Scientific study of the extent of transverse movement of the median nerve at the wrist during active wrist extension in static positions of the upper limb tension test one

Objective. Longitudinal glide of the median nerve is affected in typical entrapment neuropathies such as carpal tunnel syndrome. The upper limb tension test one (ULTT1) is used by clinicians to assess patients' responses to passive movements that affect the median nerve. ULTT1 is thought to mainly assess the longitudinal glide of the median nerve; however, transverse glide of the nerve at the wrist may be a more sensitive measure of an entrapment neuropathy. Method. Sixteen wrists of four male and 11 female healthy volunteers were studied with ultrasound imaging in this small original study. Images were collected in eight different combinations of shoulder, elbow and forearm posture. In each posture the wrist was moved from full flexion to 30 degrees of extension. Results. Nerve excursion from full wrist flexion to 30 degrees of extension was mainly in a radio-dorsal direction. It ranged from a minimum of 1.8 mm (SD +/- 2.0 mm) up to 3.57 mm (SD +/- 1.86 mm) of transverse movement, and 0.22 mm(SD +/- 0.59 mm) of volar movement to 0.96 mm(SD +/- 0.76 mm) of dorsal movement. In all eight of the positions tested, forearm supination led to greater transverse movement of the nerve at the wrist. Conclusions. Transverse movement of the median nerve is most marked with forearm supination, irrespective of other changes in the kinetic chain. The nerve moves dorsally in all movements except when the forearm flexors are off-loaded in elbow extension and elbow flexion. These findings confirm the transverse movement of the median nerve at the wrist, during active wrist extension within positions of the ULTT, but that the shoulder and elbow position have little impact on the degree of movement.