The impact of hand dominance and ulnar and median nerve impairment on strength and basic daily activities.

The authors sought to determine the impact of hand dominance and its relation to function among ulnar alone and combined ulnar and median nerve lesions in leprosy patients. The study sample consisted of 62 persons affected with leprosy (mean age 36.1 years) who were either suffering from ulnar nerve lesions alone (34 patients) or combined ulnar and median lesions (28 patients). The data from the earlier work of this institution with normal hands in the adjacent rural uninvolved population were taken as controls. Grip, pulp-to-pulp, lateral, and three-jaw-chuck pinch strengths were measured using a hydraulic hand dynamometer and a pinch gauge. Basic daily activities were assessed using the battery developed at Karigiri. Means, standard errors, correlations, and t-tests were used in the analyses. The overall difference between grip and pinch strength measurements in both dominant and nondominant hands was 40% less than those in normal hands if the ulnar nerve alone was involved. If impairment of this nerve was combined with that of the median nerve, the overall difference in strength measurements increased to 51%. The hand strength of the dominant side was statistically significant between single and two nerves for pulp-to-pulp pinch (p = 0.019). No other strength tests produced statistically significantly results related to hand dominance (grip strength, lateral, chuck pinch) with either one or two nerve involvement. To observe differences in basic daily activities, scores were compared to Karigiri norms. The bilateral basic daily activities score was impaired by 45% compared with norms with only ulnar nerve involvement and by 59% with ulnar and median nerve involvement. The different pinch strengths related to basic daily activities was not significantly affected in nondominant hands, whether it was ulnar alone or combined ulnar and median nerve lesions. In this population diagnosed with leprosy, ulnar nerve impairment at the level of the elbow reduced the grip and pinch strengths and performance in basic daily activities by 40% and 45%, respectively. If combined with median nerve lesion at wrist level, the strengths and daily activity losses increased to 50% and 60%, respectively. There is no effect on grip strength either in ulnar or ulnar and median nerve injuries, irrespective of whether dominant or nondominant hands were involved. Different pinch strengths related to basic daily activities were significantly affected only in the dominant hand with involvement of these nerves.