What is MMN?

Multifocal Motor Neuropathy, or MMN for short, is a rare, life-long condition that affects the motor nerves, which control muscle movement. This leads to muscle weakness, often starting in the hands or arms.

MMN is very rare, impacting 0.6 people per 100,000. Anyone can get MMN, but it is more common in older men than women. However, we have met people from all walks of life living with the condition.

MMN is not infectious, meaning you can't pass it along to anyone else.

Causes of MMN

Experts don't know what causes MMN yet, though it's strongly believed to be an autoimmune condition. An autoimmune condition is when the immune system mistakenly recognises your own body as a threat and begins to attack part of the system. In the case of MMN, it attacks the motor nerves. Over time, this attack causes the weakness MMN is known for.

Unlike GBS or some other Inflammatory Neuropathies, MMN is not usually linked to a recent infection.

MMN Symptoms  

MMN causes muscle weakness, usually without pain or loss of sensation. Symptoms tend to begin in your hands, impacting the ability to carry out fine motor tasks like buttoning a shirt, entering your PIN number at the ATM, or typing on a keyboard. It can also affect the legs, leading to difficulty climbing stairs or running.

MMN is asymmetrical. This means it affects each side of the body differently. Your left arm may feel fine, but you discover you can't give a thumbs up or point with your right.

It's also slowly progressive. This means that, without treatment, it gradually grows more impactful. However, unlike other Inflammatory Neuropathies, it shouldn't impact breathing or swallowing.

Diagnosis of MMN

Because of the slow progressive nature of the condition, the journey to diagnosis can be a long process, with some reporting a year or two, or even more. It can look like other nerve or muscle conditions, and in some cases mask itself as the aging process.

Once in front of a Neurologist, the timeline tends to speed up, and you will receive a full clinical assessment and be given a Nerve Conduction Study. You may also receive a blood test looking for key antibodies.

MMN Treatment  

While there is no cure for MMN, the symptoms can be treated. The main treatment for MMN is IVIg (intravenous immunoglobulin). This treatment helps calm your immune system and can improve muscle strength and function, restoring independence and improving, hopefully, quality of life.

IVIg is usually given regularly, often every few weeks, to help keep your symptoms under control. Other treatments used for Inflammatory Neuropathies are generally not effective in MMN, which is why an accurate diagnosis really matters.

Living with MMN

MMN is a chronic condition, this means you have it for life, however it will not shorten your life expectancy.

With the right treatment (IVIg for most) many people are able to manage their symptoms and maintain a good quality of life.

Physiotherapy and Occupational Therapy can support physical function, while emotional and psychological support can help people adjust to living with a long-term condition. Everyone’s experience of MMN is different, and support needs can change over time.

MMN Support

Living with Multifocal Motor Neuropathy can be challenging, but you don’t have to face it alone. Inflammatory Neuropathies UK is here to support people and families affected by MMN. We provide trusted information, advice, and guidance; practical support where it’s needed; fund and undertake research; and raise awareness of rare Inflammatory Neuropathies. If you’d like to know more, you can read our blog series, explore our resources, or get in touch.

If you’re looking for support, to have a chat or ask questions, why not join our Facebook Group or read our Newsletter.