Cortical Localization of Temporal Lobe Language Sites in Patients with Gliomas

Abstract

In a series of 40 patients undergoing an awake craniotomy for the removal of a glioma of the dominant hemisphere temporal lobe, cortical stimulation mapping was used to localize essential language sites. These sites were localized to distinct temporal lobe sectors and compared with 83 patients without tumors who had undergone language mapping for the treatment of intractable epilepsy. In patients with and without temporal lobe gliomas, the superior temporal gyrus contained significantly more language sites than the middle temporal gyrus. Both patient populations also had language sites anterior to the central sulcus in the superior temporal gyrus (12-16%). The patients without tumors had significantly more language sites in the superior temporal gyrus, compared with the superior temporal gyrus of patients with temporal lobe tumors. Multiple variables were studied for their effect on preoperative and postoperative language deficits and included age, sex, number of language sites, histology, size of the tumor, and the distance of tumor resection margins from the nearest language site. The distance of the resection margin from the nearest language site was the most important variable in determining the improvement in preoperative language deficits, the duration of postoperative language deficits, and whether the postoperative language deficits were permanent. If the distance of the resection margin from the nearest language site was > 1 cm, significantly fewer permanent language deficits occurred. Cortical stimulation mapping for the identification of essential language sites in patients with gliomas of the dominant hemisphere temporal lobe will maximize the extent of tumor resection and minimize permanent language deficits.

Operative Techniques for Gliomas and the Value of Extent of Resection

“…Accordingly, if the distance of the resection margin from the nearest language site is greater than 1 cm, significantly fewer permanent language deficits occur. 30 Strict adherence to this principle when oper-ating in any region of the dominant hemisphere can substantially reduce the risk of inadvertently resection functional tissue.…”

“…Thus, using language mapping, only 1.6% (4 of 243 surviving patients) of all glioma patients had a permanent postoperative language deficit develop. One explanation for this favorable postoperative language profile may be our strict adherence to the "1-centimeter rule," first described by Haglund et al, 30 which demonstrated that a resection margin of 1 cm or more from a language site for temporal lobe tumors significantly reduces postoperative language deficits.…”

The role of functional magnetic resonance imaging in brain surgery

“…Electrocortical stimulation mapping has a good track record in neurosurgery, and most surgeons consider it a valuable technique to safely maximize tumor resection. 20,30 Electrocortical stimulation mapping relies on the principle that a particular brain area can be functionally disabled for several seconds during electrical stimulation. At first glance, the technique seems very intuitive and valid.…”

Multimodal Approach to the Surgical Removal of Gliomas in Eloquent Brain Regions

“…In these situations as well as for subcortical tumors, we test language or motor function throughout the resection even when no stimulation is applied, stopping whenever anomalies appear. Many authors have for a long time postulated a need to maintain a safe distance of at least 1 cm from a functional site (Haglund et al 1994;Carrabba et al 2007;). More recently, this concept has been evolving because accumulated experiences have clearly demonstrated that continuous cortical and subcortical stimulations can enable the surgeon to identify and preserve eloquent cortex and the white matter bundles.…”