Aging and current perception threshold measured by neurometer in normal Taiwanese adults

References Values for the Current Perception Threshold in the Pharynx Based on a Study of a Healthy Population

OBJECTIVES

The application of the current perception threshold (CPT) in the diagnosis of pharyngeal sensory abnormalities has rarely been studied, and there is a lack of reference values for this application. This study established a normal reference range for CPT in the pharynx based on a study of a healthy population.

METHODS

The CPT values of the palatoglossal arch, posterior 1/3 of the lingual body and hard palate were measured in 60 healthy individuals at 2000, 250, and 5 Hz. The influencing factors were analyzed, and reference values for the CPT were established.

RESULTS

There was no correlation between the CPT value and gender. Age was only correlated at 250 Hz level in the hard palate. The CPT values of the palatoglossal arch were 324.95 ± 82.422 at 2000 Hz, 66.90 ± 38.622 at 250 Hz, and 13 ± 14.93 (7.83-22.75) at 5 Hz. The CPT values of the posterior 1/3 of the lingual body were 359.17 ± 76.299 at 2000 Hz, 86.92 ± 35.151 at 250 Hz, and 19 ± 15.73 (13.03-28.75) at 5 Hz. The CPT values of the hard palate were 157.5 ± 61.75 (124-185.75) at 2000 Hz, 57.63 ± 28.785 at 250 Hz, and 22 ± 25.73 (11.03-36.75) at 5 Hz.

CONCLUSIONS

The CPT values of the pharynx in healthy people were not related to gender. The CPT values of the hard palate for 250 Hz stimulation were related to age, and there were no relationships between the CPT values and age for the other frequencies and loci. We established a normal reference range of CPT values in the pharynx from measurements obtained from healthy populations.

Reference Values and Influencing Factors Analysis for Current Perception Threshold Testing Based on Study of 166 Healthy Chinese

The current perception threshold (CPT) is a device which can evaluate different sensory fibers quantitatively through different frequencies of the electrical stimulus and has been applied in clinical practice. Previous studies have implied that CPT values may be affected by age, gender, and other factors, yet not conclusively. The objective of our study is to clarify the influencing factors of CPT values and establish a reference value range. Twenty healthy volunteers recruited publicly and 146 subjects who took CPT tests in the census of the national project cardiovascular and cerebrovascular diseases in rural areas of China from 2013 to 2015 were analyzed. Past medical history and demographic characteristics such as age, gender, and occupation were collected. Each subject was tested on the left index finger (or back of the left hand) and the right hallux. CPT values of 2000, 250, and 5 Hz on both sites were recorded for statistical analysis. Gender differences were shown at 2000 Hz CPT on the back of the hand and hallux (p < 0.01), and male subjects had a higher CPT. Age had a positive correlation with 250 Hz CPT on the index finger (p < 0.05, r = 1.5), 2000 Hz CPT on the back of the hand (p < 0.001, r = 1.2) and index finger (p < 0.05, r = 2.5). Manual workers had a higher 250 Hz CPT on the hallux than mental workers (p < 0.01). After investigating the impact of different factors on CPT testing, we established the reference value for subjects with different characteristics.

Age-related changes in the somatosensory processing of tactile stimulation--an fMRI study

Age-related changes in brain function are complex. Although ageing is associated with a reduction in cerebral blood flow and neuronal activity, task-related processing is often correlated with an enlargement of the corresponding and additionally recruited brain areas. This supplemental employment is considered an attempt to compensate for deficits in the ageing brain. Although there are contradictory reports regarding the role of the primary somatosensory cortex (SI), currently, there is little knowledge about age-related functional changes in other brain areas in the somatosensory network (secondary somatosensory cortex (SII), and insular, anterior (ACC) and posterior cingulate cortices (PCC)). We investigated 16 elderly (age range, 62-71 years) and 18 young subjects (age range, 21-28 years) by determining the current perception threshold (CPT) and applying functional magnetic resonance imaging (fMRI) using a 3.0 Tesla scanner under tactile stimulation of the right hand. CPT was positively correlated with age. fMRI analysis revealed significantly increased activation in the contralateral SI and ipsilateral motor cortex in elderly subjects. Furthermore, we demonstrated age-related reductions in the activity in the SII, ACC, PCC, and dorsal parts of the corpus callosum. Our study revealed dramatic age-related differences in the processing of a simple tactile stimulus in the somatosensory network. Specifically, we detected enhanced activation in the contralateral SI and ipsilateral motor cortex assumingly caused by deficient inhibition and decreased activation in later stages of somatosensory processing (SII, cingulate cortex) in elderly subjects. These results indicate that, in addition to over-activation to compensate for impaired brain functions, there are complex mechanisms of modified inhibition and excitability involved in somatosensory processing in the ageing brain.

Aging and overactive bladder may be associated with loss of urethral sensation in women

AIMS

To compare current perception thresholds (CPT) in the urethra and bladder of women with idiopathic overactive bladder to asymptomatic controls.

METHODS

Women with > or =1 urge urinary incontinence (UUI) episode per week on 7-day diary, seeking treatment for UUI underwent CPT testing using a Neurometer(R) CPT device (Neurotron, Inc., Baltimore, MD). Testing was done in the urethra and bladder at three frequencies 2,000, 250, and 5 Hz corresponding to A-beta, A-delta, and C fibers, respectively. CPT values from the women with UUI were compared to CPT values from a group of control women without lower urinary tract symptoms.

RESULTS

Forty-eight controls without lower urinary tract symptoms and 13 women with UUI were included in the analysis. Women with UUI were significantly older (mean +/- SD age 62 +/- 14 and 44 +/- 15, P < 0.0005) and more likely to be vaginally parous (P = 0.007) than control women. Urethral CPT at 2,000, 250, and 5 Hz were significantly higher in women with UUI than controls, while bladder CPT were not different between groups. Using logistic regression, to control for age and parity, urethral CPT at 5 Hz remained significantly higher in women with UUI than controls (P = 0.013).

CONCLUSION

Urethral sensation is significantly higher in older women, suggesting sensory neuropathy in the lower urinary tract increases with age and may contribute to the increase in overactive bladder seen with aging. These data reinforce the role of the urethra in lower urinary tract function.

Age and upper limb tension testing affects current perception thresholds

Current perception threshold (CPT) testing was used to quantitatively measure the sensory response to upper limb tension testing (ULTT). The study addressed the ability of ULTT to tension the intended nerve, and the influence of age on CPT. Normal subjects (n=59) performed a randomized series of CPT tests at 5 and 2,000 Hz in a resting position and in a median-nerve bias position using the Neurometer. Results indicate that ULTT impacts CPT in normal subjects, with greater effects observed in the ulnar nerve (p<0.05) than for median nerve (NS). Age was a significant covariate for CPT (2,000 Hz, p=0.032; 5 Hz, p=0.034), and Pearson correlations indicated a weak but significant correlation of age with CPT. Age had a differential impact on CPT frequencies, suggesting differential impacts on nerve fibers, with a trend towards hypoesthesia at 2,000 Hz (r=0.10 to 0.30) and toward hyperesthesia at 5 Hz (r=-0.16 to -0.28). ULTT causes measurable effects in the sensory threshold of peripheral nerve, which are more pronounced with age; increased touch threshold and decreased pain thresholds can be expected. The specificity of nerve bias elicited by specific ULTT needs further exploration.