Neuromuscular Diseases

Patients and Parents

Home Patients and Parents Know Your Conditions Neuromuscular Diseases

Introduction

Neuromuscular diseases (NMDs) are a diverse group of conditions that affect the peripheral nervous system, including muscles, muscle-nerve junctions, peripheral nerves, or motor neurons. These diseases are rare, with prevalence rates of 42 per 100,000 in the paediatric population in Hong Kong. The age of disease onset, symptom presentation, and disease progression can vary greatly, depending on the condition.

Causes

The causes of neuromuscular disorders can be either genetic / inherited or acquired.

The genetic / inherited causes may involve malfunctions of different parts of the neuromuscular system, including muscles, nerves, neuromuscular junctions, or motor neurons. Some examples are:

Muscle disorders: Duchenne muscular dystrophy, Becker muscular dystrophy, congenital muscular dystrophies, limb-girdle muscular dystrophies, myotonic dystrophy
Neuromuscular junction disorders: congenital myasthenic syndromes
Peripheral nerve disorders: Charcot-Marie-Tooth disease, hereditary sensory autonomic neuropathy
Lower motor neuron disorders: Spinal muscular atrophies
Other disorders: Channelopathies (myotonia congenita, paramyotonia congenita, hyperkalemic / hypokalemic periodic paralysis), metabolic myopathies

Acquired neuromuscular disorders can be caused by various factors. In autoimmune disorders, the body’s healthy tissues are mistakenly attacked by its own immune system. Some examples are myasthenia gravis, Guillain-Barré Syndrome and immune-mediated myositis. Other factors, such as infections, toxin exposure, nutritional deficiencies, metabolic and endocrine disorders, and adverse effects from treatment, can also cause acquired disorders.

Mode of Inheritance

The modes of inheritance for genetic / inherited neuromuscular diseases depend on the disease and the causative gene. Examples may include:

Autosomal dominant: Myotonic dystrophy, most forms of Charcot-Marie-Tooth disease and channelopathies
Autosomal recessive: Spinal muscular atrophy, most forms of congenital muscular dystrophies and limb-girdle muscular dystrophies
X-linked: Duchenne muscular dystrophy, Becker muscular dystrophy

Signs and Symptoms

Neuromuscular disorders can present at any age and with variable severity. Symptoms and signs may include:

Muscle weakness
Easy fatigue
Muscle ache
Muscle stiffness or twitching
Abnormal skin sensations, such as "pins and needles" tingling or numbness
Decrease or absent deep tendon reflex responses
Muscle atrophy, pseudohypertrophy or hypertrophy

Other symptoms may include:

Ptosis / drooping of eyelids
Limited eye movement
Problems with chewing and swallowing
Breathing problems
Stiff joints or spine problems

Diagnosis

Diagnostic evaluation begins with comprehensive history taking followed by a physical examination, and further diagnostic investigations, which can include:

Blood tests for muscle enzymes and other markers
Muscle imaging
Nerve conduction study and electromyography
Muscle or nerve biopsy
Genetic testing to confirm inherited NMD

Referral for further evaluation may be necessary if there are concerns about feeding problems, respiratory issues, cardiac problems or musculoskeletal problems.

Management

Management and treatment largely depend on the underlying causes and are personalised to individual needs. Families will be introduced to the necessary standard care and available treatment options, if applicable and indicated. They will also be invited to join the Hong Kong NMD patient registry.

References

Tsang MHY, Chiu ATG, Kwong BMH, Liang R, Yu MHC, Yeung KS, Ho WHL, Mak CCY, Leung GKC, Pei SLC, Fung JLF, Wong VCN, Muntoni F, Chung BHY, Chan SHS. Diagnostic value of whole-exome sequencing in Chinese pediatric-onset neuromuscular patients. Mol Genet Genomic Med. 2020 May;8(5):e1205. doi: 10.1002/mgg3.1205.

Acknowledgement

Principal author: Dr Sophelia Chan on behalf of Neurology Team, HKCH

Initial posting: Nov 2025