Disk fragment migration.

Abstract

This report analyzes the most frequently observed migration paths of disk fragments in 47 patients who had extruded or sequestered disks. Observations are based principally on magnetic resonance (MR) images. When disk fragments moved in a superior (42%) or inferior (40%) direction from the donor disk, the displaced disk components were most frequently (94%) dislodged into the right or left half of the anterior epidural space (AES) and rarely straddled the midline. To explain this phenomenon, the authors investigated the anatomy of the AES by dissecting four cadaver specimens and reviewing 300 MR images of the spine. They conclude that the migrating path of a disk fragment is determined by the anatomy of the AES, a fairly well-defined space delimited posteriorly by the posterior longitudinal ligament and by membranes laterally attached to it. It consists of two compartments separated by a sagitally aligned septum. During migration, sequestered disk fragments usually stay in these compartments.

Posterior Epidural Migration of Thoracic Disc Fragment

“…Because of the anatomy of the anterior epidural space (AES), most of the sequestrated disc fragment usually migrate in lateral direction in the spinal canal 6,22) . Schelling et al concluded that the migrating path of a disc fragment is determined by the anatomy of the AES, a fairly welldefined space delimited posteriorly by the posterior longitudinal ligament (PLL) and lateral membrane, attached medially to the free edge of the PLL, and stretches laterally to the wall of the spinal canal 21) .…”

“…Schelling et al concluded that the migrating path of a disc fragment is determined by the anatomy of the AES, a fairly welldefined space delimited posteriorly by the posterior longitudinal ligament (PLL) and lateral membrane, attached medially to the free edge of the PLL, and stretches laterally to the wall of the spinal canal 21) . Not only these PLL and lateral membrane, but also epidural vessels, fat and nerve roots limit posterior epidural migration of herniated disc fragments 6,13,22) . MRI, especially with gadolinium administration, appears to be the method of choice for diagnosis.…”

“…Herniated disc fragments are known to migrate within the spinal canal in rostral, caudal, and lateral directions 6,14,22). Posterior epidural migration of herniated disc fragments are rare and most cases have been reported in lumbar region 2,4,5,8,12,17,19,20) .…”

PEMLIF—a tale of two stories

“…In another landmark article, none of the factors were found to influence the direction of migration of the disc fragment in the lumbar canal (9). PEMLIF as quoted in the literature is very rare.…”

Non-traumatic acute myelopathy due to cervical disc herniation in contiguous two-level disc spaces: a case report

“…There have been no previous reports of an accurate theory regarding the pathomechanism of the direction of extruded disc material migrating to areas within the cervical spine. According to Schellinger et al [11], the migrating path of a disc fragment is determined by the anatomy of the anterior epidural space. The configuration of the anterior epidural space is identical at the superior and inferior half of a vertebral body.…”