Increasing interest in the quality of life of patients after treatment of brain tumors has led to the exploration of methods that can improve intraoperative assessment of neurological status to avoid neurological deficits. The only method that can provide assessment of all eloquent areas of cerebral cortex and white matter is brain mapping during awake craniotomy. This method helps ensure that the quality of life and the neuro-oncological result of treatment are not compromised. Apart from the medical aspects of awake surgery, its economic issues are also favorable. Here, we review the main aspects of awake brain tumor surgery. Neurosurgical, neuropsychological, neurophysiological and anesthetic issues are briefly discussed.

The aim of this literature review is to present a summary of the published literature relating the details of the different modifications of specimen preparation for white matter dissection with the Klingler technique. For this review, 3 independent investigators performed an electronic literature search that was carried out in the Pubmed, Scopus and Web of Science databses up to December 2019. Furthermore, we performed citation tracking for the articles missed in the initial search. Studies were eligible for inclusion when they reported details of at least the first 2 main steps of Klingler’s technique: fixation and freezing. A total of 37 full-text articles were included in the analysis. We included original anatomical studies in which human white matter dissection was performed for study purposes. The main three steps of preparation are the same in each laboratory, but the details of each vary between studies. Ten percent formalin is the most commonly used (34 studies) solution for fixation. The freezing time varied between 8 h and a month, and the temperature varied from − 5 to − 80 °C. After thawing and during dissections, the specimens were most often kept in formalin solution (13), and the concentration varied from 4 to 10%. Klingler’s preparation technique involves three main steps: fixation, freezing and thawing. Even though the details of the technique are different in most of the studies, all provide subjectively good quality specimens for anatomical dissections and studies.

The aim of the study is to determine which clinic, radiologic, and surgical characteristics of benign and atypical meningioma are associated with tumor progression. 335 patients who underwent gross-total resection of intracranial benign and atypical meningiomas between 2000 and 2009 were followed during the period of at least 3 years. Clinical, radiological and surgical features possibly associated with progression-free survival and influencing tumor recurrence were assessed. 291 lesions were benign (WHO Grade I) and 44 were atypical (WHO Grade II). In the median follow-up period of 82 months 34 meningiomas recurred. The 3-, 5- and 10-year progression-free survival (PFS) rates for benign and atypical tumors were 99.7 and 81.4%, 97.5 and 69.7%, 87.5 and 69.7%, respectively. In a Kaplan-Meier analysis subpial plane of surgical dissection (pial invasion) was associated with increased tumor progression both in benign (p=0.0084) and atypical cohort (p=0.0104), and bone involvement (p=0.0033) and peritumoral brain edema (p=0.0073) were associated with increased tumor progression only in atypical meningiomas. In a multivariate analysis pial invasion and WHO Grade II type were significantly associated with tumor recurrence. All recurrences in atypical meningioma group occurred within 4 years of the surgical resection. Pial invasion is an important predictor of tumor recurrence in benign and atypical meningiomas. In atypical meningiomas bone involvement and large peritumoral brain edema are associated with increased tumor progression.

Among pineal region lesions meningiomas are extremely rare and include falcotentorial and velum interpositum meningiomas. It is very difficult to discriminate between these two lesions and description of the clinical presentation and the surgical technique in approaching these tumors is limited. We respectively analyzed a series of patients harboring pineal region meningiomas with regard to clinical features, neuroimaging studies, and results of surgical treatment. Clinical data of 5 women and 1 man with pineal region meningiomas treated between January 1993 and December 2012 were retrospectively reviewed. All patients were assessed preoperatively with MRI and cerebral angiography. The only surgical approach we used was occipital transtentorial route. There were four falcotentorial and two velum interpositum meningiomas. The main presenting symptom was headache, dizziness and gait disturbance. The angiogram revealed that these tumors were fed by tentorial artery, posterior choroidal arteries, and branches of the posterior cerebral artery and in four cases additional evidence of occlusion of the galenic venous system was seen. Two patients had total resection (Simpson Grade I and Grade II) and in four patients small remnants of tumor were left (Simpson Grade III). No death occurred in this series. The most common complication after surgery was homonymous hemianopsia which fully recovered in all patients in the follow-up. The falcotentorial and velum interpositum meningiomas can be safely managed with the use of occipital transtentorial approach. Homonymous hemianopsia is the most common although always transient complication of surgery.

The insula is a lobe located deep in each hemisphere of the brain and is surrounded by eloquent cortical, white matter, and basal ganglia structures. The aim of this study was to provide an anatomical description of the insula and white matter tracts related to surgical treatment of gliomas through a transcortical approach. The study also discusses surgical implications in terms of intraoperative brain mapping. Five adult brains were prepared according to the Klingler technique. Cortical anatomy was evaluated with the naked eye, whereas white matter dissection was performed with the use of a microscope. The widest exposure of the insular surface was noted through the temporal operculum, mainly in zones III and IV according to the Berger-Sanai classification. By going through the pars triangularis in all cases, the anterior insular point and most of zone I were exposed. The narrowest and deepest operating field was observed by going through the parietal operculum. This method provided a suitable approach to zone II, where the corticospinal tract is not covered by the basal ganglia and is exposed just under the superior limiting sulcus. At the subcortical level, the identification of the inferior frontoocipital fasciculus at the level of the limen insulae is critical in terms of preserving the lenticulostriate arteries. Detailed knowledge of the anatomy of the insula and subcortical white matter that is exposed through each operculum is essential in preoperative planning as well as in the intraoperative decision-making process in terms of intraoperative brain mapping.