The International Stereotactic Radiosurgery Society (ISRS) is a global community of professionals dedicated to Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). The CNS Summit is a newly organized event by ISRS, focusing on central nervous system conditions such as spinal and skull base radiosurgery.

As we delve into the findings presented at the ISRS CNS Summit 2025, we encounter a wealth of valuable research that sheds light on the efficacy of the CyberKnife® System in the realm of stereotactic radiosurgery. Below are summarized studies that explore its impact across various conditions:

Medically Refractory Trigeminal Neuralgia

Trigeminal neuralgia (TN) presents a therapeutic challenge when medication fails. Radiosurgery with the CyberKnife System and the Gamma Knife are widely used to treat TN, but comparative studies of their effectiveness and safety are limited. An analysis of 117 patients (57 with Gamma Knife and 60 with the CyberKnife System) treated between 2007–2024 found that Gamma Knife provided faster and higher rates of pain relief at 6 months (76,9% vs 70%, p=0.04), while the CyberKnife System had a much lower recurrence rate at 2 years follow-up (Gamma Knife 34,7% vs. CyberKnife System 15,6%).

Both modalities demonstrated their strengths, however the author emphasizes that further dosimetric analysis is essential to refine understanding, strengths and limitations of each approach. The study demonstrates that stereotactic radiosurgery is a versatile and effective treatment in the management of trigeminal neuralgia.1

Optic Nerve Sheath Meningiomas

Optic nerve sheath meningioma is a rare tumor of predominantly adult age patients, including those with II neurofibromatosis, accompanied by decreased visual function and exophthalmos. Treatment options include dynamic observation, surgery, radiation therapy or a combination of these methods. Radiation therapy can be recommended for patients with intact visual functions, no severe exophthalmos and trophic eye lesions.

In this study 18 patients with optic nerve sheath meningiomas underwent hypofractionated radiosurgery on the CyberKnife System or Novalis between 2010 and 2020, with a total dose of 27.5 Gy delivered in 5 fractions. The median tumor volume was 1.5cm3, and patients had a median follow-up of 57 months. Tumor growth control was achieved in all patients, with partial responses observed in 27.8% of patients. Improvements in visual acuity, visual fields, and exophthalmos were noted without any deterioration in visual function. The findings suggest that hypofractionated radiosurgery is a safe and effective treatment option for this condition.2

Benign Vascular Tumors

Glomus tumors are benign vascular tumors originating from neuroectodermal tissues, commonly diagnosed between the fifth and sixth decade of life, occurring predominantly in women. From January 2003 to December 2023, 51 patients with tympanojugular glomangioma were treated with the CyberKnife System, with most patients receiving three fractions or a single session. The average lesion volume treated was 4457 mm³, and follow-up ranged from 5 to 150 months. Authors found of the observed 43 patients, 63% achieved disease stabilization with a single treatment, while 23% experienced dimensional regression. Nineteen patients showed a clear regression of initial symptoms.3

Radiosurgery for Skull Base Meningiomas

A retrospective study evaluated the efficacy and tolerance of radiosurgery with the CyberKnife System for treating skull base meningiomas in 30 patients between March 2020 and February 2024. The study involved both single and hypofractionated dosing schemes, with the majority of patients achieving radiological stability and experiencing minimal acute and chronic toxicity. The most common locations treated included the pontocerebellar angle, cavernous sinus, and optic nerve. The authors found results indicated that radiosurgery with the CyberKnife System is safe, effective, and beneficial for patients who are rarely suitable for complete surgical resection.4