Minimally-invasive neurosurgery is the concept of using the smallest possible opening to perform the same procedure as previously conducted via open surgery. This often involves the use of special equipment such as endoscopes and was first developed for the endoscopic treatment of hydrocephalus via 3rd ventriculostomy. This has now become quite commonplace among Neurosurgeons who are familiar with endoscopic techniques. With improved equipment and skills the endoscopic techniques have been applied to operations that pass through the CSF spaces around the brain such as nerve decompressions and vascular surgery. Lately endoscopic pituitary surgery via the nasal cavities has become established, as have some applications in spinal surgery. These advances have become possible only with the widespread availability of Neuronavigation, whereby intra-operative guidance is provided via scan information, rather than via surgical dissection of anatomical structures.
The latest concept in minimally invasive neurosurgery developed from the recognition of the Keyhole Principle. This can be best explained by analogy as looking through a keyhole gives a wide view of the room beyond and it would be possible, with the right instruments and skill, to paint a mural on the wall opposite the door through the keyhole. In neurosurgery this means using the minimum skull opening and least manipulation of the brain to achieve an operation. The surgical access is inevitably narrow and deep and requires advanced endoscopic skills and equipment. In our example the keyhole technique allows the entire opposite wall to be approached and some of the side walls but it is not possible to reach behind the door, thus a tumour on the surface may be best removed by opening the 'door'. The key-hole concept in Neurosurgery can enable tumour removal with the minimum of invasiveness using all the technical advances available, such as computer-assisted planning, Neuronavigation, endoscopy and specially adapted instruments, drills and ultrasonic aspirator. The surgery is demanding and may be protracted but the advantage for the patient is usually a better immediate recovery and improved final outcome.