Stereotactic radiosurgery A non-percutaneous (does not require needle insertion through the skin of the cheek) neurosurgical procedure that involves using a focused beam of ionising radiation to selectively damage the small unmyelinated and small myelinated pain fibres of the trigeminal nerve, while ideally sparing the rest of the nerve fibres. While several technologies purport similar results (CyberKnife® radiosurgery and other LINAC-MLC-based radiosurgery technologies), the predominant and proven technology for this non-invasive neurosurgical technique is the Gamma Knife®.