Identifying the cause of new symptoms, such as hand pain or weakness, can be challenging. Is your muscle weakness from multiple sclerosis (MS), or could it be something else, like carpal tunnel syndrome?

Symptoms of carpal tunnel syndrome and MS can overlap, and it’s also possible to have both conditions at the same time. But there are ways to tell whether it’s more likely that your arm pain and weakness are related to one condition than another. Read on to learn about carpal tunnel syndrome, MS, and how to spot the differences.

What Causes Carpal Tunnel Syndrome?

Carpal tunnel syndrome affects the hand — and sometimes the forearm — causing numbness, tingling, weakness, and pain. It happens when the median nerve, a major nerve in the hand, gets squeezed or pinched as it passes through a narrow space in the wrist called the carpal tunnel.

The carpal tunnel is made up of bones and a ligament. Inside it are the median nerve and several tendons. When the space becomes too tight, the median nerve can get compressed. This pressure can cause nerve damage, which can affect hand function.

Carpal tunnel syndrome is one of the most common nerve conditions. It affects about 3 percent to 6 percent of adults.

Risk Factors for Carpal Tunnel Syndrome

There isn’t one specific cause of carpal tunnel syndrome, but several factors can raise your risk. Risk factors of carpal tunnel syndrome include:

• Repetitive and frequent hand movements, such as typing
• Repetitive and frequent grasping movements used in sports or factory assembly lines
• Hormonal changes related to thyroid problems or menopause
• Wrist injuries, like fractures or dislocations
• Bone or joint diseases, such as osteoarthritis
• Inflammatory autoimmune diseases, such as rheumatoid arthritis
• Blood sugar changes, such as those seen in type 2 diabetes
• Taking anastrozole, a medication used to treat breast cancer
• Having a higher body weight
• Family history of carpal tunnel syndrome

According to the National Institute of Neurological Disorders and Stroke, women are three times more likely than men to have carpal tunnel syndrome. The authors of a 2018 study found that people between ages 40 and 60 are also at greater risk.

What Causes MS?

MS is an autoimmune condition. This means the body’s immune system mistakenly attacks its own tissues. In MS, the immune system targets tissue called myelin. Myelin is a protective covering around the nerves in the central nervous system (CNS), which includes your brain and spinal cord.

Myelin helps nerve signals travel quickly and efficiently. Your nerves are responsible for producing movement and sensation, so when myelin is attacked, the signals slow down or get disrupted. This can lead to a wide range of symptoms, such as:

• Loss of balance
• Muscle stiffness or spasms
• Weakness
• Tingling and numbness
• Trouble with thinking and memory.

In the U.S, more than one million people have been diagnosed with MS.

Risk Factors for MS

Like carpal tunnel syndrome, MS has no single cause. Anyone can get MS, but a few risk factors are associated with the disease:

• Genetics — Having a family member with MS or ancestry from Northern Europe
• Environment — Exposure to certain viruses (Epstein-Barr or mononucleosis), toxins such as pesticides, or smoking
• Health — Obesity, low vitamin D levels, and smoking are all linked to a higher risk.
• Age — MS is most often diagnosed between ages 20 and 40.
• Sex — Women are more likely than men to develop MS.

Common Symptoms of Carpal Tunnel Syndrome and MS

Both carpal tunnel syndrome and MS can cause tingling, numbness, pain, and weakness in the hands. Even though the symptoms may seem similar, there are a few important differences that can help tell the two conditions apart.

Tingling and Numbness

Symptoms of carpal tunnel syndrome often start gradually and get worse over time if not treated. Generally, people first experience numbness and tingling (also a common MS symptom) in their hands or fingers.

In carpal tunnel syndrome, tingling and numbness are usually felt in the thumb, the index and middle fingers, and part of the ring finger. The pinkie is usually not involved. That’s because carpal tunnel syndrome involves the median nerve, which controls only certain parts of the hand.

One MyMSTeam member shared their experience: “I’m going in for a consultation for my hand for my carpal tunnel. Both of my thumbs lock up, and three and a half out of five fingers go numb to the point of pain.”

MS can also cause tingling and numbness, but it can happen anywhere in the hands or body because it affects the central nervous system, which controls all nerve signals.

Pinkie Pain? Probably Not Carpal Tunnel Syndrome

Upper-extremity weakness and sensations of numbness, tingling, and pain are all neurological symptoms of MS. One way to tell the conditions apart is that if your pinkie is involved, it is probably not carpal tunnel syndrome. That’s because the pinkie is controlled by the ulnar nerve, which can be affected in MS, but not in carpal tunnel syndrome.

Pain in other parts of the hand and fingers, however, can occur in both conditions.

Hand Weakness

Weakness in the hand or arm is common in both conditions. You might notice that you’re losing grip strength or dropping objects more often.

The median nerve is responsible for a lot of your thumb movement and the ability to bend your fingers. In carpal tunnel syndrome, the median nerve is pinched at the wrist, so symptoms are usually experienced in the hand and sometimes stay there.

In MS, other nerves can be affected, so symptoms can happen in any muscle in the hand. Since MS is a CNS condition, it can cause weakness not just in the hand but also throughout the entire arm or other areas.

People with MS may develop a condition called claw hand. This is a type of joint contracture where the fingers and wrist get stuck in a curved, clawlike position. Carpal tunnel syndrome usually does not cause claw hand, so if you’re experiencing this symptom, it may be more likely related to MS.

Muscle Atrophy

In carpal tunnel syndrome, the thumb muscles can shrink (or atrophy) over time if the median nerve is badly compressed. This happens because the nerve isn’t sending enough signals to keep the muscle active.

In MS, muscle atrophy is less common. When it does happen, it’s often due to a lack of movement rather than direct nerve damage. It’s more likely to affect the lower leg muscles than the hands.

Other MS Symptoms

Carpal tunnel syndrome usually only affects one part of the body — the hand or wrist. So if you’re only having pain, numbness, or weakness in your hand with no other symptoms, carpal tunnel syndrome is more likely. If your hand weakness happens along with other symptoms, MS might be the cause. Other MS symptoms include:

• Changes in mood, memory, or concentration
• Other muscle dysfunction (like clumsiness, stiffness, or trouble with balance)
• Bladder problems

Even healthcare professionals sometimes confuse MS with carpal tunnel. One MyMSTeam member shared their experience: “I went to the ortho because I was diagnosed with carpal tunnel syndrome in 2009, and he tells me I don’t have carpal tunnel, but that it was MS masking itself as carpal tunnel. So I’ve had MS as far back as 2009.”

Can MS Raise Your Risk of Carpal Tunnel Syndrome?

MS affects the central nervous system, while carpal tunnel syndrome affects the peripheral nervous system (nerves outside the CNS). Studies looking at carpal tunnel syndrome in people with MS have been few and small, but they show some evidence that carpal tunnel syndrome may be more common in people with MS. A small 2018 study found that 28 percent of 75 people with MS also had carpal tunnel syndrome.

Older Age and Use of Mobility Aids

Using mobility aids for MS — such as crutches, canes, or wheelchairs, which involve repetitive (continuous) hand motions — may increase the risk of developing carpal tunnel syndrome. A small 2020 study found that people with both conditions were generally older and had lived with MS longer than those who had MS but not carpal tunnel syndrome.

An earlier study linked wheelchair and mobility aid use to a high prevalence of carpal tunnel syndrome in people with MS. The findings also linked older age with more severe carpal tunnel syndrome.

More research is needed to confirm whether having MS makes you more likely to develop carpal tunnel syndrome, but these studies suggest that using mobility aids — common among people with advanced MS — does seem to increase the risk.

If you have questions or concerns about your symptoms, it’s best to seek medical advice from a healthcare provider. They can run tests to find out what’s causing your symptoms and help you decide on the best treatment options.

Talk With Others Who Understand

MyMSTeam is the social network for people with MS and their loved ones. On MyMSTeam, members come together to ask questions, give advice, and share their stories with others who understand life with MS.

Have you been diagnosed with both carpal tunnel syndrome and MS? What helps relieve your symptoms? Share your experience in the comments below, or start a conversation by posting on your Activities page.