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Vascular and Interventional Radiology |
1 From the Department of Radiology, Centre Hospitalier de l’Université de Montréal, Hôpital Saint-Luc, 1058 Saint-Denis St, Montreal, Quebec, Canada H2X 3J4 (N.J.B.); and the Department of Bone and Joint Radiology, Massachusetts General Hospital, Boston (P.A.K., R.G.D). From the 2000 RSNA scientific assembly. Received December 27, revision requested February 8, 2001; revision received March 26; accepted April 10. Address correspondence to N.J.B. (e-mail: nathalie.bureau@umontreal.ca).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Clinical outcome and imaging findings were retrospectively studied in 12 patients (four men, eight women) aged 45–79 years (mean, 60 years) with a symptomatic lumbar facet joint synovial cyst treated with percutaneous steroid injections. At varying times after the procedure, patients were contacted for clinical follow-up, and repeat imaging was performed to verify the status of the cyst.
RESULTS: Excellent pain relief was achieved in nine (75%) of 12 patients. At follow-up imaging, the cyst completely regressed in six (67%) of these nine patients, partially regressed in two (22%) patients, and was unchanged in one (11%) patient. One (8%) of the 12 patients had transient pain relief, with recurrence of symptoms at short intervals after each of three injections. No pain relief was achieved in two (17%) of 12 patients.
CONCLUSION: Image-guided percutaneous steroid injections are often effective in the treatment of lumbar facet joint synovial cysts and may result in complete regression of the cyst.
Index terms: Computed tomography (CT), guidance, 33.12112 • Spine, cysts, 33.779 • Spine, facet joints, 33.334 • Spine, interventional procedure, 33.1269 • Steroids
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Although the diagnosis of a synovial cyst of the lumbar facet joint can be established with computed tomography (CT) (7,8), these cysts often are more conspicuous and more easily diagnosed with magnetic resonance (MR) imaging, because of its increased contrast resolution (9–13).
Traditionally thought to be an uncommon cause of painful radiculopathy (6,8,13,14), the true incidence of lumbar facet joint synovial cysts may in fact be higher, as findings in recent reports of large series suggest (5,15,16). The increasing number of recently reported lumbar facet joint synovial cysts might reflect the improved diagnostic accuracy afforded by CT and MR imaging (15,17).
Although study findings (6,14,18) have confirmed the effectiveness of image-guided percutaneous facet joint steroid injections for the treatment of symptomatic lumbar facet synovial cysts, patients with these cysts are still largely treated at surgery with laminectomy, facetectomy, and resection of the cyst (15,16,19).
Studies of the effectiveness of image-guided percutaneous treatment for lumbar facet joint synovial cysts have been based on evaluations of clinical outcome. Few investigators (6,14) have provided data about the appearance of the cysts following percutaneous treatment, and, to our knowledge, in no study was disappearance of the cyst demonstrated at imaging following percutaneous treatment. In addition, to our knowledge, no investigator has provided detailed information about the technique of injection used for percutaneous treatment of these cysts.
The purpose of this study was to determine the imaging characteristics of lumbar facet joint synovial cysts following percutaneous treatment with steroid injection and distention of the cyst and to correlate these findings with clinical outcome.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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The clinical presentations in these patients were radiculopathy alone (n = 5), low back pain and radiculopathy (n = 4), low back pain and hip pain (n = 2), or low back pain alone (n = 1). The symptomatic side correlated with the side of the synovial cyst in all cases. The diagnosis of a lumbar facet joint synovial cyst was initially established with MR imaging. MR images were evaluated for the location and size of the cyst and the presence of osteoarthritis in the adjacent facet joint. All MR examinations included sagittal spin-echo T1-weighted sequences (repetition time msec/echo time msec, 400–550/9–16), fast spin-echo T2-weighted fat-suppressed sequences (3,000– 4,000/80–102), and transverse fast spin-echo T2-weighted and/or T1-weighted sequences, which were able to demonstrate a mass in the spinal canal adjacent to a degenerated facet joint. The mass had low signal intensity on T1-weighted images and high (n = 9) or heterogeneous (n = 3) signal intensity on T2-weighted images. Gadolinium-based contrast material (gadopentetate dimeglumine, Magnevist; Schering, Berlin, Germany) was intravenously administered to three patients; it resulted in a ring of enhancement around the mass.
Three experienced musculoskeletal radiologists (N.J.B., P.A.K., R.G.D.) performed image-guided percutaneous treatment. These were outpatient procedures that required no hospitalization or preliminary laboratory testing. The procedures consisted of the acquisition of an arthrogram in the facet joint adjacent to the synovial cyst; this was followed by the injection of a local anesthetic, steroids, and normal saline.
Patients were placed in the prone position. According to the preference of the radiologist performing the procedure and the availability of the fluoroscopic or CT suites, the procedure was performed with aseptic conditions by using fluoroscopy (Polystar; Siemens Medical Systems, Iselin, NJ) (n = 6) or CT scanning (HiSpeed CT/i; GE Medical Systems, Milwaukee, Wis) (n = 6) for image guidance. A 22-gauge 9-cm spinal needle (Becton Dickinson, Franklin Lakes, NJ) was introduced into the inferior joint recess (20) when fluoroscopic guidance was used or directly into the facet joint space when CT guidance was used. First, 1.0–1.5 mL of a non-neurotoxic nonionic contrast medium (iohexol [Omnipaque 300]; Nycomed, Princeton, NJ; 300 mg of iodine per milliliter) was injected into the facet joint to document intraarticular positioning of the needle and filling of the cyst; this finding confirmed the diagnosis of lumbar facet synovial cyst. Then, in an attempt to rupture the cyst, as much as 3 mL of a solution consisting of a long-acting steroid (6 mg/mL betamethasone, Celestone Soluspan; Schering, Kenilworth, NJ) and a long-acting preservative-free local anesthetic (bupivacaine hydrochloride 0.5%, preservative free; Abbott Laboratories, North Chicago, Ill) mixed in equal quantities was injected and followed with an additional 1–5 mL of normal saline (sodium chloride 0.9%; Astra Pharma, Mississauga, Ontario, Canada) when necessary. At the time of the procedure, communication between the facet joint and the cyst and cyst rupture were evaluated.
One therapeutic injection was performed in five patients, two injections were performed in five patients (with a mean of 1.8 months [range, 1–4 months] between the injections), and three injections were performed in two patients (with a mean of 2.8 months [range, 1–6 months] between each injection). At varying intervals after the procedure, the patients were contacted by phone to assess the clinical outcome. Follow-up imaging studies were performed at varying intervals, when they were prescribed by the referring physician, before another injection or for another unrelated clinical problem.
Imaging studies—fluoroscopy (n = 1), CT (n = 2), or MR imaging (n = 11)—were performed at a mean of 11 months (range, 1–36 months) after the first therapeutic injection. One follow-up imaging study was performed in eight patients, two follow-up imaging studies were performed in three patients, and three follow-up imaging studies were performed in one patient. Two of the authors (N.J.B., P.A.K.) independently reviewed the follow-up images to determine whether the lumbar facet synovial cysts had changed in size (as measured with a ruler), compared with the size at the pretreatment examination.
One of the authors (N.J.B. or P.A.K.) contacted the patients by phone to assess the clinical outcome. The effectiveness of the therapeutic injection was assessed on the basis of relief of symptoms. Criteria are presented in Table 1.
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RESULTS |
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No pain relief was achieved in two (17%) of 12 patients; that is, they did not experience any substantial resolution of their symptoms. Follow-up images obtained at 1 and 2 months showed no change in cyst volume. Rupture of the cyst was not accomplished at the time of the injection in either patient, and communication between the facet joint and the synovial cyst could not be demonstrated in one patient. Both of these patients were referred for surgical removal of their cysts. Surgery resulted in resolution of radicular symptoms, with persistent back pain in one patient and partial resolution of the symptoms of left-sided back pain in the other patient.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Lumbar facet synovial cysts have been reported (1,3,4,15) as a cause of low back pain, radiculopathy and neurogenic claudication. In our experience, radicular symptoms are more often related to the presence of the cyst, while back pain is probably caused by osteoarthritis of the adjacent facet joint. These cysts can hemorrhage and cause acute symptoms (22). At CT, lumbar facet synovial cysts appear as low-attenuating lesions adjacent to the facet joint. They may protrude into the epidural space, indenting the thecal sac, or they may extend into the adjacent neural foramen, compressing the nerve root (12). They may show wall calcifications in as many as 30% of cases, or they may show an internal vacuum phenomenon (7,8). They appear as lesions with low to intermediate signal intensity on T1-weighted MR images. On T2-weighted MR images, the cyst capsule appears as a hypointense line, which usually is well demarcated from the high-signal-intensity intrathecal cerebrospinal fluid (10); the fluid within the cyst demonstrates high signal intensity. The signal intensity may be heterogeneous owing to the presence of hemorrhage, calcification, and the vacuum phenomenon (11,17). Enhancement of the synovial cyst wall and, occasionally, enhancement of the adjacent facet joint has been demonstrated after intravenous administration of gadolinium-based contrast material (13). The relationship with the adjacent facet joint is best depicted on transverse images.
Lumbar facet joint synovial cysts are most frequent at the L4-5 level. Concomitant osteoarthritis of the adjacent facet joint is usually present and severe, and low-grade degenerative spondylolisthesis also is a frequent finding in these patients (12,15–18).
Surgical cyst removal has been shown to be effective in the treatment of lumbar facet synovial cysts (3,5,15,16,19). In a large series of patients treated at the Mayo Clinics (Rochester, NY; Scottsdale, Ariz; Jacksonville, Fla) during 22 years, Lyons et al (15) reported good or excellent relief of preoperative radicular pain in 134 (91%) of 147 patients. All patients underwent laminectomy and resection of the synovial cyst. Partial hemilaminectomy was performed in 53% of the patients, and total hemilaminectomy or bilateral laminectomy was performed in 44%. Eighty-two percent of patients underwent medial facetectomy, while 12% underwent total facetectomy. A concomitant spinal fusion procedure was performed in 9% of the patients, and a delayed fusion procedure was required in another 2% who developed symptomatic spondylolisthesis. These authors reported a complication rate of 4%: cerebrospinal fluid leak (n = 3), discitis (n = 1), epidural spinal hematoma (n = 1), seroma requiring drainage (n = 1), deep venous thrombosis (n = 1), death secondary to cardiac dysrhythmia (n = 1).
Facet joint arthrography is a technique that is safely and easily performed with image guidance on an outpatient basis (20). Study findings have demonstrated the short-term (6,12) and long-term (14,18) effectiveness of percutaneous treatment of lumbar facet synovial cysts with steroid injections. In a series of 30 patients, Parlier-Cuau et al (18) reported excellent or good clinical outcomes at long-term follow-up (mean, 35 months) in 36% of their patients. One-third of these patients required more than one steroid injection. These studies have been based solely on clinical outcome. Few studies have provided data on imaging after percutaneous treatment to assess the status of the cysts (6,14), and, to our knowledge, no study has provided radiologic evidence of disappearance of the cyst after percutaneous treatment.
The aim of surgical treatment of lumbar facet synovial cysts is the removal of the cyst to relieve compression on the thecal sac and nerve roots. We can presume that the high success rate of this surgical technique is directly related to the removal of the cyst. Can percutaneous treatment of lumbar facet joint synovial cysts with steroid injections also achieve complete regression or at least partial regression of the cyst?
In this study, excellent pain relief and complete or partial regression of the cyst were attained in eight (67%) of 12 patients.
In previous studies, percutaneous treatment consisted of intraarticular injections of steroids after demonstration of the communication between the facet joint and the cyst at arthrography. In none of these studies was rupture of the cyst attempted during the injection. Findings from studies of percutaneous treatment of ganglion cysts in the wrists, consisting of aspiration of the cyst and steroid injections, have shown that this treatment is an acceptable alternative to surgical excision (23). We could find only one case report of aspiration of a lumbar facet synovial cyst that resulted in marked improvement in symptoms (24) and one anecdotal report of direct puncture of the cyst after opacification with contrast material (25). Aspiration of the synovial cyst contents by puncturing the adjacent facet joint has not provided clinically important results in our experience. In our study, we systematically attempted to rupture the cysts during percutaneous treatment to decompress the cysts, and we were successful in six (50%) of 12 patients. All of these patients experienced excellent pain relief. Alternatively, excellent pain relief also occurred in three (25%) of 12 patients; in these patients, rupture of the cyst was not accomplished during percutaneous treatment.
The main limitation of our study is its retrospective nature. Hence, patients were not contacted to assess clinical outcome nor did they undergo imaging at predefined times after the injections. Our study did not include a control group of patients with lumbar facet synovial cysts that were not treated with injection and follow-up MR imaging or evaluation of clinical symptoms to determine whether they would respond differently than the treated group. Retrospective assessment of clinical outcome was based on relief of symptoms, which introduced a bias of subjectivity on the part of the patients. Nevertheless, in the nine patients who had excellent clinical outcomes, we objectively demonstrated complete regression of the cyst at follow-up imaging in six patients and decreased cyst volume in two other patients.
In this study, we demonstrated that image-guided percutaneous steroid injections are effective in the treatment of lumbar facet joint synovial cysts, with 75% of patients experiencing complete resolution of their radiculopathy due to a lumbar facet joint synovial cyst. In 50% of patients, long-term follow-up imaging demonstrated complete regression of the lumbar facet synovial cyst, while decreased cyst volume was demonstrated in another 25% of patients at short-term follow-up imaging.
Although, on the basis of our results, rupture of the cyst at the time of the injection does not appear to be essential to obtain substantial relief of symptoms, the fact that our success rate at long-term follow-up was significantly higher than those of previously reported studies supports the hypothesis that rupture of the cyst does have some benefit.
It must be stressed that complete regression of the cyst at imaging may lag behind the resolution of symptoms. More than one injection may be necessary to achieve substantial relief of symptoms. Image-guided percutaneous steroid injections often are an effective alternative to surgery in the treatment of lumbar facet synovial cysts.
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FOOTNOTES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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This article has been cited by other articles:
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  N. J. Bureau Image-Guided Spine Intervention. Am. J. Roentgenol., August 1, 2003; 181(2): 526 - 526. [Full Text] [PDF]
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