A Novel Classification and Its Clinical Significance in Spinal Schwannoma Based on the Membranous Hierarchy

Abstract

BACKGROUND Spinal schwannoma is a common benign tumor. However, the high recurrence rate and incidence of surgical complications are unsolved problems. OBJECTIVE To propose a morphological classification of spinal schwannoma based on tumor-membrane relationships to increase the gross total resection (GTR) rate and to decrease the incidence of surgical complications. METHODS Histological techniques were used to study 7 adult cadavers. Following picrosirius staining, the membranes around the nerve root were observed under a microscope. Data from 101 patients with spinal schwannoma were also collected for clinical analysis. RESULTS The sleeve around the spinal nerve root consisted of dura and arachnoid tissues. The space between them gradually narrowed and fused at the proximal pole of the nerve root ganglion. Spinal schwannomas were divided into 4 types based on membranous structure: intrapial (type I), subarachnoidal (type II), intra- and extradural (type III), and extradural growth (type IV). Types II and III were further subdivided into 2 subtypes. GTR was achieved in all patients (100%), with no tumor recurrence during follow-up. Overall functional status significantly improved postoperatively. A total of 59 patients (92%) showed improvement or significant improvement postoperatively. There was no difference in surgical outcomes among the tumor classifications (P = .618). No intraoperative vertebral artery injuries or postoperative cerebrospinal fluid fistula occurred. CONCLUSION Spinal schwannoma classification based on a membranous hierarchy provides an intuitive platform for preoperative planning and intraoperative safety. This classification scheme may help surgeons better define surgical goals and anticipate or even avoid complications from resection.

Spinal Schwannomas: A Proposal for a New Classification to Aid Surgical Planning

“…Sun et al developed a classification system for spinal schwannomas that includes tumor location and volume; however, this classification system does not contain information on patients with bone erosion or tumors located at the isolated foraminal level 1 . Xin et al created a classification system based on the membranous locations of the tumor, but this study also does not provide information about bone erosion 5 . Our series reflects the surgical results of a senior surgeon with experience in transforaminal surgery in more than 200 cases (far lateral disc herniations, spinal stenoses, different spinal tumors including schwannomas, metastases, and chordomas).…”

“…Despite these advancements, preoperative planning is critical for effective treatment, and in particular, appropriate tumor categorization. Multiple classification methods for spinal schwannomas have been proposed in the literature 1,2,4,5 . Our study presents the surgical results of a senior surgeon in SSs.…”

Giant Spinal Schwannomas. Presentation of Two Cases with Interdisciplinary Surgical Resection

“…In the publication by Xin et al 2020, the current classifications were reviewed and compared, identifying the advantages and disadvantages of the use of each one, which were summarized in one list, see table 1 for a better understanding [28].…”

“…Giant Schwannomas are infrequent, however, given that most of their life they are asymptomatic when they establish clinically they have involved important structures, the direction in which they grow as well as the structures they involve and the vertebral levels they occupy will determine the complexity of the procedure for their extirpation, other surgeons and anatomists have tried to establish scales or classifications to facilitate decision making when facing them, however according to the literature review none of them has proven to be completely useful given the limitations they have demonstrated, it's not the purpose of this article to discuss the limitations of one or the other, however, Table 1 has been attached that briefly discusses them [28].…”

Commentary on “Remnant Tumor Margin as Predictive Factor for Its Growth After Incomplete Resection of Cervical Dumbbell-Shaped Schwannomas”

“…The other issue is location of the tumors in relation to the surrounding structures. Xin et al [ 3 ], demonstrated a novel classification of the schwannoma based on the membranous structures including the dura matter, the arachnoid, and the pia matter. The margins between the tumors and the surrounding structures would define the surgical dissection planes.…”