Weakness ( Muscle Weakness )

Definition
Weakness is a reduction in the strength of one or more muscles. You may tired quickly.

Alternative Names
Lack of strength; Muscle weakness
Considerations
Weakness may be subjective (the person feels weak, but has no measurable loss of strength) or objective (measurable loss of strength as noted in a physical exam). Weakness may be generalized (total body weakness) or localized to a specific area, side of the body, limb, or muscle.
A subjective feeling of weakness may be associated with infectious diseases such as infectious mononucleosis and influenza.
Weakness is more notable when it occurs in only one area of the body (localized or focal weakness). Localized weakness may follow a stroke, exacerbation of multiple sclerosis, or trauma to a motor nerve root or peripheral nerve.

Common Causes
Measurable weakness may result from a variety of conditions including metabolic, neurologic, primary muscular diseases, and toxic disorders.
METABOLIC
Addison's disease
ThyrotoxicosisNEUROLOGIC
Stroke (often localized weakness)
Bell's palsy (weakness of one side of the face)
A nerve impingement syndrome such as a slipped disk in the spine
Multiple sclerosis (may be localized)
Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease; often begins localized, gradually progressing to generalized)
Cerebral palsy (localized weakness associated with spasticity)
Guillain-Barre syndromePRIMARY MUSCULAR DISEASES
Muscular dystrophy (Duchenne)
Becker muscular dystrophy
Myotonic dystrophy
Dermatomyositis
TOXIC
Organophosphate poisoning (insecticides, nerve gas)
Paralytic shellfish poisoning
BotulismOTHER
Myasthenia gravis (an autoimmune disorder that interferes with the transmission of nerve impulses to muscle)
Poliomyelitis ("polio" -- an infectious disease that damages motor neurons)

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

Call your health care provider if
There is weakness confined to one area of the body.
There is prolonged, unexplained weakness.
You notice the sudden onset of weakness, particularly when it is localized and not accompanied by other complaints, such as fever.
You become suddenly quite weak following a typical viral illness.

What to expect at your health care provider's office
The medical history will be obtained and a physical examination performed.
Medical history questions documenting the weakness in detail may include:
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 are also present?
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 are being taken?
Are there any known allergies?
Physical examination may include special attention paid to examination of heart, lungs, and thyroid gland. If there is localized weakness, the examination will focus on the nerve and muscle functions.
Diagnostic tests that may be performed include:
Thyroid function tests and other blood tests for endocrine disorders
Blood tests such as a CBC and electrolytes
Blood tests for autoimmune disorders
Urine tests (urinalysis)
Nerve conduction studies
Lumbar puncture (CSF collection)
MRI or CT scan of your head and spine
Muscle biopsy