Atlantoaxial Synovial Cyst: Case Report and Literature Review

Os odontoideum associated with a retro-odontoid cyst treated with posterior C1-C3 fixation: A case report and literature review

Background

Os odontoideum is a rare abnormality of the upper cervical spine, and os odontoideum associated with a retro-odontoid cyst has been described as a marker of local instability.

Case description

This paper reports a case of a 52-year-old female patient who was diagnosed with os odontoideum associated with a retro-odontoid cyst. The patient underwent posterior C1-C3 fixation without surgical removal of the cyst. Magnetic resonance imaging (MRI) two days later revealed that the retro-odontoid cyst was still present and that there were no significant changes to it when compared with the preoperative MRI.

Conclusion

Retro-odontoid cysts associated with unstable os odontoideum can lead to symptomatic spinal cord compression. Posterior C1-C3 fixation can restore atlantoaxial stability by allowing the gradual resorption of the cyst and ensuring spinal cord decompression. Fixation can also avoid the surgical risk associated with a high-riding vertebral artery.

Atlantoaxial Intradural Synovial Cyst Mimicking an Extradural Lesion Adjacent to a Retro-odontoid Pseudotumor: A Case Report

Atlantoaxial synovial cysts can very rarely penetrate the dura mater into the thecal sac and cause direct neural compression. Several case reports have been available on "intradural synovial cysts" (IDSCs). In this study, we report on a case with an atlantoaxial IDSC mimicking an extradural lesion. A 90-year-old man was diagnosed with a cystic lesion located laterally to the atlantoaxial joint adjacent to the retro-odontoid pseudotumor (ROP) causing cervical spinal cord compression. Thus, surgical removal was planned. On preoperative examination, the cyst, which had a two-layer structure showing a T2-isointense small mass inside a T2-hyperintense lesion, was thought to be located in the extradural region. However, operative findings showed that the cyst was located inside the dura mater. Histopathological examination suggested a synovial cyst. No recurrence of the cyst was observed until the latest follow-up after 3 years, and the ROP decreased in size. Almost all IDSCs reported previously were observed in the medial site of the atlantoaxial joint. In our case, however, the cyst was observed adjacent to the posteromedial site of the right atlantoaxial joint and the ROP, mimicking an extradural lesion. We had no knowledge regarding the IDSC before the surgery and assumed an extradural lesion. Albeit rare, the existence of such a condition should be considered.

C1-2 cyst presenting with syringobulbia: a case report

Extradural atlantoaxial cysts are typically related to C1-2 degeneration. Intradural cysts may cause secondary syringobulbia depending on the size and cerebrospinal fluid flow obstruction. However, medullary syrinxes have not been previously described with extradural cysts. Treatment of symptomatic lesions involves surgical resection, often via a far-lateral approach, with consideration of fusion if C1-2 instability is present. We present a case of an extradural C1-2 cyst with intradural extension causing syringobulbia. Effective surgical resection was accomplished via a far-lateral, partial transcondylar approach without fusion. It is important to recognize that cysts of extradural origin may exhibit intradural extension and compress critical neurovascular structures.

Treatment of pediatric unstable os odontoideum with adjacent degenerative cyst: case presentation and literature review

Degenerative cysts associated with an unstable os odontoideum in pediatric patients are uncommon lesions. Reported treatments of such lesions have varied and yielded mixed results with the optimal surgical strategy remaining unclear. The authors report the clinical and surgical outcome of a 13-year-old patient presenting with degenerative cyst adjacent to an abnormal os odontoideum motion segment. The patient was asymptomatic from this lesion which was an incidental finding while undergoing workup for atypical headaches. Clinical and radiologic findings, operative details, and postoperative outcome are described. The patient was successfully treated with posterior cervical fusion without direct cyst decompression. Complete resolution of the cyst was demonstrated on magnetic resonance imaging at 6 months. Computed tomography 8 months postoperatively showed solid bony fusion and normal alignment. Regarding treatment goals in pediatric patients with os odontoideum degenerative cysts, the current case and literature review supports posterior instrumented fusion without direct surgical cyst resection.

Cervical myelopathy caused by ventrally located atlanto-axial synovial cysts: An open quest for the safest and most effective surgical management. Case series and systematic review of the literature

OF BACKGROUND DATA

Despite a good understanding of the natural history of spinal synovial cysts (SCs), a widespread agreement regarding their optimal management is still lacking. This is particularly true for SCs occurring at the C1-C2 level, which are rare, but oftentimes lead to a rapidly evolving cervical myelopathy.

METHODS

We report a series of 4 patients (M:F ratio=1:1; mean age 63.5 years) presenting with progressive cervical myelopathy secondary to ventrally located C1-C2 SCs. All patients underwent a postero-lateral facet-sparing intradural approach with total excision of the SCs. Functional status was assessed pre- and postoperatively with Nurick scale and the modified Japanese Orthopaedic association grading. Furthermore we conducted a systematic review, following PRISMA guidelines of pertinent literature to contextualize the options for surgical management of such lesions.

RESULTS

Complete excision of the SCs was confirmed radiologically and on histological analysis. All measures of functional status improved post-operatively, and no cyst recurrence or need for instrumented fusion were noted during follow up (range from 22 to 88 months).

CONCLUSION

Our experience suggests that the facet-sparing intradural approach provides excellent clinical outcomes without causing any C1-C2 instability. This is in keeping with the take home message emerging from our literature review, which confirms that treatment should aim at radical resection of SCs while minimizing the risk of postoperative instability.

A Modified Posterior Approach for Decompression of a Multiloculated Atlanto-axial Cyst With Myelopathy

STUDY DESIGN

Case report.

OBJECTIVE

To describe a modified posterior approach for decompression and excision of a multiloculated atlanto-axial cyst.

SUMMARY OF BACKGROUND DATA

Atlanto-axial cyst with myelopathy is rare. A direct decompression through anterior approach or an indirect decompression through posterior approach has been proposed. We report a rare multiloculated large C1-C2 cyst extending down to C3 body with myelopathy that created a dilemma in choice of approach. A modified posterior approach was adopted for decompression.

METHODS

A 72-year-old lady, known case of Rheumatoid arthritis, presented with cervical myelopathy which was rapidly progressive since 2 months being her to wheel chair bound. She had clumsiness of gait and bilateral grip weakness. Both upper and lower extremities had nonfunctional power (medical research council scale grade 2). Deep tendon reflexes were exaggerated. Sensation was reduced in trunk and both extremities. Magnetic resonance imaging and computed tomography scan showed a large multiloculated cyst compressing spinal cord. Here author used modified posterior approach from the right side to access the cyst. The C2 ganglion excision, vertebral artery isolation, and resection of the pars allowed an approach similar to transforaminal decompression in the lumbar spine. A large antero-lateral epidural part of the cyst was excised. The retro-dental cyst was decompressed by puncturing cyst. Biopsy confirmed a synovial cyst.

RESULT

The patient showed rapid neurological recovery after surgery. Postoperative magnetic resonance imaging at 3 months showed complete resolution of cyst. At 2-year follow-up, there was a complete neurological recovery with residual spasticity.

CONCLUSION

A customized posterior approach allowed near total excision of a rare multiloculated large C1-2 cyst extending to the C3 body. This allowed visualisation anterior to the spinal cord without undue retraction that saved an additional anterior decompression.

LEVEL OF EVIDENCE

5.

Transnasal and Transoral Approaches to Atlantoaxial Synovial Cysts: Report of 3 Cases and Review of the Literature

BACKGROUND

Synovial cysts are cystic masses lined with pseudostratified columnar cells and containing clear or xanthochromic fluid. Although they are commonly encountered in the lumbar spine, synovial cysts infrequently occur in the cervical spine and rarely involve the odontoid process. The causes of synovial cysts of the odontoid process are unknown, but growth of synovial rests, proliferation of multipotent mesenchymal cells, atlantoaxial instability, and trauma are thought to play a role.

CASE DESCRIPTION

We present 3 cases of atlantoaxial cysts with the associated radiographic features, surgical management, and clinical outcomes. No patient had rheumatoid arthritis. In all cases, preoperative differential diagnosis included neoplastic pathologic changes. Two patients underwent odontoidectomy through either an endonasal or a transoral approach, followed by posterior occipitocervical fusion. The third patient underwent an endoscopic transsphenoidal approach for cyst decompression.

CONCLUSIONS

Tissue diagnosis is important in confirming pathologic analysis because synovial cysts have radiographic characteristics similar to those of a wide variety of neoplasms of the craniovertebral junction.

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.