The use of ultrasound imaging to demonstrate reduced movement of the median nerve during wrist flexion in patients with non-specific arm pain.

Following clinical screening, we examined movement of the median nerve at the wrist using high-resolution (10-22 MHz) ultrasound in 16 controls and 12 patients with non-specific arm pain (also referred to as repetitive strain injury). Imaging was performed just proximal to the carpal tunnel with the wrist in neutral, 30 degrees of extension and 30 degrees of flexion. In control subjects the position of the median nerve was 4.8 (SE=0.4) mm more radial with the wrist flexed than with the wrist extended. In the twelve arm pain patients the average change was only 1.2 (SE=0.5) mm. It appears that ultrasound imaging may be helpful in diagnosing non-specific arm pain, a condition for which there are no well-defined diagnostic tests at present. The reduced nerve movement seen with ultrasound imaging confirms previous work with magnetic resonance imaging.