Intraoperative subcortical language tract mapping guides surgical removal of gliomas involving speech areas

OBJECTIVE: Subcortical stimulation can also be used to identify functional language tracts during resection of gliomas located close to 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 tract identification exerted on the extent of surgery and on the appearance of immediate and definitive postoperative deficits. METHODS: Subcortical stimulation for language tract identification was systemically used during surgical removal of 88 glioma (44 high grade and 44 low grade gliomas) 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 performances were tested by neuropsychological language evaluation preoperatively and at 3, 30 and 90 days after surgery. RESULTS: Language tracts were identified in 59% of patients with differences according to tumor location but not according to histological grade. Language tract identification influenced the ability to reach a complete tumor removal in low-grade gliomas, in which tracts were documented inside the peripheral mass of the tumor. Identification of language tracts was associated with a higher occurrence of transient postperative deficits (67.3% of cases), but a low occurence of definitive morbidity (2.3% of cases). A pattern of typical language disturbances related to the phonological and semantic system can be identified according to tumor location, with preservation being important for the maintenance of language integrity. CONCLUSION: Our study supports the routine use of subcortical for language tract identification as a reliable tool for guiding surgical removal of gliomas in or in close proximity to language areas or pathways.