Maziar Azar - MD. Professor of Neurosurgery, Skull Base Research Center, Iran University of Medical Sciences, Tehran, Iran
Farid Kazemi - MD. Associate Professor of Neurosurgery, Skull Base Research Center, Iran University of Medical Sciences, Tehran, Iran
Amin Jahanbakhshi - Assistant Professor of Neurosurgery, Skull Base Research Center, Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
Maryam Jalessi - MD. Associate Professor of Otolaryngology- Head and Neck Surgery, Skull Base Research Center, Iran University of Medical Sciences, Tehran, Iran
Elahe Amini - MD. Research assistant, ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences , Tehran, Iran
Foad Kazemi - MD. Neurosurgeon, Skull Base Research Center, Iran University of Medical Sciences, Tehran, Iran
Feyzollah Ebrahimnia - MD. Neurosurgeon, Skull Base Research Center, Iran University of Medical Sciences, Tehran, Iran
Hessam Rahatlou - MD. Skull Base Research Center, Iran University of Medical Sciences, Tehran, Iran

Background & Aim: The treatment of Parasagittal Meningioma (PSM) is always a challenge, especially when the tumor has already invaded the critical structures like venous sinuses. This study aims at evaluating the outcomes of Gamma Knife Radiosurgery (GKRS) in patients with PSM. Methods and Materials/Patients: In this descriptive retrospective study, we reviewed the medical records of 61 patients with PSM, who had undergone GKRS from 2003 to 2013. We reviewed their demographic characteristics, medical history, radiotherapy history, tumor volume, and the characteristics of radiosurgery. We also evaluated radiological tumor control following the treatment during the follow-up period. Results: In this study, 32(52.5%) patients were men, and 29(47.5%) were women. Of 61 patients, 45 had a history of operation or and radiotherapy. Their Mean±SD tumor volume was 11.35±9.20 mL (range: 1-37.9mL). The Mean±SD follow-up time was 30.28±27.48 months, and during this time, five patients died. Radiologic tumor control was achieved in (91.8%) of the patients, in whom the tumor volume decreased in 30(49.2%) patients and remained unchanged in 26(42.6%) ones. The tumor volume increased in five (8.2%) patients. Overall, the progression-free survival of the patients was (98.6%) during 12 months, and their Mean±SD percentage was 67.04±13.4% during 60 months. The edema incidence rate was (18%). There was no significant difference in GKRS characteristics, tumor volume, the history of operation, and radiotherapy among the patients, whose tumors were controlled and the patients, who experienced an increase in the tumor volume. Conclusion: Our study suggests that GKRS can be the first or second choice of treatment to control PSM. There was no association between the treatment outcome, tumor characteristics, and radiosurgery parameters. As radiosurgery management in PSMs has some limitations, a long-term follow-up is recommended to diagnose life-threatening complications, including brain edema.

Radiosurgery, Parasagittal, meningioma, Superior sagittal sinus, Treatment outcome, Cerebral edema