Abstract
BACKGROUND: Stereotactic radiosurgery (SRS) is a well-established option for the management of intracranial tumors, including meningiomas. Although valued for its low invasiveness and precision, it still carries a risk of complications. Communicating hydrocephalus is a serious, albeit rarely reported, complication of SRS. Here, the authors report two cases of communicating hydrocephalus following Gamma Knife radiosurgery (GKRS) for periventricular meningiomas. OBSERVATIONS: In both reported cases, the patients experienced a sudden deterioration in their clinical condition a few months after the second GKRS for recurrent periventricular World Health Organization grade II atypical meningiomas. The patients underwent ventriculoperitoneal shunt implantation, and cerebrospinal fluid (CSF) samples revealed elevated levels of total protein and albumin. Additionally, both patients underwent multiple resections before radiation, and some of their lesions were located near the venous sinuses. LESSONS: Though rare, communicating hydrocephalus represents a significant potential sequela of SRS for meningiomas that clinicians should be aware of. Factors such as tumor volume and location, histology, and previous irradiation or surgery can exacerbate radiation-induced damage and collectively underlie the development of hydrocephalus. The authors also speculate that the CSF protein levels can serve as a unifying marker of SRS-induced radiation damage in the form of radiation-associated tumor necrosis, radiation-induced hyperpermeability, and inflammatory response. https://thejns.org/doi/10.3171/CASE24722.