median levels of HbA1c dropped from 5.9 to 5.8% (p<0.05). In the newly prescribed cases, the median levels of γ-GTP dramatically improved from 53 to 34I U/L, but this was not statistically significant. In the newly prescribed cases, quality-of-life assessment by Adult Hypopituitarism Questionnaire; AHQ showed improvement in both psychological/social aspects and physical function, but the number of cases was small and no significant difference was obtained. Body fat percentage measured by the impedance method showed no significant change in either the switched or newly prescribed groups. There were no adverse events, but some participants commented that it was easier to forget weekly injections of somapacitan than the daily GH. [Discussion] We were able to introduce somapacitan without any major problems. In newly prescribed cases, somapacitan resulted in a significant improvement in liver function. Improvements in lipid metabolism and glucose tolerance were observed in the switched patients. Compared to the daily GH replacement therapy, somapacitan may have a higher GH replacement effect. Presentation: 6/3/2024

Abstract Disclosure: J. Sugata: None. S. Fujio: None. R. Makino: None. T. Hanada: None. R. Hanaya: None. Background: Patients undergoing surgical treatment for nonfunctioning pituitary neuroendocrine tumors (PitNET) may experience impaired secretion of growth hormone (GH). The optimal timing for assessing GH secretory function postoperatively remains unclear. In our department, we typically conduct hormone-loading tests three months after surgery. However, even in some cases without a diagnosis of growth hormone deficiency (GHD) at that point, there might be a gradual decline in Insulin-like growth factor-1 (IGF-1). Methods: We studied patients who exhibited peak GH levels > 1.8ng/ml in an insulin tolerance test (ITT) three months after undergoing surgery for nonfunctioning PitNET. We evaluated the levels of IGF-1 during the last observation, excluding cases where reoperation or radiosurgery was performed. Results: We identified 67 cases (29 males, 38 females) meeting the study criteria, with a median age of 54 years. The median follow-up time spanned 6 years (range 1-13 years). The median standard deviation (SD) scores of IGF-1 three months after surgery were -0.96, with 14 cases (21%) below -2.0 SD. At the end of the follow-up period, the median SD scores of IGF-1 were -1.31. This was significantly lower than the three-month time point (p<0.01), and 21 cases (31%) recorded were below -2.0 SD. In 6 cases suspected of severe GHD due to subjective symptoms or decreased IGF-1, ITT, or GH-releasing peptide-2 were retested. Among these, 2 cases were diagnosed with severe GHD, while the remaining demonstrated normal secretion of GH despite the low concentration of IGF-1. The IGF-1 SD scores at the end of follow-up and the three-month time-point exhibited a significant correlation (R2=0.74, p<0.01). However, no correlation was found between IGF-1 scores and peak GH concentration, age, tumor size, pituitary apoplexy, or preoperative IGF-1 SD scores. Conclusions: IGF-1 exhibited a progressive decrease in the majority of cases without severe GHD, with some cases showing reductions greater than -2.0 SD. Our findings emphasize the importance of cases with long-term clinical follow-up low IGF-1 after PitNET surgery, even when GH secretion appears normal. Presentation: 6/1/2024

BACKGROUND:Although the anatomy of the Sylvian fissure is understood, there is little information on where to start its dissection in the pterional transsylvian (PT-TS) approach. At small craniotomy using the PT-TS approach, we set the entry point to the Sylvian fissure at 15 mm behind the anterior edge of the craniotomy along the Sylvian fissure and designated this site "point 15." Here we compared the utility of "point 15" with the Sylvian point (point on the Sylvian fissure giving rise to the horizontal and anterior ascending rami) that had been recommended earlier as the entry site for opening the Sylvian fissure. MATERIALS AND METHODS:This study includes 16 patients with 7 ruptured and 9 unruptured anterior circulation aneurysms. We evaluated the usefulness of "point 15" in the PT-TS approach for aneurysmal neck clipping with respect to the adequacy of anatomical exposure and low invasiveness. RESULTS:In 12 patients "point 15" provided for excellent anatomical exposure of the Sylvian fissure; complete neck clipping was possible with minimal brain retraction and damage. In two patients with ruptured aneurysms and thick subarachnoid hemorrhage and in two patients with unruptured aneurysms, the dissection had to be enlarged 3 to 4 mm distally without reaching the Sylvian point. In the latter two patients the Sylvian veins were tethered to frontal and temporal lobes. CONCLUSIONS:The "point 15" was an easily set entry point to the Sylvian fissure. It provided for sufficient anatomical exposure at surgery for anterior circulation aneurysms; additional posterior dissection was required in rare cases. We found that "point 15" was useful in small craniotomies using the PT-TS approach.