Cranial and peripheral neuropathy in rheumatoid arthritis with special emphasis to II, V, VII, VIII and XI cranial nerves

Background: Cranial neuropathy in rheumatoid arthritis (RA) is relatively rare compared to the frequently reported peripheral neuropathy. Methods: We investigated the occurrence of subclinical cranial and peripheral nerve involvement in 55 patients with RA. Results: Patients had a mean age of 43.1 years and a mean duration of illness of 6.4 years. All patients presented with electrophysiological findings suggestive of peripheral neuropathy. In addition, 69.1% of them had entrapment neuropathies, in which carpal tunnel syndrome was the most common (54.6%). Sensorimotor neuropathy at sites other than usual entrapment sites was diagnosed in 70.9%, while bilateral distal sensory neuropathy in lower limbs was identified in 29.1%. Among cranial nerves examined, optic and vestibulocochlear neuropathies were common (29.1% of eyes and 40% of ears examined). Spinal accessory neuropathy was reported in 21.8% of records. Neither facial nor trigeminal nerves were affected. Electrophysiological characteristics of neuropathies were indicative of axon loss. Significant association was identified between neuropathy and patients’ ages ( P < 0.01), duration of the illness ( P < 0.001), presence of rheumatoid nodules ( P < 0.001) and disease stages ( P < 0.001). Conclusions: Our results indicate that cranial and non‐compressive neuropathies are not uncommon in RA. This extends the pathologic disease spectrum. We do not confirm, but suggest the contribution of chronic immune‐mediated vasculitis and/or neurotoxicity in RA neuropathies. Of clinical importance, subclinical neuropathy may never progress and/or be of clinical significance, which contradicts that of comparable diseases, such as systemic lupus erythematosus. Advances in genetics implicate a complex immune genetics which controls susceptibilities and adaptive molecular mechanisms as a culprit of phenotypical heterogenicity among related diseases.