Operations using a frameless stereotactic system with a marker: Technical note

One of the most critical problems in navigation systems is that of brain sh ifts during operations. In order to solve this problem, we developed a simp le method using a marker placed prior to microsurgery to provide a referenc e point. We produced a thin probe. After the dural incision, the probe, cov ered with a silicone tube, was inserted into the target point. Then only th e probe was removed, leaving the silicone tube in place. This tube moved to gether with the brain, which deviated during the operation, and throughout the operation indicated the same point as that which it was pointed at firs t. This result suggests that this is a simple and useful method to allow na vigation systems to accommodate brain shifts during operations.