Yasser Jeelani, Abdulkerim Gokoglu, Tomer Anor, Ossama Al-Mefty and Alan R. Cohen
Conventional approaches to the atrium of the lateral ventricle may be associated with complications related to direct cortical injury or brain retraction. The authors describe a novel approach to the atrium through a retrosigmoid transtentorial transcollateral sulcus corridor.
Bilateral retrosigmoid craniotomies were performed on 4 formalin-fixed, colored latex–injected human cadaver heads (a total of 8 approaches). Microsurgical dissections were performed under 3× to 24× magnification, and endoscopic visualization was provided by 0° and 30° rigid endoscope lens systems. Image guidance was provided by coupling an electromagnetic tracking system with an open source software platform. Objective measurements on cortical thickness traversed and total depth of exposure were recorded. Additionally, the basal occipitotemporal surfaces of 10 separate cerebral hemisphere specimens were examined to define the surface topography of sulci and gyri, with attention to the appearance and anatomical patterns and variations of the collateral sulcus and the surrounding gyri.
The retrosigmoid approach allowed for clear visualization of the basal occipitotemporal surface. The collateral sulcus was identified and permitted easy endoscopic access to the ventricular atrium. The conical corridor thus obtained provided an average base working area of 3.9 cm2 at an average depth of 4.5 cm. The mean cortical thickness traversed to enter the ventricle was 1.4 cm. The intraventricular anatomy of the ipsilateral ventricle was defined clearly in all 8 exposures in this manner. The anatomy of the basal occipitotemporal surface, observed in a total of 18 hemispheres, showed a consistent pattern, with the collateral sulcus abutted by the parahippocampal gyrus medially, and the fusiform and lingual gyrus laterally. The collateral sulcus was found to be caudally bifurcated in 14 of the 18 specimens.
The retrosigmoid supracerebellar transtentorial transcollateral sulcus approach is technically feasible. This approach has the potential advantage of providing a short and direct path to the atrium, hence avoiding violation of deep neurovascular structures and preserving eloquent areas. Although this approach appears unconventional, it may provide a minimally invasive option for the surgical management of selected lesions within the atrium of the lateral ventricle.
Emad Aboud, Mohammad Abolfotoh, Svetlana Pravdenkova, Abdulkerim Gokoglu, Murat Gokden and Ossama Al-Mefty
Epidermoid tumors arise from misplaced squamous epithelium and enlarge through the accumulation of desquamated cell debris. Optimal treatment consists of total removal of the capsule; therefore, giant and multicompartmental tumors are particularly challenging. A conservative attitude in handling the tumor capsule is common given concerns about capsule adherence to neurovascular structures, and thus the possibility of recurrence is accepted with the intent of minimizing complications. This study focuses on the outcome of surgery in patients with giant epidermoid tumors for which total capsule removal was the aim.
The authors conducted a retrospective analysis of all patients with giant epidermoid tumors treated by the senior author (O.A.), who pursued total removal of the capsule through skull base approaches. Patients were divided into 2 groups: one including patients with de novo tumors and the other consisting of patients who presented with recurrent tumors.
Thirty-four patients had undergone 46 operations, and the senior author performed 38 of these operations in the study period. The average tumor dimensions were 55 × 36 mm, and 25 tumors had multicompartmental extensions. Total removal of the tumor and capsule was achieved with the aid of the microscope in 73% of the 26 de novo cases but in only 17% of the 12 recurrent tumor cases. The average follow-up among all patients was 111 months (range 10–480 months), and the average postsurgical follow-up was 56.8 months (range 6–137 months). There were 4 recurrences in the de novo group, and every case had had a small piece of tumor capsule left behind. One patient died after delayed rupture of a pseudoaneurysm. In the de novo group, the average preoperative Karnofsky Performance Scale (KPS) score was 71.42%, which improved to 87.14% on long-term follow-up. In the group with recurrences, the KPS score also improved on long-term follow-up, from 64.54% to 84.54%. In the de novo group, 3 cases (11.5%) had permanent cranial nerve deficits, and 4 cases (15.4%) had a CSF leak. In the recurrence group, 3 cases (25%) had new, permanent cranial nerve deficits, and 1 (8.3%) had a CSF leak. Two patients in this group developed hydrocephalus and required a shunt.
Total removal of the capsule of giant epidermoid tumors was achieved in 73% of patients with de novo tumors and was associated with improved function, low morbidity and mortality, and a lower risk of recurrence. Surgery in patients with recurrent tumors was associated with higher morbidity and persistence of the disease.