Stereotactic techniques are being applied increasingly in open cranial operations to improve the accuracy of the approach to intracranial targets. At the same time, there is more use of anatomic information from preoperative magnetic resonance imaging, especially surface imaging, and of functional information from techniques such as magnetoencephalography, positron emission tomography, and somatosensory evoked potential testing.1,2 (Magnetoencephalography is a noninvasive method of monitoring the spatial and temporal pattern of neurophysiological activity within the brain; unlike electroencephalography, which measures electrical activity within the brain, magnetoencephalography measures the magnetic fields caused by such electrical activity.) The combination of such anatomic and functional data helps the surgeon plan the least harmful trajectory to the patient's lesion, with avoidance of injury to cortical areas that are important for movement, sensation, and speech.
The use of endoscopic techniques in neurosurgery dates back to 1910 when a urologist named L'Espinasse used a cystoscope to fulgurate
Wilkins RH. Neurological Surgery. JAMA. 1994;271(21):1684-1685. doi:10.1001/jama.1994.03510450056031