A US study has provided neuroimaging evidence that centralised pain pathways consistent with fibromyalgia can co-exist with the peripheral inflammatory pain pathways in rheumatoid arthritis.
Functional MRI brain scans were performed on 54 patients with rheumatoid arthritis and symptoms of ‘fibromyalgianess’.
They found rheumatoid arthritis patients who reported high levels of fibromyalgianess demonstrated significantly higher functional connectivity between the default mode network (DMN) and insula cortex – a recognised neurobiological feature of primary fibromyalgia.
They said DMN-insula functional connectivity had previously been observed in other central sensitisation pain conditions including IBS, chronic back pain and migraine.
“We have shown that central sensitisation is not confined to individuals with ‘primary’ FM and co-exists in patients with the biologically distinct disorder of rheumatoid arthritis,” they said.
This showed RA was a mixed pain state, with many patients’ symptoms being related to CNS rather than classic inflammatory mechanisms.
“Further, the ACR FM survey appears to be a strong surrogate for this neurobiological marker of central sensitisation and, in the future, could be a useful tool to support clinicans’ evaluation of pain and inform subsequent management,” the study authors said in Arthritis & Rheumatology.
Clinical Professor Geoff Littlejohn from Monash University told the limbic Australian data suggested about 20-25% of people with rheumatoid arthritis also have fibromyalgia.
“And often it confuses treatment of the underlying condition so you might increase the rheumatoid arthritis medications to manage the fibromyalgia.”
He said some doctors struggled with the concept of fibromyalgia.
“This study says there is genuine neurophysiological change happening – that this is a genuine abnormality not an imagined psychological condition. And the more we understand the mechanisms of the problem, the more people will see it for what it is.”
“It validates the fact that fibromyalgia can be a component of the symptoms that patients with rheumatoid arthritis are presenting with and therefore we need to treat those separately.”
“So if someone has widespread pain, aching and fatigue, you might be talking about stress factors in their life or activating exercise programs which have been shown to be beneficial or you may use some very simple medication to help better quality sleep rather than increasing the cortisone or changing the biologic to a new one. So you are looking at a set of management strategies.”