7 Causes of Myopathy

7 Causes of myopathy

May of us take our muscles for granted – they allow us to walk, run and even breathe. The importance of muscles is something you might only think about when you exercise or watch your favorite athlete in action on TV, but they really have an effect on your everyday life. But what happens when something goes wrong with our muscles? When your muscles are not working like they should is when you may notice them. That’s where myopathy comes in.

Myopathy is a medical condition in which the muscles get damaged causing impairment of movement, weakness of muscles or other aspects of health, depending on the type of muscle affected. Myopathy may be either inherited or acquired and there are many causes of myopathy – some you might expect and others that might surprise you. In this blog, we will take a deeper look into myopathy, its symptoms, and some of its common causes.

What is Myopathy?

Myopathy is a medical term used to describe a group of diseases that cause muscle weakness due to dysfunctional muscle fibers. This can lead to problems with movement, exercise tolerance, and general health. There are different types of myopathies such as:

structure of human muscle
  • Congenital myopathies: developmental delays in motor skills with possible skeletal and facial abnormalities present at birth.
  • Muscular dystrophies: progressive weakness in voluntary muscles that may be present at birth.
  • Mitochondrial Myopathies: caused by genetic abnormalities in the mitochondria.
  • Glycogen Storage Diseases of Muscle: caused by genetic mutations that affect the enzymes and metabolism of glycogen and glucose.
  • Myoglobinuria: caused by metabolic dysfunction that affects myoglobin.
  • Dermatomyositis: inflammatory myopathy of skin and muscle.
  • Myositis Ossificans: bone grows in muscle tissue.
  • Familial Periodic Paralysis: episodes of limb weakness.
  • Polymyositis, inclusion body myositis, and related myopathies: inflammatory myopathies of skeletal muscle.
  • Neuromyotonia: alternating episodes of muscle stiffness and twitching.
  • Stiff-Man Syndrome: episodes of rigidity and reflex spasms.
  • Common muscle cramps and stiffness
  • Tetany: prolonged spasms in the limbs.

Symptoms of Myopathy

The most common symptom of myopathy is muscle weakness. However, other symptoms may occur depending on the type of myopathy you have.

Some common symptoms of myopathy include:

  • Muscle weakness, fatigue, or pain
  • Trouble breathing, especially when exercising
  • Problems standing or walking
  • Swallowing problems
  • Fatigue and muscle stiffness
  • Muscle cramps or twitches

Common Causes of Myopathy  

As mentioned above, myopathy can be either inherited or acquired. Inherited myopathies cause muscle weakness from birth and are inherited from an immediate family member. The symptoms may worsen as you age or lead to other complications, such as respiratory distress and cardiac issues. Inherited myopathies are caused by genes and include:

  • Muscular Dystrophies
  • Congenital Myopathy
  • Metabolic Myopathy
  • Mitochondrial Myopathy
  • Channelopathies
  • Myotonia Congenita

Acquired myopathies can be caused by a variety of factors that affect the muscles’ ability to function properly. These types of myopathies can develop at any time during your life and symptoms may vary widely from person to person. Common causes of acquired myopathy can include:


bacteria and virus that can cause myopathy

In some cases, it can be an infection that causes myopathy. Viral infections such as HIV, influenza, and Epstein-Barr have been associated with myopathy. Staph and streptococci have also been associated with myopathy as has Lyme disease and parasitic infections like trichinosis.

Autoimmune Reactions

Inflammatory/autoimmune myopathy occurs when the body starts to attack the muscle tissue and/or impedes muscle function. Autoimmune conditions such as sarcoidosis, lupus, and rheumatoid arthritis can all contribute to this type of myopathy. However, some cases of inflammatory myopathies have no known cause. There are four types of chronic inflammatory myopathies: polymyositis, dermatomyositis, inclusion body myositis, and necrotizing autoimmune myopathy.


Alcohol abuse can cause myopathy as well as other health issues. It’s not just your liver that pays the price for all those drinks – your muscles may start to show the effects as well. Acute alcoholic myopathy can develop due to binge drinking and chronic alcoholic myopathy can develop as a result of years of alcohol abuse.

Medical Conditions

There are many medical conditions that can lead to myopathy. These conditions can affect the muscles directly or they may interfere with how the muscles function. Some common medical conditions that cause myopathy include: diabetes, thyroid disease, lupus, and rheumatoid arthritis. Others that are less common can include Scleroderma, Sjorgren’s syndrome, sarcoidosis, electrolyte imbalances, and primary/familial amyloidosis.

Nutritional Deficiencies

A lack of certain vitamins and minerals can contribute to myopathy. For example, deficiencies of vitamin D and vitamin B12 have been identified as being related to myopathies. Excess iodine consumption has also been found to lead to hyperthyroidism, which can contribute to myopathy.

Drug-induced Myopathy

Certain types of drugs have been known to damage muscle fibers and can lead to what is known as drug-induced myopathy. In cases where more than one of the following drugs are used, then the risk of developing myopathy increases. Many drugs are associated with myopathy including:

prescription medication
  • Cholesterol medications: statins, fibrates, niacin, and ezetimibe
  • Steroids
  • Propofol
  • Amiodarone
  • Colchicine
  • Chloroquine
  • Antivirals and protease inhibitors
  • Omeprazole
  • Tryptophan

In Conclusion

If you’re having trouble with your muscles, it may be an indication of a more serious condition. Muscle weakness and fatigue can also indicate certain types of myopathy which is why it’s important to determine the cause before attempting any treatment. Inherited myopathies are those caused by genetics, whereas acquired myopathies develop over time and can have a variety of causes. In some cases, there may be various factors contributing to muscle damage. If you are experiencing muscle weakness, fatigue, or pain and you’ve ruled out other possible causes such as injury or overuse of the muscle, then it’s time to see a neurologist.

Headshot of Premier Neurology & Wellness Center Practitioner Kashouty

Dr. Kashouty, a diplomate of the American Board of Psychiatry and Neurology (ABPN), practices general neurology with fellowship trained specialization in clinical neurophysiology. Dr. Kashouty finds the form and function of the nerves and muscles the most interesting part of neurology, which is what led him to specialize in neurophysiology with more emphasis on neuromuscular conditions. He treats all neurological diseases, but his main focus is to treat and manage headaches, movement disorders and neuromuscular diseases.