Carpal Tunnel Syndrome Diagnosis

Early carpal tunnel syndrome diagnosis and treatment are essential 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 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

Physical Exam for Carpal Tunnel Syndrome

Depending on the severity of your symptoms, your hand surgeon will classify your carpal tunnel syndrome as mild, moderate, or severe, which will help you formulate a treatment plan. 

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. The 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 hand surgeon may ask you to show him any hand or wrist movements that bring on pain, tingling, or numbness.   

Tinel Sign

Your doctor will tap on the area of your wrist overlying the median nerve. The Tinel sign is present when a tingling or a shock-like sensation occurs in the fingers (Figure 1).

Wrist Flexion and Median Nerve Compression

Flexion of the wrist and fingers produces compression of the median nerve (Figure 2).

Phalen Test

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 to present if tingling or numbness is felt in the fingers within 1 minute (Figure 3).

Median Nerve Compression

Manual carpal compression involves applying pressure over the carpal tunnel, which is considered “positive” if tingling occurs within 30 seconds of applying pressure (Figure 4).

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 helpful to gauge nerve compression severity and aid in decisions regarding surgical intervention. In some cases, a nerve conduction study (NCV) or electromyogram (EMG) may be done to confirm the diagnosis of carpal tunnel syndrome and check for other possible nerve problems.  A nerve conduction study measures how well and 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

While carpal tunnel syndrome is a clinical diagnosis, an imaging test may be necessary to evaluate structural abnormalities, swelling, bone, ligaments, and soft tissues in the wrist, forearm, or neck. The three main imaging tests for the evaluation of carpal tunnel syndrome are carpal tunnel ultrasound, MRI, and X-ray.