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Neurology India, Vol. 54, No. 1, January-March, 2006, pp. 38-41 Original Article Intraspinal synovial cysts: A retrospective study Acharya R, Patwardhan RV, Smith DR, Willis BK, Fowler M, Nanda Anil Department of Neurosurgery, Louisiana State University Health Sciences Center in Shreveport, Shreveport, Louisiana Code Number: ni06007 Abstract Background: We report the clinical presentation, radiographic studies, intraoperative findings, histopathological analysis, and post-treatment outcome in 26 patients diagnosed with spinal synovial cysts (SSCs).Aims: To describe the clinical presentation, radiographic studies, operative findings, and postoperative follow-up in 26 patients with SSCs. Settings and Design: The study was retrospective in design, involving chart review. Individual patient data was tabulated and patterns were recognized. Materials and Methods: The charts for 26 patients who underwent surgical extirpation of SSC between April 1993 and October 2002 were retrospectively reviewed. Specifically, initial clinical presentation, pertinent radiographs (X-rays, magnetic resonance imaging, computed tomography), intraoperative findings, histopathology, and postoperative follow-up were noted. Statistical Analysis Used: Patient data was tabulated and analyzed for patterns in demographics, symptoms and histopathology. Results: SSCs were more common in females than males (17:9 ratio). Presenting symptoms were back pain with radiculopathy in 13 (50%), radicular pain in the absence of back pain in 10 (38%), and back pain without radicular pain in three (11%). In addition, 17 patients (65%) had sensory deficit, and 9 (35%) had motor deficit. Most SSCs occurred at the lumbar (19/26) or lumbosacral (5/26) regions, with only 2 (2/26) in the thoracic region. One patient had bilateral SSC at the L4-5 level. Intraoperatively, each cyst was located adjacent to a degenerated facet joint. These lesions could grossly be identified intraoperatively and histopathological confirmation was achieved in all the cases. Conclusions: SSCs are important lesions to consider in the differential diagnosis of lumbar epidural masses and surgical resection leads to significant improvement in the majority of cases. Keywords: Extradural, facet joint, spine, synovial cyst Introduction We report the clinical presentation, radiographic studies, intraoperative findings, histopathological analysis, and post-treatment outcome in 26 patients diagnosed with SSC. Results from the present study, in the context of findings from other pertinent series, are reviewed.Materials and Methods The charts of 26 patients treated for SSCs between April 1993 and October 2002 were retrospectively reviewed. Specifically, clinical presentation (initial history and physical examination), radiographic studies (X-rays and magnetic resonance imaging (MRI) in 26 patients, with computed tomography (CT) in one), intraoperative findings, histopathology, and post-operative follow-up were noted. Individual data for each patient appears in [Table - 1]. Collectively, specific patterns for SSCs were recognized. The median age at diagnosis was 55.9years (range = 27 to 80 years). Females were more frequently affected (17:9 ratio) in comparison to males. With respect to distribution of pain, a radicular distribution was the presenting symptom in almost all cases (23/26), accompanied by back pain in 13 cases. Back pain alone was found in only three cases. Sensory deficits were common (17 out of 26 patients, 65%), with motor deficits being less frequent (9 out of 26 patients, 34%) at presentation. The mean duration of symptoms prior to diagnosis was 12.7 months (range = 1 to 36 months). Results The majority of SSCs were located in the lumbar (19 out of 26, 73%) or lumbosacral (5 out of 26, 19%) regions, with only two SSC (7%) located in the thoracic region of the spine. One patient had bilateral SSC at L4-5 level (case no 23). Only one patient had history of prior trauma, while six others underwent prior surgery for herniated disc excision, canal stenosis, instability, or a benign lesion. One patient had a disc herniation associated with the SSC. All patients underwent surgical excision of the cyst. Nineteen patients underwent laminectomy, while in five patients, the excision could be accomplished through a hemilaminectomy. One partial facetectomy was also performed. In one patient, the inter-laminar space was wide enough so the cyst was visualized after incising the ligamentum flavum not requiring any bone removal (case no 24). The adherence of some SC to the dura can make the dissection really problematic in some instances (Risk of dural tear, risk of root lesion with the Kerrison, risk of incomplete SC resection). Postoperatively, significant pain relief was noted in practically all patients. Sensorimotor deficits improved in all patients, however, four of the patients continue to demonstrate mild sensory deficits. Postoperative complications included a cerebrospinal fluid wound leak following resection of a lumbosacral SSC in one patient, which required subsequent intraoperative primary repair and a superficial wound infection, which was treated successfully by a 1-week regimen of antibiotics. Histopathologically, 11 specimens revealed a true synovial epithelial lining; the remainder were either ganglion cysts (where no epithelial lining was present) or had features of both true synovial and ganglion cysts, as discussed in greater detail in the following section (see "Histopathology" under the Discussion section). Dystrophic calcification was present in the walls of 3 ganglion cysts. Discussion In 1877 Baker defined synovial cysts in association with an adjacent degenerated joint.[1] The description of a spinal synovial cyst (SSC), in turn, is credited to Von Gruker, who initially discovered this lesion while performing an autopsy.[1],[2] The clinical presentation, imaging findings, treatment, and prognosis related to these lesions have since been better characterized by numerous studies [Figure - 1]. [1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18],[19],[20],[21],[22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32] The majority of studies reported thus far describe findings related to a small number of patients, 32. Only three of these studies involve more than 20 patients.[1],[33],[34]
Histopathology In our study, the tissue from each histolopathologically reviewed case revealed a cyst with a thick fibrous wall. In 11 patients the cystic structures were partially lined by synovial cells, hence depicting a "true synovial cyst" [Figure - 2]. In the remaining patients, either no epithelial lining or rare flattened cells with significant chronic inflammatory changes were present. As previously mentioned, such features may represent the continuum between true synovial cysts and ganglion cysts [Figure - 3]. The presence of calcium, as noted in 3 of the ganglion cyst walls, supports the degenerative, metaplastic changes, which may be associated with these lesions. The facetectomy, is definitely not recommendable. The bipolar coagulation of the synovial membrane preserving the interapophyseal joint is also recommended to avoid synovial cyst recurrence.[34] There is no doubt that synovial cysts express a local instability in predisposed individuals, preferably females. However, it is rarely a mobile instability such as in spondylolysis. It behaves like a transient local degenerative instability occurring during a limited period of the lifetime. Conclusion Spinal synovial cysts are likely degenerative lesions with a juxta-facet location. Most occur at the lumbar (L4-5) region and are associated with radicular symptoms, which are best visualized by MRI. Our experience supports that with a careful understanding of the anatomy as visualized by imaging studies, surgical decompression can lead to significant improvement in symptoms.Acknowledgment The authors thank Ms. Jeanie McGee and Tedd Chambers for their editorial assistance in preparing this work.References
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