Early carpal tunnel syndrome diagnosis and treatment are important to avoid permanent damage to the median nerve. A detailed history including medical conditions, how the hands have been used, and whether there were any prior injuries is essential for carpal tunnel syndrome diagnosis.
There are six major diagnostic clinical criteria for the carpal tunnel syndrome diagnosis. They are: numbness and tingling in the median nerve distribution, night time numbness, weakness and/or atrophy of the thenar muscles, Tinel sign, positive Phalen's test, and loss of two-point discrimination.
Depending on the severity of your symptoms, your doctor will classify your carpal tunnel syndrome as mild, moderate, or severe, which will help you formulate a treatment plan.
Physical Exam for Carpal Tunnel Syndrome
A physical examination is necessary to determine if your complaints are related to carpal tunnel syndrome, or an underlying disorder that mimics carpal tunnel syndrome symptoms. Sensation should be tested in all regions of the hand, forearm, and upper arm. The wrist is examined for tenderness, swelling, warmth, and discoloration. Each finger should be tested for sensation, and the muscles at the base of the hand should be examined for strength and signs of atrophy. Your doctor may ask you to show him any hand or wrist movements that bring on pain, tingling, or numbness.
Your doctor will tap on your wrist, on the area overlying the median nerve. The Tinel sign is present when tingling or a shock-like sensation occurs in the fingers.
Phalen test involves holding your forearms upright by pointing the fingers down while pressing the backs of the hands together. Carpal tunnel syndrome is likely present if tingling or numbness is felt in the fingers within 1 minute.
Durkan’s Median Nerve Compression Test
Manual carpal compression involves applying pressure over the carpal tunnel, and it is considered "positive" if tingling occurs within 30 seconds of applying pressure.
Two point discrimination is the ability to differentiate two points on the skin, which are near one another. Your doctor will test your two-point discrimination by touching the skin of your hand and fingers with a sharp pointed object.
Electrodiagnostic Tests for Carpal Tunnel Syndrome
Electrodiagnostic testing can be helpful to confirm or exclude carpal tunnel syndrome when the clinical diagnosis is uncertain. It is also useful to gauge severity of nerve compression and to aid in decisions regarding surgical intervention. In some cases, nerve conduction study (NCV) or electromyogram (EMG) may be done to confirm the diagnosis of carpal tunnel syndrome as well as to check for other possible nerve problems. A nerve conduction study measures how well and how fast the nerves can send electrical signals. An electromyogram measures the electrical activity of muscles at rest and during contraction. The electrodiagnosis rests upon demonstrating impaired median nerve conduction across the carpal tunnel in the context of normal conduction elsewhere.
Rarely, carpal tunnel syndrome may occur in the absence of an abnormal electrodiagnostic study, and positive findings may be obtained in individuals without clinical symptoms of carpal tunnel syndrome.
Imaging Studies for Carpal Tunnel Syndrome
Imaging studies are rarely needed. An x-ray may be taken to check for the other causes of the complaints such as hand arthritis or a hand fracture. Rarely, ultrasound imaging is used to show impaired movement of the median nerve. Magnetic resonance imaging (MRI) can show the wrist anatomy but to date has not been especially useful in diagnosing carpal tunnel syndrome.