In the first year of the project, Professor Blamire and his team have developed their MRI technique which measures motor units in leg muscles. This improves the image quality. The researchers then used this technique to measure motor units in healthy participants. They achieved this by activating individual motor nerves and their associated muscle fibres with brief electrical pulses. The team will also measure motor unit activity when participants voluntarily move their muscles, without the electrical pulses. They will use this information to create a plan to study motor units in people with SMA, which is the next phase of the research.
What are the aims of the project?
This project aims to overcome the limitations of current ways of measuring the progression of SMA, by developing a pioneering, non-invasive technique based on MRI.
Why is this research important?
Muscles are controlled by nerves, called motor neurons, which carry electrical messages from the spinal cord to muscles telling the muscles to move. Each motor neuron ‘speaks to’ a number of muscle fibres, together called a motor unit. Each muscle is made up of many motor units.
In SMA, motor neurons are lost and for each motor neuron that dies, that motor unit no longer functions. Measuring the number of motor units and their function is therefore one way to measure the progression of SMA, and it can also be useful in the diagnosis of some people with SMA.
The techniques currently used for this involve electrically stimulating nerves and measuring their electrical activity; this is called electromyography (EMG). However, these can be invasive, painful tests, often requiring a needle to be inserted, making them unattractive especially for children. They can also be technically challenging, time consuming and may only tell us about a small proportion of the nerves (the easily accessible ones).
To overcome these limitations, Professor Blamire and his team have been developing a novel, non-invasive technique based on MRI, which they have been testing in people with amyotrophic lateral sclerosis (ALS; a form of motor neuron disease). They have been able to show motor unit number and function quickly and using a pain-free method.
What will the researchers do?
In this project, the team will address the technical challenges in taking this new technique, called motor unit MRI (MUMRI) from an experimental method to one that can be used in people with SMA. They will maximise the image quality of the scans, design a protocol for MUMRI in people with SMA and develop software for analysis of the images.
Having done this, they will run a small, proof of concept trial in people with SMA, using healthy individuals with no muscle wasting condition and people with ALS as comparison groups. Participants will be assessed using the new MUMRI technique as well as the current gold-standard tests that are used in the clinic to evaluate progression; EMG and clinical assessment. This data will then be used to assess how accurately MUMRI can measure the progression of SMA.
How will outcomes of this research benefit people with spinal muscular atrophy?
This research may pave the way to a new, improved way of measuring the progression of SMA that is non-invasive and pain free.
The technique is also expected to be quicker and more sensitive than existing EMG methods. This would be valuable because it would allow changes to be detected earlier, which would be beneficial for diagnosis and for measuring how effective a potential new treatment is, for example in clinical trials.
As MUMRI is a completely new way of measuring motor unit function, it is also hoped that it may provide new information about how SMA progresses.
Project leader: Professor Andrew Blamire
Institute: Newcastle University
Condition: spinal muscular atrophy
Duration: Three years
Total cost (£): 218,566
Official title: MR imaging of motor unit dynamics as a non-invasive disease biomarker in spinal muscular atrophy
Find out more about Dr Blamire’s MRI technique in our feature article
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