Carpal tunnel syndrome and manual milking: nerve conduction studies in 43 cases

Abstract

From 1989 to 2004, 3125 consecutive patients had electrodiagnosis of carpal tunnel syndrome (CTS); from these 43 cases (1.38%) were associated to manual milking; mean age was 44.9 years and 88.4% were male. The mean time in the milking profession was 247 months; the mean daily milking time was 146 minutes; symptoms referred at electrodiagnostic consultation had lasted on average 34 months, 83% were bilateral. The median sensory nerve conduction study was abnormal in 75.6% to the right and 66.7% to the left hand. The median nerve motor distal latency (MDL) was abnormal in 92.1% to the right and in 80.0% to the left hand. There were no differences between right and left for all electrophysiological parameters. In CTS related to manual milking most cases were men, with the MDL more affected than the sensory distal latencies and the electrophysiological abnormalities were found to be symmetric. Manual milking could be a natural model for occupational CTS. In contrast to idiopathic CTS, there was a greater involvement of motor fascicles; this finding is remarkable for CTS.