Optical electromyography for the diagnosis of nerve and muscle disorders

Lead Research Organisation: University of Sheffield
Department Name: Neurosciences


Problems with nerves and muscles lead to weakness. This can result in difficulties with activities we all take for granted, such as holding a pen or walking around the house. There are many potential causes of muscle weakness and it can take a long time for doctors to work out why someone is weak. Often, lots of tests are required. Two of the most commonly used tests are electromyography, known as 'EMG', and muscle biopsy.

In EMG, a small needle is inserted into muscles and the electrical activity of the muscle is recorded. This can give doctors clues as to the cause of the weakness, but most of the time the findings do not diagnose a specific condition. Sometimes a muscle biopsy may also be required. This is a more invasive test, in which muscle is cut out and sent to a laboratory for further tests. The results can take a long time to come back, during which patients are uncertain about what is wrong with them.
To try and improve the way in which patients with weak muscles are diagnosed, we have created a new test which we call 'optical EMG'. In this, the EMG test is carried out in combination with a beam of light of a single colour. The EMG signal can help target the light to where it is needed. When the light makes contact with the muscle, some of it has its energy, or colour, changed. In our previous work we have shown that we can collect light which has undergone this change and use it to identify the causes of muscle weakness. Shining the light at muscle gives very quick results, unlike the long wait after a muscle biopsy. So far, we have done this with muscle biopsy samples but not in living patients.

In this project we will develop the 'optical EMG' equipment so that recordings can be performed in people. We will get approval from the appropriate regulatory authorities to do this. We will then test our new device in patients under investigation for conditions that cause muscle weakness. The study will tell us if 'optical EMG' can be used safely in patients and if we can make high quality recordings. We will also learn what patients think of our new test. We hope this will lead to further development of the technology and ultimately a test that can provide patients with a diagnosis much more quickly, helping them get the right care for their condition.

Technical Summary

The NHS Long Term Plan for Neurology calls for "Urgent national action to speed up diagnosis". Neuromuscular disorders result in muscle weakness, cause significant morbidity and mortality, and can take years to diagnose, often requiring invasive tests. A better diagnostic pathway is needed.

Our goal is to improve the diagnostic pathway for neuromuscular disorders by developing a comprehensive, minimally invasive bedside test of muscle health.

To do this, we developed an in vivo assessment of muscle using fibre optic Raman spectroscopy to evaluate biochemical changes in muscle via a needle probe. We demonstrated a high diagnostic performance in preclinical models of human diseases (area under receiver operating characteristic curve (AUROC, >0.85). Recordings caused no motor impairment. Human muscle biopsy data have shown the technique can rapidly identify muscle disease (AUROC 0.74-0.87) and differentiate between diseases (AUROC 0.76-0.95). We have since combined Raman spectroscopy with electromyography (EMG), which records the electrical activity of muscle, to create 'optical EMG'.

Here, we will evaluate "optical EMG", which combines the multiple muscle, electrophysiological sampling of EMG, with the molecular specificity of Raman spectroscopy.

We will redesign our prototype to regulatory requirements and undertake bench and in vivo preclinical testing. We will undertake first-in-human testing in patients under investigation for motor neurone disease and myopathy, two conditions in need of a better diagnostic pathway.

We will develop a commercialisation strategy, connect with stakeholders and understand the economic benefits of optical EMG. This work will be used to advance discussions with potential partners/licensees.

At the study end we will have demonstrated the feasibility and safety of optical EMG in target patient groups. The work will provide the platform for further development and the improved diagnosis of neuromuscular disorders.


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