intraoperative subcorticAl language tract mapping guides surgical removal of gliomas involving speech areas

Subcortical stimulation can be used to identify functional language tracts during resection of gliomas located very close or within language areas or pathways. The objective of the present study was to investigate the feasibility of the routine use of subcortical stimulation for identification of language tracts in a large series of patients with gliomas, and to determine the influence that identification of subcortical language tracts exerted on the extent of surgery and the appearance of immediate and definitive post- operative deficits. Subcortical stimulation for the identification of language tracts was sys- tematically used during surgical removal of 88 gliomas (44 high grade and 44 low grade) involving language pathways. Procedures were performed during asleep-awake craniotomy. Subcortical stimulation was continuously alternated with surgical resection in a back-and-forth fashion. Language performance was tested by neuropsychological language evaluation preop- eratively and at 3, 30, and 90 days after surgery. Language tracts were identified in 59% of patients, with differences according to tumor location but not according to histological grade. Identification of language tracts influenced the ability to achieve complete tumor removal in low-grade gliomas, where tracts were documented inside the peripheral mass of the tumor. Identification of language tracts was asso- ciated with a higher occurrence of transient postoperative deficits (69.2%), but a low definitive morbidity (2.3%). A pattern of typical language distur- bances related to the phonological and semantic system can be identified based on tumor location, the preservation of which is important for the maintenance of language integrity. Our study supports the routine use of subcortical stimulation for identification of language tracts as a reliable tool for guiding surgical removal of gliomas in, or in close proximity to, language areas or path- ways