The ultrasound marketers are really pushing the possible use of ultrasound in diagnosis of nerve entrapment.  Nerve conduction study, however, has the advantage of many years of use in having established itself as a very useful tool in the objective evaluation of nerve entrapment.  Ultrasound on the other hand is literally just shades of grey.  It is not as user-friendly and depends on a person’s knowledge of anatomy and interpretation skills, therefore, it is very subjective.   

In a study published in January 2019 in the Journal of AAOS comparing patients who underwent both median nerve ultrasound and electrodiagnostics increased cross-sectional area of the median nerve at the distal wrist crease was correlated with increased abnormality on electrodiagnostic study.  Electrodiagnostic studies have never tied directly to the symptoms or to the prognosis of the person who undergoes treatment for carpal tunnel.

At this point in time, I personally don’t feel that use of ultrasound makes good clinical sense in the evaluation of nerve entrapment in the upper extremity.  It is a lot of added cost without proved benefit.