Surgical management of brainstem-expanding lesions: the role of neuroimaging.

The brainstem is no longer regarded as an inoperable area, thanks to the huge advances that have been made in neurosurgery recently. Preoperative planning based on modern neuroimaging techniques (high-resolution magnetic resonance imaging and helical computed tomography) and advances in microneurosurgery and neuroanesthesia allows brainstem surgery to be performed with acceptable morbidity and mortality rates. Most surgically treated, space-occupying lesions in the brainstem are hematomas, and they are usually associated with cavernoma hemorrhage. However, over the last 25 years, there have also been reports from widely recognized neurosurgical centers on the positive clinical results of partial and even complete removal of brainstem tumors, mostly of glial origin. In this article, we focus on surgical planning based on neuroimaging techniques and its application for the surgical management of cavernomas, with or without hemorrhage, and focal and exophytic tumors. First of all, we review the indications for surgery of these lesions, until now almost always following imaging criteria, using the most surgically oriented classifications (especially in brainstem gliomas). In addition, we review the current controversy regarding the need for biopsy or if we can still manage them in base of imaging criteria. We also describe advances in the most significant imaging techniques in this field, emphasizing those in diffusion tensor imaging and neuronavigation. Finally, we present several cases to illustrate the role of neuroimaging in this field and to demonstrate the importance of neuroradiologists and neurosurgeons working together before and during the surgery.