weakness

Measurable weakness may result from a variety of conditions including metabolic, neurologic, primary muscular diseases, and toxic disorders.

METABOLIC

• Addison's disease
• Hyperparathyroidism
• Low sodium or potassium
• Thyrotoxicosis

NEUROLOGIC

• Amyotrophic lateral sclerosis
• Bell's palsy
• Cerebral palsy
• Guillain-Barre syndrome
• Multiple sclerosis
• Pinched nerve (for example, caused by a slipped disk in the spine)
• Stroke

PRIMARY MUSCULAR DISEASES

• Becker muscular dystrophy
• Dermatomyositis
• Muscular dystrophy (Duchenne)
• Myotonic dystrophy

TOXIC

• Botulism
• Organophosphate poisoning (insecticides, nerve gas)
• Paralytic shellfish poisoning

OTHER

• Anemia
• Myasthenia gravis
• Poliomyelitis

Follow prescribed therapy for treating the underlying cause of the weakness.

Call your doctor if you have:

• Prolonged, unexplained weakness
• Sudden weakness, particularly when it is in one area and not accompanied by other complaints, such as fever
• Sudden weakness following a viral illness
• Weakness in one area of the body

The doctor will examine you and ask questions about your medical history and symptoms, such as:

• Time pattern
  • When did the weakness begin?
  • Did it begin with an illness or injury?
  • Did it occur suddenly or gradually?
  • Is the weakness worse in the morning or at night?
  • Is the weakness noticed only after strenuous activity or exercise?
  • Did it start following a typical viral illness, such as a cold?
  • Did it start after a vaccination?
• Quality
  • Is the weakness constant or does it come and go, sometimes effecting different parts of your body?
  • Does the weakness affect breathing?
  • Does it affect talking, chewing, or swallowing?
  • Does it affect walking, climbing stairs, sitting, getting up?
  • Does it affect use of the hands, arms, or shoulders?
  • Is there pain with the weakness?
  • Is there numbness or tingling with the weakness?
• Location
  • Is the weakness limited to a specific area?
  • Has the area of weakness increased or decreased?
• Aggravating factors
  • What makes the weakness worse?
    • Physical activity
    • Rest
    • Hunger
    • Fatigue
    • Pain
    • Stress
• Relieving factors
  • Does anything help relieve the weakness?
    • Rest
    • Eating
    • Pain relief
• Other symptoms
  • What other symptoms do you have?
    • Fever
    • Injury
    • Pain
    • Numbness or tingling
    • Vomiting
    • Diarrhea
    • Weight loss
    • Headaches
    • Changes in vision
    • Change in skin color or temperature of the area affected
    • Change in mental state, alertness, or responsiveness
• Additional important information
  • What medications do you take?
  • Do you have any allergies?

Physical examination may include special attention paid to examination of heart, lungs, and thyroid gland. If there is a local area of weakness, the examination will focus on the nerve and muscle functions.

Diagnostic tests that may be done include:

• Blood tests for autoimmune disorders
• Blood tests such as a CBC and electrolytes
• Lumbar puncture (CSF collection)
• MRI or CT scan of your head and spine
• Muscle biopsy
• Nerve conduction studies
• Thyroid function tests
• Urinalysis

Olney RK. Weakness, Disorders of Movement, and Imbalance. In Kasper DL, Braunwald E, Anthony S. Fauci AS, eds. Harrison’s Internal Medicine. 16th ed. New York, NY: McGraw-Hill; 2005.