IMR Press / JIN / Volume 22 / Issue 1 / DOI: 10.31083/j.jin2201017
Open Access Original Research
Intraoperative Cortico-Cortical Evoked Potentials for Monitoring Language Function during Brain Tumor Resection in Anesthetized Patients
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1 Clinical Neurophysiology, Hospital Universitario La Princesa, 28006 Madrid, Spain
2 Biomedical Research Institute, Hospital Universitario La Princesa, 28006 Madrid, Spain
3 Neurosurgery, Hospital Universitario La Princesa, 28006 Madrid, Spain
4 Neurosurgery, Clínica Nuestra Señora del Rosario, 28006 Madrid, Spain
5 Neurosurgery, Autonomous University of Madrid, 28006 Madrid, Spain
*Correspondence: jesus.pastor@salud.madrid.org (Jesús Pastor)
Academic Editor: Gernot Riedel
J. Integr. Neurosci. 2023, 22(1), 17; https://doi.org/10.31083/j.jin2201017
Submitted: 13 August 2022 | Revised: 29 September 2022 | Accepted: 9 October 2022 | Published: 13 January 2023
(This article belongs to the Special Issue Brain Stimulation and Neuroimaging)
Copyright: © 2023 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license.
Abstract

Background: Cortico-cortical evoked potentials (CCEPs) have been used to map the frontal (FLA) and parietal (PLA) cortical regions related to language function. However, they have usually been employed as a complementary method during sleep-awake surgery. Methods: Five male and two female patients received surgery for tumors located near language areas. Six patients received general anesthesia and the sleep-awake method was used for patients with tumors located near the cortical language areas. We performed motor and somatosensory mapping with CCEPs to identify language areas and we monitored responses during surgery based on the mapping results. Electrocorticography was performed throughout the surgery. Single pulses of 1 ms duration at 5–20 mA were delivered by direct cortical stimulation using one grid at one region (e.g., FLA) and then recording using a second gird at another area (i.e., PLA). Next, reversed stimulation (from PLA to FLA) was performed. The charge density for electrical stimulation was computed. Sensibility, specificity, predictive positive values, and predicted negative values were also computed for warning alterations of CCEPs. Results: Gross tumor resection was achieved in four cases. The first postsurgical day showed language alterations in three patients, but one year later six patients remained asymptomatic and one patient showed the same symptomatology as previously. Seizures were observed in two patients that were easily jugulated. CCEPs predicted warning events with high sensibility and specificity. Postsurgical language deficits were mostly transitory. Although the latency between frontal and parietal regions showed symmetry, the amplitude and the relationship between amplitude and latency were different for FLA than for PLA. The charge density elicited by CCEPs ranged from 442 to 1768 μC/cm2. Conclusions: CCEPs have proven to be a reliable neurophysiological technique for mapping and monitoring the regions associated with language function in a small group of anesthetized patients. The high correlation between warning events and postsurgical outcomes suggested a high sensitivity and specificity and CCEPs can be used systematically in patients under general anesthesia. Nevertheless, the small number of studied patients suggests considering these results cautiously.

Keywords
brain mapping
direct cortical stimulation
intraoperative neurophysiological monitoring
motor evoked potentials
somatosensory evoked potentials
Funding
FIS PI17/02193/Ministerio de Sanidad
FEDER (Fonds Europeen de Developpement Economique et Regional)
Figures
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