Rheumatoid arthritis - with cervical spine manifestations

Clinical History

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.

Imaging Findings

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).

Discussion

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.

Differential Diagnosis List

Final Diagnosis

Advanced rheumatoid arthritis involving the cervical spine

URL:	https://www.eurorad.org/case/11507
DOI:	10.1594/EURORAD/CASE.11507
ISSN:	1563-4086