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J Orthop Sci (2006) 11:81–84DOI 10.1007/s00776-005-0961-1

Case report

Lumbar discal cyst followed by intervertebral disc herniation:MRI findings of two cases

Masako Tokunaga1, Toshimi Aizawa2, Hironori Hyodo1, Hirotoshi Sasaki1, Yasuhisa Tanaka2,and Tetsuro Sato1

1 Department of Orthopaedic Surgery, Sendai Orthopaedic Hospital, 24 Izai aza Higashi-tori, Wakabayashi-ku, Sendai 984-0038, Japan2 Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan

medial thigh. The MRI findings 10 days after the onsetwere consistent with intervertebral disc herniation atthe L3/4 level that had spread to the L3 vertebral bodyon the right; an extradural mass of isointensity signal onT1-weighted images (T1WI) and mixed iso- and highintensities on T2-weighted images (T2WI) was seen.Its periphery was enhanced by gadolinium-diethylenetriamine-pentaacetic acid (Gd-DTPA) (Fig.1). The MRI revealed that the L3/4 intervertebral dischad mild degeneration. Conservative treatment re-lieved the patient’s symptoms.

At 54 days after the onset, MRI showed that thecranial part of the extradural mass had changed tohomogenously high signal intensity on T2WI (Fig. 2).His symptoms worsened again, and MRI 90 days afterthe onset showed that the whole extradural mass was ofisointensity on T1WI and homogenously high intensityon T2WI (Fig. 3A,B). Discography (Fig. 3C) followedby computed tomography (CT) at the L3/4 level showedthat contrast medium flowed into the extradural mass.These radiological findings indicated that he had anintervertebral discal cyst at the L3/4 level.

Right L3 hemilaminectomy was performed, and atwo-compartment cyst was found tightly adherent toboth the dura mater and the L3 and L4 nerve.Hemorrhage was encountered when ablation of the cystfrom the surrounding extradural tissues was attempted,although the exact bleeding point could not beconfirmed. The cyst contained bloody serous fluid. Itwas removed en bloc with part of the posterior annulusof the intervertebral disc. The patient experienced adramatic resolution of symptoms with quadriceps femo-ris of grade 5 on the MMT scale.

Case 2

A 13-year-old boy came to our hospital in July 2002because of an approximately 2-month course of lowback pain and numbness of the lateral right leg. His

Introduction

Several kinds of intraspinal cyst, such as the perineuralcyst,1 sacral cyst,1 synovial cyst,2 extradural ganglioncyst,3,4 and cyst of the ligamentum flavum,5 as well aspremembranous hematomas6 and intraspinal gas,7,8

cause symptoms and signs resembling those of lumbardisc herniation.9,10 In 1997 in Japanese and in 2001 inEnglish, Toyama et al.11 and Chiba et al.9 first describedcysts with distinct connections to the intervertebral discand named them “lumbar discal cysts.” Several possiblecauses of these cysts can be suggested: a simple variantof normal disc degeneration,12 resorption of preexistingherniation, hematoma associated with disc prolapse,and mucoid degeneration as in a ganglion cyst.9 How-ever, the pathogenesis of discal cyst is uncertain.

Here, we report two cases of lumbar discal cyst.From magnetic resonance image (MRI) findings, weconfirmed that the discal cyst could have developedfrom the absorption process of an intervertebral discherniation. Our patients or the family were informedthat the data concerning the cases would be submittedfor publication.

Case reports

Case 1

A 38-year-old man developed acute low back pain andweakness of the right lower extremity in January 2001.Neurologically, right L3 or L4 radiculopathy was indi-cated; slight weakness (grade 4) on the manual muscletest (MMT) scale was detected in the quadriceps femo-ris, and there was sensory disturbance on the anterior to

Offprint requests to: T. SatoReceived: January 24, 2005 / Accepted: August 29, 2005

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82 M. Tokunaga et al.: Discal cyst followed by herniation

condition was diagnosed as right L5 radiculopathy witha positive straight leg raising test (SLRT) at 20° andMMT grade 4 weakness of the extensor hallucis longusmuscle. MRI findings were consistent with interverte-bral disc herniation at L4/5, with an extradural mass ofisointensity on T1WI and low intensity on T2WI; it washeterogeneously enhanced by Gd-DTPA (Fig. 4). TheL4/5 intervertebral disc appeared to have mild degen-eration. His symptoms were not alleviated by conserva-tive treatment. One month later, the mass showedisointensity on T1WI and uniformly high intensity onT2WI (Fig. 5A,B). Discography and CT revealed around mass connected to the L4/5 disc cavity in theextradural space (Fig. 5C,D). His condition was thendiagnosed as an intervertebral discal cyst at the L4/5level.

Fenestration of the right L4/5 was performed. A darkred cyst was identified in the right extradural space,continuous with the intervertebral disc and adherent tothe L5 nerve root. We needled the cyst wall and aspi-rated about 2ml of pure blood. A transligamentous her-niation was also detected at the cranial portion of the

cyst. Both the cyst and herniated mass were carefullyremoved. His condition completely disappeared.

Histology

In both cases, the cyst wall on pathologic microscopicexamination was composed of fibrous tissue withneovascularity and hemosiderin deposits. No epitheliallining was identified. In case 1, the presence ofcartilaginous tissue was confirmed in the cyst wall(Fig. 6).

Discussion

Lumbar intervertebral discal cyst is a new clinical entity,and its clinical symptoms are indistinguishable fromthose of a typical disc herniation.9,10 Ten cases of thisdisorder, to our knowledge, have been reported in theEnglish-language literature.9,12 All of the patients weremen, and it tends to appear at a slightly younger agethan intervertebral disc herniation (mean age at opera-tion was 29 years; range 19–46 years). The cyst is de-tected at higher disc levels than typical disc herniation:L2/3 in two cases, L3/4 in two cases, L4/5 in five casesand L5/S in one case. The patient in our case 2 was a 14-year-old boy, the youngest of the reported cases; and incase 1, the cyst originated from the L3/4 intervertebraldisc. Their clinical and histological findings were similarto those in the other reported cases.

In almost all reported cases, MRI findings indicatedonly mild disc degeneration, as in our cases.9,10,12 In allbut one case, the extradural mass showed low signalintensity on T1WI and high signal intensity on T2WI,which was consistent with a cyst containing liquid.Chiba et al.9 speculated that the discal cyst does notdevelop as a consequence of absorption of the disc her-niation. The corresponding disc did not show severe

Fig. 1A–C. Magnetic resonance imaging (MRI) 10 days afteronset in case 1. A Axial T1-weighted image (T1WI) throughthe L3 pedicles. An isointensity mass is located on the rightside of the extradural space (arrow). B Sagittal T2-weightedimage (T2WI). A mass showing iso- and high-intensity signals

Fig. 2. MRI 54 days after onset in case 1. On T2WI, the masson the posterior L3 body shows high signal intensity withisointensity cranially

has migrated from the L3/4 intervertebral disc (arrow).C Gadolinium-diethylenetriamine-pentaacetic acid (Gd-DTPA)-enhanced MRI. The periphery of the extradural massis clearly enhanced (arrow)

A,B C

83M. Tokunaga et al.: Discal cyst followed by herniation

degeneration, and no herniated disc was detected onrepeated MRI studies of their patient.9

Regrettably, there was no description on the durationbetween the onset of the symptoms and subjecting thepatients to MRI in most of the previous cases. In addi-

tion, in those cases there was a long preoperative inter-val (17 months on average).9 In our cases, however,repeated MRI from the early stages of the onset clearlyindicated that the discal cyst developed during the proc-ess of disc herniation absorption. Interestingly, the MRIfindings of a case described by Coscia and Broshears12

were consistent with disc herniation, although a fluid-filled cystic structure was identified during surgery. Thisreport also indicated the possibility that a discal cystcould originate from disc herniation. Of course, lumbardiscal cyst includes several types of intraspinal cyst witha distinct connection to the corresponding interverte-bral disc.9,10 Different kinds of cyst may have differentpathogeneses.

Another doubt has arisen as to whether the intraspi-nal mass on the initial MRI showed a hematoma at acertain stage. The time course of MRI findings of cases

Fig. 3A–C. MRI and discogram 90 daysafter the onset in case 1. A SagittalT1WI shows an isointensity mass thathas migrated from the L3/4 interverte-bral disc (arrow). B Axial T2WI throughthe L3 pedicles. A clear oval cyst withhomogenously high signal intensity isdetected. C Discogram of L3/4 showsthat the cyst is connected to the interver-tebral disc (arrow)

Fig. 4A–C. MRI on the initial visit ofcase 2. A Axial T1WI through the L5pedicles. An isointensity mass is de-tected in the right side of the extra-dural space (arrow). B Sagittal T2WI.A low-intensity mass is located behindthe L4/5 intervertebral disc. C Theextradural mass is heterogeneouslyenhanced by Gd-DTPA (arrow)

Fig. 5A–D. MRI, discography, and computed tomography(CT) discogram before operation in case 2. A Sagittal T1WIpresents an isointensity mass locating at the L4/5 disc level(arrow). B Axial T2WI through the L5 pedicles. On the rightside of the L5 vertebra, a cyst with high signal intensity is

A,B C

A,B C

clearly detected. C Discogram of L4/5 shows the connectionbetween the cyst and the intervertebral disc (arrow). D CTdiscogram shows a cyst filled with contrast medium in the rightextradural space

Fig. 6. Histology of case 1. The cyst wall is composed offibrous tissue with neovascularity and hemosiderin deposits(arrow). Cartilaginous tissue is also confirmed in the cyst wall(arrowhead). H&E. Bar 100 mm

A,B C,D

84 M. Tokunaga et al.: Discal cyst followed by herniation

1 and 2 and of hematoma are summarized in Table 1.13

The initial MRI findings for our cases were identicalwith those seen with protruding intervertebral discshown by Gd-DTPA enhancement.14 In addition, thechanges in signal intensity were inconsistent with thetime course of a hematoma, which behaves in a predict-able fashion depending on the biochemical form of thehemoglobin, methemoglobin, and hemosiderin.13 If amass is a hematoma, it should show high signal intensityon T1WI and high intensity on T2WI.13

Histologically, there may be no specific findings sug-gesting the origin of the lumbar discal cyst, which has nolining cells, similar to an extradural ganglion cyst.3,9,12

The cysts of our patients contained bloody serous fluid;and particularly in case 2, significant hemorrhage wasdetected in the cyst at operation. The followingpathogenesis might apply in our cases: Intervertebraldisc herniation developed and during the process ofabsorption, fibrous tissue with vascularization coveredthe prolapsed disc, with small vessels continuing intothe herniated disc material.15 The tissue was absorbedby macrophages from the periphery, whereas, theinfiltrated vessels connected with the epidural venousplexus. Minor forces may have broken those vessels,with hemorrhage occurring in the absorbed space of theprolapsed disc. Hemorrhage stopped when intracysticpressure became elevated, and the hematoma was ab-sorbed. Simultaneously, fibroblasts in the fibrous tissuecovering the herniated disc might have a role in cystformation,16–18 causing the discal cyst to develop.

References

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2. Yuh WTC, Drew JM, Weinstein JN, McGuire CW, Moore TE,Kathol MH, et al. Intraspinal synovial cysts: magnetic resonanceevaluation. Spine 1991;7:740–5.

3. Brish A, Payan HM. Lumbar intraspinal extradural ganglion cyst.J Neurol Neurosurg Psychiatry 1972;35:771–5.

4. Kao CC, Uihlein A, Bickel WH, Soule EH. Lumbar intraspinalextradural ganglion cyst. J Neurosurg 1968;29:168–72.

5. Baker JK, Hanson GW. Cyst of the ligamentum flavum. Spine1994;19:1092–4.

6. Wiltse LL, Fonseca AS, Amster J, Dimartino P, Ravessoud FA.Relationship of the dura, Hofmann’s ligaments, Batson’s plexus,and a fibrovascular membrane lying on the posterior surface ofthe vertebral bodies and attaching to the deep layer of the poste-rior longitudinal ligament: an anatomical, radiologic, and clinicalstudy. Spine 1993;18:1030–43.

7. Raynor R, Saint-Louis L. Postoperative gas bubble foot drop: acase report. Spine 1999;24:299–301.

8. Yoshida H, Shinomiya K, Nakai O, Kurosa Y, Yamaura I. Lum-bar nerve root compression caused by lumbar intraspinal gas:report of three cases. Spine 1997;22:348–51.

9. Chiba K, Toyama Y, Matsumoto M, Maruiwa H, Watanabe M,Nishizawa T. Intraspinal cyst communicating with the interverte-bral disc in the lumbar spine: discal cyst. Spine 2001;26:2112–8.

10. Koga H, Yone K, Yamamoto T, Komiya S. Percutaneous CT-guided puncture and steroid injection for the treatment of lumbardiscal cyst: a case report. Spine 2003;28:E212–6.

11. Toyama Y, Kamata M, Matsumoto M, Nishizawa T, Koyanagi T,Suzuki N, et al. Pathogenesis and diagnostic title of intraspinalcyst communicating with intervertebral disc in the lumbar spine.Rinsho Seikei Geka 1997;32:393–400 (in Japanese).

12. Coscia MF, Broshears JR. Lumbar spine intracanalicular discalcyst: two case reports. J Spinal Disord Tech 2002;15:431–5.

13. Thulborn KR, Atlas SW. Intracranial hemorrhage. In: Atlas SW,editor. Magnetic resonance imaging of the brain and spine. NewYork: Raven Press; 1991. p. 175–222.

14. St. Amour TE, Hodges SC, Laakman RW, Tamas DE, James CA,Glasier CM. Disc bulge and herniation. In: St. Amour TE,Hodges SC, Laakman RW, Tamas DE, James CA, Glasier CM,editors. MRI of the spine. New York: Raven Press; 1994. p. 60–74.

15. Carreon LY, Ito T, Yasmada M, Uchiyama S, Takahashi H, IkutaF. Histologic changes in the disc after cervical spine trauma: evi-dence of disc absorption. J Spinal Disord Tech 1996;9:313–6.

16. Ohshima M, Ogoshi T, Ogawa H, Muto A, Suzuki K, Otsuka K.Effect of dental cyst epithelium-conditioned medium on colla-genase production by periodontal ligament fibroblasts. J NihonUniv Sch Dent 1997;39:31–3.

17. Ricard J, Pelloux H, Pathak S, Pipy B, Ambroise-Thomas P.TNF-a enhances Toxoplasma gondii cyst formation in humanfibroblasts through the sphingomyelinase pathway. Cell Signal1996;8:439–42.

18. Ohshima M, Nishiyama T, Yamazaki Y, Yokosuka R, Maeno M,Otsuka K. Hepatocyte growth factor is a predominantchemoattractant for gingival epithelial cells produced by radicularcyst-derived fibroblast-like cells. J Oral Sci 2000;42:101–6.

* ** ***

Table 1. MRI findings for cases 1 and 2 and hematoma

Signal intensity

Type of MRI Case 1 Case 2 Hematoma

T1WI iso Æ iso iso Æ iso iso or low Æ high Æ high Æ iso or low

T2WI iso Æ high low Æ high low Æ low Æ high Æ lowGd enhancement Positive at periphery Positive Negative

MRI, magnetic resonance imaging; Gd, gadolinium; iso, isointensity; 2M, 3M, 2 and 3 months after the onset; T1WI, T1-weighted image; T2WI,T2-weighted image* First several days; **several days to months; ***several days to indefinitely

2M

2M

3M

3M * ** ***