ABSTRACT
The need to precisely localize targets within the brain and to refer them to important anatomical structures has occupied neurosurgeons since the early years of intracranial surgery. Craniometry, developed by neuroanatomists in the 19th century, was the first practical method of surgical navigation. It is still being used today as a crude but useful means to correlate the position of superficial brain anatomy with readily identifiable cranial hallmarks. Stereotaxis, first introduced by Horsley and Clarke in 1908 [1], represented the first big leap into deep brain localization. Advances in intracranial imaging and computer science enabled the evolution of stereotaxis, from a method that allowed the precise localization of a point in space in the human brain [2], to the capability of defining the whole contents of the head in a threedimensional matrix [3-5]. This later development was crucial to intraoperative navigation. Computer reconstruction of images in different planes and three-dimensional rendering gave the neurosurgeon a display of anatomy that helps in the planning of surgical trajectories to deep-seated lesions and with the ability to ‘‘see’’ around the pathology to be treated. During the
1980s and early 1990s, several makers of stereotactic equipment developed computerized packages for volumetric stereotaxis in conjunction with stereotactic frames. Any frame reduces the working space available to the surgeon, particularly when the trajectory involves the lateral or posterior aspect of the skull. This limited the appeal of the newer computerized stereotactic systems, leading to the development of new approaches to neuronavigation.
