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Definition

Numbness describes a loss of feeling in a part of the body. It also is often used to describe other changes in sensation, such as burning or a pins-and-needles feeling. Numbness can occur along a single nerve on one side of the body. Or numbness may occur on both sides of the body. Weakness, which is usually caused by other conditions, is often mistaken for numbness.

Causes

Numbness is caused by damage, irritation or compression of nerves. A single nerve branch or several nerves may be affected. Examples include a slipped disk in the back or carpal tunnel syndrome in the wrist. Certain diseases such as diabetes or toxins such as chemotherapy or alcohol can damage the longer, more-sensitive nerve fibers. These include the nerve fibers that go to the feet. The damage can cause numbness.

Numbness commonly affects nerves outside of the brain and spinal cord. When these nerves are affected, it can cause a lack of feeling in the arms, legs, hands and feet.

Numbness alone, or numbness associated with pain or other unpleasant sensations, isn't usually due to life-threatening disorders such as strokes or tumors.

Your doctor needs detailed information about your symptoms to diagnose the cause of your numbness. A variety of tests may be needed to confirm the cause before treatment can begin.

Possible causes of numbness include:

Brain and nervous system conditions

• Acoustic neuroma
• Brain aneurysm
• Brain AVM (arteriovenous malformation)
• Brain tumor
• Guillain-Barre syndrome
• Herniated disk
• Paraneoplastic syndromes of the nervous system
• Peripheral nerve injuries
• Peripheral neuropathy
• Spinal cord injury
• Spinal cord tumor
• Stroke
• Transient ischemic attack (TIA)
• Transverse myelitis

Trauma or overuse injuries

• Brachial plexus injury
• Carpal tunnel syndrome
• Frostbite

Chronic conditions

• Alcohol use disorder
• Amyloidosis
• Charcot-Marie-Tooth disease
• Diabetes
• Fabry's disease
• Multiple sclerosis
• Porphyria
• Raynaud's disease
• Sjogren's syndrome (a condition that can cause dry eyes and a dry mouth)

Infectious diseases

• Leprosy
• Lyme disease
• Shingles
• Syphilis

Treatment side effects

• Side effects of chemotherapy or anti-HIV drugs

Other causes

• Heavy metal exposure
• Thoracic aortic aneurysm
• Vasculitis
• Vitamin B-12 deficiency

When to see a doctor

Numbness can have a variety of causes. Most are harmless, but some can be life-threatening.

Call 911 or seek emergency help if your numbness:

• Begins suddenly.
• Follows a recent head injury.
• Involves an entire arm or leg.

Also seek emergency medical care if your numbness is accompanied by:

• Weakness or paralysis.
• Confusion.
• Trouble talking.
• Feeling dizzy.
• Sudden, bad headache.

You are likely to have a CT scan or MRI if:

• You've had a head injury.
• Your doctor suspects or needs to rule out a brain tumor or stroke.

Schedule an office visit if your numbness:

• Begins or worsens gradually.
• Affects both sides of the body.
• Comes and goes.
• Seems related to certain tasks or activities, particularly repetitive motions.
• Affects only a part of a limb, such as your toes or fingers.