Carpal tunnel syndrome

Carpal tunnel syndrome is caused by compression of the median nerve as it travels through the carpal tunnel in the wrist. The median nerve supplies sensation to the thumb, index, middle, and part of the ring finger and controls some small muscles at the base of the thumb.

Symptoms include numbness, tingling, and pain in the hand and fingers, often worse at night. Risk increases with repetitive hand use, pregnancy, diabetes, thyroid disease, and rheumatoid arthritis. Early treatment with splinting, activity modification, and sometimes corticosteroid injection can relieve symptoms. Surgery to release the transverse carpal ligament is effective when conservative measures fail or when nerve damage is significant.

Typical symptoms include:

• Numbness, tingling, or burning in the thumb, index, middle, and radial half of the ring finger
• Symptoms that often wake people at night or are present on waking
• Pain that may radiate up the forearm
• Weakness or clumsiness of the hand; dropping objects
• Occasional swelling sensation in the fingers
• Relief by shaking the hands (“flick sign”)

Symptoms may be intermittent at first and become more constant. Severe, long-standing compression can cause permanent sensory loss and atrophy of the thumb muscles (thenar atrophy).

Anything that narrows the carpal tunnel or increases pressure within it can compress the median nerve. Contributing factors include:

• Anatomic predisposition (smaller tunnel)
• Repetitive or forceful hand and wrist use
• Wrist injuries and swelling
• Pregnancy-related fluid retention
• Inflammatory conditions (rheumatoid arthritis)
• Diabetes, hypothyroidism, and obesity
• Workplace factors involving vibrating tools or prolonged extreme wrist postures

In many cases multiple factors combine; sometimes no single cause is identified.

Risk factors include:

• Female sex
• Pregnancy
• Diabetes and metabolic syndrome
• Thyroid disorders
• Rheumatoid arthritis and other inflammatory arthropathies
• Obesity
• Repetitive hand use and certain occupations
• Family history / anatomic factors
• Prior wrist fracture or dislocation

Without treatment, ongoing compression can lead to:

• Permanent median nerve damage
• Persistent numbness and pain
• Thenar muscle atrophy and loss of grip and pinch strength
• Reduced hand function affecting work and daily tasks

Strategies that may help:

• Take breaks during repetitive hand work; vary tasks
• Maintain neutral wrist posture; avoid prolonged extreme flexion or extension
• Use ergonomic tools and keyboard setups
• Keep hands warm
• Manage underlying conditions (diabetes, thyroid disease, rheumatoid arthritis)
• Maintain a healthy weight

Diagnosis is based on:

• History of characteristic nocturnal and activity-related sensory symptoms in the median nerve distribution
• Physical examination — Phalen’s test, Tinel’s sign at the wrist, sensory testing, and thenar strength
• Nerve conduction studies and electromyography (EMG) to confirm median neuropathy at the wrist, assess severity, and exclude other neuropathies or radiculopathy
• Ultrasound or MRI in selected atypical cases

See a clinician for persistent hand numbness, tingling, or weakness that interferes with sleep or daily activities. Early evaluation helps prevent permanent nerve damage.

Treatment is stepwise:

Conservative

• Wrist splints in neutral position, worn at night and during aggravating activities
• Activity modification and ergonomic adjustments
• Treatment of underlying conditions
• Short courses of NSAIDs for pain (do not treat the nerve compression itself)
• Corticosteroid injection into the carpal tunnel — can provide months of relief and confirm the diagnosis

Surgery — carpal tunnel release (open or endoscopic) cuts the transverse carpal ligament to enlarge the tunnel. Indicated for failed conservative care, severe or progressive neurologic deficits, or advanced EMG findings. Most people have good relief of nocturnal symptoms; recovery of strength and sensation depends on the degree of prior nerve damage.

Helpful daily measures:

• Wear the splint as directed, especially at night
• Take frequent breaks from repetitive tasks; stretch gently
• Keep wrists in a neutral position while typing or using tools
• Apply cold packs if the wrist is sore after activity
• Follow post-injection or post-surgery instructions carefully
• Report worsening weakness or constant numbness promptly

Bring:

• Symptom pattern (which fingers, night symptoms, aggravating activities)
• Work and hobby hand-use details
• Medical history (diabetes, thyroid, arthritis, pregnancy)
• Prior treatments and any prior nerve tests
• Questions about splinting, injections, and surgery timing