Stereotactic Radiosurgery — Procedure Guide, Recovery & Risks | MyMedicPlus

Stereotactic radiosurgery (SRS) is a non-invasive procedure that delivers a single large radiation dose (12-24 Gy) precisely to an intracranial target using convergent beams, exploiting steep dose fall-off to spare surrounding tissue. Platforms include Gamma Knife (201 cobalt-60 sources), CyberKnife (robotic LINAC), and dedicated LINAC (HyperArc, Trilogy).

Primary indications: brain metastases (1-4 lesions, each below 3 cm), acoustic neuroma (vestibular schwannoma), meningioma, trigeminal neuralgia (70-90 Gy to the nerve root), cerebral arteriovenous malformations (AVM), and selected pituitary adenomas not cured by surgery or medication.

A stereotactic head frame is applied under local anaesthesia (Gamma Knife) or a frameless thermoplastic mask is fitted. High-resolution MRI and CT are acquired and co-registered for target delineation. The radiation oncologist and neurosurgeon plan the dose prescription; 201 cobalt sources converge simultaneously (Gamma Knife) or the robotic arm circles the head (CyberKnife). Treatment takes 20-90 minutes.

Outpatient procedure; patients go home the same day. Mild headache, scalp tenderness, and fatigue are common for 24-48 hours; managed with paracetamol and short-course dexamethasone. No activity restriction post-treatment. AVM obliteration is confirmed at 2-3 years by MRI or angiography. Tumor response is assessed by MRI at 3 months and 6-monthly thereafter.

Radiation necrosis occurs in 5-10% of patients at 1-2 years and may mimic recurrence on MRI; managed with dexamethasone, bevacizumab, or surgical resection. Transient brain edema is common in larger lesions. Cranial nerve injury risk for skull base tumors (2-5%). Alopecia at entry points (Gamma Knife). Re-treatment is limited by cumulative dose constraints.

Brain metastasis local control is 85-95% at 12 months with SRS, equivalent to whole-brain radiotherapy but preserving neurocognition. AVM obliteration is achieved in 70-80% at 3 years for lesions below 3 cm. Acoustic neuroma tumor control exceeds 95% at 5 years. Trigeminal neuralgia pain relief is achieved in 70-80% of patients within 6 months.