Neuromuscular Disorders

What are the symptoms of a neuromuscular disorder?

Symptoms depend heavily on which part of the system is affected and which specific condition you have, but several patterns come up again and again.

• Muscle weakness, which may be constant or come and go through the day
• Muscle wasting (shrinking) over time
• Twitches, cramps or spasms
• Muscle pain
• Numbness, tingling or other unusual sensations
• Feeling tired more quickly than normal
• Difficulty with coordination, balance or walking
• Drooping eyelids, double vision, or other changes to facial muscles
• Difficulty speaking, chewing or swallowing.

In more severe cases, weakness can reach the muscles used for breathing, which is treated as a medical priority rather than something to monitor at home.

What causes neuromuscular disorders, and who is at risk?

Many neuromuscular disorders are genetic. You might inherit an altered gene from a parent, or a mutation might happen on its own, affecting one gene or more than one. Others are acquired during your lifetime rather than inherited.

• An autoimmune reaction, where your immune system mistakenly attacks nerve or muscle tissue
• A vitamin deficiency, such as low vitamin B12, which can damage the insulation surrounding nerves
• An injury, or pressure on a nerve
• A toxin, certain medicines, or heavy metal exposure
• Malnutrition or a metabolic problem
• An infection
• Sometimes, no clear cause is ever found.

Risk varies enormously by specific condition. Some, like myasthenia gravis, are more common in women and tend to appear in adulthood. Others, like spinal muscular atrophy, are genetic and usually show up in infancy or childhood. Peripheral neuropathy, the most common category overall, affects almost 1 in 10 people in the UK, while a specific inherited condition like Charcot-Marie-Tooth disease affects 1 in every 2,500.

Are there different types of neuromuscular disorder?

Doctors often group neuromuscular disorders by which part of the system, from spinal cord to muscle, is affected.

• Motor neuron conditions: damage to the nerve cells in your spinal cord that control movement. Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy fall into this group
• Peripheral nerve conditions: affect the nerves running from your spinal cord to your limbs. Charcot-Marie-Tooth disease is a well-known inherited example, alongside peripheral neuropathies linked to diabetes, autoimmune conditions or toxins
• Neuromuscular junction conditions: affect the connection point where a nerve signal is passed to a muscle. Myasthenia gravis, where your immune system attacks this connection, is the best-known example
• Muscle conditions (myopathies): affect the muscle fibres directly. Muscular dystrophy, including the Duchenne and Becker forms, is the best-known inherited example, alongside inflammatory forms like dermatomyositis and polymyositis.

How are neuromuscular disorders diagnosed?

Your doctor will start with your medical and family history and your symptoms, then carry out a physical and neurological examination. Depending on what they find, you may be referred to a neurologist for further tests.

• Electromyography (EMG), which checks the electrical activity in your muscles
• A nerve conduction study, which checks how well signals travel along your peripheral nerves
• Blood tests, which can pick up enzyme abnormalities or markers of an autoimmune condition, such as the specific antibody test used for myasthenia gravis
• Imaging, such as an MRI, CT scan, or ultrasound of the muscles and nerves
• A muscle biopsy, where a small sample is removed and examined under a microscope
• Genetic testing, to confirm an inherited condition.

How are neuromuscular disorders treated?

Non-surgical treatment

• Medicines, tailored to the specific condition, for example to calm an overactive immune system or manage symptoms directly
• Physiotherapy and occupational therapy, to help maintain strength, movement and independence
• Speech and language therapy, if swallowing or speech is affected
• Nutritional support
• Mobility aids and other equipment to support daily life.

Surgical treatment

Surgery isn't a routine or first step for most neuromuscular disorders. Where it's used, it tends to be for a specific complication of a specific condition rather than for the disorder as a whole, so your care team can advise whether it's relevant to you.

Many neuromuscular disorders are lifelong, and while a good number don't currently have a cure, treatment can still meaningfully improve symptoms, mobility and day-to-day function, and in some cases can slow how quickly the condition progresses.

When should I see a doctor?

See a doctor if you notice sudden or unexplained muscle weakness. They can assess your symptoms and arrange the right tests to look for an underlying cause, rather than you needing to work out which type of disorder might be responsible yourself.