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What causes decreased muscle function? 12 possible conditions

What Is Muscle Function Loss?

Muscle function loss occurs when your muscles do not work or move normally. Complete muscle function loss, or paralysis, is a complete loss of muscle function in which your muscles are unable to contract normally.

If your muscles lose function, you will be not be able to properly operate the affected part of your body. This symptom is often the signal of a serious problem within the body, such as a severe injury, a drug overdose, or coma. Loss of muscle function can be permanent or temporary. However, all instances of muscle function loss should be treated as a medical emergency.

What Conditions Cause Loss of Muscle Function?

Loss of muscle function is often caused by a failure in the nerves that send signals from the brain to the muscles, causing them to move.

Muscle function tends to occur in what are called voluntary muscles. Voluntary muscles are skeletal muscles that you have full control over. Involuntary muscles, such as the heart and intestinal smooth muscles are not within your conscious control. However, they too can cease functioning. The loss of function in involuntary muscles can be fatal.

Common causes for the loss of voluntary muscle function are diseases of the muscles and diseases of the nervous system.

Diseases of the Muscles

Diseases that directly affect the way the muscles function are responsible for most cases of muscle function loss. Two of the more common muscle diseases that cause muscle function loss include muscular dystrophy and dermatomyositis.

Diseases of the Nervous System

Diseases that affect the way nerves transmit signals to the muscles can cause muscle function loss. Common nervous system conditions that cause paralysis are:

  • Bell’s palsy (causes partial paralysis of the face)
  • Lou Gehrig’s disease
  • botulism
  • neuropathy
  • polio
  • stroke

Many of the diseases that cause loss of muscle function are hereditary (present at birth). However, severe injuries account for a large number of paralysis cases. Long-term drug use and medication side effects can also cause muscle function loss.

Types of Muscle Loss

There are several types of muscle function loss. The loss of muscle function is placed into one of two categories: partial or total. Partial muscle function loss only affects a part of the body; this is the main symptom in stroke victims. Total muscle function loss, or paralysis, affects the entire body, and is often seen in people with severe spinal cord injuries.

If loss of muscle function affects both the top half and the bottom half of the body, it is called quadriplegia. If it affects only the bottom half of the body, it is called paraplegia.

Identifying the Cause of Muscle Function Loss

Before undergoing any treatment, the doctor will first diagnose what’s causing muscle function loss. The location of muscle function loss, the amount of your body affected, and your other symptoms all give clues regarding the underlying causes.

Things to Tell Your Doctor

Let your doctor know if the loss of muscle function came on suddenly or gradually.

Also, mention the following:

  • any additional symptoms
  • types of symptoms
  • medications you’re taking
  • if you’re having trouble breathing
  • if the loss of muscle function is temporary or recurrent
  • if you have difficulty gripping items


After the physical examination and review of your medical history, your doctor will administer tests to see if a nerve or muscle condition is causing the loss of muscle function.

These tests might include, but are not limited to:

  • muscle biopsy: in this test, a small piece of muscle tissue is removed for examination
  • nerve biopsy: in this test, a small piece of a potentially affected nerve is removed for examination)
  • MRI (magnetic resonance imaging) scan of the brain: this test is used to check for the presence of tumors or blood clots in the brain
  • nerve conduction study: this test uses electrical impulses to test nerve function

Treatment Options for Muscle Function Loss

Even after treatment, paralysis may remain partially or totally. The outlook depends on the cause and severity of your loss of muscle function. Treatment options are tailored to your particular needs, and may include:

  • physical therapy
  • medications (such as aspirin or warfarin to lessen future possibility of damage, such as with strokes)
  • occupational therapy
  • surgery (a way of repositioning a damaged muscle)
  • functional electrical stimulation (a procedure to stimulate paralyzed muscles by sending electrical shocks to the muscles)

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See a list of possible causes in order from the most common to the least.


Stroke Overview

A stroke (a "brain attack") is a medical emergency in which part of the brain is deprived of oxygen. This occurs when an artery that supplies oxygenated blood to the brain becomes damaged and brain cells begin to die.

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Poliomyelitis, or polio, is a highly contagious disease that is caused by a virus that attacks the body's nervous system. It is most likely to be contracted by children under five years old.

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Bell’s Palsy

Bell's palsy is a condition that affects movement of the muscles in the face as a result of damage to the seventh cranial nerve controlling them. Significant damage of this nerve can result in paralysis of the face.

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Spinal Cord Injury

A spinal cord injury, or damage to the spinal cord, is an extremely serious type of physical trauma. It will likely have a lasting and significant impact on most aspects of daily life. According to the Nationa...

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ALS (Lou Gehrig's Disease)

Amyotrophic Lateral Sclerosis (ALS) is not contagious. It is a degenerative disease that affects the brain and spinal cord. A chronic disorder, it causes a loss of control of voluntary muscles. The nerves controllin...

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Guillain-Barre Syndrome

Guillain-Barre syndrome is a rare but serious autoimmune disorder. An infectious disease, like the stomach flu or a lung infection, usually triggers it.

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Brain Abscess

A brain abscess forms when fungi, viruses, or bacteria reach your brain through a wound in your head or an infection somewhere else in your body.

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Myasthenia Gravis

Myasthenia gravis is a neuromusclar disorder. It results in weakness of the skeletal muscles, and can cause double vision and drooping of the eyelid.

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Reye's Syndrome

Reye's syndrome is a rare condition that results in sudden swelling and inflammation of the liver and brain and is often accompanied by a red scaly rash. It is not contagious.

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Dermatomyositis is a rare inflammatory disease. It's an inflammatory myopathy, which is a condition that occurs when your muscles become inflamed.

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Botulism (or "botulism poisoning") is a rare, but very serious illness that is transmitted through a very common source-the food we eat. Botulism poisoning is caused by a type of bacteria that is present everywher...

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Tay-Sachs Disease

Tay-Sachs is a disease of the central nervous system; it is a neurodegenerative disorder. Tay-Sachs most commonly affects infants. In infants, it is a progressive disease that is unfortunately always fatal. Rarely...

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This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.