The Course of the Nerve Root in the Neural Foramen and Its Relationship with Foraminal Entrapment or Impingement in Adult Patients with Lumbar Isthmic Spondylolisthesis and Radicular Pain

Abstract

The purpose of this study was to demonstrate the course of a nerve root in the neural foramen and its relationship with foraminal entrapment or impingement in 19 adult patients with isthmic spondylolisthesis and radicular pain. Myelo-computed tomography and magnetic resonance imaging showed that the course of the nerve root was normal (ie, medial and then inferior, along the pedicle) in 10 patients and was deviated posteriorly in 9 patients. The patients with a normal nerve root course (N-NRC) had either a bony callus projecting medially into the spinal canal (n = 6) or a low mean percentile of vertebral slip (n = 4; 13.9 +/- 1.3). Those nine patients with a posteriorly deviated nerve root course (PD-NRC) had no medially projecting bony callus in the spinal canal but had a higher mean percentile of vertebral slip (n = 9; 31.5 +/- 10.1; P = 0.005). In the neural foramen, nerve roots of the N-NRC patients were entrapped craniocaudally between the pedicle and superior part of the intervertebral disc. In contrast, nerve roots of the PD-NRC patients were impinged ventrodorsally between the posterosuperior part of the intervertebral disc and either bony callus projecting inferiorly toward the neural foramen or fibrocartilaginous mass arising around the isthmic defect. The foraminal craniocaudal entrapment and ventrodorsal impingement highly agreed with the side of radicular pain (kappa= 0.73, P < 0.001). Our results demonstrate that the medially projecting bony callus and the percentile of vertebral slip affect the course of the nerve root in the neural foramen, which in turn determines the foraminal craniocaudal entrapment or ventrodorsal impingement. These two mechanisms, based on the course of the nerve root, correlate well with the side of radicular pain.

The Mysterious Role of Epidural Fat Tissue in Spine Surgery

“…The dorsal nerve root and dorsal root ganglion are found posterior, and marginally superior to the ventral root. 11,12 Exit points of radicular arteries and veins are accompanied by nerve root cuffs that are surrounded by neural elements with a possible increment of 10-12 mm around the ganglion. 13 Epidural venous vessels in both anterolateral and posterolateral positions fill the spinal epidural space with a decussating intersection between the spinal nerve root and epidural space in their respective dural cuffs.…”

“…Blood vessels and EF can be seen in the superior section of the intervertebral foramen. The dorsal nerve root and dorsal root ganglion are found posterior, and marginally superior to the ventral root 11,12. Exit points of radicular arteries and veins are accompanied by nerve root cuffs that are surrounded by neural elements with a possible increment of 10–12 mm around the ganglion 13…”

Transforaminal or translaminar approach for dorsal root ganglion and dorsal nerve root. Anatomical reason for technique decision

“…Nerve roots cuffs are lateral prolongations of dura mater (Reina et al, 1996, 1997; Dittmann et al, 1998) (Fig. 2c), arachnoid lamina (Reina et al, 2007b, 2010) and pia mater (Reina et al, 2004, 2008a) that enclose nerve roots, in their way across the epidural space towards the intervertebral foramen and the dorsal root ganglion within the intervertebral foramen (Hasue et al, 1989; Kikuchi et al, 1994; Kim et al, 2004). The thickness of nerve root cuffs is formed by internal cellular and external fibrillar components.…”

Lumbar Foraminal Stenosis Classification That Guides Surgical Treatment

“…Although there are many anatomical, morphometric, and radiological studies performed on the subject, there are no systematic treatments or classification systems for a treatment strategy. [1][2][3][4] The purpose of this study was to evaluate the clinical signs of foraminal stenosis to provide a classification and treatment algorithm.…”