I can operate with the patient awake under local anaesthetic so that I can identify the eloquent areas of the brain by stimulating the brain with an electrode. The patient is given simple tasks to perform by my anaesthetist so that we can see if I am causing any damage as the operation proceeds. If I am operating on the spinal cord – which is even more vulnerable than the brain – I can use a method of electrical stimulation known as evoked potentials to warn me if I am about to cause paralysis.
