Distal median nerve dysfunction
Neuropathy - distal median nerve
Distal median nerve dysfunction is a form of
A common type of distal median nerve dysfunction is
Typing all day on a computer keyboard can be tough on your wrists. If you type for hours at a time, day after day, eventually you may really start to feel some discomfort. The numbness, pain, and tingling you feel in your hands and wrists may be carpal tunnel syndrome, and it can have such a big effect on your life that you may eventually need surgery to treat it. Doing any repetitive motion with your hands, whether it's typing, sewing, driving, or writing, can cause carpal tunnel syndrome. The condition gets its name from an area in your wrist called the carpal tunnel. Running through this tunnel is the median nerve, which sends feeling to your palm and most of your fingers. When you do the same task over and over again, especially flexing and extending the wrist, you put pressure on the median nerve. Over time, it swells up inside the carpal tunnel until it's so tight in there that the nerve gets pinched. The classic symptoms of carpal tunnel syndrome are numbness and tingling in your hand, including the thumb, index, middle, and half of the ring finger. The discomfort is usually worse at night. And anytime you may not be able to grip things as tightly in the affected hand, and you can feel pain that may stretch all the way from the wrist to your elbow. Your doctor can run tests on your hand to confirm that your numbness, weakness, and pain are due to carpal tunnel. You may also have nerve conduction studies, or tests of the muscles. If you're feeling a lot of discomfort from carpal tunnel wearing a wrist splint especially at night could help. In addition, short term oral or injected glucocorticoid medications can help by reducing swelling. Studies have also shown some benefit from physical or occupational therapy techniques, and yoga. About half of the people with carpal tunnel though will eventually need a procedure called carpal tunnel release to lift pressure off the pinched nerve. Surgery is a more permanent solution, but whether it works depends on how severe the nerve damage is, and how long you've had it. You may not be able to completely avoid the repetitive flexing or extending the wrist that gave you carpal tunnel in the first place, especially if it's part of your job. But, you can make some adjustments, for example, by using special devices like a cushioned mouse pad, wrist braces, or a raised keyboard, to relieve the pressure on your wrists. Take occasional breaks whenever you're going to be typing or doing any other repetitive task for long periods of time. And if you are having any numbness, tingling, or pain in your hands or wrists, see your doctor sooner rather than later. Letting carpal tunnel syndrome go untreated could leave you with a permanently damaged nerve.
A diagnosis of carpal tunnel syndrome may follow testing the affected hand for numbness, tingling, weakness and/or pain in specific areas. Muscle and nerve conduction tests may also help affirm or rule out carpal tunnel syndrome.
Causes
Dysfunction of one nerve group, such as the distal median nerve, is called a mononeuropathy. Mononeuropathy usually means there is a local cause of the nerve damage. Diseases affecting the entire body (systemic disorders) can also cause isolated nerve damage.
This condition occurs when the nerve is inflamed, trapped, or injured by trauma. The most common reason is trapping (entrapment) by a ligament in the wrist. Trapping puts pressure on the nerve where it passes through a narrow area. Wrist fractures may injure the median nerve directly. Or, it may increase the risk for trapping the nerve later on.
Inflammation of the tendons (tendonitis) or joints (arthritis) can also put pressure on the nerve. Some repetitive movements increase the chance of developing carpal tunnel entrapment. Women are more affected than men.
Problems that affect the tissue near the nerve or cause deposits to form in the tissue can block blood flow and lead to pressure on the nerve. Such conditions include:
- Too much growth hormone in the body (acromegaly)
- Diabetes
- Underactive thyroid (hypothyroidism)
- Kidney disease
- Blood cancer called multiple myeloma
- Pregnancy
- Obesity
In some cases, no cause can be found. Diabetes can make this condition worse.
Symptoms
Symptoms may include any of the following:
- Pain in the wrist or hand that may be severe and wake you up at night, and that may be felt in other areas, such as the upper arm (this is called referred pain)
- Sensation changes in the thumb, index, middle, and part of the ring fingers, such as a burning feeling, decreased sensation, numbness and tingling
- Weakness of the hand that causes you to drop things or have difficulty grasping objects or buttoning a shirt
Exams and Tests
Your health care provider will examine your wrist and ask about your medical history. Tests that may be done include:
- Electromyogram (EMG) to check the electrical activity of the muscles
- Nerve conduction tests to check how fast electrical signals move through a nerve
- Neuromuscular ultrasound to view problems with the muscles and nerves
- Nerve biopsy in which nerve tissue is removed for examination (rarely needed)
- Magnetic resonance neurography (very detailed imaging of the peripheral nerves)
Treatment
Treatment is aimed at the underlying cause.
If the median nerve is affected by carpal tunnel syndrome, a wrist splint can reduce further injury to the nerve and help relieve symptoms. Wearing the splint at night rests the area and decreases inflammation. An injection into the wrist may help with symptoms, but it won't fix the underlying problem. Surgery may be needed if a splint or medicines don't help. Using proper ergonomics at work is essential. For example, you should use proper wrist support if you use a keyboard and mouse for computer work.
For other causes, treatment may involve any of the following:
- Medicines to control nerve pain (such as gabapentin or pregabalin)
- Treating the medical problem causing nerve damage, such as diabetes or kidney disease
- Physical therapy to help maintain muscle strength
Outlook (Prognosis)
If the cause of the nerve dysfunction can be identified and treated, there is a good chance of full recovery. In some cases, there is some or complete loss of movement or sensation. Nerve pain may be severe and persist for a long time.
Possible Complications
Complications may include:
- Deformity of the hand (rare)
- Partial or complete loss of hand movement
- Partial or complete loss of sensation in the fingers
- Recurrent or unnoticed injury to the hand
When to Contact a Medical Professional
Call your provider if you have symptoms of distal median nerve dysfunction. Early diagnosis and treatment increase the chance of curing or controlling symptoms.
Prevention
Prevention varies, depending on the cause. In people with diabetes, controlling blood sugar may reduce the risk of developing nerve disorders.
For people with jobs that involve repetitive wrist movements, a change in the way the job is performed may be needed. Frequent breaks in activity may also help.
References
Craig A. Neuropathies. In: Cifu DX, ed. Braddom's Physical Medicine and Rehabilitation. 6th ed. Philadelphia, PA: Elsevier; 2021:chap 41.
Katirji B. Disorders of peripheral nerves. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 106.
Toussaint CP, Kvint S, Ali ZS, Zager EL. Distal entrapment syndromes: carpal tunnel, cubital tunnel, peroneal, and tarsal tunnel. In: Winn HR, ed. Youmans and Winn Neurological Surgery. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 276.
Waldman SD. Carpal tunnel syndrome. In: Waldman SD, ed. Atlas of Common Pain Syndromes. 4th ed. Philadelphia, PA: Elsevier; 2019:chap 50.
Version Info
Last reviewed on: 4/25/2022
Reviewed by: Joseph V. Campellone, MD, Department of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
