The Pathogenesis of Ventral Idiopathic Herniation of the Spinal Cord: A Hypothesis Based on the Review of the Literature

Abstract

Idiopathic ventral herniation of the spinal cord (SC) is not often encountered in daily practice. Its clinical prevalence, however, will increase through increasing awareness and more frequent use of MRI. A clear explanation of its pathophysiology has never been formulated. It was hypothesized that the findings during surgery might indicate the real causative mechanism. An extensive literature search was performed, using Embase, PubMed, and Google Scholar. Titles and abstracts were screened by two investigators, using strict inclusion and exclusion criteria. Reference lists of the full paper versions of each included article were checked. The following data were registered for the articles included: age, gender, level of herniation, relation to intervertebral disk, duration of symptoms, findings from surgery, and outcomes. Nine cases treated at our department were added. A total of 117 articles reporting on 259 patients were included. Including our cases, 268 patients were reviewed. Females outnumbered males (160/100). The mean age was 51.3 ± 12.0 years. In 236 patients, the duration of symptoms was reported: 55.5 ± 55.6 months. In 178 patients, the intraoperative findings for the herniated part of the SC were not mentioned. In 59 patients, a tumor-like extrusion was seen, without any alteration to the SC. Deformation of the SC itself was never observed. Biopsies of these structures were without clinical consequence. Based on the intraoperative findings reported in literature and the cases presented, acquired causes, such as trauma and erosion of the dura due to a herniated disk, were not plausible. We hypothesize that a non-functioning appendix to the SC can only develop during an early embryologic phase, in which several layers separate. We propose renaming this entity as congenital transdural appendix of the SC.

Genetic analysis of spinal dysraphism with a hamartomatous growth (appendix) of the spinal cord: a case series

“…have been suggested for this anomaly. As has been reported, many arguments contradict this hypothesis [1].…”

“…Since the location of this entity is relatively constant in most patients with a late presentation and mild neurologic symptoms, a defect in the normal development of the spinal cord, resulting in a tethered spinal cord, was suggested. This defect is always located in the anterolateral thoracic part of the spinal cord between the intumescentia cervicalis and intumescentia lumbalis [1]. In an earlier report [1], the hypothesized mechanism that resulted in a defect of neurulation between 30 and 60 days of gestational age is extensively described.…”

“…This defect is always located in the anterolateral thoracic part of the spinal cord between the intumescentia cervicalis and intumescentia lumbalis [1]. In an earlier report [1], the hypothesized mechanism that resulted in a defect of neurulation between 30 and 60 days of gestational age is extensively described. Other authors have also supposed that the defect was congenital [9][10][11].…”

“…Spinal dysraphism with a hamartomatous growth is also known as idiopathic ventral herniation of the spinal cord [1]. It is a very rare entity with a low prevalence.…”

Thoracic idiopathic spinal cord herniation in a young patient: a diagnostic and therapeutic challenge

“…It is defined as the gliding of the spinal cord through a dural defect, which is usually located anteriorly in the thoracic region 1. A total of 200 cases have been reported, and it is believed that the identification of the pathology has increased due to routine MRI 2. ISCH is now considered to be a reversible cause of thoracic myelopathy, most frequently encountered in women above the age of 40 3.…”