The Relationship Between Jugular Foramen Schwannoma and Surrounding Membrane Structures and Its Surgical Application.

Abstract

Background and objectives: Surgical resection of jugular foramen (JF) schwannomas with minimal neurological complications is challenging because of their difficult-to-access location and complex relationships with surrounding neurovascular structures, even for experienced neurosurgeons. In this article, we elucidate the membranous anatomy of JF schwannomas, with the aim of reducing iatrogenic injury to the lower cranial nerves (LCNs) during surgery.

Methods: The clinical data of 31 consecutive patients with JF schwannomas were reviewed. The relationship between the tumor and the surrounding membranous structures was observed during dissection. Samples were analyzed using Masson's trichrome and immunofluorescence staining to study the membranous characteristics. Histological-radiographic correlations were also summarized.

Results: In this series, we found that all 3 type B, 2 type C, and 8 type D tumors (according to the Kaye-Pellet grading system) were entirely extradural in location, whereas the 18 type A tumors could be subdural (9 cases) or extradural (9 cases), which frequently could not be predicted preoperatively based on whether the tumor had intraforaminal extension. The dural capsule, when present, could be used as an insulating layer to protect LCNs. With this subcapsular dissection technique, postoperative LCN dysfunction occurred in 10 patients (32.3%), which was usually temporary and mild.

Conclusion: The different relationships between the tumor and membranous structures of the JF is related to the distinct point of tumor origin and the complex anatomy of the meningeal dura within the JF. Subcapsular dissection technique is recommended for better preservation of LCNs when the dural capsule is identified.