Cracking the Cause, Treatment, and Prevention of Mouse Arm

Have you ever felt weakness, tingling, or sudden loss of grip in your fingers after prolonged computer use? These seemingly minor issues may be signs of "mouse arm"—a common term for carpal tunnel syndrome (CTS). 

What is "Mouse Arm"?  

"Mouse arm," also known as carpal tunnel syndrome, refers to a condition involving the carpal tunnel, a narrow passage located in the centre of the wrist. This tunnel houses the median nerve and several tendons. The most common cause of carpal tunnel syndrome is repetitive wrist movements or prolonged overuse, which can lead to inflammation and swelling of the tendons within the tunnel. This, in turn, puts pressure on the median nerve.

When the carpal tunnel becomes narrower and the median nerve is compressed, symptoms begin to appear. The median nerve plays a crucial role in controlling forearm movements and provides sensation to the thumb, index finger, middle finger, and half of the ring finger. It also governs certain hand motions. When the median nerve is compressed, it can lead to the following symptoms: 

• Numbness in the hand, wrist, or fingers, especially the fingertips
• Tingling or pain in the hand, wrist and fingers
• Weakness that affects the ability to grip objects or perform tasks such as holding a pen, using a phone, or typing
• In severe cases, symptoms may extend to the elbow or shoulder, and muscle wasting in the hand can occur 

If carpal tunnel syndrome is left untreated, the muscles at the base of the thumb may atrophy, and in severe cases, individuals may lose the ability to distinguish between hot and cold through touch. It is vital to seek advice and evaluation from a physiotherapist as soon as symptoms appear to ensure timely and effective treatment. For further assistance, consider booking an appointment with a qualified physiotherapist for a thorough assessment.

Causes of "Mouse Arm"

Carpal tunnel syndrome arises when the space within the carpal tunnel narrows, compressing or damaging the median nerve. The compression can disrupt the nerve's ability to transmit signals to its designated areas in the hand and fingers. Common causes of this narrowing include:

• Inflammation or swelling of the tendons in the wrist from repetitive strain/stress
• Diabetes or other metabolic disorders: These conditions can affect the nerves, making them more susceptible to compression.
• Arthritis
• Wrist fractures or injuries

Who is at higher Risk of CTS?

Carpal tunnel syndrome can affect anyone, but some groups are more susceptible, including:

• Individuals who frequently use their wrists for repetitive tasks
• Pregnant or post-menopausal women
• Women in general, as their carpal tunnels are anatomically narrower than men’s, making them 3–10 times more likely to develop the condition
• Individuals over the age of 40
• Those with a family history of carpal tunnel syndrome
  
  

Certain medical conditions can also increase the likelihood of developing carpal tunnel syndrome, including 

• Rheumatoid arthritis
• Gout and gouty arthritis
• Hypothyroidism
• Diabetes
• Obesity
• Amyloidosis
• Hyperpituitarism
• Kidney failure
• Alcoholism

Diagnosis and Treatment: Do You Have "Mouse Arm"?

Early diagnosis and treatment are key to preventing permanent nerve damage. To confirm carpal tunnel syndrome, clinicians and physiotherapists may perform the following tests and evaluations:

Physical Examinations

The hands, arms, shoulders and neck are assessed to determine if your symptoms are related to daily activities or underlying conditions. These examinations also help rule out other conditions that may mimic carpal tunnel syndrome. Key areas of focus include: 

• Wrist: Checking for tenderness, swelling, warmth, or discoloration
• Fingers: Testing sensation in each finger individually
• Base of the palm: Evaluating muscle strength and signs of muscle atrophy, especially the thenar eminence (mound at the base of the thumb)
• Laboratory and X-ray: Identifying or excluding conditions such as diabetes, arthritis, or wrist fractures

Specialised Provocation Tests

• Tinel’s Test: Lightly tapping or pressing on the median nerve in the wrist. A positive Tinel’s sign occurs if this produces tingling or a shock-like sensation in the fingers
• Phalen’s Test: Pressing the backs of the hands together with fingers pointing downward. Increased tingling or numbness within one minute is a positive result.
• Reverse Phalen’s Test: Pressing the palms together with fingers pointing upward then lowering the wrists maximally. Increased tingling or numbness within 30-60 seconds is positive.
• Activity-Based Provocation Tests: Patients may be asked to perform specific movements that typically trigger their symptoms

Nerve Function and Imaging Studies

While physical and provocation tests provide useful clues, additional nerve and imaging tests are often required to confirm a diagnosis:

• Nerve Conduction Studies: Electrodes are placed on the hand and wrist to deliver mild electrical impulses, measuring the speed of nerve signal transmission
• Electromyography (EMG): A fine needle inserted into the muscle measures electrical activity, helping assess the extent of nerve damage
• Ultrasound Imaging: Visualise abnormalities in the median nerve

Treatment Options of CTS: From Non-Surgical Care to Surgery 

Conservative Treatments

• Use of wrist splints: Preferred initial treatment worn at nighttime to maintain a neutral wrist position. Recommended follow-up evaluation in 1-2 months.
• Medications: In specific cases, medications can help alleviate the pain and swelling associated with carpal tunnel syndrome
  • Non-steroidal anti-inflammatory drugs (NSAIDs): Over-the-counter pain relievers such as aspirin or ibuprofen can ease short-term symptoms or those caused by intense activity
  • Diuretics ("Water Pills"): May help reduce swelling in the wrist
  • Corticosteroids: Injected directly into the wrist or taken orally (e.g., prednisone). Corticosteroids can relieve pressure on the median nerve, providing quick, temporary relief for mild to moderate symptoms. (Caution: long-term use of corticosteroids is not recommended without medical supervision, especially for individuals with diabetes or those at risk, as it may affect insulin regulation
  • Vitamin B6 supplementation: May ease symptoms of carpal tunnel syndrome

• Exercise: Stretching and strengthening exercises can be beneficial for individuals whose symptoms have subsided or those in recovery. These exercises, often guided by a physiotherapist or occupational therapist
• Alternative Therapies: Practices such as yoga have been shown to reduce pain and improve grip strength in individuals with carpal tunnel syndrome

Surgical Interventions

If symptoms persist for six months or longer, or if significant muscle damage in the hand occurs due to carpal tunnel syndrome, surgery may become necessary. The procedure involves releasing the pressure on the median nerve by cutting the ligament around the wrist. This is typically performed under local anaesthesia and does not require an overnight hospital stay. The main surgical options include:

• Open Release Surgery: A traditional procedure involves making an incision up to 2 inches long on the wrist to access and cut the transverse carpal ligament, thereby enlarging the carpal tunnel. Usually performed as an outpatient procedure under local anaesthesia, open surgery is commonly used unless specific medical conditions require otherwise.
• Endoscopic Surgery: Compared to traditional open release surgery, endoscopic surgery may allow quicker functional recovery and result in less post-operative discomfort. During this procedure, the surgeon makes two small incisions—one on the wrist and one on the palm. A tiny camera attached to a tube is inserted, enabling the surgeon to view the tissues on a monitor while cutting the transverse carpal ligament (the connective tissue linked to the joint).

Prevention is Better Than Cure: Say Goodbye to "Mouse Arm"!

For many office workers, prolonged use of computers and keyboards, combined with poor posture, is a leading cause of carpal tunnel syndrome. However, making small adjustments to your posture and workspace can help prevent "mouse arm." Here are some tips: 

• Ensuring your elbows are level with your keyboard and mouse.
• Keeping your back straight and shoulders relaxed to reduce strain, stretching your hands, wrists, and arms during work breaks.
• Allow adequate arm and hand rest in-between doing repetitive hand movements or using vibrating instruments or machineries.

If you notice any symptoms of "mouse arm," it is crucial to seek professional advice as soon as possible. If you have any concerns, you're welcome to arrange a consultation with our physiotherapist at your convenience.

References

1. Carpal Tunnel Syndrome. (2025, June 2). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/4005-carpal-tunnel-syndrome
2.  Professional, C. C. M. (2025, March 14). Median nerve. Cleveland Clinic. https://my.clevelandclinic.org/health/body/21889-median-nerve
3.  職業安全健康局. 認識「滑鼠手」 預防紓緩有法. Retrieved 15 August, 2025 from https://www.oshc.org.hk/oshc_data/files/AwardsCampaigns/Joyful@Workplace/Carpal_Tunnel_Syndrome_TC.pdf
4.  National Institute of Neurological Disorders and Stroke. Office of Communications and Public Liaison. (2012). Carpal tunnel syndrome. U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health. https://permanent.fdlp.gov/gpo50093/carpel_tunnel_FS.pd