Neurosurgery Service, Alicante University General Hospital, Alicante Institute for Health and Biomedical Research (ISABIAL - FISABIO Foundation), Alicante, Spain.
The first description of a synovial cyst involving the spine was an autopsy study by Von Gruker 1).
Kao et al. later confirmed this in 1974 3).
They are relatively rare, only 3 cases were identified in a series of 1500 spinal CT exams 4) but the frecuency of diagnosis may be on the rise due to the widespread use of MRI and an increasing awareness of the condition.
Eyster et al. reviewed approx. 1,800 MRIs and CTs over one and half year and found 11 (0.6% of) cases of lumbar synovial cysts of the spine 5). However Doyle et al., 6) found a prevalence of 2.3% anterior and 7.3% posterior spinal cyst in a review of 303 retrospective analyses of MRIs. Similarly Lemish et al. 7) identified 10 cysts in 2,000 reviews of CT lumbar spines.
Most of the patients with lumbar cysts tend to be in their sixth decade of life with a range that is varied from as early as 28 years to as late as 94 years 10). A female bias has been reported often 11) , but others refute that.
They are extremely rare in adolescence and young adulthood, only two pediatric cases have been reported in the literature, but they could be considered in the differential diagnosis in adolescent patients with low back pain and radiculopathy. Surgical removal of LSC could be considered as a treatment option to provide immediate and safe symptomatic relief 12).
They may be bilateral.
Typically situated posterolateral in the spinal canal, intraspinal facet cysts often cause radicular symptoms. Rarely, the midline location of these synovial or ganglion cysts may cause thecal sac compression leading to neurogenic claudication or cauda equina syndrome.
It is a benign condition, and the symptoms and level of pain or discomfort may remain stable for many years.
The fluid-filled sac creates pressure inside the spinal canal, which can give a patient all the symptoms of stenosis of the spine.
The pain probably comes from the venous blood around the nerves not being able to drain, which leads to pain and irritation of the nerves. Sitting down allows the blood to drain and relieves the pressure.
Lumbar facet cysts are most common at the L4-L5 level and often are associated with spondylosis and degenerative spondylolisthesis. Advanced imaging studies have increased diagnosis of the cysts 24).
Characteristic findings on magnetic resonance imaging obviate the need for any additional radiological studies 25).
The detection rate of JFC improves with increasing lordosis of the spine and under weight-bearing conditions, particularly when standing. Unstable slipping or increased angular movement affects the size of JFC 26).
Intraspinal synovial or ganglion cysts are uncommon lesions associated with degenerative lumbosacral spine disease. CT usually reveals cystic lesions adjacent to a facet joint, and they may show calcification. MR imaging of four surgically confirmed cases of intraspinal synovial cysts revealed subtle signal changes compared with CSF. Short TR/TE images showed the lesions to be slightly hyperintense in three cases and isointense in one case. Long TR/TE sequences revealed a hyperintense appearance in two cases and a hypointense appearance in the others. A peripheral rim of decreased signal on long TR/TE images probably reflects fine calcification or hemorrhage in the margins of the cysts. The multiplanar and contrast characteristics of MR make this technique well suited to the diagnosis of herniated disk, degenerative facet disease, and synovial cyst 27).
Typically seen as a calcified cystic lesion adjacent to a facet joint.
CT may also show adjacent facet joint arthropathy +/- presence of gas.
This entity cannot be reliably distinguished from ganglion cyst on standard MRI. However, communication with the joint space after intra-articular injection with contrast reliably differentiates the two.
Gas within the cyst is pathognomonic for a synovial cyst
Facet joint cysts may contain complex fluid as a result of internal debris or haemorrhage
Neural based cysts can usually be differentiated by imaging as these cysts show intimate relation with the adjacent nerve, rather than with the adjacent joint space
Calcification within cyst wall appears low signal intensity on both T1 and T2 weighted images whereas haemorrhagic cysts display increase intensity compared to CSF likely due to T1 shortening from methaemoglobin.
The cysts do not always possess the signal characteristics of a simple cyst, so contrast administration may be needed in some cases. It is important to remember that they are a cause of peripherally enhancing masses in the extrathecal space anywhere along the spinal canal.
Distinction of these types is difficult without histology and is clinically unimportant 28).
Contradictions in the terminology applied to lumbar juxtafacet cysts arise from the frequent sparsity of synovial lining cells, which has led to synovial cysts often being called “ganglion cysts” despite lacking confirmatory pathology.
Cysts having an extensive or meagre synovial cell lining are common in the ligamentum flavum of patients with symptomatic lateral or central stenosis. The cysts communicate with the facet joint by a bursa-type channel within the ligamentum flavum. Advanced osteoarthritis of the facet joint causes the liberation of fragments of cartilage and bone into the synovial fluid of the joint space. This enables some fragments to escape from the joint into the channel and become lodged within its wall where they provoke granulation tissue and scar formation. The tissue response to articular debris may block the synovial-lined channel to cause synovial cyst formation 29).
Optimal treatment of the cysts remains controversial.
There is one case report of a cyst that resolved spontaneously 30).
If symptoms persis with conservative treatment, some promote cyst aspiration or facet injection with steroids 31) while most advocate surgical excision of the cyst.
First-line treatment is nonsurgical management consisting of oral NSAIDs, physical therapy, bracing, epidural steroid injections, and/or cyst aspiration. Given the high rate of recurrence and the relatively low satisfaction with nonsurgical management, surgical options, including hemilaminectomy or laminotomy to excise the cyst and decompress the neural elements, are typically performed. Recent studies suggest that segmental fusion of the involved levels may decrease the risks of cyst recurrence and radiculopathy 32).
Surgical removal of juxtafacet cysts is recommended for immediate symptomatic relief. Concomitant spinal fixation to prevent progression of spinal spondylolisthesis or cyst recurrence depends on cyst size, involvement of surrounding structures, degree of preoperative spondylolisthesis, and facet joint destruction 33).
The controversy about conservative versus surgical treatment and the need for concomitant fusion still exists 34).
Targeted Radiofrequency Ablation as an Adjunct in Treatment of Lumbar Facet Cysts 35).
There are three main non-surgical treatment options for synovial cysts in the lumbar spine:
Observation and activity modifications
General non-surgical treatments for pain relief
Observation and Activity Modification
If the synovial cyst is not creating a lot of dysfunction or pain in the patient’s daily life, no medical treatments may be necessary. Since the pain is usually caused by certain positions, changing positions is a reasonable way to deal with the pain as long as a patient can still function adequately.
In conjunction with activity modification, patients will typically find pain relief with a range of possible nonsurgical remedies, including but not limited to:
Application of ice and/or heat, which is especially effective for activity related pain and discomfort
Pain medications, including non-steroidal anti-inflammatory medications (such as ibuprofen), acetaminophen, and/or prescription pain medications
Rest, which is most effective for brief periods, such as a few hours or a day or two
Almost all treatment regimens will include some form of exercise and stretching routine. For aerobic exercise, it may be preferable for the patient to try stationary biking instead of walking, because in the seated position (leaning forward) the patient should be fairly comfortable.
36 consecutive patients with JFC and the same number of controls, with degenerative diseases without JFC were match paired for demographics and spine segment. Parameter assessment was by T2-weighted axial MRI scans. JFC diagnosis was confirmed histopathologically. Group comparison was by Student's t-test for continuous variables and X(2) for categorical variables. RESULTS: Nineteen female and 17 male patients, aged between 45 and 85 years (mean 67.19±10.3 years) had a mean JFC size of 9.26±4.8mm occurring most frequently in the segment L4-L5 (75% n=25) and on the left side (61%). Mean FJ orientation of the study group was significantly more coronal compared to controls (left side 42° vs 36°, p<0.02*, 95% confidence interval: 0.9-11.5 and right side 43° vs 37°, p<0.02*, 95% confidence interval: 0.6-10.6 respectively). However, individual intersegmental analysis for study group patients showed the JFC bearing side to be significantly more sagittally oriented 40°±11.2° compared to 45°±13.2° for the side without FJC (p<0.03*, 95% confidence interval: 8.1-1.7). 50% of the study group showed FJ asymmetry compared to 30% in controls, with a trend for FJ tropism (p<0.07). Severe (grade 3) FJ arthritis was significantly more predominant in the study group 23/33 (p<0.001*) as compared to controls. CONCLUSIONS: Compared to a control group, JFC occurrence is associated with significant higher rates of arthritis and coronally orientated FJ. At intersegment comparison within the same patient cysts located in more sagittally orientated FJ and the asymmetric segments show a trend for FJ tropism 36).
One observer undertook a review of MRI of the lumbar spine from one facility in a series of 303 patients referred mostly for back pain or radiculopathy. The presence of lumbar facet joint synovial cysts, their relationship to the facet joint, the degree of associated facet joint osteoarthritis, the presence of spondylolisthesis, and the degree of associated disc degeneration were recorded.
Seven anterior cysts (prevalence = 2.3%) were identified, only two of which did not clearly cause nerve root compression. Twenty-three posterior cysts in 22 patients (prevalence = 7.3%) were identified. Statistically significant associations with increased frequency and severity of facet joint osteoarthritis and with spondylolisthesis were demonstrated compared to patients without cysts.
Both anterior and posterior lumbar facet joint synovial cysts are rare. Posterior cysts are more common than anterior cysts. Both types of cysts are related to facet joint osteoarthritis but not to disc disease 37)
Spinal instability may be a cause of juxtafacet cyst formation and the pain and disability that occur after surgical excision of the cyst. To determine the role of instability, a retrospective review of charts identified 60 facet cysts in 56 patients treated over a 6-year period. Three patients developed an asynchronous cyst at the same level but on the opposite side of the previously resected cyst and one patient had a recurrent cyst in the same location. Forty-one cysts were present in patients with radiculopathy and 16 in patients with neurogenic claudication. Two patients presented with myelopathy and one had cauda equina syndrome. Thirty-six of the 60 cysts were located at L4-5, the most mobile segment. Fifteen patients had spondylolisthesis, of whom two experienced worsening spondylolisthesis postoperatively. Seven patients had scoliosis and 20 had systemic arthritis. Fifty-five cysts were resected via mesial facetectomy. Six of the patients undergoing this procedure had transverse process fusions at initial surgery for preoperative instability. Two others required fusion for post-operative instability and increased spondylolisthesis. Follow-up review was available in 95% of patients with an average duration of 12 months. Forty patients had excellent relief of symptoms, 12 had occasional back pain, and one patient did poorly. Flexion/extension views of the spine are recommended both pre- and postoperatively to identify the need for fusion in patients with juxtafacet cysts 38).
Over the past 18 months Eyster and Scott. have encountered 11 cases of symptomatic lumbar synovial cysts. This experience occurred during a period during which some 1,800 lumbar computed tomographic scans were done. The apparent increased incidence of these lesions is most likely due to the increased diagnostic ability made possible by the advent of high-resolution computed tomography and magnetic resonance imaging. This is a report and discussion of our 11 cases with a review of the literature. There is nothing distinctive in the physical findings or in the histories of our patients, but we have found, as have others, that high-resolution computed tomographic scanning and magnetic resonance imaging significantly enhance the diagnosis of such lesions 39).
Intraspinal synovial cysts can be accurately diagnosed by computed tomography (CT). Lemish et al., report ten cases of lumbar intraspinal synovial cysts (LISC) that highlight the clinical and radiologic features 40)
13 patients with synovial or ganglion cysts of the spinal facet joints causing nerve root compression. These cysts were found in both the cervical and the lumbar spine, and the anatomical location of each cyst corresponded to the patient's signs and symptoms. In no case was there evidence of intervertebral disc abnormality found at operation. The patients ranged from 49 to 77 years of age and included 4 men and 9 women. Radiographic evidence of facet degenerative change and degenerative spondylolisthesis was frequently but not invariably noted. The extradural defects defined with positive contrast myelography or postmyelography computed tomographic scanning were usually posterior or posterolateral to the common dural sac and were misinterpreted as extruded discs in the majority of cases. Treatment consisted of laminectomy and surgical excision of cysts. All patients reported improvement or resolution of their presenting symptoms 41).
Four patients who had low-back pain and sciatica were diagnosed as having a lumbar intraspinal extradural synovial cyst adjacent to a facet joint between the fourth and fifth lumbar vertebrae. The patients ranged in age from forty-nine to seventy-one years, and the symptoms and signs involved the fourth or fifth lumbar-nerve roots. Roentgenographically, degeneration of the intervertebral discs and facet joints was noted in every patient. Degenerative spondylolisthesis was also a frequent finding. Myelography and computed tomographic scans aided in diagnosis, revealing a soft-tissue lesion, occasionally rimmed with calcification, adjacent to the involved facet joint. The treatment was surgical excision of the cyst, as well as complete laminectomy if there was concomitant spinal stenosis. Follow-up, ranging from eighteen to twenty-five months, revealed complete resolution of the sciatica in all patients 42).
A patient with a juxta-facet cyst and conjoined nerve roots. A 66-year-old man presented with left leg pain from the past 4 months. Neurological examinations revealed L5 and S1 radiculopathy on the left side. Magnetic resonance imaging(MRI)detected a mass lesion located near the left intervertebral joint at the level of L5/S1 and canal stenosis at the level of L3/L4. A juxta-facet cyst was diagnosed by arthrography. We performed a curettage and resection of the mass, posterior lumbar interbody fusion at the level of L5/S1, and laminectomy at the level of L3/L4. Conjoined left L5/S1 nerve roots were observed during surgery. The patient recovered from the symptoms of L5 and S1 radiculopathy immediately after surgery. Postoperative review of the preoperative computed tomography images revealed bony abnormality in the L5/S1 joint. The authors speculate that the bony abnormality may be associated with the development of conjoined nerve roots and the juxta-facet cyst 43).
A 57-year-old woman presented with a 2-year history of progressively worsening lower back pain, left leg pain, weakness, and paresthesias. Imaging showed a giant, completely calcified mass arising from the left L5-S1 facet joint, with coexisting grade I L5 on S1 anterolisthesis. The patient was treated with laminectomy, excision of the mass, and L5-S1 fixation and fusion.
The patient had an uncomplicated postoperative course and had complete resolution of her symptoms as of 1-year follow-up.
When presented with a solid-appearing, calcified mass arising from the facet joint, a completely calcified juxtafacet cyst should be considered as part of the differential diagnosis 44).
A case of a lumbar spinal extradural cyst is reported. An accurate preoperative diagnosis was made using magnetic resonance imaging. Characteristic findings on magnetic resonance imaging obviate the need for any additional radiological studies. The clinical features, radiological findings, and pathogenesis of these lesions are discussed 45).
A patient with posttraumatic lumbar radicular paresthesias is presented. The preoperative diagnosis of an epidural synovial cyst was considered. At surgery, an epidural synovial microcystic mass was found emanating from a distracted L4-5 facet joint and dissecting into the layers of the ligamentum flavum. A brief review of the condition is presented 46).
A case of intraspinal synovial cyst with sciatic pain diagnosed by CT, that showed spontaneous resolution and clinical improvement with medical treatment and comment on another two cases of this unusual entity discovered among over 1500 spinal CT explorations 47).