Gamma Knife Neurosurgery – a Review

Gamma Knife radiosurgery has an established therapeutic role in neurosurgery with around 250,000 cases treated and a follow up over 20 years. The success and control rates have improved as more experience of appropriate dosage has been gained and as more planning accuracy has been achieved by new machines, new computer programs and better quality control. The currently quoted control rates for benign lesions less than 3cm diameter are: astrocytoma grade 1 – 92%, astrocytoma grade 2 – 87%, acoustic neuroma (vestibular schwannoma) – 96%, meningioma – 96 to 99%, non-secretory pituitary adenoma – 92%, GH and ACTH secreting adenomas – 80%, prolactin secreting adenomas – 40%, chordoma and chondrosarcoma – 73%, glomus tumour 100%, epilepsy (mesial temporal sclerosis) – 81%, trigeminal neuralgia – 83%, parkinsonian tremor 88%, parkinsonian rigidity/bradykinesia – 66%, obsessive compulsive neurosis – 60%, arterio-venous malformation 90%, cavernoma – 86%, uveal melanoma – 84%. In malignant glioblastoma, mean survival of 116 weeks has been described. In cerebral metastases the lesions can be controlled in almost every case so that survival then depends on the extracerebral disease. In many cases these various results have been achieved after failure of surgery or radiotherapy treatments. Complications are significantly less than with microsurgery, radiotherapy or LINAC based radiosurgery. The method is more cost effective than traditional surgical treatment and is also more acceptable for the patients.