Carpal tunnel syndrome is caused by pressure on the median nerve. The carpal tunnel is a narrow passageway surrounded by bones and ligaments on the palm side of your hand. When the median nerve is compressed, the symptoms can include numbness, tingling and weakness in the hand and arm.
You’re working at your desk, trying to ignore the tingling or numbness you’ve had for some time in your hand and wrist. Suddenly, a sharp, piercing pain shoots through the wrist and up your arm. Just a passing cramp? It could be carpal tunnel syndrome.
The carpal tunnel is a narrow passageway of ligament and bones at the base of your hand. It contains nerve and tendons. Sometimes, thickening from irritated tendons or other swelling narrows the tunnel and causes the nerve to be compressed. Symptoms usually start gradually. As they worsen, grasping objects can become difficult.
Carpal Tunnel Syndrome (CTS) is a common problem affecting hand function, caused by compression of the median nerve at the wrist. The carpal tunnel is formed by the multiple bones in the wrist and the transverse carpal ligament that forms the roof of the carpal tunnel. The median nerve and nine tendons run through the carpal tunnel.
Carpal tunnel syndrome can result from inflammation and enlargement of the median nerve, inflammation and enlargement of the tendons, thickening of the transverse carpal ligament or by the presence of a mass lesion (for example, a tumor or cyst) within the carpal tunnel or a combination. Regardless of the direct cause, the end result is pressure on the median nerve and dysfunction.
Carpal tunnel syndrome is a common condition that causes pain, numbness, and tingling in the hand and arm. The condition occurs when one of the major nerves to the hand — the median nerve — is squeezed or compressed as it travels through the wrist.
The National Institute of Neurological Disorders and Stroke (NINDS), describe carpal tunnel syndrome (CTS) as the “most common and widely known of the entrapment neuropathies in which the body’s peripheral nerves are compressed or traumatized.”
CTS affects between 3 percent and 6 percent of adults in the United States. It normally develops between the ages of 45 and 64 years, and the prevalence increases with age. It can appear in one or both wrists. It is more common in women than in men.
Without treatment, CTS can have a negative impact on a person’s quality of life. Eventually, the median nerve can become severely damaged, and there may be permanent numbness in the fingers and permanent weakness in the muscles that are innervated by the median nerve.
In most patients, carpal tunnel syndrome gets worse over time, so early diagnosis and treatment are important. Early on, symptoms can often be relieved with simple measures like wearing a wrist splint or avoiding certain activities.
What Is Carpal Tunnel Syndrome?
Carpal tunnel syndrome is a condition affecting one of the main nerves in the wrist area. The carpal tunnel is a space created by the natural arch of the wrist bones. A thick band called the transverse carpal ligament creates a roof to the tunnel. This means that the size of the tunnel cannot change, as the bones and ligament act like solid walls. Nine tendons that bend the fingers and thumb and the median nerve pass through the tunnel.
The median nerve provides feeling (sensation) to the skin of the thumb, index and middle fingers, as well as half the ring finger. The nerve also provides the communication line to the muscles at the base of the thumb (thenar muscles).
For most patients, the cause of their carpal tunnel syndrome is unknown. Any condition that exerts pressure on the median nerve at the wrist can cause carpal tunnel syndrome. Common conditions that can lead to carpal tunnel syndrome include obesity, pregnancy, hypothyroidism, arthritis, diabetes, and trauma. Tendon inflammation resulting from repetitive work, such as uninterrupted typing, can also cause carpal tunnel symptoms.
Carpal tunnel syndrome from repetitive maneuvers has been referred to as one of the repetitive stress injuries, although this relationship remains controversial in the evidence based literature. Some rare diseases can cause deposition of abnormal substances in and around the carpal tunnel, leading to nerve irritation. These diseases include amyloidosis, sarcoidosis, multiple myeloma, and leukemia.
Symptoms of carpal tunnel include:
- Burning, tingling, or itching numbness in your palm and thumb or your index and middle fingers
- Weakness in your hand and trouble holding things
- Shock-like feelings that move into your fingers
- Tingling that moves up into your arm
You might first notice that your fingers “fall asleep” and become numb at night. It usually happens because of how you hold your hand while you sleep.
In the morning, you may wake up with numbness and tingling in your hands that may run all the way to your shoulder. During the day, your symptoms might flare up while you’re holding something with your wrist bent, like when you’re driving or reading a book.
Early on in the condition, shaking out your hands might help you feel better. But after some time, it may not make the numbness go away.
As carpal tunnel syndrome gets worse, you may have less grip strength because the muscles in your hand shrink. You’ll also have more pain and muscle cramping.
Your median nerve can’t work the way it should because of the irritation or pressure around it. This leads to:
- Slower nerve impulses
- Less feeling in your fingers
- Less strength and coordination, especially the ability to use your thumb to pinch
The most likely cause of carpal tunnel syndrome is extra pressure on the median nerve at the wrist inside the tunnel. This extra pressure can come from swelling (inflammation) of the contents inside the tunnel. When pressure results in nerve symptoms, it is called a compressive neuropathy. While the exact carpal tunnel syndrome causes are usually unknown and due to the patient’s personal anatomy, there are many factors that can contribute to the increased pressure or inflammation, including:
- Rheumatoid arthritis
- Psoriatic arthritis
- Arthritic spurs of the carpal bones
- Ganglion cysts
- Wrist fracture or dislocation of the wrist
- Repetitive motions performed at work or home
Even making a tight closed fist or holding the wrist in bent or extended positions can put increased pressure on the median nerve. A prolonged or constant fist or bend (like a fist during sleep, reading a book, or some other activities) may put enough pressure to cause the numbness/tingling. If the funny feeling in the fingers just began, this is easily resolved by moving the fingers back and forth and out of the position. If the pressure continues off and on for weeks to months, the symptoms may come on faster after the activity or wrist position is created. It may also take longer for the symptoms to go away after the activity stops. Eventually, symptoms can become constant.
Repetitive activities in the workplace with forceful or repetitive gripping or vibration can also increase symptoms. However, it is complicated to determine if the work activity is the main cause of the symptoms or if work is incidentally just aggravating a condition that is already present (unrelated to work). The determination of cause of symptoms requires experienced and specialized health care providers to provide an opinion, taking many factors into account.
There are some risk factors that increase the chances of getting carpal tunnel syndrome. For example, women are more likely than men to experience carpal tunnel syndrome. It is more likely to occur with aging. Each decade someone is alive, there are more people that experience carpal tunnel syndrome. Thus, it is rare in children and adolescents and more common in ages 40 and over. Carpal tunnel syndrome is more common in people with obesity, diabetes, alcohol addiction, fibromyalgia and hypothyroidism. If you have carpal tunnel syndrome, your children may be more likely to get it. Also, during pregnancy, hormonal changes and extra body fluid retention may add swelling and pressure into the tunnel.
While symptoms can sometimes be worse at night, sleep has not been shown to cause carpal tunnel. Some people get symptoms while driving a car. This is also not necessarily the primary cause of the problem. The wrist position during driving or sleep, for example, may simply aggravate the symptoms.
Examination Of The Wrist
Your doctor or health professional will ask you to describe your symptoms. They will take a look at your hand and wrist to assess how bad the condition is. If the wrist is swollen due to arthritis or tendon swelling, this could be the cause of your symptoms.
If you’ve had the condition for some time, there may be signs of muscle wasting at the base of the thumb. If the problem is severe, your thumb, index and middle fingers may be insensitive or numb to either a gentle touch or a pin prick.
Your doctor may tap over the median nerve on the palm side of your wrist, this is known as Tinel’s test. Or they may ask you to bend your palm towards your forearm for up to a minute, which is known as Phalen’s test.
These tests can help to diagnose carpal tunnel syndrome, but they aren’t reliable, so you may also have one of the tests described below.
Sometimes carpal tunnel syndrome can be mistaken for something else, such as pressure on nerves in the neck due to disc problems or arthritis, which can cause similar symptoms.
A nerve conduction test may help and can be used to measure how bad the compression of the nerve is.
These tests can be done in several ways, but one common way is to see how your nerve reacts when a small electric current is put through one of your fingers. Electrodes will be attached to your skin on the fingers and wrist to measure the speed of your nerve’s response to the current.
This test doesn’t measure how bad your symptoms are, but it can show how badly damaged the nerve is. When the nerve is damaged, the speed at which messages travel between the finger and the wrist is slower.
Ultrasound scans are sometimes used in diagnosis, because the nerve can become swollen before it goes through the carpal tunnel and this can be seen on a scan. Ultrasounds can also show some of the causes of carpal tunnel syndrome, including swelling in the tendons or joint.
Carpal Tunnel Syndrome Treatment
Your treatment will depend on your symptoms and how far your condition has progressed. You might need:
- Lifestyle changes. If repetitive motion is causing your symptoms, take breaks more often or do a bit less of the activity that’s causing you pain.
- Exercises. Stretching or strengthening moves can make you feel better. Nerve gliding exercises can help the nerve move better within your carpal tunnel.
- Immobilization. Your doctor may tell you to wear a splint to keep your wrist from moving and to lessen pressure on your nerves. You may wear one at night to help get rid of that numbness or tingling feeling. This can help you sleep better and rest your median nerve.
- Medication. Your doctor may give you anti-inflammatory drugs or steroid shots to curb swelling.
- Surgery. If none of those treatments works, you might have an operation called carpal tunnel release that increases the size of the tunnel and eases the pressure on your nerve.