Monitoring Cortico-cortical Evoked Potentials using Only Two 6-strand Strip Electrodes for Gliomas Extending to the Dominant Side of Frontal Operculum During One-step Tumor Removal Surgery

Abstract Resection of the dominant side of gliomas extending to the frontal operculum has a high-risk of permanent language dysfunction. Here, we report recording cortico-cortical evoked potentials (CCEP) using only two 6-strand strip electrodes to monitor language-related fibers intraoperatively. We examined whether this simple procedure is useful for removing gliomas extending to the dominant side of frontal operculum. This study included five cases of glioma extending to the left frontal operculum. The frontal language area (FLA) was first identified by functional mapping during awake craniotomy. Next, a 6-strand strip electrode was placed just above the FLA, while on the temporal lobe side, an electrode was placed so as to slide parallel to the Sylvian fissure toward the posterior language area. Electrical stimulation was performed using the electrode on the frontal side, and CCEPs were measured from the electrode on the temporal side. CCEPs were detected in all cases. Immediately after surgery, all patients demonstrated language dysfunction to varying degrees. CCEP decreased up to 10% in one patient, who recovered language function after 24 months. CCEP decreased slightly up to 80% in one, and in the three other cases, CCEPs did not change. These four patients soon recovered language function within 2 weeks to 1 month. This study confirmed the utility of CCEP monitoring using only two 6-strand strip electrodes during one-step surgery. We believe this simple method helped in monitoring intraoperative language function and aided predicting its postoperative recovery, in patients with gliomas extending to the dominant side of frontal operculum.

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Utility of Intraoperative Cortico-Cortical Evoked Potentials for the Evaluation of Language Function During Brain Tumor Resection

Surgical Case Reports ◽

10.31487/j.scr.2020.12.09 ◽

2020 ◽

pp. 1-4

Author(s):

Jesús Pastor Gómez ◽

Lorena Vega-Zelaya ◽

Marta Navas ◽

Pilar Martín ◽

Jesús Pastor Gómez

Keyword(s):

Evoked Potentials ◽

Language Impairment ◽

High Reliability ◽

Tumor Resection ◽

Language Function ◽

Cortical Evoked Potentials ◽

Good Spatial Resolution ◽

Brain Tumor Resection ◽

Language Area ◽

The Relationship

The cortico-cortical evoked potentials (CCEP) are a relatively recent intraoperative monitoring tool that has shown high reliability in detecting the functional language area and its connections. In this work we describe a patient with a tumor located in the language area who underwent tumor resection. A neurophysiological intraoperative mapping of the frontal and posterior language area with the anesthetized patient was carried out. Then the patient was awaked. To demonstrate the relationship between language function and CCEP, the Ojemann’s stimulation technique was used in the same electrodes were CCEPs were obtained. An alteration in the emission of language had been found on the electrodes where CCEP was obtained and in adjacent electrodes. During tumor resection we used a double check for language function: neurological evaluation and CCEPs. We obtained a biunivocal relationship between warning criteria in the CCEP and immediate language impairment on neurological examination. We always observed a significant decrease in the CCEP associated with language impairment. The CCEP are able to obtain information in real time with a good spatial resolution of the language function. Future studies should be carried out in order to analyse the robustness of this technique to perform it in anesthetized patients.

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Difficulty in identification of the frontal language area in patients with dominant frontal gliomas that involve the pars triangularis

Journal of Neurosurgery ◽

10.3171/2015.8.jns151204 ◽

2016 ◽

Vol 125 (4) ◽

pp. 803-811 ◽

Cited By ~ 11

Author(s):

Taiichi Saito ◽

Yoshihiro Muragaki ◽

Takashi Maruyama ◽

Manabu Tamura ◽

Masayuki Nitta ◽

...

Keyword(s):

Electrical Stimulation ◽

Brain Mapping ◽

Awake Craniotomy ◽

Language Function ◽

Language Mapping ◽

Positive Mapping ◽

Language Area ◽

Pars Triangularis ◽

Language Areas ◽

Dominant Side

OBJECTIVE Identification of language areas using functional brain mapping is sometimes impossible using current methods but essential to preserve language function in patients with gliomas located within or near the frontal language area (FLA). However, the factors that influence the failure to detect language areas have not been elucidated. The present study evaluated the difficulty in identifying the FLA in dominant-side frontal gliomas that involve the pars triangularis (PT) to determine the factors that influenced failed positive language mapping. METHODS Awake craniotomy was performed on 301 patients from April 2000 to October 2013 at Tokyo Women's Medical University. Recurrent cases were excluded, and patients were also excluded if motor mapping indicated their glioma was in or around the motor area on the dominant or nondominant side. Eighty-two consecutive cases of primary frontal glioma on the dominant side were analyzed for the present study. MRI was used for all patients to evaluate whether tumors involved the PT and to perform language functional mapping with a bipolar electrical stimulator. Eighteen of 82 patients (mean age 39 ± 13 years) had tumors that showed involvement of the PT, and the detailed characteristics of these 18 patients were examined. RESULTS The FLA could not be identified with intraoperative brain mapping in 14 (17%) of 82 patients; 11 (79%) of these 14 patients had a tumor involving the PT. The negative response rate in language mapping was only 5% in patients without involvement of the PT, whereas this rate was 61% in patients with involvement of the PT. Univariate analyses showed no significant correlation between identification of the FLA and sex, age, histology, or WHO grade. However, failure to identify the FLA was significantly correlated with involvement of the PT (p < 0.0001). Similarly, multivariate analyses with the logistic regression model showed that only involvement of the PT was significantly correlated with failure to identify the FLA (p < 0.0001). In 18 patients whose tumors involved the PT, only 1 patient had mild preoperative dysphasia. One week after surgery, language function worsened in 4 (22%) of 18 patients. Six months after surgery, 1 (5.6%) of 18 patients had a persistent mild speech deficit. The mean extent of resection was 90% ± 7.1%. Conclusions Identification of the FLA can be difficult in patients with frontal gliomas on the dominant side that involve the PT, but the positive mapping rate of the FLA was 95% in patients without involvement of the PT. These findings are useful for establishing a positive mapping strategy for patients undergoing awake craniotomy for the treatment of frontal gliomas on the dominant side. Thoroughly positive language mapping with subcortical electrical stimulation should be performed in patients without involvement of the PT. More careful continuous neurological monitoring combined with subcortical electrical stimulation is needed when removing dominant-side frontal gliomas that involve the PT.

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Intraoperative cortico-cortical evoked potentials for the evaluation of language function during brain tumor resection: initial experience with 13 cases

Journal of Neurosurgery ◽

10.3171/2014.4.jns131195 ◽

2014 ◽

Vol 121 (4) ◽

pp. 827-838 ◽

Cited By ~ 33

Author(s):

Taiichi Saito ◽

Manabu Tamura ◽

Yoshihiro Muragaki ◽

Takashi Maruyama ◽

Yuichi Kubota ◽

...

Keyword(s):

Brain Tumors ◽

Evoked Potentials ◽

Tumor Resection ◽

Awake Craniotomy ◽

Technical Problems ◽

Cortical Evoked Potentials ◽

Language Area ◽

Time Required ◽

Subcortical Mapping ◽

Stimulation Of

Object The objective in the present study was to evaluate the usefulness of cortico-cortical evoked potentials (CCEP) monitoring for the intraoperative assessment of speech function during resection of brain tumors. Methods Intraoperative monitoring of CCEP was applied in 13 patients (mean age 34 ± 14 years) during the removal of neoplasms located within or close to language-related structures in the dominant cerebral hemisphere. For this purpose strip electrodes were positioned above the frontal language area (FLA) and temporal language area (TLA), which were identified with direct cortical stimulation and/or preliminary mapping with the use of implanted chronic subdural grid electrodes. The CCEP response was defined as the highest observed negative peak in either direction of stimulation. In 12 cases the tumor was resected during awake craniotomy. Results An intraoperative CCEP response was not obtained in one case because of technical problems. In the other patients it was identified from the FLA during stimulation of the TLA (7 cases) and from the TLA during stimulation of the FLA (5 cases), with a mean peak latency of 83 ± 15 msec. During tumor resection the CCEP response was unchanged in 5 cases, decreased in 4, and disappeared in 3. Postoperatively, all 7 patients with a decreased or absent CCEP response after lesion removal experienced deterioration in speech function. In contrast, in 5 cases with an unchanged intraoperative CCEP response, speaking abilities after surgery were preserved at the preoperative level, except in one patient who experienced not dysphasia, but dysarthria due to pyramidal tract injury. This difference was statistically significant (p < 0.01). The time required to recover speech function was also significantly associated with the type of intraoperative change in CCEP recordings (p < 0.01) and was, on average, 1.8 ± 1.0, 5.5 ± 1.0, and 11.0 ± 3.6 months, respectively, if the response was unchanged, was decreased, or had disappeared. Conclusions Monitoring CCEP is feasible during the resection of brain tumors affecting language-related cerebral structures. In the intraoperative evaluation of speech function, it can be a helpful adjunct or can be used in its direct assessment with cortical and subcortical mapping during awake craniotomy. It can also be used to predict the prognosis of language disorders after surgery and decide on the optimal resection of a neoplasm.

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