Somatosensory evoked responses (SERs) to mechanical (tapping) stimulation were recorded in 24 patients with occupational vibration disease, and they were compared with those recorded in 48 normal subjects. Tapping stimuli were applied on the finger, the palm and the forearm of the bilateral sides. On the other hand, SERs to electrical stimulation were recorded in 5 of the patients, and these were compared with SERs to mechanical stimulation. 1. Some peaks in 32 out of 48 SERs to mechanical stimulation on the finger were absent, and peak latencies in 10 out of the remaining 16 SERs were abnormally prolonged. On the other hand, only 2 out of 27 SERs to mechanical stimulation on the forearm were abnormal. 2. Some peaks in 27 out of 35 SERs recorded in patients with numb sensation in the fingers were absent and peak latencies in the remaining 8 SERs were abnormally prolonged. 3. With respect to the absence of peaks in SERs, P2 and N2 peaks were more frequently absent than N3 and P4 peaks. 4. Peak latencies of the SERs in the patients with occupational vibration disease were abnormally prolonged. The difference of the peak latency between the patients and the controls was statistically significant. 5. Ten SERs to mechanical stimulation and 10 SERs to electrical stimulation were recorded in 5 patients. Nine out of the 10 SERs to mechanical stimulation were abnormal, while only 2 out of the 10 SERs to electrical stimulation were abnormal. 6. Based on a close relationship between abnormal SERs to mechanical stimulation and the numb sensation in the finger of the patients, it was concluded that sensory disturbances in the occupational vibration disease was due to the lesion in the peripheral nerve. Therefore, SERs to mechanical stimulation can be used for detecting some localized sensory abnormality due to the lesion in the peripheral nerve.
