70-year-old female patient with longstanding advanced rheumatoid arthritis (affecting multiple joints) presented with neck pain following a minor fall. The pain was constant in nature and occipital-posterior cervical in location. There were no associated focal neurological deficits. She was evaluated with a CT examination as well as flexion and extension radiographs.
The radiographs (Fig. 1a-b) demonstrate advanced uncovertebral as well as facet joint degenerative changes affecting most of the cervical region. There is anterior translation of C1 on C2 with an anterior atlanto-odontoid distance of 6mm and a posterior atlanto-odontoid distance of 10mm. There is no dynamic instability between flexion and extension. Spinous processes erosion is seen involving C3 to C5.
The CT examination (Fig. 2a-e) shows erosion of the odontoid peg (arrowed on Fig. 2a) and atlanto-axial subluxation with antero-lateral translation of C1 of C2. Superior migration (cranial settling) of the odontoid peg is seen (Fig. 2b) with the odontoid tip at 6mm above the McGregor line (drawn from hard palate to occiput: normal <4.5mm). CT images are also able to better demonstrate facet joint arthropathy dominating at the upper to mid cervical levels and multilevel uncovertebral degenerative changes. A left C2/3 facet joint fusion is also shown (Fig. 2d-e).
Background
Rheumatoid arthritis involving the cervical spine was first described by Garrod in 1890 [1]. Cervical involvement can occur in over 80% [2]. It tends to be more common with longstanding disease and in those with multi-articular involvement. The upper cervical spine gets primarily affected [3]. Typical initial patient symptoms include neck and occipital pain [3]. Subtle signs of myelopathy may also be present [1].
Imaging perspective
There are some classical changes that can occur in cervical spine involvement with rheumatoid arthritis. These include:
1. Atlanto-axial subluxation: considered one of the commonest manifestations and may be seen in up to 33% of patients [4]. An atlanto-axial subluxation greater than 9mm with vertical settling and a posterior atlanto-odontoid interval less than 14mm are thought to correlate well with the presence of neurologic deficits. The presence of atlanto-axial subluxation has been associated with an up to eight-fold increase in mortality [5].
2. Vertical (cranial) settling / atlanto-axial impaction: thought to affect up to 8% of patients [6]. It is represented by odontoid migration > or =5 mm rostral to McGregor's line (a line drawn from the posterior aspect of the hard palate to the occiput), a sagittal canal diameter <14 mm, or a cervicomedullary angle of <135 degrees [7]. The presence of cranial settling is considered as one of the most dangerous of cervical manifestations [8].
3. Sub-axial subluxation [3]: can occur to varying degrees and refers to subluxation of joints inferior to the atlanto-axial articulation.
4. Spinous processes erosion [9]
5. Apophyseal (facet) joint arthropathy +/- fusion: may be present in around 9% of patients and may correlate with the degree of severity of cervical myelopathy [10].
Outcome
Non-operative management does not alter the natural history of cervical disease. Main surgical options include either an anterior or a posterior cervical fusion.
Traditional indications for surgery have been intractable pain and the presence of neurologic deficits.
Primary surgical objectives are to achieve stabilisation of affected segments and relief of neural compression by reduction of subluxation or by direct decompression. An arthrodesis may also provide adequate pain relief. Neurological recovery occurs more consistently in patients with lower grades of pre-operative myelopathy.
Teaching points
This case highlights some of the classical imaging features seen in cervical spine involvement with rheumatoid arthritis. While there was no focal neurological deficit in this case, the patient was referred for surgical management given the overall severity of symptoms and imaging findings.
Advanced rheumatoid arthritis involving the cervical spine
1. The lateral flexion-extension X-ray of the cervical spine shows abnormal alignment in the upper cervical region. There is a noticeable anteroposterior displacement between C1 (atlas) and C2 (axis), which increases during flexion, suggesting atlanto-axial subluxation.
2. Coronal and sagittal CT reconstructions show asymmetry of the atlanto-axial joint surfaces and an increased distance between the anterior arch of the atlas and the odontoid process. An upward displacement of the odontoid process can be seen, raising suspicion of vertical (cranial) settling.
3. The lower cervical region also demonstrates varying degrees of narrowing of the apophyseal joint spaces and possible erosive changes, with evidence of partial vertebral body or spinous process resorption or destruction. These multilevel findings are consistent with rheumatoid arthritis (RA) affecting the cervical spine.
4. The posterior soft tissue shadow appears somewhat thickened; however, there is no clear evidence of spinal canal stenosis, and no obvious signs of acute neurological compromise due to spinal cord compression are currently observed.
Based on the above imaging findings and the patient’s medical history, the primary possible diagnoses include:
Considering the patient’s long-term multi-joint RA history, persistent neck-occipital pain, and relevant imaging findings, the most likely diagnosis is:
“Rheumatoid Arthritis Involving the Cervical Spine (with Atlanto-Axial Subluxation and Vertical Settling).”
1. Surgical vs. Conservative Management:
- Given the significant atlanto-axial instability and signs of basilar invagination, even in the absence of marked neurological deficits, the need for surgical intervention should be thoroughly evaluated.
- Surgery aims to stabilize the cervical spine and prevent potential spinal cord or nerve damage. Posterior or combined anterior-posterior fusion and fixation may be considered.
- If the patient has fragile bones (osteoporosis) or poor surgical tolerance, a comprehensive risk assessment should guide the final therapeutic decision.
2. Medication Management:
- Continue regular RA medications (such as DMARDs and/or biologics) to slow joint destruction.
- Pain control and anti-inflammatory medications can be used as necessary to relieve symptoms and improve mobility.
3. Rehabilitation and Exercise Prescription (Following the FITT-VP Principle):
Disclaimer:
The above report is based on the provided clinical history and imaging data for reference only. It does not replace an in-person consultation or professional medical diagnosis and treatment. If there are further questions or progression of symptoms, please seek timely evaluation from a relevant specialist clinic or hospital.
Advanced rheumatoid arthritis involving the cervical spine
