Utility of vibration sense testing for use in developing countries: Comparison of extinction time on the tuning fork to vibration thresholds on the vibratron II

measurement of vibration sense loss is a useful tool to detect early impact s of neurotoxic chemicals. Measurement methods are needed for developing co untries that are culturally unbiased, and which can be used under field con ditions where electricity may be unavailable. Extinction time on a 256 Hr t uning fork was compared to vibration threshold measured on the Vibratron II for precision and agreement amongst 306 fruit farm workers as part of a st udy investigating neurobehavioural impacts of organophosphates in South Afr ica in 1993. Simultaneous data were also available from a Ig accelerometer attached to the post of the Vibratron for comparisons. Precision of the tun ing fork and Vibratron II appeared comparable and CVs (2.5 to 8.9%) were lo wer than that reported in the literature. Agreement of the tuning fork with the Vibratron was moderate (Spearmans correlation coefficient of the order of 0.39 to 0.42) whereas agreement between Vibratron and Accelerometer was high (Spearmans correlation of coefficient of the order of 0.78 to 0.83). Height, age and schooling were predictors of vibration sense for the Vibrat ron and accelerometer but only schooling for extinction time on the tuning fork. Height modified the variability of the Vibratron and accelerometer. D elays in application of the tuning fork to the base of the medial malleolus of 3 seconds or more were associated with average increases in extinction time of 1.7 s. The tuning fork, as standardised in this study, represents a relatively quick, easy and low-technology device with good utility, that i s relatively resistant to the usual confounders for vibration threshold mea surement. Further studies to explore ifs validity in relation to of her wel l-recognised methods for detection of subtle neurotoxic impacts should be e ncouraged. (C) 2000 Inter Press, Inc.