Delayed symptomatic cerebral vasospasm after transsphenoidal resection of pituitary adenoma.

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Subtemporal Approach and Its Infratentorial Extension: Review and a Comparative Analysis of Different Techniques.

Introduction Surgical resection of lesions occupying the incisural space is challenging. In a comparative fashion, we aimed to describe the anatomy and surgical approaches to the tentorial incisura and to the rostral brainstem via the intradural subtemporal approach and its infratentorial extensions. Methods Six fresh human head specimens (12 sides) were prepared for the microscopic dissection of the tentorial incisura using the intradural subtemporal approach and its infratentorial extensions. Endoscope was used to examine the anatomy of the region inadequately exposed with the microscope. Image-guided navigation was used to confirm bony structures visualized around the petrous apex. Results Standard subtemporal approach provides surgical access to the supratentorial brainstem above the pontomesencephalic sulcus and to the lateral surface of the cerebral peduncle. The linear or triangular tentorial divisions can provide access to the infratentorial space below the pontomesencephalic sulcus. The triangular tentorial flap in comparison with the linear incision obstructs the exposure of anterior incisural space and of the prepontine cistern. Visualization of the brainstem below the trigeminal nerve can be achieved by the anterior petrosectomy. Conclusion Infratentorial extension of the intradural subtemporal approach is technically demanding due to critical neurovascular structures and a relatively narrow corridor. In-depth anatomical knowledge is essential for the selection of the appropriate operative approach and safe surgical resections of lesions.

Cortical and white matter anatomy relevant for the lateral and superior approaches to resect intraaxial lesions within the frontal lobe.

Despite being associated with high-order neurocognitive functions, the frontal lobe plays an important role in core neurological functions, such as motor and language functions. The aim of this study was to present a neurosurgical perspective of the cortical and subcortical anatomy of the frontal lobe in terms of surgical treatment of intraaxial frontal lobe lesions. We also discuss the results of direct brain mapping when awake craniotomy is performed. Ten adult cerebral hemispheres were prepared for white matter dissection according to the Klingler technique. Intraaxial frontal lobe lesions are approached with a superior or lateral trajectory during awake conditions. The highly eloquent cortex within the frontal lobe is identified within the inferior frontal gyrus (IFG) and precentral gyrus. The trajectory of the approach is mainly related to the position of the lesion in relation to the arcuate fascicle/superior longitudinal fascicle complex and ventricular system. Knowledge of the cortical and subcortical anatomy and its function within the frontal lobe is essential for preoperative planning and predicting the risk of immediate and long-term postoperative deficits. This allows surgeons to properly set the extent of the resection and type of approach during preoperative planning.

Anatomical aspects of the insula, opercula and peri-insular white matter for a transcortical approach to insular glioma resection.

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.

Cortical and Subcortical Anatomy of the Parietal Lobe From the Neurosurgical Perspective.

Introduction: The anatomical structures of the parietal lobe at the cortical and subcortical levels are related mainly to sensory, visuospatial, visual and language function. The aim of this study was to present an intraoperative perspective of these critical structures in terms of the surgical treatment of intra-axial lesions. The study also discusses the results of the technique and the results of direct brain stimulation under awake conditions. Materials and Methods: Five adult brains were prepared according to the Klingler technique. Cortical assessments and all measurements were performed with the naked eye, while white matter dissection was performed with microscopic magnification. Results: Intra-axial lesions within the parietal lobe can be approached through a lateral or superior trajectory. This decision is based on the location of the lesions in relation to the arcuate fascicle/superior longitudinal fascicle (AF/SLF) complex and ventricular system. Regardless of the approach, the functional borders of the resection are defined by the postcentral gyrus anteriorly and Wernicke's speech area inferiorly. On the subcortical level, active identification of the AF/SLF complex and of the optic radiation within the sagittal stratum should be performed. The intraparietal sulcus (IPS) is a reliable landmark for the AF/SLF complex in ~60% of cases. Conclusion: Knowledge of the cortical and subcortical anatomical and functional borders of the resection is crucial in preoperative planning, prediction of the risk of postoperative deficits, and intraoperative decision making.

Utility of preoperative electrophysiological testing of the facial nerve in patients with vestibular schwannoma.

PURPOSE: The aim of this study was to analyze the utility of various preoperative electrophysiological tests of the facial nerve CNVII in predicting CNVII function after vestibular schwannoma surgery. METHODS: This retrospective study included 176 patients who had preoperative facial nerve electroneurography and electrically evoked blink reflex testing. We defined the following variables: axonal degeneration of CNVII (AD-CNVII), trigeminal nerve damage (D-CNV), disturbances in the short-latency pathway of the blink reflex (D-BR), and any changes in electrophysiological test results (A-EMG). RESULTS: AD-CNVII, D-CNV, D-BR, and A-EMG were noted in 24%, 10%, 64%, and 71% of the patients, respectively. Negative D-CNV correlated with good CNVII function in early (p = 0.005) and long-term follow-up (p = 0.003) but was not an independent prognostic factor for postoperative facial muscles function. D-CNV appeared to be closely related to tumor size. D-BR was related to tumor size and had no predictive value. AD-CNVII (amplitude reduction of 50% or more compared to the healthy side) was an independent factor associated with increased risk of facial muscles weakness (p = 0.015 and p = 0.031 for early and late outcomes, respectively). CONCLUSIONS: Further studies are needed to establish which tests and cut-off values are the most useful for predicting post-surgical facial nerve function.

Clinical Course and Results of Surgery for Chronic Subdural Hematomas in Patients on Drugs Affecting Hemostasis.

OBJECTIVE: An apparent increase of use of drugs affecting hemostasis in our neurosurgical department since the 1990s has encouraged us to investigate whether these drugs influence the clinical course and results of surgery for chronic subdural hematoma (CSDH). METHODS: This retrospective analysis included 178 patients admitted for CSDH from 2007 to 2011 who were divided into two groups: on drugs affecting hemostasis (40; 22%) and no bleeding disorders (138; 78%). Medications in the first group included oral anticoagulants (33; 82.5%), antiplatelets (5; 12.5%) and low molecular weight heparins (2; 5%). RESULTS: The patients on drugs affecting hemostasis were older (74.3±7.4 vs. 68.4±14.8; p-value 0.01) and the group without bleeding disorders had more head trauma history (61% vs. 38%, p-value 0.01). The groups did not differ in bilateral hematoma rates (25% vs. 20%, p-value=NS). At diagnosis, mean hematoma thickness was lower in patients on drugs affecting hemostasis (18.7±7.4 mm vs. 21.9±7.9 mm, p-value<0.01). Average stay of hospital was 1 day longer in patients on drugs affecting hemostasis (11.7±4.1 vs.10.9±5.3, p-value=NS) and was related to the necessity of bleeding disorder reversal. Mean neurological status at presentation was similar between the groups (p-value=NS) as was the likelihood of hematoma recurrence (p-value=NS). Glasgow Outcome Scale results were comparable. CONCLUSION: Patients on drugs affecting hemostasis are less often aware of a head trauma history, possibly suggesting a higher CSDH risk after minor trauma in this group. In these patients, smaller hematomas are symptomatic, probably due to faster hematoma formation. Drugs affecting hemostasis do not affect treatment results.