Myopathy/Inflammatory Myopathy

Myopathy is the term used to describe a neuromuscular disorder in which the muscle fibers do not work properly due to multiple causes and the result is muscle weakness or involuntary movement or spasm. Inflammatory myopathy (myositis)  occurs when the muscle weakness is caused by inflammation from a number of causes.

Myopathies may be inherited or acquired. Myopathies are grouped based on a number of factors.

  • Congenital myopathies often appear as developmental delays in motor skills right from birth; you may notice skeletal and facial abnormalities. Curvature of the spine or scoliosis is representative of this group.
  • Muscular dystrophies  appear as progressive weakness in voluntary muscles which is sometimes evident at birth.
  • Mitochondrial myopathies  are caused by genetic abnormalities in cellular mitochondria, the structures that control energy in muscle cells. Kearns-Sayre syndrome is representative of this group.
  • Glycogen storage diseases of muscle are caused by mutations in the genes that control the enzymes that metabolize glycogen and glucose (blood sugar). Cori’s disease is representative of this group.
  • Myoglobinuria occurs when the metabolism of muscle fuel (myoglobin) is disrupted. Dimauro disease is an example of this type of condition.
  • Dermatomyositis  involves an inflammatory reaction of skin and muscle.
  • Myositis ossificans is caused by the calcification of muscle tissue.
  • Familial periodic paralyses are inherited neurological disorders caused by mutations in the genes that regulate sodium and calcium channels in nerve cells.
  • Polymyositis and inclusion body myositis  can be caused by injury, infection, drug side effects, allergies or autoimmune diseases.
  • Neuromyotonia, also known as Isaacs' syndrome, is characterized by alternating episodes of twitching and stiffness. The exact cause is unknown.
  • Tetany, the involuntary contraction of muscles, is usually caused by a lack of calcium or an excess of potassium.

In most myopathies, you may experience weakness involving the muscles near the core of your body, as well as cramps, stiffness, spasm, pain and fatigue in those muscles.

Diagnosis  of Myopathy
It is difficult to diagnose many myopathies until the symptoms have progressed to an observable point. Our team will ask you for a medical history and perform a physical exam. 

To help determine which form of myopathy is most likely your condition, we will perform a neurological examination to determine how well you can rise from a chair and walk and we will test your coordination and knee-jerk reaction. We may perform imaging, neurological and blood tests to determine if you have any endocrine abnormalities, heart problems, mental dysfunction, muscle atrophy or skin rashes; our task will be to determine if your muscle weakness follows any particular pattern .Early in your condition, we may suggest a serum enzyme test to measure how much muscle protein is circulating in your blood.

Our team may identify which muscles are weakened and how much by using an electromyograph; a muscle tissue biopsy can provide information on cell and protein abnormalities.

Treatment Options  for Myopathy
Different types of myopathies have many varied causes, so no single treatment for myopathy exists . Treatments range from those that address the symptoms to those that target specific causes of the condition. Some therapies common to many myopathies are drug and physical therapies, structural support for the patient, surgery and massage. Our team will work with you to evaluate the best mix of therapies for your treatment plan.


Our physicians at Houston Methodist specialize in managing myopathy at the following convenient locations.