What is numbness?

Numbness is a loss of feeling or sensation in an area of the body. It can be complete or partial. It is usually a sign of a problem with nerves in the body, although it is a common symptom of many different medical conditions.

Most cases of numbness are not serious. In more severe cases, it causes complications related to not feeling pain (for example, causing burns if unable to feel the pain from high heat) or being unaware of what’s happening to parts of the body (for example, falling if unable to feel the position of one’s feet). It can also be a sign of a serious underlying condition such as diabetes or multiple sclerosis.

What are the possible causes of numbness?

Numbness has many possible causes. A problem with a nerve or nerves usually causes the symptom. When a nerve is damaged or compressed, it interferes with the body’s ability to feel normal sensations.

Some cases of numbness involve abnormal pressure on the nerves in and around the spine. Conditions that may cause this numbness include:

• Collapsed backbone due to osteoporosis
• Compressed spinal cord
• Ruptured or herniated disc
• Pinched nerve due to arthritis, bone spurs

Other medical conditions that may cause numbness include:

• Diabetes
• Infections such as HIV or Lyme disease
• Kidney disease
• Medications or drug use
• Multiple sclerosis
• Stroke
• Arthritis
• Tumor
• Spread of cancer to the spine
• Animal and insect bites
• Exposure to poisons/toxins

How is numbness diagnosed?

Doctors diagnose numbness based on your symptoms, medical history and a physical exam (testing touch, temperature, reflexes and muscle function). Your doctor will ask you about the affected body part(s) and to describe the numbness. Other questions will include when the numbness started, how quickly the numbness began, the events or activities you were engaged in around the time the numbness began, and if you have any other symptoms. Answers to these questions helps your doctor determine the cause of the numbness.

Tests to identify the disorder causing numbness include:

• Blood tests. A doctor takes a sample of blood to look for signs of conditions including diabetes, kidney disorders and vitamin deficiencies.
• Imaging tests. Tests such as X-rays, CT scans, and MRIs allow doctors to look for issues affecting the nerves and spinal cord, such as a herniated disc or a tumor or to look at the brain for signs of stroke, multiple sclerosis, tumors, and other brain disorders.
• Nerve conduction studies. In this test, electrodes are place over the nerve(s) to be studied and the muscle supplied by the nerve. A brief electric pulse is sent to the nerve. The test determines if the nerve transmitted the signal properly and at normal speed. If not, this is a sign of nerve injury or damage.
• Electromyography. In this test, a small needle is inserted in a muscle. Electrical activity is recorded when the muscle is at rest and contracted. This test, often performed with nerve conduction studies, helps detect damage to nerves and muscles.

How is numbness managed or treated?

Treatment for numbness varies according to the cause. The goal of treatment is to correct the condition causing the numbness. Your doctor will determine the best treatment for you based on the underlying condition and the nerves involved. Some common treatments for numbness include:

• Nerve pain medications
• Regulating blood sugar in people with diabetes
• Physical therapy exercises to strengthen the spine or help ease movement
• Surgery to remove a tumor or repair a problem in the spine

When should I call the doctor?

Because the causes of numbness vary greatly, some cases require more urgent medical care than others. Seek emergency medical attention if numbness is accompanied by:

• Confusion
• Inability to control bladder or bowel movements
• Loss of consciousness
• Difficulty breathing
• Loss of sensation in face or trunk of body
• Paralysis
• Speech or vision changes
• Rapid or sudden weakness

Also seek emergency care if:

• Numbness comes on suddenly
• Numbness occurs in the “saddle area” (thighs, buttocks, genitals)
• Numbness affects an entire arm, entire leg, or one entire side of the body
• Numbness occurs below a certain level in the body (for example, below the chest)
• Numbness or weakness quickly spreads to other areas of the body

Most cases of numbness are less urgent, but a doctor should still assess them. Contact your doctor if numbness:

• Does not have an obvious cause
• Occurs during repeat activities/motions
• Causes loss of strength or muscle control over time
• Is accompanied by a rash