Numbness often has a simple explanation, but it may signal a host of different diseases or even be the first symptom of a medical emergency like a stroke. Keep reading to learn about some of the conditions that could be causing your numbness and know when you should be concerned.
Common Causes of Numbness
Any position or disease process that blocks nerve signals can lead to numbness.
- If you've ever sat on your foot for too long and stood up only to find it feels completely "asleep," you've likely been compressing nerves in your leg, ankle or foot. Those uncomfortable pins and needles are usually the sign of nerve function re-establishing itself.
- Herniated or degenerating discs in the spine or narrowing of the spinal column may press on spinal nerves, causing numbness or abnormal sensations in any area of the body served by those nerves (often in the legs).
- Any mass, enlarged vessel, scar tissue or swelling from infection or injury may also cause local compression of nerves. One common example is carpal tunnel syndrome, which occurs when the median nerve in the wrist becomes compressed by surrounding tissue, causing numbness and tingling in the hand.
Lack of Oxygen and Nutrients
If nerves are not getting enough oxygen or nutrients, nerve signals may not fire correctly and you can experience numbness.
- Atherosclerosis, or cholesterol buildup in peripheral arteries (peripheral arterial disease) may block blood flow to nerves.
- In frostbite and Raynaud's syndrome, blood vessels constrict and deprive nerves and tissue of oxygen, glucose and other nutrients they need to function properly.
- Decreased or absent oxygen flow to part of the brain, as in a stroke or a transient ischemic attack (TIA), can also cause sudden numbness in any part of the body.
- Vitamin deficiencies, including B12 and thiamine, may result in numbness. These deficiencies are more common with severe alcoholism.
- Accidentally ingesting lead or some heavy metals may also cause numbness, as can imbalances in calcium, potassium, or sodium.
Damaged or inflamed nerves may cause numbness.
- Diabetes can cause peripheral nerve damage, leading to peripheral neuropathy – usually in the feet, toes and fingers.
- Skin problems may also cause numbness. Burns (and radiation therapy) may destroy nerve fibers, leading to numbness.
- Infections including shingles and Lyme disease may also lead to numbness.
Numbness may be the first symptom of a variety of brain conditions:
- Numbness is often one of the first symptoms of multiple sclerosis, which may affect any part of the body.
- Migraines, seizures and tumors or brain masses may also cause numbness by affecting how the brain transmits signals to nerves.
- Anxiety and hyperventilation may also lead to temporary numbness.
When to Seek Help
Your doctor can help you determine the cause of your numbness, many of which can be treated. However, be sure to know when you need emergency treatment.
Go to a Hospital or Call 911 Immediately If:
- Your numbness is accompanied by weakness or the inability to move.
- Your numbness occurs directly following injury to your head, neck or back.
- You cannot control the movements of your extremities or involuntarily lose control of your bowels or bladder
- You feel confused or have lost consciousness for any amount of time.
- Your speech is slurred or altered, or you have experienced vision changes or trouble walking.
- Your numbness is accompanied by a severe, sudden headache or dizziness.
- You have numbness of the pelvic region (including the buttocks and perineum) in a "saddle" distribution.
- Your numbness begins suddenly or involves an entire arm or leg.
Contact Your Doctor If:
- Your numbness has no obvious cause (such as whacking your funny bone or sitting on your foot for too long).
- The numbness starts gradually and worsens over time.
- Your numbness comes and goes or is related to particular tasks such as repetitive motions.
- You also have pain in your neck, arm or fingers.
- You have also noticed increased urination.
- The numbness or tingling worsens consistently when you walk.
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