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.

Dural arteriovenous fistulas (DAVF) involving the anterior and posterior condylar vein at the skull base are rare but important to recognize. Due to the highly variable anatomy of the venous system of the skull base, detailed anatomical knowledge is essential for correct diagnosis and appropriate treatment of these lesions. In this report we review the normal anatomy of the condylar veins and describe rare and, to our knowledge, not previously reported anatomical variants. We also highlight the treatment modalities for these lesions with focus on the endovascular transvenous occlusion based on four consecutive cases from our center.

Abstract:Minimally invasive neurosurgery requires a detailed knowledge of microstructures, such as the arachnoid membranes. In spite of many articles addressing arachnoid membranes, its detailed organization is still not well described. The aim of this study is to investigate the topography of the arachnoid in the anterior cranial fossa and the middle cranial fossa. Rigid endoscopes were introduced through defined keyhole craniotomies, to explore the arachnoid structures in 110 fresh human cadavers. We describe the topography and relationship to neurovascular structures and suggest an intuitive terminology of the arachnoid. We demonstrate an " arachnoid membrane system " , which consists of the outer arachnoid and 23 inner arachnoid membranes in the anterior fossa and the middle fossa. The inner membranes are arranged in two " arachnoid membrane groups " in the examined regions. The first is the carotid membrane group, located in the suprasellar region, consisting of seven paired and three unpaired inner membranes and the outer arachnoid on its base. The second is the Sylvian membrane group, composed of three inner membranes of the Sylvian fissure and completed by the outer arachnoid. Our findings should be very helpful in understanding the complex organization of the cranial arachnoid, which is mandatory for the safe and effective use of minimally invasive endoscopic techniques.

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