Nerve sheath tumors (NSTs) mostly consist of schwannomas and neurofibromas and are considered as one of the most common intraspinal tumors [1]. These may be classified as intramedullary, intradural extramedullary, or extradural tumors along with their location. Most NSTs are intradural extramedullary tumors without extradural components [2,3]. Typically, they arise in the dorsal nerve root of the cervical and lumbar spine and manifest a dumbbell morphology on imaging studies in the presence of a neural foramina or prevertebral space extension [[4], [5], [6]]. The peak incidence of spinal NSTs is in the fourth decade without sexual predilection [2,3].

It is important to understand the relationship between an NST tumor and the surrounding structures, the most important of which is the dura mater, during surgery. Therefore, research has focused on formulating a classification along the anatomic relationship of a tumor with the dura mater and the intervertebral foramen varies depending on the level of the tumor [[7], [8], [9], [10]]. However, it is difficult to determine whether these cumbersome and complicated systems are intradural or extradural with (Eden type 1, 2) or without intradural components (Eden type 3, 4) in some boundary cases as these also show intermediate to moderate interobserver reliability and intraobserver reproducibility [11,12].

As opposed to intradural extramedullary NSTs, which have been extensively studied as they have relatively high incidence and show clear findings on magnetic resonance imaging (MRI), both intradural–extradural (IED) and extradural-only (EDO) spinal NSTs have not been studied because of their relatively small incidence [2,6,13,14]. From the surgical procedure, including repair of the dural defect, IED tumors present a higher incidence of complications and postoperative neurologic deterioration [15]. Consequently, it is important to be informed of the existence of intradural components preoperatively in extradural NSTs for surgical strategies related to dura repair [[16], [17], [18], [19]]. The aim of this study was to identify the characteristic imaging findings of IED NSTs from EDO NSTs and to assess the diagnostic performance of these findings in detecting the presence of intradural components in IED NSTs on conventional MRI.