Background Atlantoaxial subluxation (AAS) is important and potentially life threatening complication of Rheumatoid arthritis (RA). It is defined when the space between odontoid process from C2 and arch of the atlas exceeds more than 3 mm. Instability in atlantoaxial joint may result with numerous neurological symptoms, compression of spinal cord and ultimately quadriparesis or quadriplegia.

Objectives Aim of the study was to determine the frequency and the characteristics of atlantoaxial instability among our patients with RA and its dependence on the nature of the disease.

Methods 92 outpatients from University Rheumatology Clinic in Skopje, with classical RA (ACR criteria 1988) were examined for the AAS. In all cases were analysed the duration of the disease, haematological and serological tests, disease activity (DAS 28), visual analogue scale (VAS) for the degree of articular pain and verbal rating scale (VRS).for cervical-occipital pain. All patients underwent native and functional x-ray, CT scan and MRI of cervical spine. A complete neurological examination was obtained, with SEP of the n. medianus et n. tibialis.

Results Atlantoaxial instability, with expressed cervical-occipital symptomatology, occurred in 54 from 92 (58,69%) patients with RA. AAS appeared significantly more often in patients with longer duration of the disease (p<0,0001), in cases with significant cervical-occipital pain (VRS p<0,0001), with stronger joint pains (VAS), with higher values of SR (p=0,002), CRP (p=0,023), RF (p=0,000005), anti CCP (p=0,00003), and DAS 28 (p<0,0001). Anaemia and thrombocytosis (p=0,0008) appeared significantly more in cases with AAS. Anterior AAS, (mostly combined with other types) was the most frequent type, presented in 41 participants (75,92%). In one case posterior AAS was detected, what is very rare finding. Positive SEP was significantly higher in the group with AAS

Conclusions AAS is serious extra-articular manifestation of RA. Cervical subluxation may be a general anesthetic risk and risk for a neck injury. Routine cervical radiographs with the head in flexed position should be recommended in need of general anaesthesia and in situations with risk for a neck injury.

Acknowledgements Rheumatoid arthritis, atlantoaxial subluxation.

Disclosure of Interest None declared