A method for immobilizing the head and allowing neurosurgeons to guide instruments into the inner portions of the brain precisely during NEUROSURGERY. It also is called stereotaxic surgery or stereotactic surgery. The term means “solid arrangement.” A device called a stereotaxic halo is fitted over the person’s head and held in place by four screws inserted into the skull. This is done with local anesthesia to numb the areas where the screws are placed; most people experience very little discomfort after the halo is attached. The halo is a lightweight but rigid frame that supports the instruments during surgery permitting the neurosurgeon to align their insertion into the brain with imagery obtained from
MAGNETIC RESONANCE IMAGING (MRI). During surgery the neurosurgeon attaches additional components that hold and guide instruments during surgery. This system allows complete coordination with computer-generated images for surgery that proceeds literally cell by cell. This is especially important in neurosurgery because the brain’s structures are less consistent among individuals than are the structures of other organ systems, and mistakes can have permanent and disastrous consequences. microelectrode recording is often used with stereotaxis as a complementary technique to ensure that the anatomic target neurons exhibit the correct physiology; different neuronal groups have different electrical firing patterns.