Digital sensory nerve conduction velocity and vibration perception threshold in peripheral neurological test for hand-arm vibration syndrome.

To evaluate peripheral neuropathy in patients with vibration syndrome, an examination was conducted of sensory nerve conduction velocity (SCV) in the digital segment of the median nerve in the middle finger and vibration perception threshold (VPT) at 125 Hz on the same middle fingertip. In addition, possible correlations were investigated between the two measurements. SCVs in the digital segment were measured by stimulating at the wrist electrically and recording from two pairs of electrodes in the finger. Fractionated SCVs were also measured in the palm-to-finger, wrist-to-palm, and elbow-to-wrist segments. The subjects were 52 patients with vibration syndrome and 40 healthy controls of similar age. SCVs in the digital segment and the wrist-to-palm segment were significantly slower in the patients than in the controls, and VPTs were higher in the patients. The strongest correlation of VPTs with SCVs among nerve segments measured was shown in the digital segment. With an increase in VPTs, SCVs in the digital segment tended to be slower, and slowed digital SCVs were encountered more frequently: 13% in VPTs below 5.0 dB and 56% in VPTs above 17.5 dB. Slowed digital SCVs were found in 43% of the patients and increased VPTs were encountered in 92%.