Endoscopic approach-routes in the posterior fossa cisterns through the retrosigmoid keyhole craniotomy: an anatomical study.

Endoscopy in cerebellopontine angle surgery is an increasingly used technique. Despite of its advantages, the shortcomings arising from the complex anatomy of the posterior fossa are still preventing its widespread use. To overcome these drawbacks, the goal of this study was to define the anatomy of different endoscopic approaches through the retrosigmoid craniotomy and their limitations by surgical windows. Anatomical dissections were performed on 25 fresh human cadavers to describe the main approach-routes. Surgical windows are spaces surrounded by neurovascular structures acting as a natural frame and providing access to deeper structures. The approach-routes are trajectories starting at the craniotomy and pointing to the lesion, passing through certain windows. Twelve different windows could be identified along four endoscopic approach-routes. The superior route provides access to the structures of the upper pons, lower mesencephalon, and the upper neurovascular complex through the suprameatal, superior cerebellar, and infratrigeminal windows. The supratentorial route leads to the basilar tip and some of the suprasellar structures via the ipsi- and contralateral oculomotor and dorsum sellae windows. The central endoscopic route provides access to the middle pons and the middle neurovascular complex through the inframeatal, AICA, and basilar windows. The inferior endoscopic route is the pathway to the medulla oblongata and the lower neurovascular complex through the accessory, hypoglossal, and foramen magnum windows. The anatomy and limitations of each surgical windows were described in detail. These informations are essential for safe application of endoscopy in posterior fossa surgery through the retrosigmoid approach.

Endoscopic surgery for tumors of the pineal region via a paramedian infratentorial supracerebellar keyhole approach (PISKA).

The tumors of the pineal region represent a significant challenge in terms of patient selection and surgical approach. Traditional surgical options were commonly used to approach this area causing considerable surgical morbidity and mortality. We report for the first time on a series of endoscopic procedures for lesions of the pineal region performed via an infratentorial supracerebellar keyhole approach (PISKA) in the prone position using endoscope-assisted and endoscope-controlled technique. A single-institution series of 11 consecutive patients (five male and six female patients [11 total cases]; mean age 21 years, range 1-75 years) treated via the endoscope-assisted and endoscope-controlled PISKA for a pathological entity in the pineal region was retrospectively reviewed. The mean follow-up time was 24 months. The endoscopic PISKA was successfully used to approach a variety of pineal lesions, including pineocytoma (three patients), pineal cysts (four patients), germinoma, lipoma, medulloblastoma, and glioblastoma (one patient each). Gross total resection was achieved in ten cases and subtotal resection in one case. The mean preoperative tumor volumes were approximately 2 × 2 cm. Five patients developed postoperatively transient Parinaud's syndrome. One patient underwent surgical revision for cerebrospinal fluid leak. There was no mortality. Ten patients had an uneventful postoperative course with restitutio ad integrum after a mean follow-up duration of 13.5 months. The endoscopically PISKA is a safe and effective minimally invasive approach that enables endoscopic treatment of different lesions of the pineal region with comparable results to standard microsurgical technique but less morbidity.

Feasibility and accuracy of a voxel-based neuronavigation system with 3D image rendering in preoperative planning and as a learning tool for young neurosurgeons, exemplified by the anatomical localization of the superior sagittal sinus.

It is essential for a neurosurgeon to know individual anatomy and the corresponding anatomical landmarks before starting a surgery. Continuous training, especially of young neurosurgeons, is crucial for understanding complex neuroanatomy. In this study, we used a neuronavigation system with 3D volumetric image rendering to determine the anatomical relationship between the sagittal suture and the superior sagittal sinus (SSS) in patients with intracranial lesions. Furthermore, we discussed the applicability of such system in preoperative planning, residency training, and research. The study included 30 adult patients (18 female/12 male) who underwent a cranial computed tomography (CT) scan combined with venous angiography, for preoperative planning. The position of the sagittal suture in relation to the SSS was assessed in 3D CT images using an image guidance system (IGS) with 3D volumetric image rendering. Measurements were performed along the course of the sagittal sinus at the bregma, lambda, and in the middle between these two points. The SSS deviated to the right side of the sagittal suture in 50% of cases at the bregma, and in 46.7% at the midpoint and lambda. The SSS was displaced to the left of the sagittal suture in 10% of cases at the bregma and lambda and in 13% at the midpoint. IGSs with 3D volumetric image rendering enable simultaneous visualization of bony surfaces, soft tissue and vascular structures and interactive modulation of tissue transparency. They can be used in preoperative planning and intraoperative guidance to validate external landmarks and to determine anatomical relationships. In addition, 3D IGSs can be utilized for training of surgical residents and for research in anatomy.

Supraorbital Keyhole Approach to the Skull Base: Evaluation of Complications Related to CSF Fistulas and Opened Frontal Sinus.

AIM: Cerebrospinal fluid (CSF) rhinorrhea due to a breach in the frontal sinus (FS) presents one of the main postoperative complications of the supraorbital keyhole approach. The goal of this study was to further analyze the actual surgical morbidity and potential risk for patients due to an opened FS after a surgery via a supraorbital craniotomy and compare the results with data published in the current literature. METHODS AND PATIENTS: A total of 350 consecutive patients who underwent surgeries via the supraorbital keyhole approach for various lesions were included in this retrospective study. Information on clinical history, neurologic symptoms, surgical approach, and postoperative complications was obtained retrospectively by a review of the patients' charts, the radiologic reports, and a thorough review of pre- and postoperative cranial computed tomography (CCT) imaging. RESULTS: The frequency of CSF rhinorrhea after this type of craniotomy in the literature is reported to range between 0% and 9.1%. In this study, analysis of postoperative CCT scans revealed that 88 patients (25.1%) showed a radiographic breach of the FS. Only 8 of these patients (2.3%) developed a CSF leak with rhinorrhea postoperatively. In all cases conservative treatment with lumbar drainage failed, and therefore a surgical revision for permanent closure was required. Only one patient (0.3%) with a CSF leak also developed meningitis. CONCLUSION: Inadvertent opening of the FS during the supraorbital craniotomy is a common surgery-related morbidity; however, the risk for the patient to develop a potentially dangerous meningitis was found to be minimal.

Evaluation of a 3-dimensional voxel-based neuronavigation system with perspective image rendering for keyhole approaches to the skull base: an anatomical study.

BACKGROUND: Keeping track of the endoscope tip in 3 planes (axial, coronal, and sagittal) while performing skull base surgeries can be difficult because the surgeon is focused most on the live video images of the endoscope. For that reason, it was the aim of this anatomical cadaver study to evaluate the usefulness of a voxel-based neuronavigation system with 3-dimensional (3D) perspective image rendering for endoscopic procedures through keyhole approaches to the skull base. METHODS: On 5 whole-body fixed cadavers, frontolateral and retrosigmoid approaches were performed bilaterally using a neuronavigation system with 3D perspective image rendering (Cbyon, Med-Surgical Services Inc., Sunnyvale, California). Target points defined on the selected target structures were approached with the navigated ∅ 4-mm 0° endoscope (Storz, Tuttlingen, Germany). Using an Endocameleon 4-mm rigid endoscope capable of changing its angle of view while remaining stationary, the surgical field was checked for injuries before and after insertion of the navigated 0° endoscope. RESULTS: The median neuronavigation registration error was 0.95 mm (range 0.6 to 1.2 mm). Evaluation showed that 100% of the defined targets were reached and visualized. Neither a target structure nor neurovascular structures or surrounding brain tissue were injured by the navigated 0° endoscope. CONCLUSIONS: A neuronavigation system with 3D voxel-based perspective image rendering could potentially improve safety during complex skull base surgeries, and possibly also help to improve surgical results. Such a system, however, cannot replace a neurosurgeon's experience nor surgical skill or anatomical knowledge. It is an excellent teaching tool for young neurosurgeons, but it also has some limitations. Therefore, clinical studies will be necessary to further evaluate the benefits of this type of neuronavigation system in a clinical setting.

Differential effects of the tumor necrosis factor alpha-blocker infliximab and etanercept on immunocompetent cells in vitro.

The tumor necrosis factor-alpha (TNFα) antagonists infliximab or etanercept are used in the management of chronic inflammatory disorders but have differences in clinical activity. Here we show that both have different effects on immunocompetent cells in vitro. Peripheral blood mononuclear cells (PBMC) from 20 healthy donors were incubated with infliximab or etanercept alone and in a co-culture with recall-antigens (BCG, tetanus toxoid [TT]). Expression of the activation marker CD69 on different PBMC-subpopulations was determined by flow cytometry, release of Th1-, Th2- and macrophage/monocyte-related cytokines into the supernatants by ELISA. There were strong inter-individual differences in reactivity of PBMC of the 20 donors towards infliximab and etanercept. On the whole group level, both enhanced IL-10 production but had opposite effects on the TNFα- and IFNγ-secretion; Th2-cytokine-secretion (IL-13, IL-5) was differentially influenced. IL-13 production was significantly reduced by infliximab but not by etanercept. IL-5 secretion was strongly enhanced in individual subjects but was not significantly influenced on the whole group level. Etanercept but not infliximab significantly decreased the CD69-expression by CD8+ T- and CD56+ natural killer(NK)-cells. Co-culture with recall antigens enhanced most of these reactions. Our data indicate that individual predisposition and immunological reactivity may be an important factor influencing the therapeutic efficacy of anti-TNFα agents.