**3. Surgical technique and oncofunctional balance**

periods on average [5]. Currently, a randomized controlled clinical trial of supratotal resection for all grade gliomas in noneloquent areas is being conducted with 120 participants; primary results are expected soon (2 years OS, PFS, and Karnofsky Performance Score (KPS)) [18]. The evolution of supratotal surgery from gross total to supratotal was possible due a number of technological advances (light microscope, microneurosurgical tools, magnetic resonance imaging, neuro-navigation, brain mapping, 5-ALA fluoroscency technique, tractography, etc.). Supratotal resection, concerning recently published findings of a few independent authors,

For grade II glioma, the recommended treatment is maximally safe resection, with or without radiotherapy followed by procarbazine, lomustine, and vincristine administration or temozolomide plus radiotherapy followed by temozolomide depending of glioma features [20]. When it comes to low grade glioma in the meta-analysis, 5-year OS was markedly increased after resection of low grade glioma, increasing from 50–70% in STR to 80–95% in GTR [7]. GTR has superiority over STR and biopsy with increased OS and PFS [6, 21, 22]. But in another large study, they did not find any difference between STR and GTR in 5-year OS [23]. The impact of STR on OS must be more clearly defined. One study has shown that in younger patients with supratentorial low grade glioma, OS after GTR at 2 and 5 years was 99 and 93%,

In addition to greater OS GTR for low grade gliomas, it may impact on alerting process from low grade to high grade glioma [7]. In children after GTR, low grade glioma often does not need any further therapy, with 10 years OS rates of 90% or greater, with rare tumor recurrences [24]. In a study including patients with supratotal resection of low grade glioma with 11-year mean follow up, malignant transformation to high grade glioma did not occur. In the control group of total resection, 24% of the patients had malignant transformation from low to high grade glioma (*p* = 0.037) [19]. These promising results come from a pilot study including only 16 patients with performed supratotal resection; a larger study is needed to give a more

Recommended treatment for grade III and IV glioma, glioblastoma multiforme (GBM), includes maximally safe resection, if feasible, administration of temozolomide with combination of radiotherapy and chemotherapy depending of favorable and unfavorable prognostic factors and glioma features [20]. The median OS for GMB is 15 months and for grade III tumors between 3.5 and 10 years [14, 25]. In surgical treatment, STR shows better OS compared to biopsy without increasing morbidity [8]. As shown in a meta-analysis of 12,607 high-graded glioma in elderly patients, biopsy OS *vs*. STR was 5.71 months *vs.* 8.68 months, respectively, with lower morbidity rate and longer progression free survival in STR patients [21]. In studies assessing the extent of resection (EOR) in high-grade glioma, in the so-called volumetric studies, STR showed a shorter OS of 2 to 8 months; in nonvolumetric studies, OS was also shorter by 0.9 to 8 months [7]. In their study, Chaichana et al. showed that residual volume and EOR

respectively. The PFS rates at 2 and 5 years were 82 and 48%, respectively [13].

relevant overview of the behavior of lower grade glioma after supratotal resection.

resulted in better survival of glioma patients [13, 19].

158 Glioma - Contemporary Diagnostic and Therapeutic Approaches

**2.2. Low grade glioma surgical options**

**2.3. High grade glioma surgical options**

As mentioned before, the overall technical development has made supratotal resection possible, with adequate balance between maximal resection of tumor with paralesional region and functional consideration for the eloquent region of the brain. To increase the extent of resection, before surgery, functional MRI, white-matter tractography is performed; during the surgery, intraoperative MRI or ultrasound and 5-ALA-guided resection are used [5]. All these techniques give a rich fund of information, but when the leak of functional information occurs, it signals to us that, while operating, we approached the eloquent brain areas resection [5, 28]. Electrostimulation mapping during supratotal resection is the most important technique used to identify cortical areas and subcortical pathways involved in eloquent functions (especially motor, sensory, language, and cognitive functions) [5, 28, 29]. The usage of electrostimulation in humans started in the 19th century, but the first one in neuro-oncology was used in the 90s of the 20th century by Mitchel Berger. He applied electrostimulation for the mapping of eloquent cortical areas. Hugues Duffau extended and summarized the indication of electrostimulation usage at cortical and subcortical levels intraoperatively [29].

Intraoperative bipolar electrostimulation mapping has become a mandatory tool in neurooncology allowing to:


With intraoperative electrostimulation, resection is extended into the regions which were considered inoperable. By this extension, a great functional outcome has been documented with more than 95% of patients recovering to the normal neurological status in 3 months after the surgery, while some patients had improvement in comparison with their preoperative status. In respect of epilepsy, 80% of the patients with preoperative epilepsy did not report it after the surgery [28]. Electrostimulation is a safe, easy, accurate, and reliable technique of individualization of resection for each patient aiming to achieve the "oncofunctional balance."

**Author details**

Mirela Kalamujić<sup>3</sup>

Ibrahim Omerhodžić<sup>1</sup>

Bosnia and Herzegovina

Bosnia and Herzegovina

Bosnia and Herzegovina

Bosnia and Herzegovina

Bosnia and Herzegovina

2016.09.006

2012.11.001

**References**

\*, Almir Džurlić<sup>1</sup>

\*Address all correspondence to: ibrahimomerhodzic74@gmail.com

, Nurija Bilalović<sup>4</sup>

, Adi Ahmetspahić<sup>1</sup>

5 Department of Radiology, General Hospital of Sarajevo, Sarajevo, Bosnia and Herzegovina

[1] Goodenberger ML, Jenkins RB. Genetics of adult glioma. Cancer Genetics. 2012;**205**(12):

[2] Louis DN, Perry A, Reifenberger G, et al. The 2016 World Health Organization classification of tumors of the central nervous system: A summary. Acta Neuropathologica.

[3] The Nobel Prize in Physics 1952 [Internet]. 2018. Available from: http://www.nobelprize.

[4] Yang K, Nath S, Koziarz A, et al. Biopsy versus subtotal versus gross total resection in patients with low-grade Glioma: A systematic review and meta-analysis. World

[5] Yordanova YN, Duffau H. Supratotal resection of diffuse gliomas—An overview of its multifaceted implications. Neurochirurgie. 2017;**63**(3):243-249. DOI: 10.1016/j.neuchi.

[6] Duffau H. A new philosophy in surgery for diffuse low-grade glioma (DLGG): Oncological and functional outcomes. Neurochirurgie. 2013;**59**(1):2-8. DOI: 10.1016/j.neuchi.

[7] Hardesty DA, Sanai N. The value of glioma extent of resection in the modern neurosur-

gical era. Frontiers in Neurology. 2012;**3**:140. DOI: 10.3389/fneur.2012.00140

, Bilal Imširović<sup>5</sup>

1 Department of Neurosurgery, Sarajevo University Clinical Center, Sarajevo,

2 Department of General Practice, Health Centers of Sarajevo Canton, Sarajevo,

3 Department of Oncology, Sarajevo University Clinical Center, Sarajevo,

4 Department of Pathology, Sarajevo University Clinical Center, Sarajevo,

6 Department of Neurology, Sarajevo University Clinical Center, Sarajevo,

613-621. DOI: 10.1016/j.cancergen.2012.10.009

2016;**131**(6):803-820. DOI: 10.1007/s00401-016-1545-1

org/nobel\_prizes/physics/laureates/1952/ [Accessed: 01-03-2018]

Neurosurgery. 2018;**120**:e762-e775. DOI: 10.1016/j.wneu.2018.08.163

, Bekir Rovčanin2

and Enra Suljić<sup>6</sup>

,

http://dx.doi.org/10.5772/intechopen.82603

Neurosurgical Options for Glioma

161

"Oncofunctional balance" is the term used by Duffau to illustrate the approach to glioma resection through interaction with the patient to determine the best therapeutic sequence according to the patient's needs [31]. Intraoperative electrostimulation is used during the awake glioma surgery, which allows studying interactions between the natural history of tumor and the brain reorganization. With this approach, we are able to preserve the eloquent functions of the brain. Each patient who will undergo supratotal resection should be informed about possible deterioration of the eloquent functions, which of them are most important to him/her to achieve maximal oncofunctional balance. With this approach, glioma surgery becomes an individual surgery, especially designed for each patient.
