What does it mean when your tingly down there?

Tingling hands, feet, or both is an extremely common and bothersome symptom. Such tingling can sometimes be benign and temporary. For example, it could result from pressure on nerves when your arm is crooked under your head as you fall asleep. Or it could be from pressure on nerves when you cross your legs too long. In either case, the "pins and needles" effect -- which is usually painless -- is soon relieved by removing the pressure that caused it.

But in many cases, tingling in the hands, feet, or both can be severe, episodic, or chronic. It also can come with other symptoms, such as pain, itching, numbness, and muscle wasting. In such cases, tingling may be a sign of nerve damage, which can result from causes as varied as traumatic injuries or repetitive stress injuries, bacterial or viral infections, toxic exposures, and systemic diseases such as diabetes.

Such nerve damage is known as peripheral neuropathy because it affects nerves distant from the brain and spinal cord, often in the hands and feet. There are more than 100 types of peripheral neuropathy. Over time, the condition can worsen, making you less mobile and even disabled. More than 20 million Americans, most of them older adults, are estimated to have peripheral neuropathy.

It's important to get medical help right away for any tingling in your hands, feet, or both that’s lasted a while. The earlier the cause of your tingling is found and brought under control, the less likely you are to get what could be lifelong problems.

Diabetes is one of the most common causes of peripheral neuropathy, accounting for about 30% of cases. In diabetic neuropathy, tingling and other symptoms often first develop in both feet and go up the legs, followed by tingling and other symptoms that affect both hands and go up the arms. About two-thirds of people with diabetes have mild to severe forms of nerve damage. In many cases, these symptoms are the first signs of diabetes.

In another 30% of peripheral neuropathy cases, the cause is unknown, or "idiopathic."

The remaining 40% of cases have a variety of causes such as:

Nerve entrapment syndromes. These include carpal tunnel syndrome, ulnar nerve palsy, peroneal nerve palsy, and radial nerve palsy.

Systemic diseases. These include kidney disorders, liver disease, vascular damage and blood diseases, amyloidosis, connective tissue disorders and chronic inflammation, hormonal imbalances (including hypothyroidism), and cancers and benign tumors that impinge on nerves.

Vitamin deficiencies. You need vitamins E, B1, B6, B12, and niacin for healthy nerves. A B12 deficiency, for example, can lead to pernicious anemia, an important cause of peripheral neuropathy. But too much B6 also can cause tingling in the hands and feet.

Alcoholism. People who have alcoholism are more likely to lack thiamine or other important vitamins because of poor dietary habits, a common cause of peripheral neuropathy. It's also possible that alcoholism itself can cause nerve damage, a condition that some researchers call alcoholic neuropathy.

Toxins. These include heavy metals such as lead, arsenic, mercury, and thallium, and some industrial and environmental chemicals. They also include certain medications -- especially chemotherapy drugs used for lung cancer -- but also some antiviral and antibiotic drugs.

Infections. These include Lyme disease, shingles (varicella zoster), cytomegalovirus, Epstein-Barr, herpes simplex, and HIV and AIDS.

Autoimmune diseases. These include chronic inflammatory demyelinating polyneuropathy, Guillain-Barre syndrome, lupus, and rheumatoid arthritis.

Inherited disorders. These include a group that may have sensory and motor symptoms; the most common type is known as Charcot-Marie-Tooth disease.

Injury. Often related to trauma, nerves can be compressed, crushed, or damaged in other ways, resulting in nerve pain. Examples include nerve compression caused by a herniated disk or dislocated bone.

Multiple sclerosis. The disease causes your body’s immune system to attack the fatty myelin sheath around nerve fibers all around your body. Tingling in the hands and feet is a common symptom.

If you seek care for your tingling hands or feet, your health care provider will do a physical exam and take an extensive medical history addressing your symptoms, work environment, social habits (including alcohol use), toxic exposure, risk of HIV or other infectious diseases, and family history of neurological disease.

They also may perform other tests, such as:

• Blood tests. These can include tests to detect diabetes, vitamin deficiencies, liver or kidney dysfunction, other metabolic disorders, and signs of abnormal immune system activity.
• An examination of cerebrospinal fluid. This can identify antibodies associated with peripheral neuropathy.
• An electromyogram (EMG), a test of the electrical activity of muscle
• Nerve conduction velocity (NCV)

Other tests may include:

Successful treatment depends on an accurate diagnosis and treatment of the cause of the tingling. As long as the peripheral nerve cells have not been killed, they can regenerate.

Although there are no treatments for inherited types of peripheral neuropathy, many of the acquired types can be improved with treatment. For example, good blood sugar control in diabetes can help keep diabetic neuropathy from getting worse, and vitamin supplements can correct peripheral neuropathy in people with vitamin deficiencies.

General lifestyle recommendations include keeping weight in check, avoiding exposure to toxins, following a doctor-supervised exercise program, eating a balanced diet, and avoiding or limiting alcohol. Recommendations also include quitting smoking, which constricts blood supply to blood vessels supplying nutrients to peripheral nerves.

In some cases, tingling and other symptoms of peripheral neuropathy may be eased with prescriptions developed for treating seizures and depression.