Surgical strategies for nonenhancing slow-growing gliomas with special reference to functional reorganization: review with own experience

Analysis of the Factors Affecting the Prognosis of Glioma Patients

This retrospective study was carried out to investigate factors affecting the prognosis of gliomas for better management of treatment. Clinical data from 186 glioma patients treated in our hospital from January 2013 to June 2016 were analyzed. There was slightly more male than female patients in the cohort. The main clinical symptoms included sudden limb twitching, headache and fatigue, vomiting, vision reduction and speaking disorders. The malignancy was high and the prognosis was poor in the patients, with an overall survival rate of 54.84 % by October 2017. Univariate analysis showed that the prognosis was mainly affected by age, tumor grade, preoperative Karnofsky performance status (KPS), surgical method, postoperative radiotherapy and chemotherapy, and postoperative use of temozolomide (TMZ). Multivariate Cox regression analysis showed that the independent risk factors for the prognosis were old age (≥ 60), advanced tumor, partial tumor resection, KPS of < 70, no chemotherapy after operation and < 4 courses of postoperative TMZ. The prognosis is negatively affected by age, tumor grade, KPS, and partial tumor resection. Surgical resection combined with chemotherapy and multi-course use of TMZ prolongs the survival time of patients.

Critical Neural Networks in Awake Surgery for Gliomas

From the embarrassing character commonly infiltrating eloquent brain regions, the surgical resection of glioma remains challenging. Owing to the recent development of in vivo visualization techniques for the human brain, white matter regions can be delineated using diffusion tensor imaging (DTI) as a routine clinical practice in neurosurgery. In confirmation of the results of DTI tractography, a direct electrical stimulation (DES) substantially influences the investigation of cortico-subcortical networks, which can be identified via specific symptoms elicited in the concerned white matter tracts (eg., the arcuate fascicle, superior longitudinal fascicles, inferior fronto-occipital fascicle, inferior longitudinal fascicle, frontal aslant tract, sensori-motor tracts, optic radiation, and so forth). During awake surgery for glioma using DES, it is important to identify the anatomo-functional structure of white matter tracts to identify the surgical boundaries of brain regions not only to achieve maximal resection of the glioma but also to maximally preserve quality of life. However, the risk exists that neurosurgeons may be misled by the inability of DTI to visualize the actual anatomy of the white matter fibers, resulting in inappropriate decisions regarding surgical boundaries. This review article provides information of the critical neuronal network that is necessary to identify and understand in awake surgery for glioma, with special references to white matter tracts and the author's experiences.

[The structure of activation of the language zone in patients with intracerebral tumors according to fMRI with respect to tumor location and the functional asymmetry profile]

MATERIAL AND METHODS

A total of 50 patients were examined prior to surgical resection of intracranial tumors of the temporal and frontal lobes. Left-sided tumors were observed in 33 patients and right-sided tumors were observed in 17 patients. The functional asymmetry profile was determined using self-assessment, the Annet questionnaire, and the dichotic listening task. Twelve patients were left-handers or retrained left-handers and the remaining 38 patients were right-handers. FMRI examination was carried out on a 3.0 T SignaHDxt magnetic resonance tomograph (GE). The standard language block design paradigm was used in the study. We used the following tests: 1) recitation of months in reverse order; 2) generation of nouns according to the initial letters shown on the screen (K, M, L, N, P, C); 3) generation of verbs according to simple actions shown on the screen; 4) producing sentences using nouns shown on the screen; 5) listening to text through headphones. Data were processed using the standard BrainWave PA software (General Electric). Z-test was used in the range from 6 to 9. In all the studies, p<0.001. Statistical data processing included the nonparametric Spearman's test to determine the correlation between lateralization of the detected activation zone under speech load and tumor location (tumor is adjacent to the language zone, invades the language zone, or is located far from the language zone), as well as left- or right-handedness.

RESULTS

Among 16 patients (right-handers and 2 left-handers) the activation of language zones was observed only on the left side; in one left-handed patient, Broca's area was detected only on the right side. In other patients (including right-handers with right-sided tumors), lateralization of language zones was different, including bilateral. Statistical processing revealed that bilateral activation of both Broca's and Wernicke's areas was more frequently observed in left-handers. Broca's area was more frequently detected on the left side in the presence of a distant tumor, while this trend did not apply for Wernicke's area.

CONCLUSION

Localization of activation of Broca's area is more dependent on tumor location, while it depends on personal characteristics of an individual in the case of Wernicke's area.

Directional migration of adult hematopoeitic progenitors to C6 glioma in vitro

Multiform glioblastoma is the most common primary, highly invasive, malignant tumor of the central nervous system, with an extremely poor prognosis. The median survival of patients following surgical resection, radiation therapy and chemotherapy does not exceed 12–15 months and thus, novel approaches for the treatment of the disease are required. The phenomenon of the directed migration of stem cells in tumor tissue presents a novel approach for the development of technologies that facilitate the targeted delivery of drugs and other therapeutic agents to the tumor foci. Hematopoietic cluster of differentiation (CD)34⁺/CD133⁺ stem cells possess significant reparative potential and are inert with respect to normal neural tissue. The aim of the present study was to investigate the substantiation ability of adult hematopoietic progenitors to the directed migration of glioma cells. A C6 glioma cell line, a culture of hematopoietic CD34⁺/CD133⁺ stem cells and primary cultures of rat astrocytes and fibroblasts were used. The cells were co-cultured for five days. The results revealed the formation of cell shaft hematopoietic stem cells on the perimeter of the culture inserts containing the glioma culture. However, this was not observed in the wells with fibroblast and astrocyte cultures. The results indicated that hematopoietic stem cells exhibit a high potential for the directional migration of C6 glioma cells, which allows them to be considered as a promising cell line for the development of novel anticancer biomedical technologies and increases our understanding with regard to previously unclear aspects of glial tumor carcinogenesis.

Intraoperative functional mapping and monitoring during glioma surgery

Glioma surgery represents a significant advance with respect to improving resection rates using new surgical techniques, including intraoperative functional mapping, monitoring, and imaging. Functional mapping under awake craniotomy can be used to detect individual eloquent tissues of speech and/or motor functions in order to prevent unexpected deficits and promote extensive resection. In addition, monitoring the patient’s neurological findings during resection is also very useful for maximizing the removal rate and minimizing deficits by alarming that the touched area is close to eloquent regions and fibers. Assessing several types of evoked potentials, including motor evoked potentials (MEPs), sensory evoked potentials (SEPs) and visual evoked potentials (VEPs), is also helpful for performing surgical monitoring in patients under general anesthesia (GA). We herein review the utility of intraoperative mapping and monitoring the assessment of neurological findings, with a particular focus on speech and the motor function, in patients undergoing glioma surgery.