Finger numbness or tingling is caused by abnormalities in the nerves responsible for the perception of touch in those locations. The medical term for a nerve abnormality is neuropathy. Many different types of neuropathy can lead to finger numbness. Infections, medications, toxins and systemic diseases are frequent underlying causes of this aggravating and sometimes dangerous symptom.
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Long-standing diabetes can damage the nerves of the extremities, a condition called diabetic peripheral neuropathy. The National Institute of Diabetes and Digestive and Kidney Diseases reports 60 to 70 percent of people with diabetes have some form of neuropathy. Diabetic peripheral neuropathy often begins with pain, burning or tingling, which commonly affects the feet but may also involve the fingers. As the condition progresses, the affected fingers frequently become numb.
Medications and Toxins
Certain medications and toxins can damage the nerves responsible for sensation in the hands. Damage to these nerves may cause tingling or numbness. A number of drugs that may cause this type of damage, including amiodarone (Cordarone), cisplatin (Platinol), disulfiram (Antabuse), isoniazid (Laniazid), metronidazole (Flagyl), nitrofurantoin (Macrobid, Macrodantin) and phenytoin (Dilantin). Some medications used to treat HIV infection may also cause numbness or tingling in the hands and feet, including didanosine (Videx) and stavudine (Zerit). Toxins that may cause nerve damage and numbness include arsenic, lead, thallium and mercury.
Some infections can cause nerve abnormalities that may manifest as numbness in the fingers. HIV infection can damage the peripheral nerves of the extremities, causing pain, abnormal sensations and numbness. Peripheral neuropathy is the most common brain or nerve-associated complication of HIV/AIDS. Leprosy is another potential culprit of extremity numbness. This rare infection is caused by Mycobacterium leprae. Loss of sensation is a characteristic symptom of leprosy and often involves the hands. The inability to feel pain or temperature leads to frequent accidental injuries in people with leprosy.
Autoimmune diseases, in which the immune system launches a mistaken attack on nerves and other body tissues, can cause sensory abnormalities, including numbness in the fingers. Systemic lupus erythematosus and Sjögren's syndrome are examples of autoimmune diseases that commonly cause sensory deficits such as tingling or numbness in the hands and feet.
Injuries and Inflammation
Pressure on the nerves to the hands is a common cause of numbness in the fingers. Injuries to the wrist that cause swelling may lead to numbness in the fingers. Carpal tunnel syndrome is a frequent cause of finger numbness due to inflammation and swelling in the wrist. A number of factors may contribute to the development of carpal tunnel syndrome, including fluid retention, use of vibrating hand tools, rheumatoid arthritis and hypothyroidism.