stereotaxic

Stereotaxic refers to stereotaxy, a surgical and research technique that uses a three‑dimensional coordinate system to locate targets within the brain or other internal structures and to guide interventions with precision. It typically relies on a fixed reference frame attached to the skull or a frameless navigation system to relate patient anatomy to a standardized atlas or imaging data.

Planning and execution involve imaging data such as CT, MRI, or PET to identify the target and plan a safe trajectory. Instruments, including biopsy needles, electrodes for deep brain stimulation, or laser and radiofrequency probes, are advanced along a defined path. Modern frameless systems use real-time tracking and image fusion to verify placement.

Human stereotaxy developed in the mid‑20th century, with early frame-based methods introduced by Horsley and Clarke and later popularized for human use by Spiegel and Wycis in 1947. The Talairach atlas introduced in 1988 provided a widely used coordinate framework, later complemented by AC–PC references and increasingly by image‑guided neuronavigation.

Applications include diagnostic brain biopsy, therapeutic lesioning for movement disorders and epilepsy, implantation of deep brain stimulation electrodes, stereotaxic delivery of tracers or therapeutics, and planning for radiosurgical procedures such as Gamma Knife or CyberKnife.

Modern stereotaxic methods routinely achieve submillimeter to a few millimeters of accuracy, depending on the system and target. Risks include hemorrhage, infection, edema, and misregistration; procedures require careful planning, intraoperative verification, and postoperative imaging.

See also: AC–PC coordinate system, Talairach coordinates, neuronavigation, functional neurosurgery, stereotactic radiosurgery.