What is Myopathy?

By , MD, PhD

Myopathies are a group of disorders characterized by a primary structural or functional impairment of skeletal muscle. They usually affect muscle without involving the nervous system, resulting in muscular weakness. The latter represents one of the most common complaints among patients presenting to family physicians or neurology specialist.

Nevertheless, fatigue, exercise intolerance and myalgias can also occur in a plethora of non-myopathic conditions. Therefore a comprehensive evaluation of each patient should include a thorough examination and combination of adequate laboratory, radiologic, electrodiagnostic and pathologic studies.

Clinical presentation of myopathies

Myopathies can manifest with either “negative” or “positive” symptoms. Negative symptoms include muscle weakness, exercise intolerance and fatigue, while so called positive symptoms usually encompass cramps and myalgias, with occasional contractures, myotonia and myoglobinuria.

Weakness is the most common and most reliable clinical indicator of myopathy. The affected individuals can experience difficulty performing tasks which require the use of proximal muscles, such as getting up from a chair, lifting objects or climbing steps. Distal weakness is less common, although it can be the most prominent symptom in some types of myopathy (e.g. inclusion body myositis, myotonic dystrophy and genetic distal myopathies).

On the other hand, fatigue and exercise intolerance are less reliable negative symptoms as they often reflect the general level of conditioning, emotional disturbance or the impairment of cardiopulmonary status in elderly people. When these symptoms are truly present, additional clinical features are asses in order to exclude certain metabolic myopathies or mitochondrial cytopathies.

Myalgias refer to generalized muscle pain or tenderness. Similar to fatigue, myalgia represents a common complaint which can occur in a myriad of both benign and serious disease processes. Constant muscle pain in a proximal distribution is often characteristic for inflammatory myopathies (such as polymyositis and dermatomyositis), whereas episodic myalgias after exercise arise suspicion that metabolic myopathies can be present.

Cramps are common in metabolic myopathies such as myophosphorylase deficiency (also known as McArdle’s disease) and in hypothyroid myopathy. Joint contractures are uncommon in patients with muscular symptoms, but their presence can facilitate in establishing the diagnosis. Myotonia is often found in sodium or chloride channelopathies, as well as in the myotonic dystrophies.

Various associated symptoms are present in many myopathies and can aid in narrowing the differential diagnosis among rheumatologic, endocrine and inflammatory conditions. For example, dysphagia may appear with weakness in inclusion body myositis and systemic sclerosis, whereas menorrhagia often coincides with the weakness that occurs in hypothyroidism.

Ways to diagnose the condition

The evaluation of patients suspected of having a myopathy always begins with a detailed medical history. The physical examination aims to achieve an objective confirmation of the subjective severity and distribution of muscle symptoms. Further diagnostic tests are ordered to add laboratory evidence in support of or against the suspected diagnosis.

Measurement of serum enzymes is a widely used approach for diagnosing suspected muscle disease. Creatine kinase (CK), also known as creatine phosphokinase, represents preferable screening tool because (unlike lactate dehydrogenase, aldolase and other enzymes) it has relative predominance in skeletal muscle, it is not falsely elevated by hemolysis, and is readily released in cellular injury.

Still, CK elevation is not synonymous to the presence of a myopathy. Many individuals with active motor neuron diseases or severe active axonal neuropathies can exhibit mild to moderate increase in CK levels. Furthermore, muscle trauma, viral infections, strenuous exercises, generalized seizures and even therapy with certain drugs may all be accompanied by transient, albeit severe CK elevation.

Electromiography (EMG) represents the most informative part of the electrodiagnostic study in myopathic disorders. It can confirm the presence of a myopathy, narrow down the differential-diagnostic possibilities, as well as identify an appropriate biopsy site. Still, it must be noted that abnormalities in the EMG can be subtle and very patchy in distribution. Nerve conduction studies and needle myography represent additional diagnostic possibilities.

If the diagnosis is still inconclusive after all the aforementioned approaches, a muscle biopsy is warranted for patients who have a suspected myopathy. Such critical evaluation is necessary as treatments for the myopathies depend on the particular disease and its specific causes.

Further Reading

Last Updated: Mar 2, 2015

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Comments
  1. lalmani kaushik lalmani kaushik India says:

    my father feels that he is ok when he is in sitting or in rest position but i dont know what happens to him when he try to walk ,when he try to get up from floor (when he is sitting on floor) at these moment he is not able to get  up from the floor as well as he is not able to walk even 100 steps. this type of walking problem he is facing from last 7 years he has gone through every treatment like acupressure physical exercise medical treatment and many more but all in vain, doctors also perform many test like MRI, Muscles Biospy, X-  ray of hip joint, Brain screening etc, but all in vain Because all reports were normal doctors have also done some blood test checked CPK in blood and many test but as usual reports are normal. Can i have any suggestion from any doctor hat what we should do, so that my father will overcome with this problem...........My email Id is   kaushik.anshu@rocketmail.com

    • NageshKumar Silla NageshKumar Silla India says:

      Hello,
      this is the same case for my mother as well
      she cant climb stairs, cant get up from floor sitting position and requires lot of support and lot of effort to overcome these actions
      off-course, walking would be easy for her but problem comes while climbing stairs, getting into bus,getting into train, getting up from sitting position
      her walking style also changed (in lingering manner). we have approached several doctors from past 5 to 6 years. but no use and diagnosis stated that she is being suffering from myopathy (after examining small piece of her muscle part from her left thigh), this will be done only at NIMANHs, Bangalore only (I dont know about rest of India)
      Doctors, said, there is no treatment apart from doing pysyhiotherypy for rest of her life and some chance of improvement
      we even joined in one of the nature cure institute located at bangalore-but no improvement despite undergoing for several theripies like acupunture, mud therepy and etc

      our only hope is to consult auyervedic or some old traditional method that could be available at Kerala, I heard many of these kind were treated at kerala
      so, please help me if you have any information if you can get from your friends belongs to Kerala

      thanks
      NKS
      my phone number :- +919986251531

  2. Rainer L Rainer L Australia says:

    I think it is pathetic that so many people have to resort to the internet in order to get adequate answer's because their Doctors are incapable doing so. I note Statins causing much of this problem. Doctors keep pushing it as well as the Cardiologists regardless if it affects anyone's quality of life or even cause severe damage else where. For that very reason I stopped the Statins. Been on all of them and had been unwell during all those years. Now my lower Limbs feel sort of numb as if a rubber band has been placed just around under my knees. Perhaps I can blame this as being the result of the Statins. In the U.S Talk Shows , Interviews of medical professors e.t.c who condemn the use of Statins. I figured I rather have a quality of life than feeling unwell every day of the week and to prevent other damage to my Body. Good luck!

  3. lalmani kaushik lalmani kaushik India says:

    Hello Nagesh, this is lalmani kaushik,
    I read your last post and found that, your mother have the same problem as my father have, My father has also been treated in the India's biggest hospital ie. AIIMS  Doctors of AIIMS Newdelhi  told us that MY father has a problem of Muscles Distrophy.......which was reported after  doing a test of the muscle piece of his thigh. I dont know Were the doctors right or not?
    With their reports, I am not satisfied.
    I think  they just said this only for closing our case because it was in a Govt hospital  .
    I request you Nagesh
    Fortunatey, if you will find a good and successful treatment for your mother then please let me inform my mobile number is 09582715587.

  4. Jan N Stevie Michaels Jan N Stevie Michaels United States says:

    A most impressive clinical observation of five vitamin D-deficient patients who suffered from myopathy, a disease of bone and muscle tissue proves that vitamin D helps relieve pain. Patients were confined to wheelchairs and experienced severe fatigue, weakness, and chronic pain. After receiving 50,000 IU per week of vitamin D, all regained enough strength and energy within four to six weeks to be mobile and functional, and their aches and pains disappeared.
    From

  5. Rosy Georgia Rosy Georgia India says:

    my dad is suffering from the same problem. myopathy is a vitamin D deficiency disease. if the patient is a vegetarian then try to increase dairy products like cheese, milk, ghee, butter, and others like mushroom, soya bean, corn flakes and other cereals. other options are fish, fish has the highest IU of vitamin D; sunlight is the best option for natural vitamin D. medicines available are vitamin D injections, cod liver oil capsules, etc.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
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