Diagnosing Carpal Tunnel Syndrome
What is carpal tunnel syndrome?
Carpal tunnel syndrome is a common medical condition that affects the hand(s) and wrist(s). The carpal tunnel passage is a narrow canal/tube located in each wrist. It holds the median nerve and tendons that connect the hand and forearm. The median nerve controls movement and sensation in the thumb and the fingers except the pinky and half of the ring finger.
Carpal tunnel syndrome occurs when the carpal tunnel is compressed or becomes too narrow, which creates pressure on the median nerve. The resulting inflammation can cause loss of sensation in the fingers and hand.
The diagnostic process for carpal tunnel syndrome typically begins with a medical history and a physical exam. Imaging studies and nerve tests may also be ordered to confirm a diagnosis, diagnose atypical cases, or determine the degree of severity.
A medical history can provide clinical clues of carpal tunnel syndrome. A diagnosis of carpal tunnel syndrome may be suspected based on the following:
- A history of symptoms that include pain or abnormal skin sensations in the palm of the hand, thumb, index or middle fingers
- Current medical conditions and history of injuries
- Activities and times that improve or worsen symptoms (Symptoms may worsen at night or during certain activities, such as holding a phone.)
A physical exam can reveal indicators of carpal tunnel syndrome. Some of these signs include the following:
- Asymmetric appearance or strength in the neck, arms, wrists or hands
- Reduced thumb strength or movement
- Positive Tinel’s sign (tingling or a mild shock sensation when the inside of the wrist is tapped)
- Positive Phalen’s sign (numbness or tingling when placing both elbows on a flat surface with forearms vertical and both wrists flexed at 90 degrees for 60 seconds)
Several medical tests may be ordered during the diagnostic process. These include imaging studies, electromyography, and nerve conduction study.
- Imaging studies, such as X-rays, can be used to exclude other possible causes of wrist pain, such as a fracture. Ultrasound and MRI images may reveal compression or swelling of the median nerve.
- Electromyography (EMG) is a test in which a small needle is inserted into a muscle to measure and evaluate the electrical activity of the muscle. This test can register any damage to muscles controlled by the median nerve. It can also help rule out other potential causes of symptoms.
- Nerve conduction study (NCS) is a test in which two electrodes are placed on the skin to measure the speed of electrical impulses. The results of a nerve conduction study can indicate slowed electrical impulses in the carpal tunnel of the wrist.