Atlantoaxial degenerative articular cysts

Cervical Myelopathy Caused by Non-Rheumatic Retro-Odontoid Pseudotumor: An Investigation of Underlying Mechanisms and Optimal Surgical Strategy

STUDY DESIGN

Retrospective case-control study.

OBJECTIVE

This study aimed to identify the underlying pathologies of non-rheumatic retro-odontoid pseudotumors (NRPs), which would help establish an appropriate surgical strategy for myelopathy caused by NRP.

METHODS

We identified 35 patients with myelopathy caused by NRP who underwent surgery between 2006 and 2017. An age- and sex-matched control group of 70 subjects was selected from patients with degenerative cervical myelopathy. Radiographic risk factors for NRP were compared between cases and controls. We also assessed surgical outcomes following occipital-cervical (O-C) fusion, atlantoaxial (C1-2) fusion, or C1 laminectomy.

RESULTS

Patients with NRP had significantly lower C1 sagittal inner diameter, C2-7 range of motion (ROM), C2-7 Cobb angle, and C7 tilt, as well as significantly higher C1-2 ROM, atlantodental interval (ADI), and C1-2 to O-C7 ROM ratio. Multivariate regression analysis revealed that ADI, C2-7 ROM, and C7 tilt were independent risk factors for NRP. Neurological recovery and pseudotumor size reduction were comparable among surgical procedures, whereas post-operative cervical spine function was significantly lower in the O-C fusion group than in the other groups.

CONCLUSION

Non-rheumatic retro-odontoid pseudotumor was associated with an increase in ADI, suggesting that spinal arthrodesis surgery is a reasonable strategy for NRP. C1-2 fusion is preferable over O-C fusion because of the high prevalence of ankylosis in the subaxial cervical spine. Given that 29% of patients with NRP have C1 hypoplasia, such cases can be treated by posterior decompression alone. Our study highlights the need to select appropriate surgical procedures based on the underlying pathology in each case.

Retro-odontoid pseudotumor presenting double layer on MRI: A case report

Background:

Retro-odontoid pseudotumors (ROPs) typically present as a single mass posterior to the odontoid ranging from isointense to hypointense relative on T1-weighted magnetic resonance (MR) imaging (MRI T1WI). Here, a patient with ROP exhibited the double-layer sign on the MRI T1WI characterized by an initial ventral layer posterior to the odontoid process followed by a secondary dorsal layer.

Case Description:

An 84-year-old male presented with cervical myelopathy attributed to ROP resulting in atlantoaxial instability on dynamic X-ray studies, and the double-layer sign on the T1 MR accompanied by a cystic component. MR following C1–C2 posterior fusion, the patient’s myelopathy resolved and both layers spontaneously regressed on the follow-up MR studies.

Conclusion:

The MR-documented double layer sign with ROP, likely attributable to reactive hypertrophy of the transverse ligament with cystic components, may demonstrate spontaneous MR regression with symptom resolution following a C1–C2 posterior fusion.

Synovial Cyst of the Atlantoaxial Joint Removed through a Posterior Intradural Approach

Introduction. Synovial cysts rarely develop in the atlantoaxial joint. We report a case of posterior C1-2 laminectomy for a synovial cyst of the atlantoaxial joint which passed through the dorsal dura and put pressure on the cervical spinal cord. Case Presentation. A 62-year-old man with rapid progression of pain and weakness in the left upper extremity presented to our hospital. A cervical spine X-ray showed left C5-6 and C6-7 stenoses. A cervical magnetic resonance imaging showed an intradural extramedullary cystic lesion on the right side of the ventral cervical spinal cord at the C1-2 level and severe compression of the cervical spinal cord. Because a cyst was partially enhancing, a tumor lesion was not identifiable. Due to severe spinal cord compression, we performed intradural cyst removal via a posterior intradural approach with C1-2 laminectomy and left-sided C5-6 and C6-7 foraminotomies. One year after surgery, the cyst did not recur, and atlantoaxial instability did not appear. Discussion. A compressive lesion on the cervical spinal cord was not identified preoperatively as a synovial cyst. However, intraoperative and pathological findings suggested that the compressive lesion can be a synovial cyst which passed through the dorsal dura. The surgical treatment strategy for a synovial cyst of the atlantoaxial joint is controversial due to factors, such as the presence of atlantoaxial instability, level of cyst causing compression of the cervical spinal cord, severity of myelopathy, and cyst location. In the present study, the cervical spinal cord was highly compressed and the cyst was located on the right side of the cervical spinal cord; we chose cyst removal through a posterior intradural approach with C1-2 laminectomy.

Spontaneous Regression of a Retroodontoid Transverse Ligament Cyst: A Case Report

BACKGROUND AND IMPORTANCE

Transverse ligament cysts (TLC) are rare, surgically complex lesions arising posterior to the odontoid process of C2. Direct compression of the cervicomedullary junction is a devastating consequence of untreated lesions. We report the first case of spontaneous TLC regression without surgical intervention.

CLINICAL PRESENTATION

A 75-yr-old woman presented to an outside hospital with acute episodes of left face and upper extremity numbness. Magnetic resonance imaging (MRI) demonstrated a well-circumscribed 5.8 mm cystic mass at the atlantoaxial junction, posterior to the odontoid process, most consistent with a TLC. She presented to our institution 1 yr later with symptoms of progressive occipital neuralgia seeking surgical treatment. No evidence of cervical myelopathy was identified on clinical examination. Repeat MRI showed near doubling of the cyst, with no brainstem edema. The patient elected for surveillance of the cyst with a transforaminal steroid injection at C1-C2 for her occipital neuralgia. One year later, symptoms of occipital neuralgia had resolved and she remained neurologically intact; MRI of the cervical spine showed near complete involution of the cyst.

CONCLUSION

Symptomatic TLCs are often managed with surgical decompression and, in selected cases, fusion with good functional outcome. However, these interventions carry high risk of postoperative morbidity, particularly in the elderly. Conservative surveillance is rarely reported as a viable option. We present the first case of spontaneous TLC regression in the absence surgery or neck bracing. In select patients without acute myelopathy, clinical and radiographic surveillance may be considered for the management of TLCs.

Clinical and Radiographic Outcomes of C1 Laminectomy Without Fusion in Patients With Cervical Myelopathy That Is Associated With a Retro-odontoid Pseudotumor

PURPOSE

A retro-odontoid pseudotumor that is not associated with rheumatoid arthritis or hemodialysis is clinically rare. The majority of surgeons select transoral resection as the surgical treatment, often followed by posterior fusion or posterior decompression and fusion. In contrast, some authors have reported success with simple decompression without posterior stabilization in cases where atlanto-axial instability (AAI) is either absent or minor. In this study, we have evaluated the clinical and radiographic outcomes of C1 laminectomy without fusion as the surgical treatment for patients with cervical myelopathy that is associated with a retro-odontoid pseudotumor.

METHODS

A retrospective chart review was conducted on 10 patients who underwent C1 laminectomy without fusion for cervical myelopathy associated with a retro-odontoid pseudotumor.

RESULTS

The average follow-up time was 29 months. All cases were graded as Ranawat grade 3a or 3b. After surgery, myelopathy improved in all of the patients. In 2 patients, the atlas-dens interval increased in the flexed position; however, this did not result in any clinical problems. The size of the retro-odontoid mass (measured on magnetic resonance images at least 12 mo after surgery) decreased in 4 of the 10 cases.

CONCLUSIONS

AAI progression and mass enlargement were our primary concerns for this surgical option; however, C1 laminectomy did not cause severe AAI progression, no patients showed serious mass enlargement, and all patients demonstrated neurological improvement. This surgical strategy is beneficial especially for elderly patients given the risks of other surgical options that use an anterior transoral approach or posterior fusion.

Retro-odontoid mass without atlantoaxial instability causing cervical myelopathy: a case report of transdural surgical resection

INTRODUCTION

Retro-odontoid mass rarely occur in patients with noninflammatory retro-odontoid lesions without atlantoaxial instability. We describe a rare case of retro-odontoid mass without atlantoaxial instability operated on by a transdural approach.

CASE PRESENTATION

The patient was an 83-year-old man who presented with a retro-odontoid mass causing symptomatic cervical myelopathy. Preoperative magnetic resonance imaging (MRI) revealed that the mass was severely compressing the spinal cord. We operated on it via a C1 laminectomy and performed tumor resection by a transdural approach. Pathological findings from the operative specimen confirmed the diagnosis; histopathological examination revealed that the mass contained fibrinoid material, and collagenous tissue with myxoid changes, but no granulation or a granulomatous lesion. Postoperative MRI confirmed spinal cord decompression. The patient's symptoms were alleviated, and he has not had a recurrence or cervical instability in the 7 years since his surgery.

DISCUSSION

We successfully used a transdural approach in the present case and have observed no recurrence for 7 years postoperatively. C1 laminectomy is reportedly beneficial, especially for elderly patients, given the risk of other surgical options using an anterior transoral approach or posterior fusion. However, most tumors do not attenuate after C1 laminectomy alone; hence, we think that tumor resection by the transdural approach is one effective method to perform enucleation of the tumor after C1 laminectomy.

Intradural synovial cyst of the atlantoaxial joint: a case report

BACKGROUND

Intradural synovial cysts of the cervical spine represent a rare disease entity, causing stenosis of the spinal canal and thereby leading to progressive myelopathy. In particular, at the cranio-cervical junction early intervention is necessary to prevent permanent neurological dysfunction. We present the case of a 74-year-old man who presented with moderate cervicogenic headache, gait disturbance and progressive left-sided weakness. Magnetic resonance imaging (MRI) of the cervical spine confirmed a left-sided cystic mass located anteriorly at the craniovertebral junction compressing the surrounding structures.

METHOD

Surgical decompression was performed by means of a minimal left-sided laminectomy of C1. Postoperatively, the patients symptoms slowly improved, albeit a persistent ataxic gait.

RESULTS

Intraoperatively, a large intradural cyst was removed via a minimal suboccipital craniectomy combined with laminectomy of C1. Histopathological evaluation revealed a synovial cyst without any features of neoplasia. Despite not using craniocervical instrumentation, no clinical or radiological signs of atlantoaxial instability were observed up to 2 years after surgery.

CONCLUSIONS

Cystic lesions located at the atlanto-axial joint are a rare cause of cervical myelopathy. Preoperative imaging of the cervical spine should include not only MRI and computerised tomography (CT) but also dynamic imaging. Dorsal decompression without instrumentation prevents progressive neurological decline and may allow cord function to recover. If there is additional preoperative instability, instrumentation and fusion may be necessary.

Immediate Reduction of a Retro-odontoid Synovial Cyst Following Lateral Atlantoaxial Joint Puncture and Arthrography: A Case Report

STUDY DESIGN

Case report.

OBJECTIVE

We report on a case with a retro-odontoid synovial cyst, and the immediate reduction of the cyst was confirmed after lateral atlantoaxial joint puncture and arthrography.

SUMMARY OF BACKGROUND DATA

Retro-odontoid synovial cysts are rare diseases located posteriorly to a dense axis. Because most reports have focused on surgical treatment, only a few have examined nonsurgical treatment. However, several months are required after nonsurgical treatment until cyst regression.

METHODS

A 52-year-old female presented with atlantoaxial instability. She complained of neck pain and numbness in her hands. Magnetic resonance imaging revealed a retro-odontoid synovial cyst. Lateral atlantoaxial joint puncture and arthrography were performed.

RESULTS

Two days after treatment, the patient showed significant improvement in the numbness of her hands, and a follow-up magnetic resonance imaging revealed an immediate reduction in the cyst. During a 4.5-year follow-up period, no recurrence of the clinical symptoms occurred.

CONCLUSION

Lateral atlantoaxial joint puncture may immediately reduce retro-odontoid synovial cysts, and the lateral atlantoaxial joint has a communication channel with the retro-odontoid synovial cyst via the atlantodental joint. Once disappearance of the cyst is confirmed, an acceptable long-term outcome can be achieved with nonsurgical treatment even in cases with atlantoaxial instability.

LEVEL OF EVIDENCE

N/A.

The role of spinal fusion in the treatment of cervical synovial cysts: a series of 17 cases and meta-analysis

Object

This study was undertaken to compare surgical outcomes between patients with atlantoaxial versus subaxial cervical synovial cysts (CSCs) and to compare outcomes between patients who underwent decompression alone versus decompression and fusion for the treatment of CSCs.

Methods

The authors present a series of 17 cases involving patients treated at their institution and report the surgical outcomes. Due to the rarity of CSCs, a meta-analysis was conducted, and results of the literature search were combined with the case series to enhance the power of the study.

Results

Seventeen patients underwent surgical treatment for CSCs at our institution: 3 patients (17.6%) had atlantoaxial cysts and 14 (82.3%) had subaxial cysts. Of the 17 patients, 16 underwent a decompression and fusion; most patients experienced symptom resolution at last follow-up, and there were no cyst recurrences. A total of 54 articles (including the current series) and 101 patients were included in the meta-analysis. The mean age at presentation was 64 ± 13.9 years, and the most common symptoms were motor and sensory deficits. Forty-one patients (40.6%) presented with atlantoaxial cysts, and 60 (59.4%) with subaxial cysts. There were no significant differences between groups in terms of presenting symptoms, Nurick scores, surgical treatment, or surgical outcomes. Fifty-two patients (51.4%) underwent surgical decompression without fusion, while 49 patients (48.6%) underwent fusion. The preoperative Nurick scores were significantly lower in the fused group (p = 0.001), with an average score of 1.32 compared with 2.75 in the nonfused group. After a mean follow-up of 16.5 months, a difference of means analysis between final and preoperative Nurick scores revealed that patients who received a decompression alone improved on average 1.66 points (95% CI 1.03–2.29) compared with 0.8 points (95% CI 0.23–1.39) in the fused group (p = 0.004). However, there was no statistically significant difference in symptom resolution between the groups, and the rate of cyst recurrence was found to be 0%.

Conclusions

In this study, patients with CSCs had similar outcomes regardless of cyst location and regardless of whether they underwent decompression only or fusion. In the authors' institutional experience, 16 of 17 patients underwent fusion due to underlying spinal instability. While there were no reports of cyst recurrence in their series or in the literature in patients who only received decompression, this is likely due to the limited follow-up time available for the study population. Longer follow-up and prospective and biomechanical studies are needed to corroborate these findings.

Brown-séquard syndrome caused by a cervical synovial cyst

Synovial cysts are recognized as an uncommon cause of radicular and myelopathic symptoms. They are most frequently found in the lumbar region. The cervical spine or cervicothoracic junction is a rare location for a degenerative intraspinal synovial cyst as compared with the lumbar spine. At given cervical spinal levels, synovial cysts probably share clinical features with disc herniation and stenosis. However, the pathogenesis of synovial cysts remains still controversial. Here, we report a rare case of a synovial cyst in the lower cervical spine presented as Brown-Séquard syndrome and include a brief review of the literature. To the best of our knowledge, no previous report has been issued in the English literature on a synovial cyst presenting with Brown-Séquard syndrome. Neurologic function recovered completely after complete removal of the cyst and expansive laminoplasty.

Ventral occipito-atlanto-axial fluid-filled lesion causing dynamic spinal cord compression in a cat

Cystic lesions affecting the vertebral canal or spinal cord have rarely been reported in cats. A 3-year-old female neutered domestic longhair cat presented for evaluation of a 2-year-history of episodes of ataxia and paresis affecting all limbs. Neurological examination was consistent with a lesion in the C1-C5 spinal cord segments. Magnetic resonance imaging (MRI) showed a fluid-filled lesion at the occipito-atlanto-axial region causing dynamic spinal cord compression on flexion of the neck. The imaging characteristics were compatible with a juxta-articular cyst. To our knowledge, this is the first report of a fluid-filled lesion causing dynamic cervical spinal cord compression in a cat and highlights the importance of performing flexion-extension MRI views in diagnosing cases with dynamic spinal cord compression.

Extramedullary spinal cysts in dogs

OBJECTIVE

To (1) synthesize the terminology used to classify extramedullary spinal cysts in dogs to clarify some of the commonly reported misconceptions, and (2) propose a classification scheme to limit confusion with terminology.

STUDY DESIGN

Literature review.

METHODS

An online bibliographic search was performed in January 2013 for articles relating to extramedullary spinal cysts in dogs using PubMed (http://www.pubmed.gov/) and Google Scholar (http://scholar.google.com/) databases. Only peer-reviewed clinical literature describing cystic lesions pertaining to the spinal cord and associated structures was included.

RESULTS

From 1962 to 2013, 42 articles were identified; 25 (95 dogs) reported meningeal cysts, 10 (24 dogs) described 60 extradural cysts, 3 reports (18 dogs) described discal cysts or acute compressive hydrated nucleus pulposus extrusions (HNPE). Spinal cysts were categorized by location based on cross-sectional imaging as meningeal or extradural non-meningeal. Sub-classification was then performed based on surgical findings and pathology. Meningeal cysts included arachnoid diverticulae and Tarlov (perineural) cysts. Extradural non-meningeal cysts included intraspinal cysts of the vertebral joints, ligaments and discs. Discal cysts also fit this category and have been reported extensively in humans but appear rare in dogs.

CONCLUSIONS

Extramedullary spinal cysts should be first classified according to location with a sub-classification according to pathologic and surgical findings. Previous canine cases of discal cysts appear to represent a different disease entity and the term acute compressive HNPE is therefore preferred.

Atlantoaxial instability in monozygotic twin sisters: degenerative or congenital disease?

The authors report on two 70-year-old monozygotic twin sisters who both suffered severe nontraumatic atlantoaxial instability. If either had been a solitary case, degenerative atlantoaxial instability would have been the most straightforward diagnosis. In this case report the authors attempt to answer the question of whether an underlying congenital predisposition might be involved.

Retro-odontoid cystic mass treated by laminectomy and C1-C2 fixation

Retro-odontoid cysts associated with chronic atlantoaxial subluxation are extremely rare. This article describes a case of retro-odontoid cystic mass associated with chronic atlantoaxial subluxation and its management with posterior C1 and partial C2 laminectomy and C1-C2 pedicle screw fixation without resection of the retro-odontoid cyst. A 64-year-old woman experienced a sudden onset of neck pain, hand and foot paresthesia. Atlantoaxial instability associated with a retro-odontoid cystic mass was found in the imaging. The patient underwent posterior C1 and partial C2 laminectomy and C1-C2 pedicle screws fixation without resection of the retro-odontoid cyst. During the 24 months followup period, the cyst disappeared completely and the patient remained symptom free and returned to independent daily living. These findings suggest that posterior laminectomy and fixation without resection of the retro-odontoid cyst is relatively simple and safe and the results are satisfactory.

Ganglion cyst of the cruciate ligament with atlantoaxial subluxation

BACKGROUND

Ganglion cysts of the cruciate ligament are rare and sometimes asymptomatic. The authors present three cases of ganglion cysts of the cruciate ligament with atlantoaxial subluxation, which has rarely been reported previously.

METHODS

Generally, ganglion cysts of the cruciate ligament are reported as case reports. Several theories regarding the process of cyst formation and the development of treatment options have been described. However, trans-oral decompression with total removal of the cyst may be one of the options for treatment of this kind of disease.

RESULTS

A retrospective review of three patients, two female and one male patient, with a mean age of 68 years was conducted. The operation performed was a trans-oral decompression with cyst removal for all patients. Clinical outcomes were evaluated after the operation. All patients underwent trans-oral decompression with total removal of the cyst, followed by posterior fusion and pathologic examination of the cyst, revealing myxoid stroma with an absence of synovial linings.

CONCLUSION

The ganglion cysts and synovial cysts of the cruciate ligament are two different diseases with different presentation, pathogenesis, pathophysiology, and pathologic findings.

Hemorrhagic synovial cyst associated with rheumatoid atlantoaxial subluxation

Synovial cyst on prevertebral space of C1-2 joint is rare but may be associated hemorrhagic event. We describe a case of a 72-year-old woman who presented with sudden severe headache in her left occipital area with dyspnea. She had rheumatoid arthritis for 14-years. Large hemorrhagic cystic mass was seen around prevertebral space of the atlantoaxial joint on the left side on cervical MRI (magnetic resonance image) and it obstructed the nasopharyngeal cavity. Aspiration of the cystic lesion was performed via transoral approach, followed by posterior occipito-cervical fusion. The specimen was xanthochromic, suggesting old hemorrhage. The patient was tolerable on her postoperative course and showed good respiration and relieved headache. We suggest that repeated microtrauma due to atalantoaxial subluxation associated with rheumatoid arthritis as a main cause of hemorrhagic event on the cyst.

Pathophysiology of regression of synovial cysts of the lumbar spine: the 'anti-inflammatory hypothesis'

The term 'synovial cysts' of the lumbar spine refers to cysts that arise from the zygapophyseal joint capsule of the lumbar spine. Although several cases of regression of lumbar spine synovial cysts after oral anti-inflammatory therapy as well as local steroid injection have already been reported in the literature, no study up to now has addressed the role of 'inflammation suppression' in the regression of such lesions. In fact most of the previous studies have regarded 'spontaneous rupture' as well as 'instability resolution' as the most probable explanations for such phenomenon. In this article the authors review the current experimental data about the role of cytokines and inflammation in the development of synovial cysts of the lumbar spine. Additionally with basis on both our clinical experience of regression of a synovial cyst after conservative treatment with a non-steroidal anti-inflammatory drug (Cox-2 inhibitor) as well as on the experimental data supporting the multi-factorial effects of such drugs on the lumbar facet joints, the authors hypothesize that inhibition of inflammation might play a significant role in the pathophysiology of lumbar spine synovial cysts' regression.

Intraosseouss degenerative cyst of the axis approached via transcervical extrapharyngeal avenue

Intraosseous degenerative cysts (IDC) of the cervical spine are rare. IDC within C2 have been reported in three articles only. We report a patient with neck pain due to a IDC within C2. We discuss the differential diagnosis of these lesions and the surgical approaches to reach this complex anatomical region.

Atlantoaxial Synovial Cyst Associated with Instability in a Chihuahua

Objective. To describe an atlantoaxial degenerative cyst associated with instability.Animal. Chihuahua, male, 5 years old.Methods. Ever since colliding with a large dog two years prior to presentation, the dog suffered recurrent episodes of intractable cervical pain. Over time, the pain attacks increased in frequency and intensity. On presentation, pain was clinically localized to the high cervical region. No neurological deficits were observed. CT and MRI revealed an atlantoaxial degenerative articular cyst associated with instability, causing cervicomedullary compressive myelopathy. On MRI the cyst appeared hypointense in T1W and hyperintense in T2-weighted sequences, with rim enhancement. The dog was treated surgically by cyst fenestration and ventral stabilization using a 1.5 mm Butterfly Locking plate and cancellous bone graft placed within the atlantoaxial joint after cartilage removal. Histological examination of a sample of the cyst wall confirmed a degenerative articular cyst. The dog recovered uneventfully after surgery and remained pain free throughout the 2-year followup.Conclusion. Atlantoaxial degenerative articular cyst associated with instability is a rare finding in dogs.Clinical Relevance. The presence of an atlantoaxial degenerative articular cyst appears not to worsen the prognosis of instability treatment. Atlantoaxial fusion and cyst fenestration may provide good long-term results.

A large retro-odontoid cystic mass caused by transverse ligament degeneration with atlantoaxial subluxation leading to granuloma formation and chronic recurrent microbleeding case report

BACKGROUND CONTEXT

Noninfectious nontumorous retro-odontoid masses are rare, and masses have not been reported to extensively compress the spinal cord. We encountered a case of a large retro-odontoid lesion that extensively compressed the spinal cord.

CASE REPORT

A 76-year-old-man reported experiencing a sudden onset of neck pain, hand and foot paresthesia, dysarthria, and dysphagia. When symptoms had not eased by 10 days of treatment with external stabilization and bed rest, he was referred to our hospital. Dynamic radiographs of the cervical spine showed that the atlantodental interval widened from 2 mm on extension to 7 mm on flexion. Computed tomography did not reveal abnormality of the odontoid process or the presence of a high-density area that could suggest calcification in or near the cystic mass. Fluid-attenuated inversion recovery axial magnetic resonance image showed a mass that was 3.0-cm wide, 2.7-cm high, and 2.5-cm thick that severely compressed the lower brain stem. T2-weighted magnetic resonance imaging showed that the mass contained a solid part posterior to the C2 dense area, extending rostrally, compatible with the presence of degenerated and hypertrophic ligaments. We performed surgical decompression of the lesion combined with atlantoaxial fixation. The partly cystic mass, which was located extradurally, had xanthochromic content, indicating microbleeding. Dysarthria and dysphagia immediately disappeared, and neurologic symptoms disappeared by 1 month. At 1-year follow-up, the patient remained symptom free, and computed tomography scans did not show recurrence of the mass. The pathologic diagnosis of degenerative ligament tissue with chronic recurrent microbleeding and associated granulation was made.

DISCUSSION

A possible explanation why the cyst grew to an exceptionally large size is that the transverse ligament of axis became degenerated and hypertrophic because of chronic mechanical stress by atlantoaxial subluxation. Then, a part of the ligament developed reactive granulation with small vessel formation. Finally, rupture of these small vessels caused repeated episodes of microbleeding, resulting in formation of a large cyst. The observation of degenerative ligament tissue, granulation formation, and microbleeding differentiated it from a synovial cyst or a ganglion cyst. The presence of hemosiderin deposits suggested chronic recurrent microbleeding. Taking all our findings together, we believe that our case of retro-odontoid cystic mass is different from the others that have been reported. Atlantoaxial instability may cause a large mass, such as we described here, so that careful observation is important.

Cervical juxtafacet cyst after anterior cervical discectomy and fusion

Anterior cervical discectomy and fusion (ACDF) is a common neurosurgical procedure, and the benefits, long-term outcomes, and complications are well described in the literature. The development of a juxtafacet joint cyst resulting in radiculopathy is a rare outcome after ACDF and merits further description. The authors describe a patient in whom a juxtafacet joint cyst developed after ACDF procedures, resulting in surgical intervention. When a juxtafacet joint cyst develops after ACDF, symptoms can include radiculopathy, neck pain, and neurological symptoms such as paresthesias and motor weakness. The presence of a juxtafacet joint cyst implies instability in that region of the spine. Patients with this pathological entity may require decompression of neural elements and fusion across the segment involved with the cyst.

Using precisely controlled bidirectional orthopedic forces to assess flexibility in adolescent idiopathic scoliosis: comparisons between push-traction film, supine side bending, suspension, and fulcrum bending film

STUDY DESIGN

A prospective study.

OBJECTIVE

To validate the effectiveness of push-traction film (PTF) in assessment of curve flexibility in adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

There is no agreement among surgeons about the most advantageous method in flexibility evaluation of scoliosis. As all methods available provide the orthopedic force from one direction and use a single torque, it is difficult for them to achieve the postoperative correction; also they could not meet the needs for different types of curves.

METHODS

Precisely controlled bidirectional (push and traction) orthopedic forces were applied for curve flexibility evaluation in 31 consecutive adolescent idiopathic scoliosis patients. The correction rate (CR) of postoperation, supine side-bending, suspension, and fulcrum bending radiographs were compared with PTF in instrumented main thoracic (MT) and thoracolumbar/lumbar curves. Correlation and linear regression analyses were also been done to find the best predictor among the four methods.

RESULTS

In MT group, CR of PTF was significantly higher than that of side bending (P = 0.010) and suspension (P = 0.000) but not significantly different from that of fulcrum bending (P = 0.335). In TL/L group, CR of PTF was significantly higher than that of suspension (P = 0.000), but not significantly different from that of side bending (P = 0.681) and fulcrum bending (P = 0.382). There was no significant difference between CR of PTF and postoperation in both MT (P = 0.122) and TL/L (P = 0.068) groups. Correlation and linear regression analyses showed that PTF provided the highest correlation of the four methods, with the postoperative angle in both MT (r = 0.957) and MT/L group (r = 0.779).

CONCLUSION

To our knowledge, this was the first report about using precisely controlled bidirectional correction forces for curve flexibility evaluation. Although it did not achieve the best CR among the four methods studied, correlation and regression analyses confirmed that PTF was a more stable and accurate method to predict flexibility. We believe that further exploration of a more rational push-traction force ratio would help to obtain a better flexibility.

Subaxial cervical synovial cysts: report of 35 histologically confirmed surgically treated cases and review of the literature

STUDY DESIGN

Retrospective study

OBJECTIVE

The authors' aim of the present study is to report their experience with subaxial cervical synovial cysts hoping to provide further insight into these lesions including the presenting symptoms, possible mechanisms of cyst development associated with cervical level, surgical treatments and clinical outcomes.

SUMMARY OF BACKGROUND DATA

Synovial cysts are relatively common in the lumbar spine and very uncommonly identified in the subaxial cervical spine. Several case reports and a few small series have been reported in the literature over the past four decades.

METHODS

The authors retrospectively reviewed the cases of 35 patients who underwent surgical treatment for histologically confirmed symptomatic subaxial cervical synovial cysts between 1993 and 2009. The presenting symptoms, age, sex, cervical level, operation, complications and outcomes were analyzed in this cohort. Preoperative and postoperative neurologic assessments were done by staff neurologists independent of the operating surgeon. This study was approved by the Mayo Clinic institutional review board.

RESULTS

Thirty-five patients underwent surgical treatment for their synovial cysts and follow-up for at least 12 months postoperatively. The mean follow-up time was 49 months (range, 12-134). There were no deaths associated with the surgery. There was one postoperative infection in a patient undergoing a decompressive laminectomy and posterior instrumented fusion. Patient outcomes were assessed using the Modified Rankin Score for 12 patients was 0, 17 patients was 1, 4 patients was 2, and 2 patients was 3.

CONCLUSION

This series of 35 patients with subaxial cervical synovial cysts surgically treated over a period of 17 years illustrates the relative rarity of these lesions. Magnetic resonance imaging is currently the optimal radiographic study to identify these lesions. Surgical resection can be an effective treatment.

Cystic deterioration of the C1-2 articulation: clinical implications and treatment outcomes

OBJECT

Synovial cysts of the cervical spine are rare. Further, synovial cysts of the C1-2 articulation, or retroodontoid cysts, are very rare, with fewer than 20 cases reported overall. The authors report on a single-institution series of 10 patients with C1-2 retroodontoid synovial cysts.

METHODS

The charts of 10 patients with pathologically confirmed synovial cysts following resection between January 1998 and June 2009 were reviewed. The clinical presentation, radiographic findings, surgical management, and pre- and postoperative functional levels (reported as a modified Rankin outcome) are reported.

RESULTS

All 10 patients underwent attempts at complete resection of the synovial cyst; none of the lesions were simply aspirated. All 4 patients with an initial recommendation of observation alone ultimately underwent surgery because of their swift neurological deterioration. The mean age at surgery was 75.4 ± 4.6 years (range 54-81 years). The mean presenting cyst volume was 4.6 ± 1.7 cm(3). Nine of 10 patients underwent transoral resection of the cyst with posterior fusion. Six of the 10 patients underwent additional posterior laminectomy for decompression. The hospital length of stay varied from 2 to 45 days, with a mean of 19 ± 7 days. All patients undergoing transoral decompression had varying degrees of difficulty with postoperative dysphagia, diagnosed using videofluoroscopy. All patients improved in their modified Rankin Scale score after surgical intervention with a mean follow-up of 42 months (95% CI 12-72 months).

CONCLUSIONS

Synovial cysts of the atlantoaxial joint are rare. They occur in older patients in whom clinical deterioration is likely to occur. In most cases, these cysts can be diagnosed preoperatively. Transoral decompression with posterior fusion is an effective treatment for C1-2 degenerative cysts and can be accomplished with few complications. However, the ideal treatment for these lesions remains unknown.

A modified "far-lateral" approach for safe resection of retroodontoid dural cysts

Cystic mass lesions at the ventral craniocervical junction have been described only rarely in the past, however, they have received more attention with improved imaging modalities in recent years. These lesions have been approached by various operative procedures. A modified "far-lateral" approach combined with a C1 hemilaminectomy without fusion was used to safely remove the cyst and decompress the cervical medulla in a 72-year-old woman with cervicooccipital pain and paresthesia in both arms. Following surgery, complete resolution of symptoms was achieved, and no recurrence at 1 year follow-up was detected. A modified "far-lateral" approach offers several advantages when compared with other operation techniques.

Craniovertebral instability due to degenerative osteoarthritis of the atlantoaxial joints: analysis of the management of 108 cases

Object

The authors retrospectively analyzed a series of 108 patients in whom was diagnosed atlantoaxial instability due to degenerative osteoarthritis of the atlantoaxial joints. The management issues in such cases are discussed.

Methods

One hundred eight patients with osteoarthritis of the atlantoaxial joints and resultant craniovertebral instability—diagnosed on the basis of presenting clinical features, radiological imaging, and direct observation of the joint status during surgery—were retrospectively analyzed. Between 1990 and 2008, these patients were treated with a C1–2 lateral mass plate and screw method of atlantoaxial fixation and joint distraction using bone graft with or without the assistance of metal spacers.

Results

Patient ages ranged from 48 to 84 years (average 63 years). There was a history of mild to moderate head and/or neck trauma 2 months to 11 years prior to diagnosis in 40% of the cases. All patients had symptoms of neck pain, and 82% of the patients had progressive myelopathy. A reduction in the height of the atlantoaxial lateral mass complex (100%), mobile atlantoaxial dislocation (100%), basilar invagination (68%), and periodontoid degenerative tissue mass (90%) were the more frequently encountered radiological features. Two patients died in the immediate postoperative period. At an average follow-up of 64 months, all surviving patients remarkably improved to varying degrees in their neurological condition.

Conclusions

Atlantoaxial joint arthritis frequently leads to craniovertebral instability and cord compression. Treatment by joint distraction and lateral mass fixation can be an optimum form of treatment.

Case report. Atlantoaxial synovial cyst causing isolated unilateral hypoglossal nerve paralysis

Cervical synovial cysts are rare entities that are, most of the time, asymptomatic. They can cause nerve root or spinal cord compression, especially when acute haemorrhage or a marked increase in size occurs. Isolated unilateral hypoglossal nerve paralysis caused by compression of its cisternal segment is also an extremely rare condition. We report the case of a 51-year-old woman who presented with dysarthria and tongue fasciculation. MRI revealed an atlantoaxial synovial cyst that extended cranially through the hypoglossal canal and compressed the fibres of the left XII nerve on its cisternal segment. To our knowledge, this is the first case report of XII nerve paralysis being caused by an atlantoaxial synovial cyst.

Surgical approach for synovial cyst of the atlantoaxial joint: a case report and review of the literature

STUDY DESIGN

Case report and review of the literature.

OBJECTIVE

We describe the first case of a synovial cyst arising from pseudarthrosis of a previous dens fracture. The literature is reviewed and etiological, diagnostic, and therapeutic options of atlantoaxial cysts are discussed.

SUMMARY OF BACKGROUND DATA

Symptomatic synovial cysts of the atlantoaxial joint are rare. To the authors' knowledge only 24 cases have been reported.A 60-year-old patient presented with bilateral hand numbness, quadrihyperreflexia, and gait deterioration. Magnetic resonance imaging of the cervical spine disclosed a cystic mass located at the transverse ligament of dens axis causing bulbomedullary compression.

METHODS

Surgery was performed via transoral image guided approach. The ventral atlas arch, dens, transverse ligament, tectorial membrane, and the compressing cyst were removed, followed by a C0-C3 fusion.

RESULTS

Two months postsurgery the patient recovered completely from the cervical myelopathy with transient remnant dysparesthesia of the finger tips.

CONCLUSION

Magnetic resonance imaging findings are not specific enough to establish a preoperative diagnosis. Radical resection via image-guided transoral route followed by posterior fusion allows complete resection of the cystic lesion and results in excellent long-term decompression.

Conservative treatment of an atlantoaxial degenerative articular cyst: case report

BACKGROUND

Atlantoaxial degenerative articular cysts are rare lesions that can cause extradural compression of the cervicomedullary junction. When symptomatic, they usually require surgical treatment. We report an unusual case of spontaneous regression of an atlantoaxial degenerative articular cyst after conservative treatment with an external cervical brace along with a systemic therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids. We also discuss the potential pathogenetic mechanisms involved.

PURPOSE

To describe a case of significant volume reduction of an atlantoaxial articular degenerative cyst in a patient treated with a Philadelphia collar and anti-inflammatory drugs.

STUDY DESIGN

Case report with analysis of the literature.

METHODS

A 80-year-old patient was admitted to our institution with a history of progressive tetraparesis, ataxic gait, and cervical pain. A cervical spine magnetic resonance imaging (MRI) scan showed an extradural mass lesion behind the dens of C2 causing significant compression of the cervicomedullary junction, suggesting the diagnosis of atlantoaxial degenerative articular cyst. The patient refused surgery in favour of a conservative treatment with a Philadelphia collar and a short-term course of NSAIDs and corticosteroids.

RESULTS

After 6 weeks, the patient's neurological condition improved, and a 6-month follow-up cervical spine MRI scan revealed an almost complete regression of the atlantoaxial cystic lesion. At a 1-year follow-up, his clinical condition was further improved.

CONCLUSIONS

Atlantoaxial articular degenerative cysts are rare lesions that should be included in the differential diagnosis of those extradural lesions that can cause a ventral or ventrolateral compression of the cervicomedullary junction. They most commonly occur in elderly female patients affected by diffuse arthrosic degeneration of the cervical spine, with or without clear radiological signs of atlantoaxial instability, and have a typical appearance on MRI imaging. Surgery, with direct excision of the cyst and/or a C1-C2 fusion, is the first treatment of choice. Nevertheless, our report points out the possibility of a significant spontaneous regression of these lesions following a simple conservative strategy based on the use of an external cervical brace together with a systemic anti-inflammatory therapy.

Surgical treatment of nonrheumatoid atlantoaxial degenerative arthritis producing pain and myelopathy

STUDY DESIGN

A retrospective review.

OBJECTIVE

The purpose of this study was to evaluate the clinical and pathologic findings and surgical treatment outcomes for atlantoaxial osteoarthritis.

SUMMARY OF BACKGROUND DATA

Nonrheumatoid atlantoaxial osteoarthritic degeneration can occur at either the atlantodental articulation or lateral mass articulations. This condition may present with neck pain or myelopathy in the setting of a compressive degenerative pannus. There is a paucity of literature on this topic with only case reports and small case series.

METHODS

A retrospective chart review was performed to identify patients treated for C1-C2 osteoarthritis. Patient demographics, clinical presentation, neurologic examination, visual analog pain scores, radiographic findings, surgical treatment, outcomes, and complications were recorded for each patient.

RESULTS

Twenty-six patients (18 with pannus at the atlantodental articulation and 8 primarily with lateral mass articulation arthritis; 10 men, 16 women; mean age 74 years) were surgically treated for atlantoaxial osteoarthritis. Eleven patients presented primarily with complaints related to myelopathy (all with a degenerative pannus) and 15 presented with cervicalgia only. All patients were treated with posterior atlantoaxial arthrodesis, and 13 patients with myelopathy or severe canal compromise from an irreducible subluxation also had transoral odontoidectomy. All myelopathic patients had improvement in neurologic function (10 of 11 improved 1 Ranawat grade). Neck pain improved in 93% of patients with preoperative neck pain complaints (mean visual analog score before surgery = 7.0, follow-up = 1.3). Fusion was demonstrated in all patients with adequate follow-up.

CONCLUSION

Atlantoaxial osteoarthritis can result in neck pain and myelopathy. In the setting of a degenerative pannus and myelopathy, most patients will improve neurologically after transoral decompression and arthrodesis. Patients with pannus and no myelopathy were effectively treated with posterior fusion alone, although 2 with irreducible subluxation required an initial transoral decompression to allow realignment before fusion. Posterior arthrodesis alone provided significant pain relief in most patients.

Regression of an atlantoaxial degenerative articular cyst associated with subluxation during conservative treatment

✓ The presence of an atlantoaxial degenerative articular cyst is rare; when present this lesion extends posteriorly to the dens, causing cervicomedullary compressive myelopathy. The authors describe a symptomatic case of this lesion associated with atlantoaxial subluxation in a 76-year-old man. The patient’s neurological symptoms resolved and corresponded to a reduction in the size of the cyst. After 8 months of continued conservative treatment, in which the patient wore a Philadelphia collar, the cyst spontaneously regressed. Subsequently, a C1–2 posterior fusion was performed to treat the atlantoaxial subluxation.

Cervical degenerative cyst located within the body of C2: a case report and review of the literature

STUDY DESIGN

A case report and review of the literature are presented.

OBJECTIVES

To describe the clinical course and treatment of a patient with an unusual intraosseous degenerative cyst within the body of the axis, as well as review the literature regarding these lesions.

SUMMARY OF BACKGROUND DATA

Intraosseous degenerative cysts of the cervical spine are extremely rare. To our knowledge, only 4 prior case studies have described these lesions, 2 of which were seen in the body of C2.

METHODS

A case report of a 58-year-old patient with neck pain and an intraosseous cyst within the axis is presented with a review of the pertinent literature.

RESULTS

History, examination, radiographic evaluation, and histology revealed this lesion to be an intraosseous degenerative cyst within the body of C2. The patient was treated with anterior surgical biopsy/curettage and posterior stabilization with structural graft enhancement.

CONCLUSION

Although rare, intraosseous cervical degenerative cysts should be present in any differential diagnosis of cystic lesions seen in the cervical spine.

[Retro-odontoid synovial cyst with Forestier's disease]

STUDY DESIGN

We report one case of 66-year-old man with Forestier disease and spinal cord compression by retro-odontoid synovial cyst.

OBJECTIVES AND METHODS

Although retro-odontoid synovial cysts remain rare, an increasing number have been reported in the literature. Affecting adults in the sixth decade of life, retro-odontoid synovial cysts produce slowly progressive upper spinal cord symptoms. Diagnosis can be achieved by means of magnetic resonance imaging (MRI). Association with Forestier's disease has been reported in only one previous study. Cyst probably develop as a result of enhanced mechanical stress on the only remaining mobile joint. In the literature treatment of retro-odontoid mass associated with Forestier has usually involved occipito-cervical fusion with transoral decompression.

RESULTS

In this report we describe a patient treated by the posterolateral route with good short- and mid-term clinical and radiological outcome.

CONCLUSIONS

In comparison of transoral route, the advantages of the posterolatral route are shorter hospitalization and lower morbidity especially in elderly patients with operative risk factors.

Synovial Cyst at the C1-C2 Junction in a Patient with Atlantoaxial Subluxation

Synovial cysts of the cervical spine causing myelopathy are rare. The pathogenesis of these cysts is often attributed to degenerative changes of the facet joints or microtrauma. The authors report a synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation without a congenital anomaly or inflammatory conditions. A 72-year-old man presented with a progressive right-sided myelopathy attributed to a C1-C2 synovial cyst accompanied by atlantoaxial subluxation and C3-C6 spondylosis. Magnetic resonance imaging of the cervical spine showed a large cystic mass compressing the spinal cord located at the C1-C2 junction. A C1 hemilaminectomy, complete evacuation of the cyst contents, and posterior atlantoaxial fusion were performed, and a double-door laminoplasty was also done at C3-C6. The patient showed significant improvement of paresthesia and motor weakness of the right upper and lower extremities immediately after the operation. Synovial cysts should be considered in the differential diagnosis of an extradural mass of the upper cervical spine. Posterior fusion combined with direct excision of the cyst may be the optimum treatment of a synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation.

Kyste synovial atlanto-axoïdien

The case of a 62-year-old patient with an atlanto-axial synovial cyst is presented. The narrowing of the spinal canal was associated with anterior medullar compression and neurological deficit. A transoral approach with odontoid resection was performed. The diagnostic of synovial cyst was histologically confirmed. Secondary atlanto-axial instability required posterior fixation completed by C1-C2 transarticular screw fixation. The follow-up showed an improvement of the neurological deficit. Similar cases reported in the literature are reviewed and discussed.

An Expanding Cervical Synovial Cyst Causing Acute Cervical Radiculopathy

Synovial cysts of the cervical spine occur infrequently in the spinal canal and are most often associated with degenerative facet joints. Despite the prevalence of degenerative spinal disease, symptomatic synovial cysts are extremely uncommon. We report a rare case that showed an exacerbation of a cervical radiculopathy due to an acute expansion of the synovial cyst. Magnetic resonance (MR) images originally revealed a small cystic extradural lesion when the patient presented with neck pain and slightly numbness in the right hand. The patient's complaints subsequently subsided after administration of pain killers. However, 2 weeks after this, the patient experienced a spontaneous, sudden, severe radiating pain into the right arm without any accompanying cervical injury. MR images showed that the cyst had become markedly increased in size in the intervening 4 weeks and compressed the spinal cord laterally. Because the arm pain was so severe and neurologic examinations revealed the paralysis of the C8 nerve root, the synovial cyst was excised surgically and a good clinical outcome achieved. Thus, even if symptoms are mild and the size of the synovial cyst is small, acute expansion of the cyst might be rarely observed and careful management, including surgical consideration, is needed.

Intraspinal synovial cyst communicating with the C1-C2 facet joints and subarachnoid space associated with rheumatoid atlantoaxial instability

STUDY DESIGN

The first case of intraspinal synovial cyst communicating with the C1-C2 facet joints and subarachnoid space associated with rheumatoid atlantoaxial instability is presented.

OBJECTIVES

To describe the diagnosis and successful treatment of a synovial cyst of the C1-C2 junction in a patient with rheumatoid arthritis and atlantoaxial instability.

SUMMARY OF BACKGROUND DATA

Intraspinal synovial cysts of the C1-C2 junction are extremely rare. Neither association with rheumatoid atlantoaxial instability nor communication with the C1-C2 facet joints and the subarachnoid space has been previously reported in a synovial cyst of the C1-C2 junction.

MATERIALS AND METHODS

The clinical and radiologic features of a 71-year-old woman with a symptomatic synovial cyst of the C1-C2 junction with rheumatoid atlantoaxial instability are detailed. Posterior atlantoaxial fusion alone was performed.

RESULTS

Preoperative magnetic resonance images demonstrated a large cystic mass around the dens, compressing the spinal cord. The mass was of low signal intensity on T1-weighted images, was of high signal intensity on T2-weighted images, and was enhanced marginally with gadolinium-DTPA on T1-weighted images. Computed tomograms performed after myelography disclosed the cyst around the dens communicating with the subarachnoid space and the C1-C2 facet joints. Spontaneous regression of the cyst was identified on the magnetic resonance images 3 months after surgery. One year after surgery, myelopathic symptoms were improved.

CONCLUSION

An intraspinal cyst communicating with the C1-C2 facet joints and subarachnoid space associated with rheumatoid atlantoaxial instability was reported. Computed tomograms after myelography were useful in delineating the relationships among the synovial cyst, facet joints, and the subarachnoid space. Spontaneous regression of the cyst and clinical improvement were achieved by C1-C2 posterior fusion alone.

Intraspinal cervical degenerative cyst. Report of three cases

The authors report three cases of cervical degenerative cysts causing medullary or radiculomedullary compression. Anatomicopathological examination confirmed the fibrous nature of the cyst wall and the absence of a synovial layer. One of the cysts was embedded in the ligamentum flavum, whereas the other two were most lateral and adherent to the facet joint. The physiopathogenesis of these cysts is discussed.

Cysts of the atlantoaxial joint: excellent long-term outcome after posterolateral surgical decompression. Report of two cases

Articular cysts of the atlantoaxial joint are infrequently described and probably an underreported cause of upper cervical spinal cord compression. The authors report on two patients with cysts located posteriorly of the dens in whom a C-1 and partial C-2 hemilaminectomy with subtotal resection of the cyst provided adequate and stable decompression 1 year postoperatively. The clinical and magnetic resonance imaging features and the surgical approach are discussed after a review of the literature.

Exuberant transverse ligament degeneration causing high cervical myelopathy

Two patients with cervical myelopathy and C1-C2 retro-odontoid masses were examined. Preoperative magnetic resonance imaging studies suggested soft tissue pannus, as might be seen in rheumatoid arthritis; however, the results of serologic testing for rheumatoid factor were negative in both patients. Intraoperative findings and pathologic examination revealed degenerative fibrocartilage without inflammation or neoplasia. Similar lesions reported in the literature have been described as retro-odontoid disk hernia, damaged transverse ligaments, transverse ligament degeneration, synovial cysts, ganglion cysts, and degenerative articular cysts. These lesions may share a common pathophysiologic origin and represent a single disease process, namely exuberant degeneration of the transverse ligament.

MR imaging findings in a dog with lumbar ganglion cysts

Intraspinal cysts of the L6-L7 and L7-S1 articular process joints in a six-year-old neutered female German Shepherd Dog were diagnosed using magnetic resonance (MR) imaging. Histopathology provided a diagnosis of ganglion cysts. Clinical, laboratory, radiographic and MR imaging findings are described. Briefly, radiographic findings revealed lumbarization of the first sacral vertebra, and fusion of the first caudal vertebra to the sacrum. In addition, spondylosis and articular process osteoarthrosis occurred at L6-L7 and L7-S1. MR imaging revealed multiple, well encapsulated structures ranging in size from 3-10 mm in diameter which were found to arise from the L6-L7 and L7-S1 articular process joints. These cysts had signal intensities that varied from hyperintense to the cerebrospinal fluid (CSF) on T1 weighted images to isointense to CSF on T2 weighted images. Decompressive surgery in conjunction with arthrodesis of these joints resulted in resolution of clinical signs. The dog remained pain-free 1 1/2 years following surgical therapy.

Retro-odontoid massive calcium pyrophosphate crystal deposition--case report

An 86-year-old male presented with progressive myelopathy due to retro-odontoid massive deposits of calcium pyrophosphate dihydrate (CPPD) crystals. Magnetic resonance imaging revealed a non-enhanced isointense extradural mass on the T1-weighted image and heterogeneously intense mass on the T2-weighted image. Computed tomography showed typical punctate and linear calcifications within the mass. The mass was resected via a lateral approach resulting in marked improvement of the symptoms. Histological examination revealed birefringent rhomboid crystals consistent with CPPD. CPPD deposition should be considered in the differential diagnosis of retro-odontoid extradural mass because surgical therapy is beneficial even for elderly patients.

Cervical and thoracic juxtafacet cysts causing neurologic deficits

STUDY DESIGN

Case reports and review of the literature.

OBJECTIVES

To review the clinical features, treatment, and outcome of juxtafacet cysts.

SUMMARY OF BACKGROUND DATA

There have previously been 4 reported cases of thoracic juxtafacet cysts and 19 cases of cervical juxtafacet cysts. Cervical cysts have usually originated from the cruciate ligament and caused myelopathy. Thoracic cysts are usually signaled by myelopathy.

METHODS

The records of the Neurosurgery Department of Royal Adelaide Hospital from 1980 through 1995 were reviewed for cases of intraspinal juxtafacet cysts.

RESULTS

Eight cases of intraspinal juxtafacet cysts were identified; six were in the lumbar spine. One patient had a cervical cyst related to a facet joint and had unilateral radiculopathy. A second patient with a thoracic cyst had the gradual onset of myelopathy. Both patients had surgical excision of the cyst without resection of the adherent dura. The symptoms and neurologic signs improved in each case.

CONCLUSIONS

Cervical and thoracic juxtafacet cysts are rare lesions that are usually signaled by myelopathy. Results of surgery are excellent in most cases, even if the cyst is not completely excised.

Synovial cyst of the transverse ligament of the atlas in a patient with os odontoideum and atlantoaxial instability

STUDY DESIGN

A case report and review of the literature.

OBJECTIVE

To describe the diagnosis and successful treatment of a synovial cyst arising from the transverse ligament in a patient with os odontoideum and atlantoaxial instability.

SUMMARY OF BACKGROUND DATA

Synovial cysts arising from the transverse ligament of the atlas are extremely rare. Development of a synovial cyst is thought to be attributable to degenerative changes of the C1-C2 facet joints or to microtrauma. Direct excision of the cyst is the only treatment cited in previous reports.

METHODS

A synovial cyst arising from the transverse ligament of the atlas in a 45-year-old man with os odontoideum and atlantoaxial instability was treated surgically with posterior atlantoaxial fusion alone. The magnetic resonance images, surgical treatment, and related literature are reviewed.

RESULTS

Preoperative magnetic resonance images of the cervical spine showed a large cystic mass located ventral to the cord arising at the level of the transverse ligament of the atlas: the mass was of low signal intensity on T1-weighted images, was of high signal intensity on T2-weighted images, and was enhanced marginally with gadolinium-DTPA on T1-weighted images. Spontaneous regression of the cyst was identified on the follow-up magnetic resonance images taken 3 months after C1-C2 posterior wiring and fusion.

CONCLUSIONS

A patient with a synovial cyst arising at the C1-C2 junction ventrally at the level of the transverse ligament showed spontaneous regression of the lesion after C1-C2 posterior wiring and fusion.