Objectives: Intraoperative tumor visualization with 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence is widely applied for improved resection of high-grade gliomas. However, visible fluorescence is present only in a minority of low-grade gliomas (LGGs) according to current literature. Nowadays, antiepileptic drugs (AEDs) are frequently administered to LGG patients prior to surgery. A recent in-vitro study demonstrated that AEDs result in significant reduction of PpIX synthesis in glioma cells. The aim of this study was thus to investigate the role of 5-ALA fluorescence in LGG surgery and the influence of AEDs on visible fluorescence. Patients and Methods: Patients with resection of a newly diagnosed suspected LGG after 5-ALA (25 mg/kg) administration were initially included. During surgery, the presence of visible fluorescence (none, mild, moderate, or bright) within the tumor and intratumoral fluorescence homogeneity (diffuse or focal) were analyzed. Tissue samples from fluorescing and/or non-fluorescing areas within the tumor and/or the assumed tumor border were collected for histopathological analysis (WHO tumor diagnosis, cell density, and proliferation rate). Only patients with diagnosis of LGG after surgery remained in the final study cohort. In each patient, the potential preoperative intake of AEDs was investigated. Results: Altogether, 27 patients with a histopathologically confirmed LGG (14 diffuse astrocytomas, 6 oligodendrogliomas, 4 pilocytic astrocytomas, 2 gemistocytic astrocytomas, and one desmoplastic infantile ganglioglioma) were finally included. Visible fluorescence was detected in 14 (52%) of 27. In terms of fluorescence homogeneity ( n = 14), 7 tumors showed diffuse fluorescence, while in 7 gliomas focal fluorescence was noted. Cell density ( p = 0.03) and proliferation rate ( p = 0.04) was significantly higher in fluorescence-positive than in fluorescence-negative samples. Furthermore, 15 (56%) of 27 patients were taking AEDs before surgery. Of these, 11 patients (73%) showed no visible fluorescence. In contrast, 10 (83%) of 12 patients without prior AEDs intake showed visible fluorescence. Thus, visible fluorescence was significantly more common in patients without AEDs compared to patients with preoperative AED intake (OR = 0,15 (CI 95% 0.012–1.07), p = 0.046). Conclusions: Our study shows a markedly higher rate of visible fluorescence in a series of LGGs compared to current literature. According to our preliminary data, preoperative intake of AEDs seems to reduce the presence of visible fluorescence in such tumors and should thus be taken into account in the clinical setting.

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Meningioma is a well fluorescent tumor, with the technique sensitivity being 94.1%. In some cases, the use of fluorescence diagnostics in surgery of meningiomas improves identification of residual tumor fragments and enables correction of a surgical approach. To assess the effect of fluorescence diagnostics on the recurrence rate and disease-free duration, further research is required.

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Surgery of intracerebral tumors involving long association fibers is a challenge. In this study, we analyze the results of intraoperative mapping of the superior longitudinal, arcuate, and frontal aslant tracts in surgery of brain gliomas. Purpose. The study purpose was to compare the results of intraoperative mapping and the postoperative speech function in patients with gliomas of the premotor area of the speech-dominant frontal lobe, which involved the superior longitudinal, arcuate, and frontal aslant tracts, who were operated on using awake craniotomy. Material and methods. Twelve patients with left frontal lobe gliomas were operated on: 11 patients were right-handed, and one patient was a left-hander retrained at an early age. Histological types of tumors were represented by Grade II diffuse astrocytomas (6 patients), Grade III anaplastic astrocytomas (1 patient), Grade IV glioblastoma (1 patient), Grade II oligodendroglioma (1 patient), and Grade III anaplastic oligodendrogliomas (3 patients). The mean age of patients was 45 (29-67) years; there were 6 males and 6 females. All patients underwent preoperative and postoperative MRI with reconstruction of the long association fibers and determination of the topographic anatomical relationships between the fibers and the tumor. Surgery was performed using the asleep-awake-asleep protocol with intraoperative awakening of patients. All patients underwent cortical and subcortical electrophysiological stimulation to control the localization of eloquent structures and to clarify the safe limits of resection. For intraoperative speech monitoring, a computerized naming test was used with naming of nouns or verbs, and automatic speech was evaluated (counting from 1 to 10, enumeration of months and days of the week), which was complemented by a talk with the patient. Speech disorders before, during, and after surgery were evaluated by a neuropsychologist. The mean current strength during direct electrical stimulation was 3 (1.9-6.5) mA. Results. The association fibers were intraoperatively identified in all patients (SLF/AF in 11 patients; FAT in one patient). In 4 patients, the cortical motor speech area was intraoperatively mapped; in three cases, tumor resection was accompanied by speech disturbances outside the stimulation. During direct electrical stimulation, speech disturbances developed in 7 of 12 cases. All patients underwent control MRI within the first 48-72 h: total resection (more than 90% of the tumor) was performed in 7 cases; subtotal resection was achieved in two patients; partial resection was performed in two cases. According to postoperative MR tractography, the resected tumor bed was adjacent to the SLF/AF complex in 7 cases, located near the SLF/AF complex in three cases, and adjacent to the FAT in two cases. Postoperatively, 11 out of 12 patients had worsening of neurological symptoms in the form of various speech disturbances. In one patient, speech disturbances developed 2 days after surgery, which was associated with an increase in edema. On e...