Chapter 22 - Surgery of brainstem lesions

During the past 20 years, surgery of the brainstem has continued to represent a challenge in neurosurgery. During the 1990s a more rational and constructive approach to the surgical management of neoplastic and vascular brainstem lesions emerged. This trend has continued into the new millennium, thanks also to technological innovations such as fiber tracking, neuronavigation, intraoperative magnetic resonance imaging (MRI), and refined skull base approaches. Since 2001, when the first edition of this book was published, the field of intraoperative neurophysiological monitoring (ION) has also dramatically evolved. Yet, in those years, the cornerstone of brainstem ION techniques such as mapping of the floor of the fourth ventricle or corticobulbar motor-evoked potentials were already part of the clinical practice in some of the most experienced neurosurgical centers. During the past two decades, these techniques have become more common at many more institutions, and the cumulative experience has allowed us to better define the value and the limitations of these techniques. In this new edition, we have largely maintained all the relevant information on the functional neuroanatomy of the brainstem, which remains invaluable for a modern approach to brainstem surgery, and on the main surgical approaches to the midbrain, pons, and medulla. While the various ION techniques that are used in brainstem surgery are described elsewhere in this book, at the end of this chapter, we will shortly review their impact in our practice based on a 20-year experience with using ION-guided brainstem surgery.