Abstract

Background: Spinal synovial cysts are cystic dilatations of synovial sheaths that extrude into the spinal canal. Despite their generally benign behavior, they can cause severe symptoms due to compression of neural structures. They are most commonly found in the lumbar spine and are rare in the cervical region, especially at the atlanto-occipital junction.

Case Description: A 65-year-old presented with neck pain and headaches. The magnetic resonance imaging (MRI) revealed a degenerative cyst within the anterior foramen magnum causing anterior spinal cord and brainstem compression. Multiple surgical treatment options were discussed, and he was prescribed methylprednisolone and immobilization of his cervical spine with a rigid collar. One month later, the patient reported dramatic improvement of his symptoms, and no surgery was performed. One year later, his pain had remained much improved with the continued use of the collar and pain management (i.e., using anti-inflammatories and muscle relaxants). The 1-year follow-up MRI showed the atlanto-occipital cyst compressing the cervicomedullary junction had completely resolved along with the brainstem compression.

Conclusion: A 65-year-old presented with myelopathy attributed to a large anterior foramen magnum atlanto-occipital cyst compressing the cord. Conservative management for 1 month with a rigid cervical collar and steroids resulted in marked neurological improvement; at 1 year follow-up, the patient was markedly improved with an MR that demonstrated spontaneous cyst regression.

Keywords: Atlantoaxial arthropathy, Cervical collar, Facet arthropathy, Neck pain, Synovial cyst

INTRODUCTION

Spinal synovial cysts (SCs) are cystic dilatations of synovial sheaths that extrude into the spinal canal and can occur in various spinal regions. Their presence likely reflects excessive joint mobility/instability. They are most commonly found in the lumbar spine, are rare in the cervical region, even more uncommonly found at the atlanto-occipital junction where they can result in significant myelopathy secondary to spinal cord compression. Here, we describe an anterior atlanto-occipital SC markedly compressing the spinal cord of a 65-year-old male who spontaneously regresses utilizing steroids and a cervical collar for 1 year.

CASE PRESENTATION

History and presentation

A 65-year-old male presented with tension headaches and neck pain but no myelopathy for 2 years’ duration. At that point, the cervical magnetic resonance imaging (MRI) scan showed an anterior atlanto-occipital cyst that filled the anterior foramen magnum and caused marked ventral brainstem and upper cervical spinal cord compression [ Figure 1 ] but without intrinsic cord edema/myelomalacia. Notably, the peripheral enhancement indicated that it was a degenerative cyst. Due to the patient’s refusal of surgery, conservative management was recommended (i.e., cervical bracing/steroids). In addition, follow-up MR studies were ordered to follow the cyst.

Figure 1:

Serial magnetic resonance imaging scans before and after conservative management with the use of a soft collar illustrating resolution of a large atlanto-occipital cyst secondary to severe arthritis. Sagittal T1-weighted sequences at presentation (a), before immobilization (b), and at 3-month follow-up (c) showing complete resolution of a large atlanto-occipital cyst. Axial T2-weighted sequences at presentation (d), before immobilization (e), and at 3-month follow-up (f) showing resolution of initial brainstem compression. Sagittal T1 contrast-enhanced sequences at presentation (g) and before immobilization (h) showing atlanto-occipital cyst with an enhancing capsule causing significant brainstem compression and medullary kinking (circled in red is the atlanto-occipital cyst).

6-Month follow-up MR

The 6-month follow-up MRI showed interval enlargement of the degenerative cyst at the occipitoatlantal junction, with increased pressure on brainstem at the cervicomedullary junction. Clinically, however, he did not have any problems with ambulation or bowel and bladder control and did not report any new symptoms referable to compression of the nervous tissue. Due to the cyst size and further enlargement, surgery, consisting of a transnasal endoscopic resection of the cyst followed by occipital cervical fusion was recommended, but the patient declined. Rather, he was prescribed methylprednisolone (Medrol Dosepak) and a cervical collar. At 1-month follow-up, the patient reported dramatic improvement of his pain; he was advised to continue to wear a semi-rigid neck collar and use meloxicam as needed.

8-Month and 1-year follow-up MR scans

The next follow-up MRI 8 months after his initial presentation showed that the cyst had stabilized in size/dimension, and he had symptomatically improved; he continued to use the cervical collar. At 1-year follow-up, pain at the OC junction largely resolved using the collar, anti-inflammatory medication, and muscle relaxants. This improvement correlated with the 1-year follow-up MRI that demonstrated complete spontaneous regression of the atlanto-occipital cyst with no further evidence of kink/compression of the brainstem at the cervicomedullary junction [ Figure 1 ]. We recommended that he continues to wear his collar when physically active, with further follow-up with an MRI in 1 additional year.

DISCUSSION

SCs are cystic dilatations of synovial sheaths that extrude into the spinal canal and can occur at various spinal levels. Notably, atlanto-occipital SCs are exceedingly rare. Several treatment options are available including surgical resection (with or without stabilization and computed tomography-guided cyst aspiration) versus various conservative measures (i.e., anti-inflammatory drugs, physical therapy, supportive braces, and steroid injections). Although some spinal SCs can resolve spontaneously, most SCs at the craniocervical junction in myelopathic patients with MR-documented cord/ brainstem compression require decompression/fusion.

Literature review of five prior cases of atlanto-occipital junction SCs

We found just five other case reports of SCs at the atlanto-occipital junction; the SCs spontaneously regressed in only one patient [ Table 1 ].[ 1 - 5 ] Our patient, who declined surgery, was conservatively with steroids and a cervical collar for 1 year during which time his myelopathy improved and the repeated MR studies confirmed cyst regression.

Table 1:

Previous reported cases of atlanto-occipital joint synovial cysts, presentation, and management.

Potential mechanisms of spontaneous cyst regression

The mechanism of spontaneous cyst resolution is still unclear. Spontaneous resolution may follow spontaneous rupture, or desiccation and phagocytosis both being promoted by the inflammatory response induced by the SC itself, similar to spontaneous resolution of lumbar disk herniations. Limitation of joint mobility with the use of a cervical collar could play a role in cyst resolution, particularly in cases with spinal instability.

CONCLUSION

Here, we successfully treated a 65-year-old male with a large anterior atlanto-occipital cyst causing significant brainstem compression but without myelopathy with a cervical collar and steroids (i.e., latter PRN) for 1 year. This resulted in neurological improvement and spontaneous regression of the cyst.

Declaration of patient consent

Patient’s consent not required as patient’s identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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