An update of the imaging and diagnostic techniques in use for the preservation of eloquent areas in brain tumor surgery – An opinion paper

Background: Surgery of brain tumors has made excellent progresses over time. Its characteristic is to be an extremely invasive surgery, becoming a limit that neurosurgeons have tried to overcome with the discovery of more and more modern diagnostic tools. Aim: In brain tumor surgery the aim is to excise the tumor without creating superior function deficits, so try to spare the so-called eloquent areas. Since the early twentieth century, neurosurgeons like Penfield and Ojemann have paid attention to the preservation of the language areas as well as of the motor pathways during brain surgery. Methods and results: Cortical electrical stimulation and brain mapping were used with good results. The problem was for a long time the invasiveness of the surgery which however foresaw a craniotomy. A few years ago a new and revolutionary technique has established itself. The diffusion tensor Imaging (DTI) is a non-invasive method that includes the use of MRI, allowing the study of white matter and therefore of the cortico-spinal tracts. Then, DTI tractography is able to distinguish normal nerve fibers from those infiltrated by the tumor, detecting pathological features of white matter such as axonal damage, ischemia, inflammation, edema. Conclusions: The literature is rich in cases related to the use of DTI in brain tumors, the results are excellent if one thinks of the saving of functionally important brain areas. Therefore, the excision of malignant tumors such as gliomas and glioblastomas is followed by a different and better outcome and a different quality of life. DTI tractography today represents the best and safest way of preserving the superior cortical functions in brain tumor surgery.