Evidence that atypical juxtafacet cysts are joint derived

OBJECT

Juxtafacet cysts (JFCs) in usual locations have recently been shown to have joint connections. The pathogenesis of JFCs in unusual locations has remained obscure. The authors hypothesize that all JFCs, including atypical ones, are joint derived.

METHODS

In this study the authors sought to explain the occurrence and formation of clinical outliers of spinal JFCs. In Part I, they performed an extensive literature search to identify case reports of spinal intraneural cysts that have been unappreciated despite the fact that they should occur. In Part II, they studied far-lateral (extraforaminal) cysts treated at their institution and reported in the literature. The presence of a joint connection was specifically looked for since this finding has not been widely appreciated.

RESULTS

In Part I, 3 isolated case reports of spinal intraneural JFCs without reported joint connections were identified: 2 involving L-5 and 1, C-8. In Part II, 6 cases involving patients with far-lateral JFCs treated at the authors' institution were reviewed and all 6 had joint connections. Two of these cases had been previously published, although their joint connections were not appreciated. In 2 of the newly reported cases, arthrography confirmed a communication between the facet and the cyst. Only 1 of 5 cases in the literature had a recognized joint connection.

CONCLUSIONS

The authors believe that all JFCs are joint derived. This explanation for intraneural and extraneural JFCs in typical locations would be consistent with the unified articular (synovial) theory and the pathogenesis for intraneural and extraneural ganglion cyst formation in the limbs. Facet joints appear no different from other synovial joints occurring elsewhere. Understanding the pathogenesis of these cysts will help target treatment to the joint, improve surgical outcomes, and decrease recurrences.

Lumbar foraminal and far lateral juxtafacet cyst of intraspinal origin

BACKGROUND

Symptomatic lumbar juxtafacet cysts (JFC) arise from the facet joint and almost exclusively are located in the posterolateral spinal canal. A foraminal and far lateral JFC of intraspinal origin is an exceptional finding. We report the unique case of a lumbar intra-, trans-, and extraforaminal JFC to illustrate the rare location and unusual presentation and discuss its anatomical variants, diagnostic difficulties, and therapeutic consequences.

CASE DESCRIPTION

A patient presented with a left L3 radiculopathy. Computed tomography revealed an intraspinal cystic posterolateral mass at level L3-L4, accompanied by an intra- and extraforaminal lesion compressing the upper nerve root. Based on these findings, a JFC and an additional extraforaminal disc herniation were suspected. Magnetic resonance imaging showed that the intraforaminal and extraspinal mass communicated with the intraspinal lesion and was cystic as well. The patient was treated successfully by combining an interlaminar and paraisthmic access. Microsurgery disclosed a JFC, which had a small intraspinal, panforaminal, and large extraspinal part.

CONCLUSION

An unusual case of a JFC originating intraspinally and extending through the neuroforamen to become a symptomatic extraspinal lesion with compression of the upper nerve root is reported. The patient's excellent response to operative treatment confirmed the effectiveness of the combined microsurgical approach applied. The occurrence of JFC should be kept in mind in differential diagnosis of both intra- and extraspinal and foraminal lumbar lesions.

Synovial cyst of dens axis. A case report

Synovial cyst of dens axis is a rare pathology accounting for 0.5%-1% of all cases of spinal synovial cysts. The lesion is normally found in the final part of the lumbar tract. The etiopathogenesis is uncertain and many theories abound Clinical inspection is important and the symptoms are caused by compression of posterior roots of spinal nerves and by spinal canal stenosis. Differential diagnosis is with disc herniation or tumours, but the diagnosis can only be established after CT and MRI examination. We describe the case of an 83-year-old man who underwent radiological exmaination after ten years of symptoms. The pathology was diagnosed only after the CT and MRI investigation.