Influence of aging on thermal and vibratory thresholds of quantitative sensory testing

Abstract

Quantitative sensory testing has become a common approach to evaluate thermal and vibratory thresholds in various types of neuropathies. To understand the effect of aging on sensory perception, we measured warm, cold, and vibratory thresholds by performing quantitative sensory testing on a population of 484 normal subjects (175 males and 309 females), aged 48.61 +/- 14.10 (range 20-86) years. Sensory thresholds of the hand and foot were measured with two algorithms: the method of limits (Limits) and the method of level (Level). Thresholds measured by Limits are reaction-time-dependent, while those measured by Level are independent of reaction time. In addition, we explored (1) the correlations of thresholds between these two algorithms, (2) the effect of age on differences in thresholds between algorithms, and (3) differences in sensory thresholds between the two test sites. Age was consistently and significantly correlated with sensory thresholds of all tested modalities measured by both algorithms on multivariate regression analysis compared with other factors, including gender, body height, body weight, and body mass index. When thresholds were plotted against age, slopes differed between sensory thresholds of the hand and those of the foot: for the foot, slopes were steeper compared with those for the hand for each sensory modality. Sensory thresholds of both test sites measured by Level were highly correlated with those measured by Limits, and thresholds measured by Limits were higher than those measured by Level. Differences in sensory thresholds between the two algorithms were also correlated with age: thresholds of the foot were higher than those of the hand for each sensory modality. This difference in thresholds (measured with both Level and Limits) between the hand and foot was also correlated with age. These findings suggest that age is the most significant factor in determining sensory thresholds compared with the other factors of gender and anthropometric parameters, and this provides a foundation for investigating the neurobiologic significance of aging on the processing of sensory stimuli.

Physiological correlates of age-related decline in vibrotactile sensitivity

“…Lin et al [23] reported a significant effect of gender on vibration threshold measured at the lateral malleolus. However, the authors neither mentioned the direction of this relationship nor did they control for height differences between men and women.…”

“…Since quantitative sensory testing captures the overall function of the sensory neuroanatomical circuitry, age-related decline detected in our study could potentially arise from deterioration in multiple components of the sensory pathway, ranging from structural deformation and reduced density of sensory receptors to degraded information processing in the somatosensory cortex [23]. Studies investigating aging effects on spatial and temporal summation characteristics of the P channels that are mediated by Pacinian corpuscles and their corresponding nerve fibers suggest that the primary factor responsible for elevation in the detection thresholds of high frequency vibration in older subjects is a reduced afferent input to central nervous system (CNS) [12,13].…”

“…Notably, the age-associated decline in tactile sensitivity is steeper for vibration compared to other sensory modalities such as touch [34] and age contributes the most to increase in vibration threshold [8,23] leading to suggestions that the decline in vibrotactile sensitivity is an inherent manifestation of nervous system aging. Functionally, impaired vibrotactile sensitivity in older adults is associated with increased falls [24] and impaired compensatory stepping responses [28].…”

“…Researchers have reported a significant age-related decline in vibrotactile sensitivity as shown by increase in threshold for perception of vibration [12,23,27,34,40]. Within a healthy older population (age >65 years), the increase in thresholds is particularly notable for high frequency vibrations after the age of 70 years [27].…”

Effects of surface characteristics on the plantar shape of feet and subjects’ perceived sensations

“…Researchers such as Dyck et al (1987a, b), Adams et al (1989), and Lin et al (2005) have all shown changes in light touch, pinprick, deep pressure, vibration, and even temperature perception during aging as well as in some disease conditions. These confounding effects were eliminated in this study by limiting our choice of participants to young males of Asian origin.…”