Hand dominance effect on median and ulnar sensory evoked amplitude and latency in asymptomatic workers.

OBJECTIVE

To examine the relative effect of hand dominance on the median and ulnar sensory evoked responses and grip strength in active workers.

DESIGN

A cross-sectional or survey design.

SETTING

Workers from 4 different sites underwent on-site testing of the median and ulnar sensory nerves in both hands (antidromic stimulation, 14 cm), and testing of bilateral grip strength.

PATIENTS

224 workers, asymptomatic of hand, wrist, or finger pain, numbness, or tingling: 87% were right handed.

MAIN OUTCOME MEASURES

Amplitude and latency of the median and ulnar sensory response and the grip strength of each hand.

RESULTS

The amplitude of the median sensory response in the dominant hand was significantly lower in right handed individuals (34.6 microm V versus 38.8 microm V) but not in left handed workers (34.2 microm V versus 34.3 microm V). A similar relationship held for the ulnar evoked responses and the grip strength. Median and ulnar sensory latencies in right handed individuals did not differ side to side, whereas left handed workers had a slightly shorter latency on the left.

CONCLUSIONS

The left hand of a right handed worker may not be exposed to as much trauma, resulting in relative protection of the nerves in the hand and a higher amplitude of the left median and ulnar evoked response. Left handed individuals may be more likely to use both hands equally and thus expose the nerves in each hand to an equal amount of trauma, resulting in their sensory amplitudes being equivalent (and also equal to the dominant hand of a right handed individual).