Sensory and Autonomic Function and Ultrasound Nerve Imaging in RSI Patients and Keyboard Workers

This study examines the neurophysiological function of small sensory and autonomic and large sensory fibres in RSI patients and in office workers who intensively use visual display screen (DSE) equipment.

Flare response in relation to iontophoresis of histamine was used as a measure of small sensory C-fibre function, vasoconstriction following ice challenge to the neck as a measure of efferent autonomic function and vibration threshold as a measure of large sensory (A-fibre) function. All measurements were carried out over both hands in each subject.

Significant differences on all three measures of nerve fibre function were found in the RSI patient group and on 2 measures for the office workers.

Vibration thresholds were elevated by 47% in patients and by 21% in office workers.

Flare areas were reduced by 33% in patients and by 30% in office workers.

Reflex vasoconstriction was reduced by 20% in patients but showed no significant changes in office workers. In a separate part of the study we have used ultrasound images of the median nerve at the proximal carpal tunnel in a group of office workers to measure the amount of nerve movement occurring during 30 degrees of wrist extension to 30 degrees of flexion.

Interestingly four out of the ten office workers showed a very small or reversed nerve movement.

Finally as a means of validating our previous work looking at median nerve movement using MRI and ultrasound we have made a comparative study of nerve movement using both ultrasound and MRI in a group of controls, office workers and patients.

The two methods were in good agreement. Overall, for RSI patients a clear picture emerges of modest reductions in peripheral nerve function, involving both large and small fibre systems.

Such changes would be consistent with our hypothesis that a minor neuropathy is present in diffuse RSI.

Office workers have a similar trend, although it is not so marked, indicating possible early changes in peripheral nerve function in this occupational group.