The introduction of minimally invasive techniques has greatly improved results for intracranial neurosurgery.Stereotaxy and improved imaging techniques have reduced surgical trauma by allowing surgeons to plan the least damaging route to operative sites and by increasing surgical precision. Stereotaxy has also allowed brain biopsies to be taken from sites such as the brain stem, which were rarely sampled before because free hand biopsy was so dangerous. Brain tumours can now be treated by interstitial radiotherapy - stereotactic insertion of catheters into the lesion for loading of radioactive iodine - or radiosurgery - focusing of intense beams of radiation on lesions without needing surgical incisions. Endoscopic neurosurgery can be used to reach cavities such as the ventricular system or cystic tumours. With interventional neuroradiology fine catheters can be introduced into most vessels in the cranium for embolisation or dilatation. The development of augmentative functional neurosurgery means that movement disorders, epilepsy, and intractable pain can be treated with implanted neurostimulating electrodes. Future developments will probably include frameless stereotaxy, when the rigid attachment of stereotactic apparatus to the patient's head can be dispensed with, and at least partial automation of procedures such brain biopsy.