Numbness and tingling are common problems and feeding the nerves in the thumb and hand is difficult. If you feel numbness in your thumb or arm, nerve compression is a likely cause .
While this is less common, it is important to know if the cause is dangerous. Numbness in the hands can indicate a serious problem, such as a stroke or even a heart attack or aortic dissection . However, in these cases, the numbness is often associated with other symptoms .
There are two questions here: the meaning of the term "numbness" and the parts of the arm that produce an unusual sensation. By numbness, do you mean a 'tingling' sensation known as paresthesia or total numbness?
When you think of the thumb, are all areas of the thumb affected in the same way or is it just the front, side, or back of the thumb? The last question can be very important in helping to determine the cause of the numbness.
When to contact a healthcare provider
Numbness should be evaluated as soon as possible if it occurs suddenly, is accompanied by other problems such as weakness , has no obvious cause (for example, falling asleep in the arm), or is associated with neck or chest discomfort.
Causes of peripheral nerves
The arm is nourished by the peripheral nerves of the cords that branch between the bones of the neck. These branches twist and intertwine into a complex plexus and then develop into well-defined nerves called the median, radial, and ulnar nerves. While all three nerves are involved in thumb movement, only the radial and median nerves are involved in thumb sensation.
The median nerve provides sensitivity to the "palmar" part of the thumb, the part with the thumbprint, and the part that is hidden when you clench your fist. The nerve also innervates the palmar surface of the index and middle fingers.
The median nerve is often pinched, reducing the ability to transmit electrical signals from the skin to the spinal cord and brain. The result is numbness. Sometimes weakness can also occur, especially in the muscles that flex the thumb toward the base of the little finger.
Most often, median nerve entrapment occurs in the carpal tunnel , a narrow passage in the wrist where the median nerve travels through multiple tendons to the fingers. If the tendons become inflamed, the swelling in the narrow canal can lead to a pinched nerve . Sometimes it can be painful, but not always.
The median nerve can also be pinched somewhere in the arm, but this usually causes numbness or weakness in the arm or wrist, as well as the hand and thumb.
The superficial branch of the radial nerve is responsible for transmitting sensation from the back of the hand, the thumb, and the first two fingers to the brain. If the radial nerve is interrupted, numbness can occur on the back of the hand .
Radial nerve damage is less common than medial nerve damage. The injury is also more obvious. The cause may be, for example, a broken arm bone rather than a mild tumor compressing the nerve.
Also, if only the superficial branch is damaged, there is likely some degree of muscle weakness. In the thumb, this is most noticeable in the muscle that lifts the thumb from the index finger, as if mimicking the cocked pistol.
Injury to the ulnar nerve as it travels from the neck to the fingers can cause numbness and tingling on the sides of the hand, especially the ring and little fingers. An example is when you hit the "funny bone" and feel an unpleasant tingling sensation in your fingers.
Like the median nerve, the ulnar nerve can be pinched, especially when it passes below the elbow. When this happens, the person develops ulnar canal syndrome , which can cause numbness and tingling in the ring and little fingers, as well as muscle weakness in the hand.
Causes of the spinal cord and brachial plexus.
Nerves travel from the hand to the arm and then to the spinal cord. Like roads approaching a major city, more and more vehicles (in this case, electrical information) are intertwined as they approach the center of action: the brain.
Nerves that were once completely separated begin to work side by side, eventually converging on the brain stem, an area no larger than the thumb through which all information flows between the body and the brain.
For this reason, the closer the problem is to the brain, the more likely it is that more than one flow of information will be disrupted, such as cars piling up on a highway.
Before entering the allegorical highway of the spinal cord, electrical information essentially travels through a very complex ramp known as the brachial plexus .
While it is possible that a very small injury here could cause just one thumb to go numb, this is unlikely and generally becomes even less likely when information reaches the spinal cord. Not only would other parts of the body go numb, but it would likely cause weakness as well .
Some exceptions to the rule are worth mentioning. Sensory and motor information is separated in the spinal cord, beginning at the point where the nerve roots enter. Motor information goes to the front and sensory information goes to the back of the spinal cord.
For this reason, numbness is only possible as a result of damage to the umbilical cord. However, this numbness is likely to affect most of the body.
The tests that are often ordered are aimed at finding the exact cause of the numbness and tingling sensation to determine the best treatment plan. You shouldn't expect to pass all of these tests, but just a few that are most likely to be helpful in your individual situation.
Electromyography (EMG) or nerve conduction study (NCS) are tests to assess the function of the nerves in the arms and legs. EMG is a test that involves the use of needles in the affected muscles, while NCS involves the application of electrodes to the skin and the use of a small shock.
Both tests cause mild discomfort within a few seconds, but are easily tolerated by most people and there should be no pain or discomfort after completing them.
You may need a brain CT scan or MRI if there is a possibility that the numbness or tingling sensation is caused by a stroke, multiple sclerosis, head injury, brain tumor, or another medical condition affecting the brain. .
Guillain-Barré syndrome is characterized by severe weakness in the legs, followed by weakness in the arms and weakness in the muscles of the body, including the muscles that control breathing. GBS often begins with mild numbness or tingling in the feet or hands.
Because toxins, nutritional deficiencies, and certain infections can damage peripheral nerves, your doctor may order blood tests. However, these conditions tend to affect the entire body at once, so it would be a bit unusual for one side of the body to be more affected than the other.
Examples include lead toxicity and vitamin B12 deficiency. Diabetes and thyroid disease can also cause peripheral neuropathy.
Frequently asked questions
How to relieve numbness in the hands in carpal tunnel syndrome?
If you are slightly numb, moving your fingers can reduce the numbness, but the condition may gradually get worse. Ultimately , surgery may be required, which involves cutting the ligament in the wrist to relieve pressure. Eventually the ligaments grow back.
Is hand numbness a sign of aging?
It's not exactly a sign of aging, but it could be the result of "wear and tear" on your body, which is more likely to happen as you age. Changes in the spine that occur during normal life, such as arthritis or injury, can lead to cervical radiculopathy , a pinched nerve that can cause numbness in the hands or fingers.
How do you know if hand numbness is related to a stroke?
Numbness may be the first sign of a stroke, but other signs that raise a red flag and indicate that something serious is going on will follow. These stroke symptoms can range from the inability to think or speak clearly to sudden loss of vision or hearing.
Get the word of drug information
In most cases, thumb numbness is the result of compression of the peripheral nerve. This is annoying but not dangerous if there are no other warning signs. As long as numbness is the only problem, really aggressive treatment is generally not required.
Even if it is due to a stroke, healthcare providers may not prescribe medication unless more severe symptoms are already present. For stroke, a strong blood thinner may be prescribed, but this increases the risk of brain hemorrhage and should be used with caution.
If the numbness of the thumb or other fingers persists, it is recommended to see a doctor for evaluation, but if there are no other signs of weakness or sudden onset, it is unlikely that it is an emergency.