Direct Cortical Stimulation and fMRI

Abstract

Intracranial space-occupying lesions, particularly glial tumors, may challenge the neurosurgeon who aims at preserving neuronal function as much as possible while removing as much of the lesion as possible. It has been repeatedly questioned whether radical resection of gliomas is the method of choice because of their invasive nature, but it has also been shown recently that patients can benefit from radical resection as much as possible both in primary (Stummer et al. 2006) and recurrent gliomas as well as in low-grade gliomas (Claus et al. 2006, Sanai et al. 2008). Radical resection of glial tumors, however, is hampered by the risk of damaging neuronal functions, particularly of speech and motor functions. Therefore, early on in the development of modern neurosurgery, brain tumor surgery under local anesthesia (LA) was suggested in order to reduce the risk of immediate severe and non-reversible postoperative neurological deficit (Berger et al. 1992; Black et al. 1987; Ojemann et al. 1989; Ojemann 1988). Most of the patients are initially frightened by the suggestion of undergoing brain tumor surgery under local anesthesia. However, they accept this method when the details are fully explained to them (Danks et al. 1998). Nevertheless, there are limitations, such as patients' inability to cooperate — in the case of very young and very old patients, or a tumor located and extending in such a fashion that there is no good way to position the patient with sufficient comfort; patients with reduced cardio-pulmonary functions or seizures related to the tumor should be particularly well taken care of. Taking these precautions into account, it has been shown by many centers that it is possible to reduce the risk of a focal neurological deficit while increasing the chance to completely remove a tumor located in eloquent areas (Danks et al. 2000; Duffau 2005a, b; Duffau et al. 2003; Ebeling et al. 1995; Pinsker et al. 2007).