Table 1 Diagnostic principles of severe carpal tunnel syndrome

Symptoms

 Meet the following four symptoms:

• Severe numbness in the distribution of the median nerve of the wrist or hand;

• Obvious thenar muscle atrophy;

• Thumb opposition dysfunction;

• Two-point discrimination > 10 mm;

Signs

Meet one of the following three signs:

• Positive Tinel’s sign;

• Positive Phalen’s test;

• Positive Durkan’s test;

Electrodiagnostic testing

Meet the following two electrodiagnostic results:

• Absence of median sensory nerve action potential (SNAPS) (digit-wrist segment)

• abnormal distal motor latency (DML ≥ 4.2 ms) or absence of motor response;