Assessing cognitive functions during awake brain surgery
Elke De Witte, PhD Neurolinguistics
Postdoc researcher, Neurolinguist/Speech and language pathologist
Department of Clinical and Experimental Neurolinguistics
Free University of Brussels, UZ Brussels
Surgical treatment of brain tumours aims to maximise the quality of resection while minimising the risk of postoperative functional deficits (including speech and language impairments such as aphasia). Since brain tumours are often located in critical language areas, preserving and restoring language functions is of crucial importance. This is generally achieved by means of direct electrical stimulation (DES) during awake brain surgery, which enables identification of the critical language areas and their pathways when removing brain tumours.
Although a positive impact of DES on postoperative linguistic outcome is generally advocated, the literature is only scantily documented with information about the linguistic methods applied in awake surgery. Therefore, we developed an extensive linguistic test battery, i.e. the Dutch Linguistic Intraoperative Protocol (DuLIP) to reliably identify language areas during DES and to assess linguistic functions in the pre- and postoperative phase (De Witte et al., 2015). The clinical use of this protocol will be illustrated with some case studies.
Nowadays, intraoperative single-language mapping is evolving to a more extensive cognitive mapping using non-language tasks as well (e.g. calculation, line bisection). However, the more functions are tested, the more critical areas are identified, which may interfere with a total tumour resection. Therefore, an optimal balance has to be found between the extent of resection and the preservation of functions strongly related to outcome and quality of life of the patient. Individual anatomo-functional profiles as well as cognitive functions before and after awake surgery will be thouroughly discussed.