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Carpal tunnel syndrome accounts for about 90 percent of nerve problems in the arms.
By: Mercura Wang
Carpal tunnel syndrome (CTS) occurs when the median nerve becomes tightly compressed at the underside of the wrist between the wrist bones, tendons, and the overlying transverse carpal ligament. This compression causes numbness, tingling, or pain in the hand and wrist. The median nerve originates in the upper arm and then extends to the forearm, palm, and portions of the fingers.
The prevalence of CTS in the United States ranges from 1 percent to 5 percent of the population. It is the most commonly diagnosed disabling condition of the upper limbs and the most prevalent type of nerve problem in the arms, accounting for around 90 percent of such cases. It most often occurs among people between 45 and 65.
In an observational study, symptoms resolved within six months, especially in younger individuals. Remission rates were also higher for women.
What Are the Types of Carpal Tunnel Syndrome?
There aren’t actual types of CTS. However, CTS is sometimes classified by how it originated. For instance, most CTS cases are idiopathic, meaning they have no known cause, while others are secondary, meaning they were caused by something like an injury or orthopedic disease. Other types may include acute versus chronic CTS or unilateral versus bilateral (meaning it affects either one hand or both).
Approximately 70 percent of CTS cases exhibit bilateral involvement, depending on the nature of the individual’s work. A less favorable outlook is often associated with bilateral symptoms. In addition, symptom severity does not consistently align with the degree of nerve compression.
What Are the Symptoms and Early Signs of Carpal Tunnel Syndrome?
The median nerve in the carpal tunnel provides sensation to the thumb, index, middle finger, and half of the ring finger. It also helps the hand, wrist, and forearm move.
CTS symptoms usually start gradually, with frequent numbness or tingling in the fingers, especially the thumb, index, and middle fingers. Symptoms often first appear in one or both hands during the night, with the dominant hand usually affected first and experiencing the more severe symptoms.
Early Symptoms
Symptoms experienced during the initial phases of CTS may include the following:
Wrist, hand, and/or forearm pain.
The sensation of numbness or weakness in hands/wrists.
Numbness, tingling, burning, or pain in at least two fingers to which the median nerve supplies sensation.
Tightness or swelling in fingers/wrists/hands.
Spread of finger numbness to the palm.
Challenges in making a fist or pinching fingers together.
These symptoms may worsen throughout the day, particularly during activities involving wrist bending (e.g., driving).
Symptom Progression
As CTS progresses, symptoms increase in frequency and duration. They may include the following:
Regular numbness, tingling, or burning in the fingers.
Persistent pain and aching in the affected hand/wrist/forearm. The pain may even extend from the forearm to the rest of the arm and the shoulder.
Hand weakness.
Awkwardness and difficulty handling small items or opening jars.
The sensation of swollen fingers with a tight-wristband feeling.
Nighttime tingling, pain, or numbness that disrupts sleep.
Occasional electric-shock sensations in the wrist/hand/arm during specific movements.
Decreased grip strength, making it challenging to hold objects for an extended period.
Loss of coordination in the hand.
Inability to distinguish hot from cold (severe CTS) with the affected fingers.
CTS symptoms usually worsen at night due to sleeping with the wrist in an improper position, as it increases pressure within the carpal canal. Shaking the hand can sometimes alleviate discomfort and regain sensation.
What Causes Carpal Tunnel Syndrome?
The carpal tunnel, a narrow passageway in the wrist, is formed by carpal bones on the floor and sides and a sturdy band called the transverse carpal ligament on the roof. Due to its rigid boundaries, the carpal tunnel has a limited capacity to stretch. The median nerve passes through the carpal tunnel at the wrist. It then separates into smaller nerves, providing sensation to all but the outer ring and pinky fingers.
The median nerve also controls muscles at the base of the thumb. Accompanying the nerve are nine flexor tendons responsible for bending the fingers and thumb, all passing through the carpal tunnel.
The exact process leading to CTS and changes in nerve conduction through the wrist are currently not fully understood. Generally, CTS develops when tissues around the median nerve swell, exerting pressure on the nerve. Initially, this process is reversible, but the nerve’s insulation may wear away over time, leading to permanent nerve damage.
CTS can manifest in several different ways, sometimes in combination, including the following:
Swelling of the tenosynovium: The tenosynovium, the protective lining of tendons within the carpal tunnel, may swell due to an accumulation of synovial fluid, typically responsible for tendon lubrication.
Thickening of the transverse ligament: The transverse ligament is a fibrous tissue band shielding the median nerve, and it can thicken and broaden, impinging on the nerve instead of safeguarding it. This thickened ligament and swollen tendons can compress median nerve fibers, reducing blood flow and oxygen supply, thereby slowing nerve signal transmission through the carpal tunnel.
Swelling and enlargement of the median nerve and/or tendons.
Who Is More Likely to Develop Carpal Tunnel Syndrome?
The following factors make one more likely to develop CTS:
Female: CTS is three times more common among women. This may be due to the smaller size of a woman’s carpal tunnel, hormonal changes during pregnancy and menopause, or their higher risk of developing autoimmune disorders, also strongly associated with CTS.
Pregnancy: CTS affects 20 percent to 45 percent of pregnant mothers. This is because, in pregnancy, blood volume increases by about 45 percent, leading to increased pressure and swelling (i.e., edema) in blood vessels throughout the body. Edema compresses the median nerve, causing CTS symptoms. Although these symptoms sometimes disappear after giving birth, some women still experience them one year after delivery.
Age: CTS is rare in children and usually presents in adults aged 40 to 60.
Genetics: Having a close family member (e.g., a parent or sibling) who has experienced CTS also increases the risk.
Specific jobs: Working using repetitive motions or vibrating tools, awkward hand positions, or strong gripping can increase the risk of CTS. For instance, CTS prevalence among fish processing workers has been reported to be 73 percent. Other high-risk occupations include assembly line workers, violinists, visual artists, and carpenters.
Obesity: Obese individuals have twice the risk of developing CTS, and being overweight raises the risk of CTS by 1.5 times. Increased body mass seems to slow the transmission speed of nerve signals to the hand.
Medical conditions: These include diabetes, thyroid disease, arthritis, gout, and autoimmune diseases. Also, after mastectomy due to breast cancer, some women may experience lymphedema, an accumulation of fluids that exceeds the lymph system’s drainage capacity, leading to pain, arm swelling, and potentially CTS.
Wrist injury: Individuals with CTS secondary to a wrist fracture often experience a less favorable prognosis compared to those with idiopathic CTS.
A space-occupying lesion in the carpal tunnel: A lesion within the carpal tunnel could be a tumor, cyst, thickened synovial tissue, or bone spur.
Smoking: Smoking decreases nourishing blood flow by narrowing the arteries and encouraging plaque buildup. In addition, the carbon monoxide component of smoke further lowers the oxygen delivered, contributing to more severe CTS symptoms and delayed recovery in smokers compared to nonsmokers.
Excessive alcohol consumption: Those who abuse alcohol tend to be more at risk. This is thought to be due to the direct toxicity of alcohol on the nerve.
Sleeping with a bent wrist: This habit can be altered.
Anatomy: Having a small carpal tunnel can raise a person’s risk.
Vitamin D deficiency: Vitamin D deficiency is linked to CTS symptoms. One study found supplementing vitamin D to the proper levels could improve these symptoms.
Medications: Some medications may temporarily increase the risk of CTS, including those impacting the immune system (e.g., interleukin-2) and anticoagulant drugs (e.g., warfarin).
Cold exposure: Cold exposure, an often overlooked occupational hazard, may increase the risk of peripheral nerve entrapment. In one study, self-reported occupational exposure to contact and ambient cooling was associated with symptoms suggestive of CTS.
How Is Carpal Tunnel Syndrome Diagnosed?
Early diagnosis and treatment of CTS are crucial to prevent permanent damage to the median nerve. However, diagnosing CTS is challenging, as only a small fraction of patients display all three factors essential for a precise diagnosis: classic CTS symptoms, specific physical findings, and abnormal electrodiagnostic test results.
A doctor typically diagnoses CTS through medical history inquiry, physical examination, and nerve conduction studies.
Evaluation
The doctor inquires about the patient’s overall health, medical history, family CTS history, and symptoms. The doctor typically first considers differential diagnosis to rule out all conditions potentially causing median nerve dysfunction. The diagnostic tools used may include questionnaires and a diagram of the hand and wrist, usually divided into six regions, to assess the location of pain/numbness and identify the most severe areas.
Physical Examination
The doctor thoroughly examines the patient’s hand and wrist, performing various physical tests. These may include provocation tests checking for weakness in thumb muscles and looking for hand muscle atrophy.
The flick sign involves asking the patient about their hand movements during symptom exacerbation. Patients often demonstrate a flicking motion of the wrist and hand, resembling the action of shaking down a thermometer.
Provocation tests include the following:
Phalen’s test: This involves the patient resting elbows on a table, letting wrists dangle with fingers pointing down. Symptoms developing within a minute suggest CTS and prolonged duration may induce symptoms in non-CTS patients. This test is crucial for assessing CTS severity and treatment outcomes.
Tinel’s sign test: This is a test where the doctor taps the median nerve, eliciting tingling or a mild shock sensation.
Durkan’s test: Also known as the carpal compression test or pressure provocation test, this test entails the doctor pressing over the carpal tunnel for 30 seconds to induce tingling or shock in the median nerve.
The tourniquet test: This test uses an inflatable cuff to apply pressure to the median nerve, producing tingling or shock sensations.
Hand elevation test: In this test, the patient raises their hand overhead for two minutes to induce CTS symptoms.
Other Tests
Electrodiagnostic tests assess nerve and muscle electric waves and are the best confirmation methods for CTS diagnosis. The doctor uses them to measure the median nerve function, assess excessive pressure, determine CTS severity, and identify any additional nerve-related medical conditions. These tests may include the following:
Nerve conduction studies (NCS): Surface electrodes are attached to the hand and wrist, and small electric signals stimulate the nerves. NCSs measure signals in hand and arm nerves, detecting ineffective signal conduction. They aid in assessing the severity of the issue and guiding treatment.
Electromyogram (EMG): A wire electrode is briefly inserted into a muscle, displaying the resulting electrical activity on a screen. EMG measures muscle electrical activity, revealing nerve or muscle damage. Some experts suggest limiting its use because EMG is less accurate than NCS.
Your doctor may also run imaging tests, such as ultrasound and X-rays. Ultrasound uses high-frequency sound waves to create wrist images, aiding in evaluating the median nerve for compression signs. X-rays can provide bone images and rule out other causes, such as arthritis, ligament injury, or fractures.
What Are the Complications of Carpal Tunnel Syndrome?
With proper treatment, CTS typically leads to no complications. However, if not treated appropriately, it can result in the following:
Muscle atrophy, especially at the base of the thumb.
Permanent median nerve damage.
Permanent nerve impairment and disability.
Reduced hand dexterity due to muscle weakness and/or atrophy.
Complex regional pain syndrome, potentially the result of chronic wrist and hand pain.
Permanent weakness, numbness, and tingling.
Loss of some wrist strength.
What Are the Treatments for Carpal Tunnel Syndrome?
The primary goal of CTS treatments is to minimize or eliminate repetitive injuries to the median nerve. Initiating treatment for CTS in its early stages is more effective, so it’s essential to begin interventions as soon as the condition is diagnosed.
Your doctor determines the most suitable treatment options based on your age, overall health, medical history, current wrist condition, tolerance to medications or procedures, the presence of underlying conditions, the expected progression of the condition, and your preferences.
Nonsurgical Treatments
Conservative treatments are the first steps taken in treating CTS. They are frequently prescribed for a trial period of three months to assess their effectiveness. For mild or potentially temporary symptoms, treatment options include the following:
Avoiding/limiting symptom-inducing activities: To manage symptoms, consider avoiding or limiting daytime activities that trigger discomfort and take frequent breaks to rest the hand. This often involves reducing repetitive hand activities.
Ergonomic corrections: Ergonomic corrections for treating CTS may include optimizing workplace setups, adjusting hand positions, rearranging the position of the computer keyboard, and maintaining proper posture to reduce strain on the wrists and hands.
Cold packs: In case of redness, warmth, or swelling, applying cold packs can provide relief.
Exercises: Engaging in specific exercises, such as hand exercises and nerve gliding exercises, under the guidance of a therapist, whether physical or occupational.
Pain medication: You can take nonsteroidal anti-inflammatory drugs (NSAIDs), which include aspirin, ibuprofen, and other nonprescription pain relievers to relieve pain and inflammation. People who cannot tolerate NSAIDs can possibly take acetaminophen, which is not anti-inflammatory.
