Comparison of algorithms of testing for use in automated evaluation of sensation

Abstract

Estimates of vibratory detection threshold may be used to detect, characterize, and follow the course of sensory abnormality in neurologic disease. The approach is especially useful in epidemiologic and controlled clinical trials. We studied which algorithm of testing and finding threshold should be used in automatic systems by comparing among algorithms and stimulus conditions for the index finger of healthy subjects and for the great toe of patients with mild neuropathy. Appearance thresholds obtained by linear ramps increasing at a rate less than 4.15 microns/sec provided accurate and repeatable thresholds compared with thresholds obtained by forced-choice testing. These rates would be acceptable if only sensitive sites were studied, but they were too slow for use in automatic testing of insensitive parts. Appearance thresholds obtained by fast linear rates (4.15 or 16.6 microns/sec) overestimated threshold, especially for sensitive parts. Use of the mean of appearance and disappearance thresholds, with the stimulus increasing exponentially at rates of 0.5 or 1.0 just noticeable difference (JND) units per second, and interspersion of null stimuli, Békésy with null stimuli, provided accurate, repeatable, and fast estimates of threshold for sensitive parts. Despite the good performance of Békésy testing, we prefer forced choice for evaluation of the sensation of patients with neuropathy.

Quantitative Vibration Perception Thresholds in Normal and Diabetic Chinese: Influence of Age, Height and Body Mass Index

“…Since our study subjects were older than the pretest subjects, averaging the fourth and the fifth measurements was to guard against unstable measurements. Dyck et al [24] reported that appearance vibration thresholds obtained by linear ramps increasing at a rate less than 4.15 Ìm/s provided accurate and repeatable thresholds compared with those obtained by forcechoice testing. In this study, the increasing rates of our ramps were 0.83 Ìm/s for the validation and 1.66 Ìm/s for the normality study.…”

Quantitative sensory testing

“…[6][7][8][9] This is due in part to a subject's reaction time. A subject needs to consciously perceive the stimulus, process the information, and generate an action to indicate a response.…”

Enzyme replacement therapy improves function of C-, Aδ-, and Aβ-nerve fibers in Fabry neuropathy

“…[23][24][25] VDT, CDT, and HP were assessed using the vibratory and thermal stimulators of a CASE IV™ system (WR Medical Electronics Co., Stillwater, MN), as previously described in detail. 20,[26][27][28] We did not assess warm perception thresholds in the study participants as our study protocol was already very extensive and time consuming and included evaluations beyond the scope of the current study. Moreover, warm perception thresholds assessed with the 4, 2, and 1 stepping algorithm and the CASE IV system showed a rather high intraindividual variability.…”