Lumbar Discal Cyst: a Rare Cause of Low Back Pain and Sciatica in a Young Bodybuilder—Case Report
- 207 Downloads
A discal cyst is a rare intraspinal, extradural mass with a distinct communication with the corresponding intervertebral disc [2, 9]. All reported cases demonstrate that the clinical picture determined by discal cyst is indistinguishable from other causes of low back pain and radiculopathy such as conventional disc herniations. There is limited information on the pathogenesis, natural course, and surgical treatment. Thus, most neurosurgeons are not aware of this disease entity.
The purposes of this report are to describe a case of discal cyst and to raise awareness of the disease and its radiological findings, to consider it in the differential diagnosis of a physically active young patient presenting with sciatica and low back pain. A more accurate knowledge of a disease can lead to avoid unnecessary investigation and delayed treatment.
A 17-year-old man had a 1-week history of severe low back pain radiating to hip and left anterior thigh. The pain was worse when the patient was sitting on a toilet seat and partially relieved when he was lying down for rest. Physical examination revealed full strength in both lower extremities. There was no pain during the femoral nerve stretch test. He was referred to our hospital with impression of intraspinal tumor.
Lumbar discal cyst, intraspinal extradural cyst that communicates with the intervertebral disc, is a relatively new clinical entity that reported in the Japanese literature in the second half of the 1990s [2, 6, 14]. It occurs at a slightly younger age and at higher intervertebral levels than typical disc herniation. Its symptoms are similar with other intraspinal cystic mass lesions. A variety of cystic lesions may develop within the spinal canal including perineural cyst [13, 15], extradural arachnoid cyst , and synovial cyst of the facet joint , as well as extruded disc fragment in the epidural space . Location can be a helpful discriminating factor, as synovial cysts develop from facet joints and are therefore usually located on the posterolateral aspect of the thecal sac. It can contain mucinous fluid or blood, has synovial lining cells in its wall , and has no communication with the intervertebral disc. Perineural cysts may have the same signal characteristics as non-hemorrhagic discal cysts with a thin wall; however, they are multiple and in close relationship with the dorsal nerve root [13, 15]. They do not show peripheral enhancement following contrast administration. Extradural arachnoid cyst occurs predominantly in younger persons and is located primarily in the thoracic spine usually in the dorsal aspect of the dural sac. Enhancement of an arachnoid cyst is not seen in contrast-enhanced MR images . An extruded disc fragment in the epidural space can occur in the ventrolateral epidural space just like a discal cyst. MR image shows a non-enhancing disc fragment with surrounding thick granulation tissue .
The etiology and pathogenesis of an intraspinal discal cyst remain unknown. Two hypotheses for the formation of these cysts have been suggested [2, 6]. Chiba et al.  proposed that disc injury in the setting of mild disc degeneration causes an annulus fibrosus fissure in the posterior intervertebral disc, leading to hemorrhage of the epidural hematoma and a blood-filled or hemosiderin-containing cyst. Kono et al.  proposed that discal cysts result from focal degeneration and cystic softening of collagenous connective tissue of the disc with fluid production, similar to the mechanism of meniscal cyst formation occasionally observed in patients with meniscal degeneration in the knee. The extruded fluid incites an inflammatory response leading to reactive pseudo-membrane formation and the development of the discal cyst . We prefer this hypothesis for the pathologic findings of the cyst wall, including fibrous structure without synovial lining cells in our case, which is compatible with pseudo-membrane. Our patient presented with mild disc degeneration. His career as a bodybuilder implies a prior history of severe and repetitive mechanical stress, including raising abdominal pressure like Valsalva maneuver. But in addition to disc stress caused by bodybuilding exercises, it is plausible that bony anomalies in spine (incompletely closing of posterior arch in T12) also may contribute to further disc degeneration, and by extension, to the evolution of the discal cyst.
In most reported cases, the pain and symptoms of patients after surgical removal were remarkably relieved [4, 5, 8]. In our case, the discal cyst was easily resected using a microscopic approach. It is difficult to draw evidences on the best treatment of discal cysts as the natural history and the long-term prognosis remain unclear. Several authors have documented spontaneous resolution of discal cyst under conservative management, but surgery (endoscopic resection or laminotomy with cyst excision) is the most common treatment, especially in physically active patients [3, 8, 12]. More cases with longer follow-up are needed to provide therapeutic guidelines .
It is important to be aware of discal cyst, to recognize its appearance on MRI, and to be able to differentiate it from that of the more common cystic lesions within the spinal canal. Once discal cysts are diagnosed via a meticulous review of MR image, a gross total resection of the cyst can provide complete relief of the symptoms.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
Consent for Publication
The patient has consented to submission of this case report to the journal.
- 13.Tarlov IM. Perineural cysts of the spinal nerve roots. Arch Neurol Psychiatry. 1938;51:125–46.Google Scholar
- 14.Toyama Y, Kamata N, Matsumoto M, Nishizawa T, Koyanagi T, Suzuki N. Pathogenesis and diagnostic title of intraspinal cyst communicating with intervertebral disk in the lumbar spine. Rinsho Seikei Geka. 1997;32:393–400.Google Scholar