Our Management of Vestibular Schwannomas and Review of Literatures

There is no a clear consensus provided in the literature and there remain controversial on the treatment especially for small to medium size Vestibular schwannomas (VSs). Thus the treatment technique and approach preference vary from centre to centre. This problem too exists in our centre. The purpose of this paper is to develop a consensus in our hospital among our colleagues on the treatment of our VSs patients. We have been treating VSs patient by translabyrinthine approach from time to time for the last 5 years and found it to be a very efficient approach. This approach gives the most direct route to the tumor with excellent exposure of the internal acoustic meatus, cerebropontine angle (CPA) area without the need to retract the brain with facial nerve totally in control early in the surgery. The only problem was, when there is large posterior fossa component of the tumor present. This approach is safe with direct exposure to CPA area and have minimum intraoperative or postoperative complications.

The Long-Term Outcome of CyberKnife-Based Stereotactic Radiotherapy for Intra/ Extracranial Non-Vestibular Schwannomas: A Single-Center Experience

The long-term outcomes of CyberKnife-based hypofractionated stereotactic radiotherapy (SRT) for intra/ extracranial non-vestibular schwannomas (nVS) need to be accumulated. Patients who received SRT by CyberKnife for nVS from 2010 to 2019 were retrospectively reviewed. A total of 45 patients with nVS were identified. The mean age was 53 (± 18) years old, and 23 patients (51%) were female. Twenty-nine patients (64%) had previous procedures. As for the tumor extension, 22 (49%) nVS were classified as primary intracranial, five (11%) were classified as intra/ extracranial (dumbbell shape), and 18 (40%) were classified as primary extracranial. The median prescribed dose, covering 95% of the planning target volume, was 21 (IQR 21 – 25) Gy, and the median target volume was 7 (IQR 3.6-13.1) cm3. The local control rate of nVS for patients without neurofibromatosis type 2 (NF2) was 100%. Old age (OR 0.92, p-value 0.03) and previous surgery (OR 0.02, p-value 0.02) were significant risk factors for no symptomatic improvement. The progression-free survival was 74 (±33) months clinically and 69 (IQR 36 – 94) months radiologically. During follow-up, two cases (4%) with NF2 resulted in treatment failure, 13 cases (41%) resulted in transient tumor expansion (TTE), 10 (22%) suffered from transient adverse radiation effect (ARE), and two (4%) resulted in permanent ARE. Hypofractionated SRT by CyberKnife for head, neck, and spine nVS was an effective treatment regardless of tumor extension relative to the cranium. Although the risk of permanent ARE was low, some patients experienced transient clinical worsening due to TTE.

Histopathological Investigation of Dura-Like Membrane in Vestibular Schwannomas

The dura-like membrane (DLM) is an outermost membranous structure arising from the dura mater adjacent to the internal auditory meatus (IAM) that envelops some vestibular schwannomas (VSs). Its recognition is important for the preservation of the facial and cochlear nerves during tumor resection. This study analyzes the histopathological characteristics of the DLM. The expression of CD34 and αSMA was histopathologically analyzed in tumor and DLM tissue of 10 primary VSs with and without a DLM. Tumor volume, resection volume percentage, microvessel density (MVD), and vessel diameter were analyzed. Volumetric analysis revealed that the presence of a DLM was significantly associated with lower tumor resection volume (p < 0.05). Intratumoral vessel diameter was significantly larger in the DLM group than the non-DLM group (p < 0.01). Larger VSs showed a higher intratumoral MVD in the DLM group (p < 0.05). Multilayered αSMA-positive vessels were identified in the DLM, tumor, and border; there tended to be more of these vessels within the tumor in the DLM group compared to the non-DLM group (p = 0.08). These arteriogenic characteristics suggest that the DLM is formed as the tumor induces feeding vessels from the dura mater around the IAM.