| 〔Case Report〕 |
Early occurrence of lumbar sequestrated nucleus pulposus after
spinal fusion for lumbar degenerative spondylolisthesis: a case report |
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Yoshihiro Sakuma, Seiji Ohtori, Takana Koshi, Gen Inoue
Toshinori Ito, Hideshige Moriya and Kazuhisa Takahashi |
| (Received May 1, 2006, Accepted July 26, 2006) |
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SUMMARY
We report a rare case of L4 spinal nerve root compression by a sequestrated nucleus pulposus from the L3/4 intervertebral disc 4 months after surgery to effect posterior lateral fusion between L4 and L5 in a 72-year-old man. A search of the English-language medical literature revealed no previous similar reports.
Posterior decompression and posterior lateral fusion with pedicle screws was performed at the L4/5 level. However, 4 months later, sequestrated nucleus pulposus occurred after low back strain. The herniated nucleus pulposus from the L3/4 intervertebral disc was revealed by myelography and discography. Conservative treatment for 3 months was not effective, so surgical treatment was performed. The symptoms originating from the right L4 spinal nerve roots disappeared immediately after surgical removal of the disc herniation. A failure of absorption of the disc herniation was due to reduced vascularization caused by adhesion of the dura mater after the initial surgery.
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Key Words
| disc herniation, degenerative spondylolisthesis, spinal canal stenosis, surgery |
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I. Introduction
Lumbar intervertebral fusion with pedicle screws has become a commonplace treatment for lumbar degenerative spondylolisthesis and other lower back problems. However, complications such as infection and adjacent intervertebral instability sometimes occur after surgery. The development of instability is a time-related process. Previous investigators have reported a 7% incidence of adjacent instability at 2.4 years and 45% at 33 years after surgery［1,2］. Some authors have reported adjacent spinal canal stenosis after spinal fusion due to adjacent instability in the long term. However, we are not aware of any previous reports of nerve root compression by a sequestrated nucleus pulposus in the short term after adjacent lumbar intervertebral fusion. Here we report a rare case of L4 spinal nerve root compression by a herniated nucleus pulposus from an L3/4 intervertebral disc four months after surgery for posterior lateral fusion between L4 and L5 in a 72-year-old man.
II. Case
This report was approved by the patient after informed consent. A 72-year-old man presented with a 2-year history of bilateral sciatica involving the bilateral lower extremities and intermittent claudication. He presented at our hospital in 2004 with complaints of pain in the lateral aspects of his legs and intermittent claudication. Walking distance was less than 100 m. There was no apparent motor weakness. Sensory examination confirmed bilateral hyperalgesia in the lateral aspect of his lower legs corresponding to the L5 dermatome. X-ray examination showed L4 degenerative spondylolisthesis and instability between levels L4 and L5 ( Fig. 1). Myelography revealed subtotal stenosis of the spinal canal ( Fig. 2). Magnetic resonance imaging ( MRI) revealed spinal canal stenosis on T2-weighted images ( Fig. 2). MRI provided clear images of compression of the cauda equina ( Fig. 2). The intervertebral disc at level L3/4 showed degeneration and bulged slightly ( Fig. 2).
Because initial conservative treatment was not effective, we performed posterior decompression and posterior lateral fusion with instrumentation in January 2005 ( Fig. 3). The patient became symptom-free after surgery, and his postoperative course was uneventful until May 2005. He experienced severe low back pain and right leg pain after lower back strain. Myelography revealed stenosis of the spinal canal ( Fig. 4). Discography and CT showed clear images of a sequestrated nucleus pulposus from the L3/4 intervertebral disc ( Fig. 4). Conservative treatment for 3 months was not effective, so we performed surgery to remove the herniated nucleus pulposus and to extend the posterior lateral fusion with instrumentation in September 2005 ( Fig. 5). The ventral side of the dura mater had adhered to the posterior longitudinal ligament, and herniated nucleus pulposus was found between the posterior side of the vertebral body and the adherent tissue. The patient became symptom-free after surgery, and to date his postoperative course has been uneventful. MRI revealed complete resection of the herniated nucleus pulposus on T2-weighted imaging ( Fig. 5).
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Fig. 1
Plain roentgenogram showing L4 degenerative spondylolisthesis before initial surgery. Arrow indicates instability between L4 and L5 on bending ( C) |
Fig. 2
A, Myelogram demonstrating spinal canal stenosis from L2/3 to L4/5 level before initial surgery. B, C, D, and E, Sagittal spin-echo T2-weighted magnetic resonance imaging ( MRI) revealed spinal canal stenosis and disc degeneration from the L2/3 to L4/5 level before initial surgery. Herniated nucleus pulposus occurred at the L3/4 level after initial surgery. R: right side, L: left side
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Fig. 3
Posterior decompression and posterior lateral fusion using pedicle screws for L4 degenerative spondylolisthesis. |
Fig. 4
Four months after the initial surgery, herniated nucleus pulposus occurred at the L3/4 level. A, Myelogram demonstrating spinal canal stenosis at the L4 level. Discogram ( B) and postdiscogram CT scan ( C) showing sequestrated nucleus pulposus from the L3/4 disc.
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Fig. 5
A, Removal of disc herniation and extended posterior lateral fusion with pedicle screws. B, C, and D, MRI after this followup corrective surgery revealed no disc herniation at this level. C: L3/4 disc level, D: L4 level.
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III. Discussion
We searched the English and Japanese-language medical literature and, to the best of our knowledge, only a single case of herniated nucleus pulposus at a level adjacent to spinal fusion surgery has been reported［3］. This single case occurred in the long term［3］. We are not aware of any reports of early occurrence of herniated nucleus pulposus at a level adjacent to spinal fusion. In the current case, disc degeneration and bulging at the L3/4 level were observed before initial surgery. Four months after the initial surgery, excessive mechanical force occurred at the L3/4 level due to pedicle screw fixation between the L4 and L5 levels and strained lower back. Chow et al. studied the effect of interbody fusion on intradiscal pressure of segments above the fusion and found increased pressure levels［4］. So we considered that the occurrence of sequestrated nucleus pulposus at the L3/4 level was caused by excessive mechanical force.
Many authors have reported that in most cases sequestrated nucleus pulposus is thought to be absorbed within a few months. Spontaneous resorption of herniated disc is frequently detected by MRI. Marked infiltration by macrophages and neo-vascularization are observed upon histogical examination of herniated dis. In addition, MRI studies suggest that herniated disc resorption occurs more frequently in those completely exposed to the epidural space and that this correlates with their degree of vascularization［5］. Recent studies by MRI and CT have shown a gradual disappearance or decrease in the size of herniated nucleus pulposuses［6,7］. This decrease in the size of a herniated nucleus pulposus is often accompanied by a reduction of pain. However, the sequestrated nucleus pulposus did not disappear in the current case. Myelography revealed stenosis of the spinal canal. Discography and CT showed clear images of a large sequestrated nucleus pulposus from the L3/4 intervertebral disc. So, this large sequestrated nucleus pulposus is generally disappeared, however, the patient underwent surgery. During follow-up corrective surgery it was found that dura mater adhered to the posterior longitudinal ligament, and a sequestrated nucleus pulposus existed between the vertebral body and the adherent tissue. We could not confirm rich vasucularization in the space during surgery. Although we did not examine the histology of the nucleus pulposus because we could not harvest it in whole, we conclude that the failure of absorption of the disc herniation was due to the reduced vascularization caused by adhesion following the initial surgery.
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要旨
腰部脊柱管狭窄症に対し固定術後，4ヶ月で隣接椎間に発症した巨大椎間板ヘルニアの1例を経験した。ぎっくり腰を契機に，右下肢痛と軽度麻痺が出現した。固定術隣接椎間の椎間板ヘルニアと診断するも，3ヶ月の保存療法で軽快しなかったため，ヘルニア摘出術を行った。初回手術の癒着のため，ヘルニアは椎間板線維輪を穿破するものの，後縦靭帯とL4椎体の間に存在していた。我々が渉猟し得た限り，短期間に固定術隣接椎間に発症した椎間板ヘルニアの報告例はなく，また，初回手術癒着のため本来吸収されるべきヘルニアの治癒機転が働かなかったと考えられた。
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References
1) Lehmann TR, Spratt KF, Tozzi JE, Weinstein JN, Reinarz SJ, el-Khoury GY, Colby H. Long-term follow-up of lower lumbar fusion patients. Spine 1987; 12: 97-104.
2) Niu CC, Chen WJ, Chen LH, Shih CH. Reduction-fixation spinal system in spondylolisthesis. Am J Orthop 1996; 25: 418-24.[Pubmed]
3) Miyashita T, Yamagata M, Takahashi K, Tauchi T, Hatakeyama K, Hirayama J. A case of lumbar disc herniation after spinal fusion in destructive spondyloarthropathy. Rinshoseikeigeka 2000; 35: 1299-303. ( In Japanese).
4) Chow DH, Luk KD, Evans JH, Leong JC. Effects of short anterior lumbar interbody fusion on biomechanics of neighboring unfused segments. Spine 1996; 21: 549-55.[Pubmed]
5) Haro H, Kato T, Komori H, Osada M, Shinomiya K. Vascular endothelial growth factor ( VEGF)-induced angiogenesis in herniated disc resorption. J Orthop Res 2002; 20: 409-5.
6) Komori H, Shinomiya K, Nakai O, Yamaura I, Takeda S, Furuya K. The natural history of herniated nucleus pulposus with radiculopathy. Spine 1996; 21: 225-9.
7) Saal JA, Saal JS, Herzog RJ. The natural history of lumbar intervertebral disc extrusions treated nonoperatively. Spine 1990; 15: 683-6.[Pubmed]
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Others
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba 260-8670.
佐久間詳浩，大鳥精司，古志貴和，井上 玄，伊藤俊紀，守屋秀繁，高橋和久: 後側方固定術後短期に隣接椎間に発症した腰椎椎間板ヘルニアの1例．
千葉大学大学院医学研究院整形外科学
Tel. 043-226-2117. Fax. 043-226-2116.
2006年5月1日受付，2006年7月26日受理.
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