Spinal Meningiomas: A Comprehensive Review and Update on Advancements in Molecular Characterization, Diagnostics, Surgical Approach and Technology, and Alternative Therapies

Abstract

Spinal meningiomas are the most common intradural, extramedullary tumor in adults, yet the least common entity when accounting for all meningiomas spanning the neuraxis. While traditionally considered a benign recapitulation of their intracranial counterpart, a paucity of knowledge exists regarding the differences between meningiomas arising from these two anatomic compartments in terms of histopathologic subtypes, molecular tumor biology, surgical principles, long-term functional outcomes, and recurrence rates. To date, advancements at the bench have largely been made for intracranial meningiomas, including the discovery of novel gene targets, DNA methylation profiles, integrated diagnoses, and alternative systemic therapies, with few exceptions reserved for spinal pathology. Likewise, evolving clinical research offers significant updates to our understanding of guiding surgical principles, intraoperative technology, and perioperative patient management for intracranial meningiomas. Nonetheless, spinal meningiomas are predominantly relegated to studies considering non-specific intradural extramedullary spinal tumors of all histopathologic types. The aim of this review is to comprehensively report updates in both basic science and clinical research regarding intraspinal meningiomas and to provide illustrative case examples thereof, thereby lending a better understanding of this heterogenous class of central nervous system tumors.

Keywords: clear cell meningioma; immunotherapy; intradural extramedullary tumor; laminectomy; laminoplasty; meningioma; minimally invasive surgery; radiotherapy; spine.

Figure 1

Case One: radiographic and intraoperative imaging. (A) Axial and (B) sagittal T1-weighted thoracic MRI with gadolinium contrast demonstrating an avidly, homogenously enhancing lesion nearly filling the entirety of the spinal canal with significant ventral displacement and compression of the spinal cord (yellow arrow). (C) Axial and (D) sagittal T2-weighted MRI re-demonstrating spinal cord compression (yellow arrow) as well as a tissue plane separating the spinal cord from the extramedullary mass. (E) Intraoperative photograph depicting a large, fleshy dorsal intradural, extramedullary mass prior to resection. (F) Intraoperative photograph demonstrating the extent of spinal cord compression after resection with cauterized dural tail (white circle).

Figure 2

Case Two: radiographic and intraoperative imaging. (A) Axial and (B) sagittal T1-weighted cervical MRI with gadolinium contrast demonstrating an avidly, homogenously enhancing lesion ventrolateral to the spinal cord with extension into the adjacent neural foramen (red arrow). (C) Axial and (D) sagittal T2-weighted MRI re-demonstrating extension of the tumor into the right neural foramen (red arrow). (E) Intraoperative photograph depicting a large, fleshy ventrolateral intradural, extramedullary mass eccentric toward the right C4 and C5 neural foramina with nerve roots visibly draped over the cephalad and caudal regions of the mass (black asterisks) prior to resection. (F) Intraoperative photograph following surgical resection of the tumor.

Figure 3

Case Three: radiographic and intraoperative imaging. (A) Axial CT image of the thoracic intraspinal mass with internal calcifications in the posterolateral margin of the lesion with adjacent hyperostosis of the right lamina. (B) Axial and (C) sagittal T1-weighted thoracic MRI with gadolinium contrast demonstrating a homogenously enhancing lesion lateral to the thoracic spinal cord with significant contralateral displacement of the spinal cord (yellow arrow) and dural tail (blue arrow) in a patient with Scheuermann kyphosis. (D) Axial and (E) sagittal T2-weighted MRI re-demonstrating spinal cord compression (yellow arrow) as well as a tissue plane separating the spinal cord from the extramedullary mass. (F) Intraoperative photograph depicting a large, fleshy dorsal intradural, extramedullary mass with nerve root tethering (black asterisk) prior to surgical resection. (G) Intraoperative photograph after microsurgical tumor excision demonstrating a large resection cavity and bipolar cauterization of the dural tail (white circle), with preservation of the previously tethered nerve root (black asterisk).