Numbness is a term used to describe a lack of ability to feel touch, temperature, or pain at some place or places in the body.
What is going on in the body?
Different people mean different things when they use the word numb. As related to a physical complaint, most people use the term to describe a lack of ability to feel touch or pain on the surface of their bodies. In most cases, numbness is related to nerve damage, either temporary or permanent.
What are the causes and risks of the condition?
There are many conditions that can cause numbness, including:
diabetes mellitus, a condition in which the level of sugar in the blood is too high. This slowly damages nerves over time. Diabetic neuropathy, that is, nerve damage from diabetes, is one of the most common causes of numbness.
toxins and drugs, such as alcohol, arsenic, and certain chemotherapy medications used to treat cancer
injury or trauma to an area, including previous surgery
carpal tunnel syndrome, which can cause numbness in the hand from pressure on a nerve
vitamin deficiencies, such as lack of vitamin B12, vitamin B6, and thiamine
brain damage, such as from a stroke or brain tumor
cancer, especially lung cancer and breast cancer in the later stages, and blood cancers, such as multiple myeloma or lymphoma
infections, such as HIV, Lyme disease, and herpes zoster
hormone imbalances, such as low thyroid hormone levels called hypothyroidism, or high levels of growth hormone, sometimes called acromegaly
severe liver disease, such as cirrhosis
severe kidney disease, such as chronic renal failure
autoimmune disorders, conditions in which a person's immune system attacks his or her own body, such as lupus, multiple sclerosis or Guillain-Barré syndrome
anxiety, including a condition known as conversion disorder
- inherited conditions, such as a rare condition called hereditary sensory neuropathy
Other causes are also possible. Sometimes, no cause can be found.
What can be done to prevent the condition?
Prevention is related to the cause. For instance, avoiding alcohol can prevent cases due to alcohol abuse. Safer sex practices can reduce, but not eliminate, the risk of HIV infection. Many cases cannot be prevented.
How is the condition diagnosed?
In some cases, the reason for the numbness may be obvious from the history and physical exam. In other cases, further testing is needed. Blood tests can help diagnose hormone imbalances, HIV, diabetes, and other conditions. If multiple sclerosis is suspected, a special x-ray test of the brain, called a cranial MRI, may be ordered.
In some cases, a test called electromyography (EMG) is ordered to evaluate how well the nerves work in the affected area. In this test, special electrodes are hooked up to the skin and tiny shocks are delivered to the nerve while the response to the shocks is measured. Sometimes the EMG findings can establish the diagnosis.
Long Term Effects
What are the long-term effects of the condition?
Long-term effects are related to the cause. For instance, anxiety-related numbness is always short-term and causes no long-term physical effects on the nerves. Cancer can result in death. Strokes may cause permanent paralysis and make a person unable to talk in some cases. Continued alcohol abuse can result in liver, brain, and other organ damage.
What are the risks to others?
Numbness itself is not contagious and poses no risks to others. Certain infections that can cause numbness, such as HIV, are contagious.
What are the treatments for the condition?
Treatment is related to the cause. For those with a previous injury, there is often no effective treatment. In some cases, surgery or physical therapy can help restore some feeling to the affected area.
Those with diabetes need to control their blood sugar with diet, exercise, and medications to prevent further nerve damage. People with anxiety can be treated with medications to reduce anxiety. People with cancer may need surgery, chemotherapy, or radiation therapy. If a drug or toxin caused the numbness, it should be stopped.
What are the side effects of the treatments?
Side effects depend on the treatments used. All medications have possible side effects. For instance, medications to treat diabetes may cause low blood sugar, liver damage, or allergic reactions. Specific side effects depend on the medications used. Surgery can be complicated by bleeding, infection, or an allergic reaction to the anesthetic.
What happens after treatment for the condition?
The outcome for numbness depends on the cause. If the cause can be treated, the numbness may or may not go away. When a low thyroid hormone level is the cause, for example, the numbness often goes away after the person is treated. Numbness due to diabetes or alcohol abuse rarely goes away even after treatment. Those with cancer may die if treatment is not effective.
How is the condition monitored?
The person can monitor his or her numbness at home and report any changes or response from treatment to the healthcare professional. Further monitoring depends on the cause. Those with diabetes, for instance, need to have their blood sugar levels checked frequently.
Cecil Textbook of Medicine, 1996, Bennett et al.
Harrison's Principles of Internal Medicine, 1998, Fauci et al.