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

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<ul><li><p>J Orthop Sci (2006) 11:8184DOI 10.1007/s00776-005-0961-1</p><p>Case report</p><p>Lumbar discal cyst followed by intervertebral disc herniation:MRI findings of two cases</p><p>Masako Tokunaga1, Toshimi Aizawa2, Hironori Hyodo1, Hirotoshi Sasaki1, Yasuhisa Tanaka2,and Tetsuro Sato1</p><p>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</p><p>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 patients symptoms.</p><p>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.</p><p>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.</p><p>Case 2</p><p>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</p><p>Introduction</p><p>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</p><p>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.</p><p>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.</p><p>Case reports</p><p>Case 1</p><p>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</p><p>Offprint requests to: T. SatoReceived: January 24, 2005 / Accepted: August 29, 2005</p><p>Used Mac Distiller 5.0.x Job OptionsThis report was created automatically with help of the Adobe Acrobat Distiller addition "Distiller Secrets v1.0.5" from IMPRESSED GmbH.You can download this startup file for Distiller versions 4.0.5 and 5.0.x for free from</p><p>GENERAL ----------------------------------------File Options: Compatibility: PDF 1.2 Optimize For Fast Web View: Yes Embed Thumbnails: Yes Auto-Rotate Pages: No Distill From Page: 1 Distill To Page: All Pages Binding: Left Resolution: [ 600 600 ] dpi Paper Size: [ 595.3 785.2 ] Point</p><p>COMPRESSION ----------------------------------------Color Images: Downsampling: Yes Downsample Type: Bicubic Downsampling Downsample Resolution: 150 dpi Downsampling For Images Above: 225 dpi Compression: Yes Automatic Selection of Compression Type: Yes JPEG Quality: Medium Bits Per Pixel: As Original BitGrayscale Images: Downsampling: Yes Downsample Type: Bicubic Downsampling Downsample Resolution: 150 dpi Downsampling For Images Above: 225 dpi Compression: Yes Automatic Selection of Compression Type: Yes JPEG Quality: Medium Bits Per Pixel: As Original BitMonochrome Images: Downsampling: Yes Downsample Type: Bicubic Downsampling Downsample Resolution: 600 dpi Downsampling For Images Above: 900 dpi Compression: Yes Compression Type: CCITT CCITT Group: 4 Anti-Alias To Gray: No</p><p> Compress Text and Line Art: Yes</p><p>FONTS ---------------------------------------- Embed All Fonts: Yes Subset Embedded Fonts: No When Embedding Fails: Warn and ContinueEmbedding: Always Embed: [ ] Never Embed: [ ]</p><p>COLOR ----------------------------------------Color Management Policies: Color Conversion Strategy: Convert All Colors to sRGB Intent: DefaultWorking Spaces: Grayscale ICC Profile: RGB ICC Profile: sRGB IEC61966-2.1 CMYK ICC Profile: U.S. Web Coated (SWOP) v2Device-Dependent Data: Preserve Overprint Settings: Yes Preserve Under Color Removal and Black Generation: Yes Transfer Functions: Apply Preserve Halftone Information: Yes</p><p>ADVANCED ----------------------------------------Options: Use and No Allow PostScript File To Override Job Options: Yes Preserve Level 2 copypage Semantics: Yes Save Portable Job Ticket Inside PDF File: No Illustrator Overprint Mode: Yes Convert Gradients To Smooth Shades: No ASCII Format: NoDocument Structuring Conventions (DSC): Process DSC Comments: No</p><p>OTHERS ---------------------------------------- Distiller Core Version: 5000 Use ZIP Compression: Yes Deactivate Optimization: No Image Memory: 524288 Byte Anti-Alias Color Images: No Anti-Alias Grayscale Images: No Convert Images (&lt; 257 Colors) To Indexed Color Space: Yes sRGB ICC Profile: sRGB IEC61966-2.1</p><p>END OF REPORT ----------------------------------------</p><p>IMPRESSED GmbHBahrenfelder Chaussee 4922761 Hamburg, GermanyTel. +49 40 897189-0Fax +49 40 897189-71Email: info@impressed.deWeb:</p><p>Adobe Acrobat Distiller 5.0.x Job Option File</p><p> /ColorImageDownsampleType /Bicubic /GrayImageDict &gt; /CalCMYKProfile (U.S. Web Coated (SWOP) v2) /ParseDSCComments false /PreserveEPSInfo false /MonoImageDepth -1 /AutoFilterGrayImages true /SubsetFonts false /GrayACSImageDict &gt; /ColorImageFilter /DCTEncode /AutoRotatePages /None /PreserveCopyPage true /EncodeMonoImages true /ASCII85EncodePages false /PreserveOPIComments false /NeverEmbed [ ] /ColorImageDict &gt; /AntiAliasGrayImages false /GrayImageDepth -1 /CannotEmbedFontPolicy /Warning /EndPage -1 /TransferFunctionInfo /Apply /CalRGBProfile (sRGB IEC61966-2.1) /EncodeColorImages true /EncodeGrayImages true /ColorACSImageDict &gt; /Optimize true /ParseDSCCommentsForDocInfo false /GrayImageDownsampleThreshold 1.5 /MonoImageDownsampleThreshold 1.5 /AutoPositionEPSFiles false /GrayImageResolution 150 /AutoFilterColorImages true /AlwaysEmbed [ ] /ImageMemory 524288 /OPM 1 /DefaultRenderingIntent /Default /EmbedAllFonts true /StartPage 1 /DownsampleGrayImages true /AntiAliasColorImages false /ConvertImagesToIndexed true /PreserveHalftoneInfo true /CompressPages true /Binding /Left&gt;&gt; setdistillerparams&gt; setpagedevice</p></li><li><p>82 M. Tokunaga et al.: Discal cyst followed by herniation</p><p>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.</p><p>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</p><p>cyst. Both the cyst and herniated mass were carefullyremoved. His condition completely disappeared.</p><p>Histology</p><p>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).</p><p>Discussion</p><p>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 1946 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.</p><p>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</p><p>Fig. 1AC. 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</p><p>Fig. 2. MRI 54 days after onset in case 1. On T2WI, the masson the posterior L3 body shows high signal intensity withisointensity cranially</p><p>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)</p><p>A,B C</p></li><li><p>83M. Tokunaga et al.: Discal cyst followed by herniation</p><p>degeneration, and no herniated disc was detected onrepeated MRI studies of their patient.9</p><p>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-</p><p>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</p><p>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.</p><p>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</p><p>Fig. 3AC. 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)</p><p>Fig. 4AC. 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)</p><p>Fig. 5AD. 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</p><p>A,B C</p><p>A,B C</p><p>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</p><p>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&amp;E. Bar 100 mm</p><p>A,B C,D</p></li><li><p>84 M. Tokunaga et al.: Discal cyst followed by herniation</p><p>1 and 2 and of hematoma are summarized in Table 1.13</p><p>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</p><p>Histologically, there may be no specific findings sug-gesting the origin of the lumbar di...</p></li></ul>