Intraoperatively updated navigation systems: the solution to brain shift

Abstract

During neurosurgical operations, the soft material of the brain, the cerebrospinal fluid (CSF), the opening of the skull's cavity, the opening of the dura mater, the CSF loss along with gravity and other factors make the brain susceptible to the brain-shift phenomenon (displacement of the brain in relation with its natural position captured during imaging acquisition). As a result, after some point of the operation the neurosurgeon cannot really rely on the navigation system's guidance. The navigational inaccuracies caused by the brain-shift phenomenon and the demand for updated intraoperative imaging acquisition aiming to increase accuracy and reliability led to the development of intraoperative imaging systems. Such systems are the intraoperative ultrasound device, and the intraoperative computed tomography (ioCT) or magnetic resonance imaging (ioMRI) scanners. Each system is characterized by its own advantages and disadvantages, which are described in the present review. As a conclusion, intraoperative imaging systems provide very important advantages in various types of operations by updating the imaging scan. However, their benefit is unclear in some instances, while ioCT and especially ioMRI are associated with huge costs affordable only by specific hospitals worldwide.