Detection of suprasellar subarachnoid hemorrhage using intraoperative magnetic resonance imaging during endoscopic transsphenoidal resection of pituitary neuroendocrine tumors.

Background: Endoscopic transsphenoidal surgery (ETSS) is considered safe for the treatment of pituitary neuroendocrine tumors (PitNETs). Postoperative subarachnoid hemorrhage (SAH) is extremely rare in patients with PitNET, and information regarding the source of hemorrhage in such cases is limited. Case Description: Herein, we report the cases of a 59-year-old man and a 49-year-old woman who underwent ETSS for nonfunctioning PitNETs. Gentle subcapsular removal was performed, and no cerebrospinal fluid leakage was observed during the procedure. We routinely perform intraoperative magnetic resonance imaging (iMRI) to confirm the presence of residual tumors. In the former case, conservative treatment was selected because minimal bleeding was observed in iMRI. In the latter case, obvious arterial bleeding was observed beyond the diaphragmatic sellae before iMRI, prompting the selection of an extended transsphenoidal approach to identify the bleeding site. In both cases, iMRI revealed an SAH localized between the optic chiasm and diaphragmatic sellae adjacent to the pituitary stalk. Combined with intraoperative findings, the superior hypophyseal artery was considered the bleeding source in both cases. Hemostasis was achieved in both cases without the need for hemostatic procedures. Conclusion: SAH associated with ETSS is rare, and the source of the hemorrhage is sometimes undetectable on postoperative imaging. Herein, iMRI was useful for identifying the source and extent of the hemorrhages, allowing observation of the patients without additional intervention.