Numbness and tingling are abnormal sensations that can occur anywhere in your body, but are often felt in your hands, feet, arms, or legs.

There are many possible causes:

• Remaining in the same seated or standing position for a long time
• Injury to a nerve -- for example, a neck injury may cause you to feel numbness anywhere along your arm or hand, while a low back injury can cause numbness or tingling down the back of your leg
• Pressure on the spinal nerves such as that due to a herniated disk
• Lack of blood supply to an area -- for example, plaque buildup from atherosclerosis in the legs can cause pain, numbness, and tingling while walking (this is called vascular claudication)
• Other medical conditions, including:
  • Carpal tunnel syndrome
  • Diabetes
  • Migraines
  • Multiple sclerosis
  • Seizures
  • Stroke
  • Transient ischemic attack (TIA)
  • Underactive thyroid
• Abnormal levels of calcium, potassium, or sodium in your body
• A lack of vitamin B12 or other vitamin
• Certain medications
• Toxic action on nerves, such as that from lead, alcohol, or tobacco
• Radiation therapy

The underlying cause of numbness or tingling should be identified and then treated by your doctor. Treatment of the underlying condition may reverse the symptoms or prevent them from becoming worse. For example, if you have carpal tunnel syndrome or low back pain, certain exercises may be recommended.

If you have diabetes, your doctor will discuss ways to control your blood sugars.

Medications that cause numbness or tingling may need to be switched or adjusted. DO NOT make any changes to your medications without instructions from your doctor.

Low levels of vitamins will be treated with vitamin supplements.

Because of the decrease in feeling, a numb hand or foot from any cause may be more prone to accidental injury. Take care to protect the area from cuts, bumps, bruises, burns, or other injury.

Go to a hospital or call 911 if:

• Weakness or paralysis occurs with numbness or tingling
• Numbness or tingling occur just after a head, neck, or back injury
• You cannot control the movement of an arm or a leg or you have lost bladder or bowel control
• You are confused or have lost consciousness, even briefly
• You have slurred speech, change in vision, difficulty walking, or weakness

Call your doctor if:

• Numbness or tingling has no obvious cause (like a hand or foot "falling asleep").
• You have pain in your neck, forearm, or fingers.
• You are urinating more often
• Numbness or tingling is in your legs and worsens when you walk
• You have a rash
• You have dizziness, muscle spasm, or other unusual symptoms

Your health care provider will take a medical history and perform a physical examination, with careful evaluation of your nervous system.

Medical history questions may include the following:

• What part or parts of your body have numbness or tingling? The trunk? Your legs or feet? Your arms and hands?
• Which side of your body is involved?
• Which aspect of the specific body part? For example, is your inner thigh, calf, or foot affected? Your palm, fingers, thumb, wrist, or forearm?
• Does the numbness or tingling affect your face? Around your eyes? Your cheeks? Around your mouth? Is one or both sides of your face involved?
• Do you have other abnormal sensations?
• Do you ignore everything on the affected side?
• How long have you had the numbness or tingling?
• When did it start?
• Does anything make it worse like exercise or standing for long periods of time?
• Do you have any other symptoms?

Your doctor may also ask you questions to determine your risk for stroke, thyroid disease, or diabetes, as well as questions about your work habits and medications.

Tests that may be done include:

• Blood tests such as CBC, electrolytes, thyroid function tests, and vitamin levels
• Imaging studies like a CT scan of the head, CT scan of the spine, MRI of the head, or MRI of the spine
• Electromyography and nerve conduction studies to measure how your muscles respond to nerve stimulation
• X-ray of the affected area
• Lumbar puncture to rule out central nervous system disorders
• Ultrasound of neck vessels to determine your risk for TIA or stroke

Viera AJ. Management of carpal tunnel syndrome. Am Fam Physician. 2003; 68(2): 265-272.

Smeal WL, Tyburski M, Alleva J, Prather H, Hunt D. Conservative management of low back pain, part I. Discogenic/radicular pain. Dis Mon. 2004; 50(12): 636-669.