Multiplex microneurography: a broadband route to individualised treatment in fibromyalgia.

The cause of pain in fibromyalgia is unknown and there are no diagnostic tests.

It therefore takes a long time to be diagnosed and it is difficult to treat, with patients often trying many medicines and experiencing side effects without relief.

Pain in fibromyalgia may arise because of abnormal processes in the brain, or because of abnormal activity in pain nerves (nociceptors). This is called ‘central’ versus ‘peripheral’ pain generation.

Some patients with fibromyalgia have signs suggesting central pain, such as pain on gentle touch, others have pain suggesting peripheral pain, such as finding heat more painful than normal. We can directly detect abnormal activity in pain nerves by using a technique called microneurography. An electrode is placed into a nerve, through the skin.

The electrode has a single ‘contact’ or ‘listening’ point so it can ‘hear’ nociceptor activity, but not clearly. We must electrically stimulate the skin to artificially activate the nociceptors to make them easier to ‘hear’.

My Early Career Fellowship from Versus Arthritis, has enabled us to use new technology from animal brain experiments to better ‘hear’ pain nerve activity. In rats, we use electrodes that have multiple contacts or ‘listening’ points instead of just one. This means that activity in single nerves can be ‘heard’ from multiple different points.

This allows us to mathematically extract the activity of lots of individual nerves from the background noise. This is called clustering.

Importantly, this funding has also allowed us to construct a prototype multi-contact electrode for use in people, we have successfully demonstrated proof of principle by showing that our prototype works in rats.

Initially, we will use rat multi-contact microneurography to discover if the type of nociceptor thought to be active in fibromyalgia, is active in a rat pain model.

This will add to our understanding of that model and allow us to advance our multi-contact recording and analysis techniques, in anticipation of translating them into patients.

We will use conventional microneurography, with a single contact electrode, to record from nociceptors in fibromyalgia patients.

We will group patients into those with signs of peripheral pain generators (finding heat more painful) and those without. This will show if these signs really do tell us important information about the underlying cause of fibromyalgia pain.

Working with our engineering and device development collaborators in Newcastle University, we will improve our novel electrodes and we will obtain medical device certification so that we can use them in people. We will progress to perform a proof-of-concept study in patients with fibromyalgia.

This exciting and ambitious project will enable Dr Dunham to complete his clinical and academic training in advanced pain medicine and become a consultant senior lecturer with an established lab performing translational experimental medicine. It will deliver new knowledge informing pre-clinical pain models.

Most importantly, it will deliver clarity about the cause of pain in fibromyalgia and provide a route towards diagnosis and targeted treatment, a step towards providing better pain relief and improved quality of life to patients with fibromyalgia.