Diagnosis using electroneurography

In order to confirm the suspected diagnosis “carpal tunnel syndrome“, a diagnostic apparatus can also be connected.Electroneurography in particular is very informative here, and is therefore considered the diagnostic method of choice. The median nerve on the affected side is stimulated with an electrical stimulus at the wrist and the time until a muscular response is obtained from the thumb ball muscles supplied by this nerve is measured. This allows the nerve conduction velocity to be determined.

With the help of electroneurography, both the location and degree of damage to the nerve can be determined. If carpal tunnel syndrome is present, this period is increased. To ensure that the test delivers comparable values, measurements are always taken on both arms.

In addition, the conduction velocity of the ulnar nerve (elbow nerve) is also determined in order to have an individual reference value. In this way, possible causes for incorrect measurements, such as hands that are too cold, can be excluded. In addition to delaying the muscle reaction, the sensitive parts of the median nerve may also show a reduced nerve conduction velocity. To check this, the measured values of the median and ulnar nerves are also compared.

Diagnosis by electromyography

Electromyography (EMG), the measurement of the muscular conductivity of the affected hand, reveals, among other things, pathological spontaneous activity of the muscles supplied by the constricted median nerve. This examination method can additionally determine whether the nerve damage is temporary or permanent. As in electroneurography, the measurement is always performed in side by side comparison.

Diagnosis by ultrasound

The narrowing of the median nerve in the carpal tunnel often leads to local swelling of the nerve. This can be detected in an ultrasound examination by measuring and comparing the nerve cross section at different locations. In addition, sacculations of the wrist capsule or soft tissue tumors can be detected, which can also lead to a tightness in the carpal tunnel. If a clear constriction can be detected in this way, the determination of the nerve conduction velocity (see above) can also be omitted.