Turkish Neurosurgery 11: 108 - 110, 2001 Se//.' Epidural Migralioii of Ll/ii/biir Dis[

Cauda Equina Syndrome Caused by Posterior EpiduralMigration of an Extruded Lumbar Disc Fragment

Ekstrüde Lumbal Disk Fragmaninin Posterior EpiduralMigrasyonuna Bagli Cauda Equina Sendromu

ORHAN SEN, M. VOLKAN AYDIN, BÜLENT ERDOGAN, TÜLIN YILDIRIM, HAKAN CAN ER

Baskent University Faculty of Medicine, Departments of Neurosurgery(OS, MVA, BE, HC) and Radiology (TY), Ankara

Received : 28.2.2001 ~ Accepted : 12.4.2001

Abstract: Cauda equina syndrome due to posteriorepidural migratfon of an extruded disc fragment isextremely rare. This report describes such a case in a 36­year-old male with disc fragment extrusion at the L4-5intervertebral space. We discuss the case and review therelevant literature.

Key words: Cauda equina syndrome, lumbar dischemiation, magnetic resonance imaging

INTRODUCTION

The lumbar region is the most comman site forcentral and lateral disc hemiation, but posteriorepidural migration of an extruded disc fragmentwith cauda equina syndrome is relatively rare inthis area (lO). This condition requires urgentsurgical interventian. In this paper, we presentthe case of a patient with posterior epiduralmigratian of an extruded disc fragment thatcompressed the cauda equina. The magneticresonance imaging (MRI) features of this rare entityare highlighted.

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Özet: Cauda Equina sendromuna neden olan extrude diskfragmaninin posterior epidural migrasyonu oldukça nadirgörülen bir olgudur. Bu olgu sunumunda 36 yasinda erkekhastada L4-5 disk seviyesinde cauda equina sendromunaneden olan extrude disk fragmaninin posterior epiduralmigrasyonu anlatilarak literatür esliginde tartisildi.

Anahtar Kelimeler: Cauda equina sendromu, lumbaldisk hemisi, manyetik rezonans görüntüleme

CASE REPORT

A 36-year-old man who had suffered moderatelower back pain for 5 years developed acute-onsetsevere law er back pain, with pain radiating to bothlegs and urinary incontinence. Ten hours before hearrived at hospital, the pain had been increaseddramatically, and 6hours prior to admissian he haddeveloped urinary incontinence. There was nohistory of trauma, fever, weight lass, or any othersystemic symptoms. Palpation revealed extremetendemess in the lumbar region. The straight leg­raising test was limited to 30 degrees bilaterally.

Tiirkish Neiirosiirgery 11: 108 - 110, 2001

Reflexes were absent at the knee and ankle, and motorstrength was 3/5 in both legs. There was bilaterallumbosacral anesthesia in the 51, -2, -3, and -4dermatomes. Rectal tone was decreased, and thebulbocavernosus reflex was absent.

MRI demonstrated a large ovoid mass at theL4-5 disc space. The lesion was hypointense on T1­(Figure 1) and T2-weighted images (Figure 2), andwas located posterolateral to the thecal sac. Imagingof the lesion af ter gadolinium-OTPA injectionshowed rim enhancement (Figure 3).

The surgery involved wide bilateraldecompressive laminectomies at L4. Once theligamentum flavum was removed, we could see theextruded disc fragment at the right posterior andposterolateral dura, compressing the thecal sac.After the extruded disc fragment was removed, weperformed abilateral L4-5 discectomy.

The patient had recovered full motor, sensory,urological, and sexual functions by 1 month post­surgery.

Figure 1: A sagittal Tl-weighted image shows di scextrusion and a large free fragment.

Sel/: Epidiiml Migm/iol/ of LII/iibnr Disc

Figure 2: An axial T2-weighted image shows a largehyperintense disc fragment causing severecompression.

Figure 3: The lesion showed peripheral enhancement afterintravenous gadolonium-OTPA injection.

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Tiirkish Neiirosiirgery 11: 108 - 110, 2001

DISCUSSION

Posterior extrusion of the nucleus pulposus in the

lumbar region is a common phenomenon. Disc fragmentmigration patterns are generally restricted by theattachments of the posterior longitudinal ligament, andits associated midiine septum and peridural or lateralmembrane (1). Rostral, caudal, and lateral migration ofhemiated disc fragments in the spinal canal are also wellknown; however, posterior epidural migration of a discITagment is very unusual, and cauda equina syndrome asa result of this is extremely rare 0,5,6,10).

The reasons why extnided disc fragments migrateposteriorly are not well understood. The sagittal midlineseptum of the posterior longitudinalligament spans thespace between the vertebral body and this ligament,limiting side-to-side movement (9). Another membrane,the peridural or lateral membrane, attaches to the free edgeof the posterior longitudinalligament mediaiiy and to thewaii of spinal canal laterally, thus limiting posterolateralmigration. Anystructural fai1ureof these tissues may allowposterior epidural migration of an extruded disc fragment(3,9,11).

There are distinct clinical pictures associated withthe three main locations of cauda equina lesions in theadult. These locations are lateral, midiine inside the dura,and midiine outside the dura. Neurofibroma is the most

common lateral lesion to affect the cauda equina. The mostfrequent midline lesions inside the dura are ependyn10ma,dermoid tumor, and lipoma of the terminal cord. The mostcommon midline lesions outside the dura are simple discdisease, chordoma, metastatic disease, trauma, spinalepidural hematoma, leukemic reticu1oendotheliosis, anddirect seeding from malignant tumors, most notablymedulloblastomas, ependymomas, or pinealomas (4,7).

MRI is the diagnostic tool of choice for evaluatingacute cauda equina compression (2). In our case,intravenous gadolinium-OTP A helped distinguish thedisc fragment from other causes of cauda equinacompression, as extruded fragments show characteristicperipheral enhancement. Only three reports in theliterature have dOCUl11entedposterior migration of anextruded lumbar disc associated with cauda equinacompression 0,8,10). Two of these cases were diagnosedby myelography and computerized tomography­myelography, and one by MRI. Ourcase is only the secondweii-documented case to include MR! findings.

Seii: Epiciiirnl Migrolioii of Lillili,lir Di,(

Rapid surgical intervention is recommended for allcases of posterior migration of extruded lun1bar disc withcauda equina compression, but one of the reports in theliterature described surgery being done 9 days af tersymptoms developed. The authors reported a goodrecovery, except for residual paresis that limited dorsalmovement of the affected foot (10). We stress that, in order

to reverse the neurological symptoms and achieve fuiirecovery in these cases, MRI and surgery mu st beperformed immediately.

Correspondence: Orhan Sen, MD

Baskent University Faculty ofMedicine

Department of Neurosurgery01250 Yüregir- ADANAFax number: 0-322-3227.128

REFERENCES

1. Bonarati EA, Welch WC: Posterior epidural migrationof an extruded lumbar disc fragment causing caudaequina syndrome: Spine; 23 (3):378-81, 1990

2. Coscia M, Lepzig T, Cooper D: Acute cauda equinacompressian; Sp ine ]9:475-8, 1994

3. Ebeling U, Reulen HJ: Are there typical localisations oflumbar di sc hemiation?; A prospective study. ActaNeurochirurgia 117:143-8, 1992

4. Greenberg MS. Spine and Spinal cord. Bandbook ofNeurasurgery, fifth edition Thieme: New York 2001 (pp:285-350).

5. Uchtor T: Posterior epidural migratian of extrudedlumbar disk; Surg Neurol 32:3] 1-2, ] 989

6. Lutz JD, Smith RR, Jones BM: CT myelography of afragment of alumbar disk sequestered posterior to thethecal sac; AJNR 11:610-11,1990

7. Mathew P., Todd N.V: !ntradural conus and cauda

equina tumors: a retrospective review of presentation,diagnosis and early outcome; J Neurol NeurosurgPsychiatry 56:69-74, 1993

8. Robe P, Martin D, Lenelle J, Stevenaert A: Posteriorepidural migratian of sequestered lumbar discfragments; J Neurosurg (Spine 2) 90: 264-266, 1999

9. Schellinger D, Manz HJ, Vidic B, et al.: Disk fragmentmigration; Radiology ]75:83]-6, 1990

10. Sekerci Z, Ildan F, Yüksel M, Gül B, Kilik c: Caudaequina compressian due to posterior epidura] migrationof extruded lumbar disc; Neurosurg Rev 15:3]] -3, ] 992

11. Wiltse LL, Fonseea AS, Amster J, Dimartino P, RavessoudFA: Relatianship of the du ra, Hofmaim's ligaments, Batson'splexus, and a fibrovascular membrane lying on theposteriorsurface of the vertebral bodies and attaching to the deeplayerof theposterior longitudina! ligaments; An anatomica!,radiologic, and clinical study. Spine ]8:1030-43, ]993

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Prognosisniiich better inconus lesions.

for recovenj after operative intervention iseauda equina sYlldome than with correspollding