Carpal tunnel syndrome occurs when the median nerve becomes compressed as it passes through a narrow space in your wrist called the carpal tunnel. Hand specialists use several specific tests to confirm this diagnosis and determine the severity of nerve compression. This article explains the common testing methods used during diagnosis.
Physical Examination Tests
Hand specialists often perform simple in-clinic tests to check for signs of carpal tunnel syndrome:
Tinel’s sign: The specialist taps over the carpal tunnel at your wrist. Tingling in the thumb, index, middle, or ring fingers suggests nerve irritation.
Phalen’s test: You press the backs of your hands together with wrists bent for 30 to 60 seconds. Numbness or tingling may indicate compression.
Carpal compression tests: Pressure is applied over the carpal tunnel using one or both thumbs. Reproducing symptoms suggests nerve involvement. Durkan’s test, a variation, uses sustained thumb pressure directly over the median nerve.
Nerve Conduction Studies
These tests measure how fast electrical signals travel through the median nerve. They help confirm a diagnosis and assess how severely the nerve is affected.
Sensory nerve testing: Small electrodes are placed on your fingers to measure how quickly signals travel to your wrist. Slower signals suggest nerve compression.
Motor nerve testing: Electrodes also check how fast signals reach the muscles that move your thumb. Delays may mean the nerve is affecting muscle function.
Comparison testing: Results from your affected hand are compared to your other hand or standard reference values to confirm the diagnosis.
Additional Diagnostic Tests
When physical exams and nerve studies are inconclusive, specialists may use the following tests to assess the median nerve and wrist structures:
Electromyography (EMG): Fine needles inserted into hand muscles detect electrical activity and identify muscle damage. This test may be used when symptoms suggest carpal tunnel syndrome with muscle weakness.
Ultrasound scanning: High-frequency sound waves create images of the median nerve and surrounding tissues. Ultrasound can show nerve swelling and help identify structural abnormalities in the carpal tunnel.
MRI imaging: Magnetic resonance imaging provides detailed pictures of soft tissues, including the median nerve, tendons, and ligaments. MRI may be recommended when more detailed imaging is needed or for surgical planning.
What Your Test Results Mean
Hand specialists assess your test results alongside your symptoms and physical exam findings to determine how advanced the nerve compression is. This helps guide the next steps in care.
Mild compression: Nerve signals show only slight slowing, with symptoms that come and go. Many patients improve with splinting, activity adjustments, and monitoring.
Moderate compression: Nerve conduction studies show clear signal delay, often with more consistent numbness or weakness. At this stage, your specialist may recommend structured conservative treatment such as nerve gliding exercises or corticosteroid injections.
Severe compression: Results show significant signal slowing or reduced muscle response, often with loss of sensation or visible muscle weakness. Surgery is typically advised to relieve pressure on the nerve and prevent permanent damage.
Conclusion
Hand specialists rely on a combination of your symptoms, physical exam findings, and test results to make an accurate diagnosis. No single test is used in isolation.
Consulting a hand specialist ensures you receive the right tests and treatment plan based on the severity and cause of your carpal tunnel symptoms.
