[Study of somatosensory evoked response (SER) in patients with occupational vibration disease. Effect on SER induced by load of hot and cold water, and depressing the brachium].

Somatosensory evoked responses (SERs) to mechanical stimulation were recorded in 5 patients with occupational vibration disease and 10 grader drivers, and the results were compared with those obtained from 48 normal subjects. SERs were recorded at room temperature of 20-23 degrees C and after immersing the hand in hot (40 degrees C) or cold (10 degrees C) water for 5 minutes. SERs were also recorded while depressing the brachium and soon thereafter to examine the effect of ischemia. The following results were obtained. In SERs recorded on the finger of patients with occupational vibration disease, it was observed that some peaks of SERs were absent in 6 out of the 10 cases and that peak latency time was abnormally prolonged in 3 out of them. On the other hand, in SERs recorded on the forearm, abnormality was observed in only 1 out of them. In recording SERs in 6 patients with occupational vibration disease after immersing the hands in hot water, it was observed that abnormal SERs became normal in all 6 cases. However, these normalized SERs became abnormal in 5 out of the 6 cases within 25 minutes after removing the hands from hot water. No appreciable change could be observed in SERs recorded after immersing the hands in cold water. Partial absence of SER peaks could be observed in 2 out of 9 grader drivers while depressing the brachium. On the other hand, all SERs in 7 normal cases did not show any abnormality while depressing the brachium. The results suggest the presence of a close relationship between peripheral vascular dysfunction and peripheral somatosensory disturbance in patients with occupational vibration disease. However, it was observed that peripheral vascular dysfunction could not always trigger peripheral neural dysfunction. These findings have led to the conclusion that SERs to mechanical stimulation are more useful in the diagnosis of dysfunction of the peripheral nerve in patients with occupational vibration disease than SERs to electrical stimulation. The findings suggest that immersion in hot water and cold water and depression of the brachium are useful sensory tests for patients with occupational vibration disease and grader drivers.