Neuromuscular disease: An expert answers your questions

In this expert guide to neuromuscular disease, Dr Girija Sadalage, a highly respected consultant neurologist, answers frequently asked questions about the causes of this type of condition and how it may be passed down through families. The leading specialist also sheds light on the variations of neuromuscular disease and how they affect the body in different ways.

What is neuromuscular disease?

Our nervous system is made up of:

• the brain
• the spinal cord
• the nerves that come out of the spinal cord
• the junction between the nerve and muscle
• the muscle itself

Neuromuscular disorders are conditions which affect the part of the nervous system outside of the brain and spinal cord. This relates to the nerve (both the cell itself and the nerve fibre), the junction between the nerve and muscle and the muscle itself.

What are the main symptoms of neuromuscular disease?

Neuromuscular disorders most commonly present with weakness which may be perceived by patients in many different ways. They can feel it as weakness or may call it heaviness, deadness or numbness. This weakness can affect various different muscle groups, including your limbs. It can also affect your eye muscles, face muscles, speech and swallowing muscles and also your breathing muscles.

Patients can also present with fatigue, cramps, twitchy muscles and spasms. When nerves are affected, people can also experience sensory symptoms, such as feelings of numbness, pins and needles or a hot and cold or painful sensation. Patients can also have wasting (thinning) of the muscles but in rare cases, they can also have enlarged muscles.

What causes neuromuscular disease?

The causes of neuromuscular conditions are varied. A large proportion of patients with neuromuscular disorders have a genetically inherited condition which is passed down in families. The other causes of a neuromuscular problem can be inflammation or an overactive immune system caused by an autoimmune condition. Rarely, neuromuscular problems can result directly from a bug, like a virus, and very rarely may be an immune response to a cancer occurring elsewhere in your body.

How can I know if I'm at risk of neuromuscular disease?

The vast majority of patients with neuromuscular disease have an inherited neuromuscular problem which has been passed down through their family. If there is someone in your family who has an inherited neuromuscular problem, then you may be at risk of developing the condition yourself.

Neuromuscular disease may be dominantly inherited, meaning that you only need one abnormal copy of the gene to get the condition and this can happen if either of your parents are affected. Or you can inherit the condition in a recessive manner, which means two copies of the bad gene are needed to develop the condition. In this case, both of your parents would need to either suffer from the condition themselves or be carriers. People in this position have a twenty-five per cent chance of developing the condition and a fifty per cent chance of passing it on themselves (being a carrier).

How exactly does neuromuscular disease affect the body?

Neuromuscular conditions can affect the body in various different ways and this depends on which part of the neuromuscular system is affected; the muscle, the nerve or the junction between the nerve and the muscle.

When the muscles are affected, for example in a case of myopathy, people may experience weakness in any of the body’s muscle groups, such as the limbs, the muscles in your face, your eyes or those you use to help you speak, swallow or breathe. Additional to weakness, wasting of the muscles can occur.

In neuromuscular diseases affecting the nerves and very commonly in inherited conditions like neuropathy, weakness occurs first in the peripheries and then progressively spreads towards the centre of your body. This can also cause sensory problems of numbness or pins and needles.

If the neuromuscular problem relates to the junction between the nerve and the muscle, the presentation is slightly different. Although patients often have weakness of the muscles, the pattern is one of variable weakness, so the more you use the muscle, the more tired you can become and when you rest, you feel better.

Is neuromuscular disease life-threatening?

If a neuromuscular condition affects the muscles used for breathing or swallowing, it can become dangerous. Occasionally, some conditions, such as an immune-mediated neuropathy, can cause problems with your autonomic nervous system. This is the part of the nervous system that is used to regulate your heart rate and blood pressure, so if this is affected, the condition can become life-threatening.

What are the different treatment options?

So far, we don’t have any curative treatment options for inherited neuromuscular problems. There are some treatments for certain neuromuscular conditions where the progression can be slowed, such as spinal muscular atrophy (SMA). In other cases, however, there are no treatment options for inherited conditions but support can help patients to manage their symptoms.

On the other hand, inflammatory or immune system related neuromuscular disorders can be treated and also cured. The mainstay of this treatment is usually keeping the immune system under control with immunosuppressants, such as steroids, plasma exchange, immunoglobulins or other immunosuppressive agents.

Dr Sadalage is one of the UK’s leading consultant neurologists. If you would like to schedule a consultation with Dr Sadalage, you can do so by visiting her Top Doctors profile.