Non-Syndromic Spinal Schwannomas: A Novel Classification

Abstract

Schwannomas are the most frequent primary tumors of the spine with an incidence of 0.3-0.5/100,000 person per year. Current treatment for non-syndromic spinal schwannomas is total resection of the tumor with preservation of neurovascular structures. This study aims to report neurologic and radiologic outcome following treatment of non-syndromic spinal schwannomas along with a novel tumor classification used in our clinic. A retrospective case series was carried out with a patient sample of 82 male and female patients with non-syndromic spinal schwannomas. All patient data were retrospectively collected from the hospital records. As a routine procedure, after admittance and primary evaluation, patients' tumors were classified using CT or MRI in accordance with our proposed classification method, which employs a dual designation method with tree groups (A, B, and C) for tumor volume and four types (I, II, III, and IV) for tumor localization. Subsequent resection surgery was followed by neurological assessments and follow up at 45th, 180th, and 360th postoperative day. Along with Karnofsky performance status scale, pain, sensory deficits, and motor weakness were scored to assess neurologic recovery. Our finding indicates that patients with different tumor types significantly differ in their neurological scores and show consistent but differential neurological recovery at early and late time points postsurgery. Complications during and postsurgery were minimal, occurring only in two patients. Our findings further reinforce the established safety of total resection operations and indicate that our proposed classification is a simple, effective tool that has proven helpful in preoperative planning and avoiding unnecessary surgical approaches.

Keywords: postoperative recovery; resection surgery; spinal schwannoma; spinal tumor; tumor classification.

Figure 1

Schwannomas types (according to the present study’s novel classification system) as seen in the coronal and transverse planes.

Figure 2

Type I schwannoma (intradural localization). MRI shows a heterogeneous, contrast-enhanced intradural tumor (A–D). Postsurgery MRI confirms gross total resection, without hematoma or recurrence (E–H). Intraoperative photos before and after tumor resection (I–K).

Figure 3

Type II schwannoma (intradural localization). MRI shows a heterogeneous, contrast-enhanced intradural tumor (A–D). Postsurgery MRI confirms gross total resection, without hematoma or recurrence (E–H). A schwannoma inside the dura (I). After resection, there is no residue remaining in surgical field (J).

Figure 4

Type II schwannoma (intradural dumbbell-shaped tumor with extension to the extraforaminal region) (A,B), and with contrast enhancement (C,D). Postsurgery MRI confirms gross total resection, without hematoma or recurrence (E,F).

Figure 5

Type III schwannoma (intradural dumbbell-shaped tumor within the spinal canal and extending to the extraforaminal region). Preoperative MRI shows a tumor with extraforaminal extension (A–D). Postsurgery MRI confirms gross total resection, without hematoma or recurrence (E–H). Intraoperative view of a schwannoma extending beyond the spinal canal (I) (OB, occipital bone; C2, second cervical vertebra). Intradural part of a schwannoma (J). Postoperative view of the surgical field shows no tumor residue (K) (VA, vertebral artery).

Figure 6

Type IV schwannoma (tumor residing completely outside the root foramina). Preoperative MRI shows a giant cystic schwannoma (A–E), with heterogeneous color enhancement (D,E). Postsurgery MRI confirms gross total resection, without hematoma or recurrence (F–I).

Figure 7

Type IV schwannoma (tumor residing completely outside the root foramina). Preoperative MRI shows a giant cystic spinal schwannoma (A–C). An extraforaminal tumor in the surgical field (D) (SD, spinal dura; R, root; Tm, tumor). Postoperative view of the surgical field shows no tumor residue (E).