Investigation of the effects of Gamma Knife radiosurgery on optic pathways using diffusion tensor MRI within the first year after treatment.

PURPOSE: To investigate the radiation-induced effects of Gamma Knife radiosurgery (GKRS) for sellar-parasellar tumors on optic pathways using DTI parameters within the first year after treatment. METHODS: Twenty-five patients with sellar-parasellar tumors underwent MRI before and 3 months after GKRS, including T1WI, DTI, T2WI. Moreover, 21 patients underwent follow-up DTI 6-8 months after radiosurgery. ROIs were set on optic nerves, optic radiations, and control localizations; DTI parameters for each were calculated. Pre- and post-radiosurgery differences in DTI values were statistically compared and assessed with respect to tumor size changes. RESULTS: Following GKRS, DTI parameters, notably ADC, FA, and RD, showed statistically significant changes in optic nerves and anterior optic radiations. DTI changes were more significant in the group of cases with tumor shrinkage. In this group, DTI of the anterior optic radiations further deteriorated 3 months post-GKRS, whereas acute changes in DTI parameters of the optic nerves resolved within 6-8 months. DTI of central and posterior optic radiations did not differ significantly following radiosurgery; 6-8 months after radiosurgery, visual function was stable in 14 (56%) patients and improved in 11 (44%), showing no correlation with tumor size changes or DTI parameters. CONCLUSION: White Matter (WM) injury in the optic pathways can be induced by Gamma Knife radiosurgery targeted to sellar and parasellar tumors. Following GKRS, microstructural abnormalities occurred in the optic radiations as well as the optic nerves within the first post-treatment year. Our findings could support modifications to radiosurgical treatment strategies to minimize the risk of permanent WM injury.

Stereotactic radiosurgery for tumors of the pineal region: A single-center experience.

Tumors of the pineal region (TPRs) are rare neoplasms that are surgically challenging to resect. Conventional treatment strategies are available, but gamma knife radiosurgery (GKRS) is an alternative approach. This study presents a single-center experience with GKRS performed for TPR with and without histopathological diagnoses. The cases of 25 patients with TPRs treated with GKRS were retrospectively analyzed. Thirteen of these 25 patients had histopathological confirmation, and 13 had elevated serum alpha-fetoprotein and beta-human chorionic gonadotropin levels. The 25 patients had a mean follow-up duration of 61 months. The total response rate to GKRS was 60%, and a 53.8% decrease in the alpha-fetoprotein and beta human chorionic gonadotropin levels was observed. The findings of this study indicate that GKRS is a safe procedure for TPRs, even in the event of insufficient histopathological findings. This treatment approach provides increased Karnofsky performance scores and an extended life expectancy.

Dynamic contrast-enhanced magnetic resonance imaging for evaluating early response to radiosurgery in patients with vestibular schwannoma.

PURPOSE: This study aimed to use dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to evaluate early treatment response in vestibular schwannoma (VS) patients after radiosurgery. METHODS: Twenty-four VS patients who underwent gamma knife radiosurgery were prospectively followed up for at least four years. DCE-MRI sequences, in addition to standard MRI protocol, were obtained prior to radiosurgery, at 3 and 6 months. Conventionally, treatment responses based on tumor volume changes were classified as regression or stable (RS), transient tumor enlargement (TTE), and continuous tumor enlargement (CTE). DCE-MRI parameters, such as Ktrans, Kep and Ve, were compared according to follow-up periods and between groups. The diagnostic performance was tested using receiver operating characteristic (ROC) curves. RESULTS: Changes in tumor volume were as follows at the last 48 months of follow-up: RS in 11 patients (45.8%), TTE in 10 patients (41.7%), and CTE in three patients (12.5%). The median time required to distinguish TTE from CTE using conventional MRI was 12 months (range 9-18). The Ktrans and Ve were significantly decreased in patients with RS and TTE at 3 and 6 months, but did not differ significantly in patients with CTE. There were no significant differences in Ktrans and Ve between patients with RS and TTE at 3 and 6 months. Both Ktrans and Ve demonstrated high diagnostic performance in evaluating early treatment response to radiosurgery in patients with VS. CONCLUSION: DCE-MRI may aid in the monitoring and early prediction of treatment response in patients with VS following radiosurgery.

Reduced field of view under the surgical microscope due to personal protective equipment: lessons learned during the COVID-19 pandemic.

OBJECTIVE: During the coronavirus disease 2019 (COVID-19) pandemic, neurosurgeons all around the globe continue to operate in emergency cases using new self-protective measures. Personal protective equipment (PPE) use is recommended in all surgeries. The authors have experienced varying degrees of field of view (FOV) loss under the surgical microscope with different PPE. Herein, they aimed to investigate the effects of different PPE on FOV while using the surgical microscope. METHODS: Fifteen neurosurgeons and neurosurgery residents participated in this study. Three kinds of PPE (safety spectacles, blast goggles, and face shields) were tested while using a surgical microscope. FOV was measured using a 12 × 12-cm checkered sheet of paper on which every square had an area of 25 mm2 under the microscope. The surgical microscope was positioned perpendicular to the test paper, and the zoom was fixed. Each participant marked on the test sheet the peripheral borders of their FOV while using different PPE and without wearing any PPE. A one-way repeated-measures ANOVA was performed to determine if there was a significant difference in FOV values with the different PPE. RESULTS: FOV was significantly different between each PPE (F[3, 42] = 6339.845, p < 0.0005). Post hoc analysis revealed a significant decrease in the FOV from the naked eye (9305.33 ± 406.1 mm2) to blast goggles (2501.91 ± 176.5 mm2) and face shields (92.33 ± 6.4 mm2). There were no significant FOV changes with the safety spectacles (9267.45 ± 410.5 mm2). CONCLUSIONS: While operating under a surgical microscope safety spectacles provide favorable FOVs. Face shields increase the eye piece-pupil distance, which causes a severe reduction in FOV.

Behavioural and neurobiological consequences of 2 different chronic stressors in rats.

BACKGROUND/AIM: To compare the behavioural and neurobiological consequences of chronic headache and chronic mild stress (CMS) in rats. MATERIALS AND METHODS: Forty-eight male Wistar rats were divided into 4 groups: 1) control group, 2) chronic headache group, 3) CMS group, and 4) sham group. Their behaviour prior to (D0) and after (D14) chronic stress was analysed. Afterwards, they were exposed to the Elevated Plus Maze (EPM) in order to evaluate anxiety-like behaviour and the Forced Swim Test (FST) for observation of depressive-like behaviour. Ultrasonic vocalisations (USVs) were recorded by a USV detector system at DO and D14 and during the FST. The c-fos expressions in various brain regions were analysed 2 h after the EPM and FST. RESULTS: The control group showed significantly more sleeping behaviour at D14 (χ2 = 8.213, P = 0.042), emitted more negative and positive affect USVs at D14 (χ2 = 9.853, P = 0.020) and during FST (χ2 = 4.000, P = 0.046) than the chronic headache and CMS groups, and showed significantly less anxiety-like behaviour in the EPM than the CMS group (P = 0.021). CONCLUSION: These results suggest that CMS increases anxiety-like behaviour but not depressive-like behaviour, while chronic headache does not have a significant effect on these behaviours in rats.