Contrast-enhancing Sequestered Intervertebral Disc in Lumbosacral Spine: A Case Report and Review of Literature
Corresponding Author: Pankaj Somani, Department of Neurosurgery, Mahatma Gandhi Medical College, Jaipur, Rajasthan, India, Phone: +91 8764113536, e-mail: email@example.com
Received on: 16 May 2023; Accepted on: 13 June 2023; Published on: 16 September 2023
A 57-year-old male patient presented with severe low backache associated with left lower limb radiculopathy over the posterolateral aspect of leg and foot for the last 1 month, acute in onset and gradually progressive with left foot drop, and hypoesthesia for the last 10 days.
Contrast-enhancing magnetic resonance imaging (CE-MRI) was suggestive of peripheral rim-enhancing sequestered disc fragment in the left posterolateral spinal canal at L4-L5 level, extending into the medial aspect of left neural foramina leading to severe spinal canal stenosis.
Microscopic lumbar discectomy was done. A large sequestered disc with granulation tissue was found inside the left neural foramina, densely adherent to adjacent dura mater and nerve root which was removed by careful gentle manipulation and meticulous dissection without dural tear and cerebrospinal fluid (CSF) leak. The patient had significant improvement in his symptoms with complete relief in pain and hypoesthesia immediately after surgery and gradual improvement in the power of the left lower limb from 1/5 to 4/5 over a period of 2 weeks.
Here we review the literature and discuss the significance of rim enhancement in the case of sequestered lumbar prolapse intervertebral disc (PIVD) and its differential diagnosis.
How to cite this article: Somani P, Agarwal S, Singh J, et al. Contrast-enhancing Sequestered Intervertebral Disc in Lumbosacral Spine: A Case Report and Review of Literature. J Mahatma Gandhi Univ Med Sci Tech 2022;7(3):91–94.
Source of support: Nil
Conflict of interest: None
Patient consent statement: The author(s) have obtained written informed consent from the patient for publication of the case report details and related images.
Keywords: Case report, Low backache, Lumbar disc herniation, Peripheral rim contrast enhancement, Sequestered disc fragment, Severe lumbar canal stenosis
It is estimated that 50% of working adults will experience leg pain in any given year.1 low back pain (LBP) is the most prevalent cause of disability for people under the age of 45 and accounts for about 15% of all sick days taken from work.2,3 The lifetime prevalence is estimated to be between 60 and 90%, and the yearly incidence is 5%.3 Among these patients, a herniated lumbar disc will frequently be discovered.4
The most common site of migration into the spinal canal is on the posterolateral aspect leading to spinal canal stenosis. The intervertebral disc has been characterized as the largest nonvascularized structure in the human body, which imparts some unique attributes to it.5
Because it is simple to see the morphological abnormalities of the disc, plain magnetic resonance imaging (MRI) is helpful for evaluating disc herniation and disc degeneration. However, in cases of degenerative arthritis, disc dehydration, cartilage erosion, subchondral sclerosis, and hypertrophic alterations also occur. When a disc fragment creates a sequestered disc herniation, the inflammatory response results in granulation tissue, which is visible as a peripheral enhancement.6
Granulation tissue and reactive inflammation lead to neovascularization resulting in abnormal postcontrast enhancement of the disc annulus fibrosus, subchondral bone, and synovia.7
Hereby we report an interesting case of the large extruded disc with neovascularization and granulation tissue causing dense adhesion with adjacent structures in a 57-year-old male. We review the literature and discuss the various differential diagnosis of contrast-enhancing lesions in the lumbosacral spine canal with differentiating features of each.
A 57-year-old male patient presented to the Department of Neurosurgery in Mahatma Gandhi Medical College, Jaipur, Rajasthan, India, with a complaint of severe low back ache associated with left lower limb radiculopathy over the posterolateral aspect of the leg and foot for the last 1 month which was acute in onset and gradually progressive and pain got aggravated on coughing, sneezing or straining at stools, and relieved partially on lying down and taking analgesics. The patient also had a complaint of numbness over the left lower limb posterolateral aspect and a tingling sensation for 15 days. The patient developed weakness in the left foot for the last 10 days. He was treated conservatively with analgesics and rest but symptoms did not improve and pain gradually increased.
On Clinical Examination
The patient had left foot drop-motor power 1/5 at ankle dorsiflexion and great toe extension, also associated with hypoesthesia (nearly 50%) over the left lower limb posterolateral aspect.
Lasegue sign/straight leg raising test was positive at 30° on the left side. Fajersztajn sign/crossed leg raising test was positive beyond 45° and the bowstring sign was positive, that is, the pain gets reduced on flexion of hip and knee. Deep tendon reflexes (DTRs), bladder, and bowel habits were normal. On radiological evaluation MRI was suggestive of an ill-defined (Fig. 1), oval-shaped, lesion of size 9 x 13 x 22 mm on the left lateral aspect of the spinal canal at L4-L5 level with abnormal signal intensity, extending into the medial aspect of left neural foramina leading to severe spinal canal stenosis and causing right lateral displacement and compression leading to clumping of nerve roots of cauda equina. It appears to be hypointense on T1 and T-2 weighted imaging (T-2WI) and mildly hyperintense on short T1 inversion recovery (STIR) sequences. On contrast-enhancing MRI (CE-MRI), it showed peripheral rim enhancement suggestive of sequestered disc fragment (Fig. 2).
The patient’s chief complaints, clinical examination, and radiological findings were concordant and a definitive diagnosis of L4-L5 sequestered intervertebral disc with compression of left side L5 nerve root was established. After taking a valid written informed consent, the patient was planned for microsurgical excision of the sequestered disc along with decompression of bilateral lumbar 4 - lumbar 5 level (B/L L4-L5) nerve roots.
Under general anesthesia, with the patient in a prone position over Wilson’s frame, a midline vertical incision of size 2–3 cm was given at L4-L5 level, and hemilaminotomy of the inferior half of L4 lamina, medial (<1/2) facetectomy and one-fourth hemilaminotomy superior border of L5 lamina was done. The sequestered disc fragment was present on the left side of the thecal sac, densely adherent to the adjacent dura mater and L4-L5 nerve root.
Undercutting of the medial border of intervertebral foramina was done. The lesion was approached through the axilla between the thecal sac and L5 traversing nerve root (Fig. 3). Due to narrowed space and dense adhesions there was a constant threat to dural tear and CSF leak. The sequestered disc fragment was firm and fibrosis, with granulation tissue and neovasculogenesis all around (Fig. 4).
On gentle manipulation, careful dissection, and controlled traction, the sequestered disc fragment was delivered out from the narrowed space between the thecal sac and L5 traversing nerve root through the intervertebral foramina. Adequate nerve root decompression was ensured.
After removal of the sequestered disc fragment, the deeper part was inspected thoroughly which suggested that the lesion was communicating with intervertebral disc space which further increased the possibility of herniated intervertebral disc. The excised specimen was sent for histopathological examination which was confirmatory of degenerative intervertebral disc material with inflammatory changes without atypia/malignant changes.
The postoperative period was uneventful, the patient had significant improvement in pain and hypoesthesia immediately after surgery, and power improved to 3/5 on the third postoperative day, at the time of discharge and further improved to 4/5 at the 2-week follow-up.
The term “lumbar degenerative disc disease” includes a spectrum of disorders like disc bulge, disc protrusion (central, paracentral, intraforaminal, or far lateral), disc extrusion (with or without mitigated fragment), and internal disc disruption.
Patients may present with long-standing low-back pain and radiculopathy or acute onset with cauda equina syndrome.
Pathophysiology of PIVD
The intervertebral disc (IVD) is composed of three elements which include the nucleus pulposus, annulus fibrosus, and cartilaginous end-plate.
Lumbar disc degeneration and herniation are multifactorial processes in which both mechanical and biochemical derangements.
The process of disc degeneration occurs in both the annulus fibrosus and the nucleus pulposus. With advancing age, the mechanical strength of the annulus decreases and the nucleus also loses its water-binding capacity. As a result, the stress in the vertebral column, which in normal individuals is transmitted to the center of the end-plate, is transmitted to the peripheral portion of the vertebral body and the weakened annulus, resulting in disc herniation and compression on the adjacent nerve root. This, in turn, accelerates the degeneration of the facet joints.
The MRI is the single best method for the evaluation of degenerative disease of the spine including herniation intervertebral disc, stenosis of the central spinal canal, lateral recess, and neural foramina. Disc herniation is best detected on axial images as the eccentric posterior extension of the disc material is readily visualized. The herniated/protruded disc obliterates the epidural fat and subarachnoid space and displaces the nerve root sleeve.
Other degenerative disc changes such as blanking of the disc indicative of desiccated and dehydrated intervertebral disc, decreased disc height, irregularity of nucleus pulposus, annular tear, and modic changes in the cortical end-plate and the adjacent marrow are also visualized on plain MRI.8
Various enhancement patterns are seen on CE-MRI hence in the interpretation of lumbar spine pathology leading to more accurate diagnosis (Fig. 5).
Pattern of Contrast Enhancement
The enhancement was observed in various patterns. It is grouped into two types—intradiscal or peridiscal pattern. The intradiscal pattern was further subgrouped into linear and nodular types.
The linear intradiscal augmentation was the most prevalent of these patterns. Not only did bulging or protruding discs develop intradiscal augmentation, but so did discs that appeared to be in good health. If the periodical enhancement was discovered, it would be helpful in determining whether a disc had extruded.9
The improvement study can aid in the identification of annular tears as well.10 The peripheral enhancement of the parent disc revealed an annular tear. Epidural fibrosis of the herniated disc was linked with peridiscal enhancement.11
The enhancing pattern has also been used to distinguish the herniated or sequestered disc from other lesions with a similar appearance (Fig. 6).
Contrast enhancement in extruded, sequestered herniated disc is not very uncommon. The abnormal location of a herniated or migrated disc may cause a diagnostic dilemma with similar appearing lesions. CE-MRI can give better ideas about the pathology and help in ruling out other differentials. Hence, knowing the diagnosis accurately before surgery minimizes on-table surprises and gives better outcomes.
Accurate diagnosis and adequate treatment at an appropriate time yield excellent outcomes.
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