CASE 14642 Published on 18.04.2017

Unusual migration of lumbar disk fragment to the posterior epidural space

Section

Neuroradiology

Case Type

Clinical Cases

Authors

Arribas J, Martín C, Adrián L, Alonso E, Riñones E, Rubio M.J.

Hospital Universitario de Burgos (HUBU),
Department of Radiology;
Burgos; Spain
Email:javiag26@gmail.com
Patient

45 years, male

Categories
Area of Interest Neuroradiology spine ; Imaging Technique MR
Clinical History
Male patient, 45 years old, presented with acute onset of right lumbosciatalgia. He showed hypoesthesia in the lower extremities and paresis for dorsiflexion of the right foot, no sphincter alteration.
Imaging Findings
MRI examination showed a nodular lesion located in the posterior epidural space. It produced an important space compromise with a decrease in the diameter of the spinal canal, displacing the dural sac in the left anterolateral direction with grouping of the cauda equina roots (Fig. 3). The lesion is hypointense T1 (Fig. 1) and hyperintense T2 (Fig. 2, 3) and presents peripheral ring enhancement after administration of gadolinium (Fig. 4, 5). In addition there is extension towards the foramen and contact with the disc L3-L4 in the posterior right side edge (Fig 5). There is also evidence of enhancement of the nerve roots of the cauda equina inside the dural sac following inflammatory changes due to the compromise of space produced at this level (Fig. 4).
Discussion
Posterior epidural migration of a sequestrated disk fragment is a rare condition with few cases reported. A disk sequestration is defined as a perforation of the fibrous ring with migration of the disk to the epidural space. Usually the disk fragment is contained in the anterior epidural space which is anatomically well delimited so movement of the fragment usually occurs cranial, caudal, or lateral but seldom to the posterior space.

Most cases involve the lumbar spine and present with neurological deficits like paresis or paraesthesia. Sometimes cauda equina syndrome has been described [1].

MR imaging preferably with gadolinium administration is the method of choice for diagnosis. Disk fragments images can mimic other causes of posterior epidural space occupying lesions. Usually disk fragments exhibit low signal on T1 weighted images and high signal on T2 weighted images. Most of the disk sequestration fragments show peripheral ring contrast enhancement attributed to inflammatory changes around the sequestrated tissue. [1, 2, 3]. Due to the overlap in the image of these pathologies the diagnosis is often difficult. We have to make the differential diagnosis with tumour, abscess or synovial cyst. Tumours usually enhance in a homogeneous way on gadolinium images. Synovial cysts have typical signal intensity and are related to the facet joint. The epidural abscess usually associates inflammatory changes and clinical signs of infection [1].
Signs of a ruptured outermost annulus of the intervertebral disk can help guide the diagnosis. Also a tract-like structure with enhancement from the site of the ruptured disk to the posterior epidural space is identified [1] as in our case (Fig. 5). It suggests the route of the migration.

The main factor of patient long-term outcome is the presence of cauda equina syndrome and the period of time from the onset of symptoms to surgical treatment. Early surgery is the treatment of choice and helps prevent severe neurological deficits. In asymptomatic or mildly symptomatic patients conservative treatment is an option as the fragment may migrate to another position or be reabsorbed [2].

Our patient was treated with hemilaminectomy. At surgery a ruptured disk fragment was identified in the posterior epidural space. Postoperatively the patient’s symptoms were relieved.

It is important to consider sequestrated disk fragment migration in masses of the posterior epidural space. Ring enhancement, tract-like enhancing image connecting to the site of the ruptured disk and annulus rupture signs can be the key facts to guide the diagnosis in MRI.
Differential Diagnosis List
Posterior epidural migration of sequestrated lumbar disk fragment.
Sequestrated disk fragment and migration to the posterior epidural space
Nerve sheath tumor
Metastases
Epidural abscess
Synovial cyst from the facet joint
Final Diagnosis
Posterior epidural migration of sequestrated lumbar disk fragment.
Case information
URL: https://www.eurorad.org/case/14642
DOI: 10.1594/EURORAD/CASE.14642
ISSN: 1563-4086
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