title: Difficulty in identification of the frontal language area in patients with dominant frontal gliomas that involve the pars triangularis.
abstract: 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.
authors.affiliation: Departments of 1 Neurosurgery and.|CREST, Japan Science and Technology Agency, Tokyo.
authors.forename: Taiichi
authors.initials: T
authors.lastname: Saito
authors.affiliation: Departments of 1 Neurosurgery and.|Faculty of Advanced Techno-Surgery, Tokyo Women's Medical University.|CREST, Japan Science and Technology Agency, Tokyo.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Muragaki
authors.affiliation: Departments of 1 Neurosurgery and.|Faculty of Advanced Techno-Surgery, Tokyo Women's Medical University.|CREST, Japan Science and Technology Agency, Tokyo.
authors.forename: Takashi
authors.initials: T
authors.lastname: Maruyama
authors.affiliation: Departments of 1 Neurosurgery and.|Faculty of Advanced Techno-Surgery, Tokyo Women's Medical University.|CREST, Japan Science and Technology Agency, Tokyo.
authors.forename: Manabu
authors.initials: M
authors.lastname: Tamura
authors.affiliation: Departments of 1 Neurosurgery and.|Faculty of Advanced Techno-Surgery, Tokyo Women's Medical University.|CREST, Japan Science and Technology Agency, Tokyo.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nitta
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Tsuzuki
authors.affiliation: Faculty of Advanced Techno-Surgery, Tokyo Women's Medical University.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Konishi
authors.affiliation: Anesthesiology.
authors.forename: Kotoe
authors.initials: K
authors.lastname: Kamata
authors.affiliation: CREST, Japan Science and Technology Agency, Tokyo.|Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo; and.|Division of Neurology, Department of Internal Medicine, Showa University Northern Yokohama Hospital, Kanagawa, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Kinno
authors.affiliation: CREST, Japan Science and Technology Agency, Tokyo.|Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo; and.
authors.forename: Kuniyoshi L
authors.initials: KL
authors.lastname: Sakai
authors.affiliation: Departments of 1 Neurosurgery and.|Faculty of Advanced Techno-Surgery, Tokyo Women's Medical University.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iseki
authors.affiliation: Departments of 1 Neurosurgery and.
authors.forename: Takakazu
authors.initials: T
authors.lastname: Kawamata
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology* / Q000601:surgery*; D065711:Broca Area; D005260:Female; D005910:Glioma / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
keywords: FLA = frontal language area; PT = pars triangularis; awake craniotomy; brain mapping; diagnostic and operative techniques; glioma; language function; pars triangularis