Abnormal current perception thresholds measured by neurometer among residents in blackfoot disease-hyperendemic villages in Taiwan

Abstract

This study evaluated the possible existence of subclinical sensory nerve defects in residents of blackfoot disease (BFD)-hyperendemic villages in Taiwan characterized by long-term arsenic exposure from drinking water. Eighty-five seemingly normal subjects living in BFD villages and 75 external normal controls without exposure were recruited. All subjects were 30–75 years old, without possible causes of peripheral neuropathy and suffered from no symptoms of peripheral neuropathy. Current perception threshold (CPT) was measured by Neurometer ® at the trigeminal, median and superficial peroneal nerves with frequencies of 5, 250 and 2000 Hz. Results showed that the two groups were comparable in age, sex, body height and body weight. However, BFD residents had significantly 1.28–2.23-fold higher CPT than normal controls for all frequencies at the 3 nerves. If the mean values + 3 standard deviations (S.D.) derived from normal controls were used as cutoff points for defining abnormalities, 36 of the 85 (42.4%) residents in the BFD villages had at least one abnormal measurement. Site and frequency preferences were noted in the abnormal CPT of the BFD residents. Longer nerves (superficial peroneal and median nerves) were involved more commonly than shorter one (trigeminal); and lower frequencies (5 and 250 Hz) were more commonly involved than the higher one (2000 Hz). Stepwise regression analyses consistently showed that residency in BFD villages was significantly associated with higher CPT values after adjusting for age, sex, body height and body weight. In conclusion, abnormal CPT was observed in seemingly normal subjects without clinical neuropathy in the arseniasis-hyperendemic villages in Taiwan.