This presentation will give a brief idea on proximal myopathy, causes, clinical presentation, history and physical examination, investigations to diagnose the disease easily. It will be more helpful to medical students.
Citation preview
1. Proximal myopathy and causes AAM. Amjath Medicine 4th batch
Fhcs-eusl
2. Myopathy Any diseases of muscles. Usually affect muscle
without involving the nervous system or any disorders of neuro
muscular junction. Most common presentation is weakness. When it is
present in proximal muscles: it is called as proximal
myopathy.
3. Myopathy Primary Acquired Muscular Dystrophy (Disorders of
dystrophin) Ex: Duchenne muscular dystrophy Limb girdle muscular
dystrophy Congenital myopathies (Rare) Ex: Central core disease
Centronuclear myopathy Metabolic myopathies. Ex: Glycogen storage
diseases Lipid storage disease Secondary metabolic and endocrine
myopathies. Thyroid diseases Ex: Hyperthyroidism, Hypothyroidism
Parathyroid dysfunction Ex: Hyperparathyroidism Pituitary
dysfunction Ex: Addison's disease Corticosteroids Ex: Cushing's
disease, Exogenous steroids (especially high doses - over 25 mg per
day) Biochemical and DM. Ex: Hypokalaemia and hyperkalaemia
Secondary to acute gastrointestinal loss. Disorder of Ca Metabolism
Renal disease and Liquor ingestion.
4. Cont.. Acquired Dermatomyositis and polymyositis : these are
inflammatory myopathies with weakness, endomysial inflammation and
elevated muscle enzymes. Ex: Primary polymyositis (idiopathic
adult). Dermatomyositis (idiopathic adult). Polymyositis or
dermatomyositis associated with neoplasia. Drug-induced myopathy
Ex: Statins (Atrovastatin, Simvastatin) Corticosteroids Cocaine
Infectious causes Ex: HIV Coxsackie viruses Influenza Polymyalgia
rheumatica: Proximal myopathy with associated muscle
tenderness.
5. Clinical features Weakness predominantly affecting proximal
muscle groups (shoulder and limb girdles) is typical Weakness
manifests itself in different ways at different ages Ex: Motor
delay in the toddler years. Reduced muscle strength and power in
older children and adults. Myalgia may occur in inflammatory
myopathies. Muscle-stretch reflexes are preserved. Somatosensory
reflexes are preserved. Muscle tone normal or reduced.
6. history Common symptoms a. Symmetrical proximal muscle
weakness. b. Malaise. c. Fatigue. d. Absence of sensory symptoms
(paraesthesia). e. Atrophy of muscles (and reduced reflexes) occurs
late with myopathies (early with neuropathy).
7. How acute are the symptoms? a. Weakness over hours suggests
toxic cause or episodic paralysis. b. Weakness developing over days
- consider dermatomyositis or rhabdomyolysis. c. Weakness over
weeks suggests polymyositis, steroid myopathy, endocrine myopathy.
. Pain and tenderness without weakness - consider other causes. .
Which muscle groups are affected? a. Proximal muscle groups -
difficulty rising from chair, climbing stairs, shaving, hair
combing. b. Distal muscles - difficulty walking (flapping gait),
grasping, handwriting. . Metabolic myopathies present with: a.
Difficulty with exercise. b. Cramps and myalgia with exercise
(early with glycogen storage disorders and after prolonged exercise
with lipid storage disorders). c. Myoglobinuria. d. Progressive
muscle weakness in some metabolic myopathies.
8. Past medical history: a. Autoimmune disease: Systemic lupus
erythematosus, Rheumatoid arthritis, Polyarteritis nodosa. b.
Endocrine disease c. Renal disease d. Alcoholism . Family history:
a. Muscular dystrophy. b. Other relevant conditions or myopathies.
. Medication: a. Steroids b. Lipid-lowering drugs c. Alcohol d.
Colchicine e. Heroin
9. examination Symmetrical proximal muscle weakness. Muscle
tenderness very rare with myopathy. Fever with inflammatory causes.
There is usually no wasting but there may be hypertrophy of muscle
(atrophy is a late sign). Reflexes and sensation usually normal.
Hypotonia is common in some myopathies (for example, congenital
myopathies). There may be helpful additional signs such as the skin
changes of dermatomyositis. Urine should be examined -
myoglobinuria in acute alcoholic myopathy can cause renal tubular
necrosis.
10. Investigations Blood and urine tests These, together with
electrocardiogram (ECG) examination, are most useful in acute
situations. a. Creatine kinase (with isoenzymes) - level may be
50-100 x normal reference range. b. Electrolytes including calcium
and magnesium. c. Serum myoglobin. d. Urea and serum creatinine. e.
Urinalysis and urine microscopy - myoglobinuria inferred by
positive urinalysis with few red cells at microscopy. f. FBC. g.
ESR. h. Antinuclear antibodies.
11. ECG May show a. Changes of hypokalaemia - increased P-R
interval, U waves, wide QRS and nonspecific ST-T changes. b. Sinus
arrhythmias, deep Q waves and elevated R waves precordially.
12. Muscle biopsy Electromyography Magnetic resonance imaging
(MRI)