Idiopathic Inflammatory Myopathies
Inclusion Body Myositis
Typical rash in dermatomyositis.
Creatine kinase blood test value usually high.
||Rash may be present
||Blood tests show high
ESR, ANA, DNA antibodies, etc.
||Proximal, limb girdle
tiredness and pain. Occurs especially in elderly.
High ESR. Prednisone is often used to treat this.
Many prescription drugs (and alcohol) are associated with muscle pain
and/or cramps. Ask your doctor.
inhibitors, e.g. Simvastatin, Pravastatin (anti-cholesterol agents).
||May be low potassium,
sodium or magnesium on blood tests.
May exacerbate dehydration.
Treatment is by supplementing and/or stopping the pill. Dietary changes
may be of assistance.
myopathy is usually painless. But acute painful myopathy may occur after
||Usually high creatine
kinase. A simple blood test will confirm.
||May get severe proximal
Loosers zones (on x-ray) around femoral neck, pelvis, scapular, fibula
or metatarsals. Vitamin D deficiency is the primary cause.
Metabolic Myopathies: Carbohydrate Disorders.
|a). Disorders of
Myophosphorylase deficiency (McArdle's Disease).
Phosphorylase b kinase deficiency.
rapidly develops in the exercising muscles, and increases with continued
movement. Muscle contractures may develop. Pain after exercise may last
a long time.
Resting creatine kinase usually raised. creatine kinase always raised
Inherited (usually autosomal recessive).
|b). Disorders of
Metabolic Myopathies: Lipid Metabolism.
||Very rare - secondary
deficiency is a lot more common. Typically painless. Manifests as
progressive proximal weakness.
Lots of lipid accumulation occurs in the muscle and a low muscle
carnitine level is found on testing. Carnitine supplementation is used
as part of the treatment.
||Muscle pain during or
after prolonged activity. Often present with post-exercise muscle
swelling and pain. There may be a family history. A muscle specimen
needs to be checked for the enzyme level to confirm the diagnosis.
Myopathies: Purine Metabolism
||Muscle pain on
exercise. Exercise intolerance and stiffness, especially in the calf
muscles. Myalgia not always closely associated with exercise.
Autosomal recessive inheritance.
Muscle biopsy and analysis needed to confirm. Ischaemic forearm exercise
testing can give suggestive evidence of the diagnosis.
||Cytochrome b deficiency
and muscle pain.
Creatine kinase usually normal. Resting serum lactate may be raised.
Electromyography often not very abnormal. Muscle biopsy needed to
Coenzyme Q10 may be helpful in treatment.
Great caution needed here. CFS/ME sufferers and others are too often put
in this category without justification. Depression/frustration is a
natural side-effect of chronic pain and tiredness. Complaints of
muscle pain and severe tiredness may uncommonly be part of
a mental "defence" mechanism in a person (subconsciously)
wanting attention and sympathy. May be associated with low self esteem
and as a reaction to mental/social/physical traumas.
9. Central nervous
system problems associated with increased muscle tone (spasticity or
Cerebrovascular accident (CVA or stoke).
10. Central nervous
system problems associated with excessive motor unit activity.
||An unusual cause of
muscle pain and cramps. Electromyography helpful. Anticonvulsants may