Measurement Of Perception Threshold Research Articles

A Design and Construction of the Vibration Perception Threshold Measurement Device for Diabetes

A Design and Construction of the Vibration Perception Threshold Measurement Device for Diabetes

Long-term dopamine agonist treatment fails to restore altered central sensory processing in restless legs syndrome: Evidence from current perception threshold measurements

ObjectivesAlthough some studies have examined the impact of short-term dopamine agonist treatment on altered central sensory processing in patients with restless legs syndrome (RLS), there is a scarcity of research investigating the effect of long-term treatment with these drugs. The aim of this study is to investigate the long-term impact of dopamine agonist treatment on altered central sensory processing in RLS patients using current perception threshold (CPT) testing. MethodsWe conducted a study of 24 RLS patients, measuring their CPT values before and after dopamine agonist treatment for at least 2 months. Patients were classified as responders or non-responders based on their decrease in International Restless Legs Syndrome (IRLS) score. Clinical parameters were collected and compared pre- and post-treatment. ResultsThe mean duration of treatment with dopamine agonist was 13.6 ± 11.0 months. Our results showed that dopamine agonist treatment significantly improved clinical parameters, including the IRLS score, Visual Analogue Scale, and RLS Quality of Life questionnaire. However, CPT values did not show significant changes for all stimulus frequencies after treatment. Furthermore, we did not find any difference in CPT values before and after treatment in both responders and non-responders. ConclusionsOur study demonstrated that long-term treatment with dopamine agonists effectively reduces RLS symptoms, but does not reverse the altered central sensory processing observed on CPT testing in RLS patients. These results support the notion that the pathophysiology of RLS is multifactorial and not solely driven by dopaminergic dysfunction.

Acute physiological and functional effects of repetitive shocks on the hand–arm system: a pilot study on healthy subjects

Objectives. Exposure to hand-transmitted shocks is a widespread phenomenon in the workplace. Separate risk assessments for shocks do not exist in current international hand–arm vibration regulations, leading to potential underestimation of associated health risks. Methods. In a pilot study approach, eight healthy males were exposed to sets of 3 × 5 min of repetitive shocks and 1 × 5 min of random vibration, controlled at a weighted vibration total value of 10 m/s2. Baseline and post-exposure measurements of vibration perception thresholds, finger skin temperature, maximal grip/pinch force and the Purdue pegboard test were conducted. Muscle activity was monitored continuously by surface electromyography. Results. Shock exposures evoked a temporary increase of vibration perception thresholds with high examination frequencies. A decrease of skin temperature was hinted for shocks of 1 and 20 s–1. Electromyographical findings indicated an additional load on two forearm muscles during shock transmission. Maximum grip force and manual dexterity were not affected, and pinch force only partially reduced after the exposures. Conclusion. Physiological effects from shock exposure conform to those described for hand–arm vibration exposure in principle, although some divergence can be hypothesized. Randomized designs are required to conclusively assess the need of occupational health concepts specifically for hand-transmitted shocks.

Exploring the Use of the Current Perception Threshold in Pharyngeal Paresthesia Patients.

To explore pharyngeal sensory function by current perception threshold (CPT) measurement in paresthetic pharynx. In total, 58 healthy participants and 66 patients with pharyngeal paresthetic symptoms underwent CPT evaluation. Pharyngeal paresthesia (n = 66) was classified into three categories based on aetiologies: six cases with pain in pharynx; 34 neuropathic patients with glossopharyngeal nerve and/or vagus nerve or recurrent laryngeal nerve injury; and 26 patients with globus pharyngeus. CPT measurements were obtained from bilateral palatoglossal arch and tongue base at 2000, 250 and 5Hz stimulation frequencies. Ranked from high to low, the CPT values for the bilateral palatoglossal arches and tongue bases were: lower cranial neuropathic patients, globus pharyngeus, healthy participants and patients with pain. The CPT values for neuropathic patients on the injured side were significantly higher than those on the healthy side (P < 0.05). The CPT values for patients with pain in pharynx were significantly lower than those of healthy participants (P < 0.05) when the bilateral tongue bases were stimulated. The CPT measurement is a reliable method for quantitatively assessing pharyngeal sensory function and able to differentiate pharyngeal paresthesia between lower cranial neuropathic and subjective discomfort. Pharyngeal sensory function is more sensitive in patients with pain in pharynx. Pharyngeal sensory function is significantly reduced in lower cranialneuropathic patients, especially on the injured side. Patients with globus pharyngeus have pharyngeal hyposensitivity.

Imaging with [99mTc]HMPAO - a novel perspective: investigation of [99mTc]HMPAO leg muscle uptake in metabolic diseases.

Sensitive imaging modalities in the diagnosis of microcircular complications of the lower extremities induced by metabolic diseases are becoming a focus of interest. To investigate the [99mTc]HMPAO uptake of the legs in type 2 diabetes mellitus (T2DM) and obesity, and to search for associations with clinical parameters and nerve conducting studies. A total of 57 patients with controlled T2DM and 46 obese participants without DM were enrolled in the study. [99mTc]HMPAO SPECT/CT examinations were performed to evaluate the radiopharmaceutical accumulation of the legs. For the quantitative assessment of tracer uptake, standardized uptake value (SUVpeak) was measured in fixed spheric volumes of interest placed on both sural muscles on the attenuation-corrected images. Measurement of current perception threshold applying Neurometer (NM-01/CPT) was used to evaluate peripheral nerve dysfunction. Laboratory parameters assessing the glucose homeostasis of the study participants were also measured. In the diabetic group, significantly lower leg SUV values were detected compared to the non-DM obese group (median: 0.517 vs. 0.607; P < 0.001). Body mass index (BMI) (P < 0.0001), age (P = 0.0283), HbA1c (P = 0.0068), and glucose level (P = 0.0044) proved to be significant predictors of muscle tracer uptake. Neurometer studies showed positive correlation with HbA1c levels in the T2DM group (P = 0.0002). We assume that [99mTc]HMPAO uptake of leg muscles is associated with microcirculation, so quantitative [99mTc]HMPAO SPECT/CT might be a sensitive method for evaluating lower limb microvascular alterations. BMI, age, HbA1c, and glucose level may be significant predictors of peripheral vascular abnormalities triggered by metabolic disturbances.

Current perception threshold testing in chronic ankle instability

BackgroundDamage to sensory input is an underlying pathology of chronic ankle instability (CAI). Therefore, it is necessary to evaluate the sensory function of patients with CAI. The present study quantitatively evaluated sensory nerve function in patients with CAI and healthy controls using current perception threshold (CPT) measurements, as well as the influence of sex, age, and body mass index (BMI) on CPT values and the relations between CPT frequencies.MethodsFifty-nine subjects with CAI and 30 healthy controls participated in this study. CPT values at the anterior talofibular ligament region were recorded on the injured and uninjured sides in CAI patients and on both sides in the healthy control group. Between group differences were compared. The influence of sex, age and BMI on CPT values was evaluated. Correlations between different frequencies were also studied.ResultsThere were no significant differences in age, sex, height, weight or BMI between the CAI and healthy control groups. The CPT values did not show a significant difference by sex. The CPT values did not significantly correlate with age or BMI. Compared to the control group, the CAI group had significantly higher CPT values on the injured and uninjured sides under 250-Hz and 5-Hz electrical stimuli; the difference between the groups was significant (p < 0.01), and the effect size were large. No significant difference was observed under 2000-Hz stimuli. There were correlations between CPT values at different frequencies (p < 0.01), especially 250 Hz and 5 Hz.ConclusionThe present study revealed increased sensory thresholds in 250-Hz- and 5-Hz-related sensory nerve fibres in the injured and uninjured ankles of patients with CAI. This increase may indicate dysfunction of A-delta and C fibres. Sex, age and BMI did not significantly impact CPT values. There were correlations between CPT values at different frequencies, especially 250 Hz and 5 Hz.Level of evidenceLevel III, case-control study.

Synaptic Effect of Aδ-Fibers by Pulse-Train Electrical Stimulation.

Electrical stimulation of specific small fibers (Aδ- and C-fibers) is used in basic studies on nociception and neuropathic pain and to diagnose neuropathies. For selective stimulation of small fibers, the optimal stimulation waveform parameters are an important aspect together with the study of electrode design. However, determining an optimal stimulation condition is challenging, as it requires the characterization of the response of the small fibers to electrical stimulation. The perception thresholds are generally characterized using single-pulse stimulation based on the strength-duration curve. However, this does not account for the temporal effects of the different waveforms used in practical applications. In this study, we designed an experiment to characterize the effects of multiple pulse stimulation and proposed a computational model that considers electrostimulation of fibers and synaptic effects in a multiscale model. The measurements of perception thresholds showed that the pulse dependency of the threshold was an exponential decay with a maximum reduction of 55%. In addition, the frequency dependence of the threshold showed a U-shaped response with a reduction of 25% at 30 Hz. Moreover, the computational model explained the synaptic effects, which were also confirmed by evoked potential recordings. This study further characterized the activation of small fibers and clarified the synaptic effects, demonstrating the importance of waveform selection.

A test-retest reliability study of assessing small cutaneous fibers by measuring current perception threshold with pin electrodes.

BackgroundThe quantitative measurement of current perception threshold (CPT) has been used as a method to assess the function of nerve fibers in neuropathy diseases. The aim of this study was to assess the test-retest reliability measuring CPT using the circular pin electrodes for assessing the function of cutaneous thin nerve fibers.MethodsCPT measurement was repeated on two separate days with at least one-week interval in 55 volunteers. Superficial blood flow (SBF) and skin temperature (ST) were measured on the skin in an around area concentric to the circular pin electrodes after the process of finding CPTs. The coefficient of variation (CV) and intra-class correlation coefficient (ICC) were calculated. The correlation between each two of CPT, SBF increment and ST increment was analyzed.ResultsNo significant differences were found for CPT, SBF and ST between two sessions. SBF was found to be significantly increased after the process of finding CPT. CPT values of males were found to be higher than females. SBF increment was found to be positively correlated with ST increment. The ICC values for CPT, SBF and ST were 0.595, 0.852 and 0.728, respectively. The CV values for CPT, SBF and ST were 25.53%, 12.59% and 1.94%, respectively.ConclusionsThe reliability of CPT measurement using circular pin electrodes is fair, and need consistence of measurements in longitudinal studies.

Preliminary Measurement of Passive Gap Width Perception Threshold on Textured Surface

Preliminary Measurement of Passive Gap Width Perception Threshold on Textured Surface

Examining practice effects in repeated measurements of vibration perception thresholds on finger pulps of healthy individuals - Is it possible to improve your results over a clinically relevant test interval?

AimsTo investigate practice effects in a test-retest situation, where vibration perception thresholds (VPT) were measured in healthy subjects using a multi-frequency test method.MethodsIn eight consecutive tests, VPTs were tested in the pulps of the index and little fingers at seven frequencies (8, 16, 32, 64, 125, 250 and 500 Hz). Subjects were twenty healthy adults aged 26 to 65 years (mean 46.0 ± 11.1 years; 10 male and 10 female). The subjects were examined at six tests with intervals of one month (mean 33 ± 6; time 0 to month 5) and at two additional tests with prolonged intervals (month 12 and 18). Linear mixed model analysis was performed to investigate differences over the subsequent test occasions. To examine where potential practice effects occurred, a pairwise comparison with Bonferroni correction was made.ResultsSmall decreases in VPTs were found in 8 out of the 14 frequencies (index finger: 8, 16, 32, 250 and 500 Hz; little finger: 16, 250 and 500 Hz) within the test period from time 0 to month 5. In tests at 12 and 18 months, VPTs were increased compared to month 5, but lowered in comparison with time 0. Hence, minor significant decreases were found in three frequencies for the index finger (125, 250 and 500 Hz) and one frequency for the little finger (250 Hz) when examining VPTs with prolonged time intervals.ConclusionsWhen evaluating vibration perception thresholds in a clinically relevant time period of once or twice a year, no consideration of practice effects is necessary when interpreting the results.

Dynamic Spatial Responsiveness in Concert Halls

In musical perception, a proportion of the reflected sound energy arriving at the ear is not consciously perceived. Investigations by Wettschurek in the 1970s showed the detectability to be dependent on the overall loudness and direction of arrival of reflected sound. The relationship Wettschurek found between reflection detectability, listening level, and direction of arrival correlates well with the subjective progression of spatial response during a musical crescendo: from frontal at pianissimo, through increasing apparent source width, to a fully present room acoustic at forte. “Dynamic spatial responsiveness” was mentioned in some of the earliest psychoacoustics research and recent work indicates that it is a key factor in acoustical preference. This article describes measurements of perception thresholds made using a binaural virtual acoustics system—these show good agreement with Wettschurek’s results. The perception measurements indicate that the subjective effect of reflections varies with overall listening level, even when the reflection level, delay, and direction relative to the direct sound are maintained. Reflections which are perceptually fused with the source may at louder overall listening levels become allocated to the room presence. An algorithm has been developed to visualize dynamic spatial responsiveness—i.e., which aspects of a three-dimensional (3D) Room Impulse Response would be detectable at different dynamic levels—and has been applied to measured concert hall impulse responses.

Factors Affecting and Adjustments for Sex Differences in Current Perception Threshold With Transcutaneous Electrical Stimulation in Healthy Subjects

ObjectiveCurrent perception threshold (CPT) measurement is a noninvasive, easy, and semi‐objective method for determining sensory function using transcutaneous electrical stimulation. Previous studies have shown that CPT is determined by physical characteristics, such as sex, age, physical sites, and presence of neuropathy. Although the CPT reported in males is clearly higher than that in females, the reason for this difference remains unclear. This study investigates the cause of sex‐based differences in CPT and suggests an adjustment method, which may suppress the sex difference in CPT.Materials and MethodsElectrical stimulation was applied with PainVision® via five sizes of circular surface electrodes. Seventy healthy participants were examined thrice under each electrode. The relationship among body water percentage, body fat percentage, and CPT was then analyzed.ResultsCPT values are higher in males than that in females, with statistically significant sex differences with each electrode pairs (EL 1: p < 0.001; EL 2: p = 0.006; EL 3: p < 0.001; EL 4: p < 0.001; EL 5: p < 0.001). By adjusting for body fat percentage or body water percentage, the log‐transformation values (CPT values) no longer exhibit sex differences with any electrode pairs (body fat: p = 0.09; body water: p = 0.08).ConclusionWe conclude that sensitivity for perceiving electrical stimulation can be influenced by the subjects' characteristics, such as body fat or body water percentages.

From Perception Threshold to Ion Channels—A Computational Study

Small-surface-area electrodes have successfully been used to preferentially activate cutaneous nociceptors, unlike conventional large area-electrodes, which preferentially activate large non-nociceptor fibers. Assessments of the strength-duration relationship, threshold electrotonus, and slowly increasing pulse forms have displayed different perception thresholds between large and small surface electrodes, which may indicate different excitability properties of the activated cutaneous nerves. In this study, the origin of the differences in perception thresholds between the two electrodes was investigated. It was hypothesized that different perception thresholds could be explained by the varying distributions of voltage-gated ion channels and by morphological differences between peripheral nerve endings of small and large fibers. A two-part computational model was developed to study activation of peripheral nerve fibers by different cutaneous electrodes. The first part of the model was a finite-element model, which calculated the extracellular field delivered by the cutaneous electrodes. The second part of the model was a detailed multicompartment model of an Aδ-axon as well as an Aβ-axon. The axon models included a wide range of voltage-gated ion channels: NaTTXs, NaTTXr, Nap, Kdr, KM, KA, and HCN channel. The computational model reproduced the experimentally assessed perception thresholds for the three protocols, the strength-duration relationship, the threshold electrotonus, and the slowly increasing pulse forms. The results support the hypothesis that voltage-gated ion channel distributions and morphology differences between small and large fibers were sufficient to explain the difference in perception thresholds between the two electrodes. In conclusion, assessments of perception thresholds using the three protocols may be an indirect measurement of the membrane excitability, and computational models may have the possibility to link voltage-gated ion channel activation to perception threshold measurements.

Strong association between vibration perception thresholds at low frequencies (4 and 8 Hz), neuropathic symptoms and diabetic foot ulcers.

AimsTo investigate whether multi-frequency measurement of vibration perception thresholds (VPTs) can identify individuals with a high risk of developing diabetic foot ulcer or neuropathic symptoms.MethodsVPTs were measured at six different frequencies (4, 8, 16, 32, 64 and 125 Hz) on metatarsal heads 1 and 5 on the sole of the foot using a standard VibroSense Meter device in 535 type 1 diabetic (T1DM) patients and 717 non-diabetic control subjects. VPTs in control subjects were used to establish normal values for five different age groups for male and female subjects respectively. Normal values were defined as a VPT below the mean plus 1.66 x standard deviation for each group. Various definitions of abnormal VPTs were tested using either all frequencies, only lowest VPT frequencies (4 and 8 Hz) or only highest VPT frequencies (64 and 125 Hz).ResultsThe VPTs were higher in T1DM patients than in non-diabetic control subjects matched for age and gender. The low frequencies, 4 and 8 Hz, particularly were associated with the risk of diabetic foot ulcer (OR 40.7 [5.4–308.4], p = 0.0003) and with difficulties in balance and or gait (OR 1.89 [1.04–3.46], p = 0.04) difficulties and weakness (OR 2.77 [1.25–6.16], p = 0.01). The VPTs at the 125 Hz frequency were higher in short duration (≤ 10 yrs.) T1DM patients compared to age- and gender-matched control subjects.ConclusionsVibration perception thresholds at low frequencies seem to be a better indicator of the risk of developing diabetic foot ulcers, gait or balance problems or weakness of the foot. The 125 Hz frequency, however, seemed to be impaired earlier and it was the only pathological VPT frequency in patients with short duration of diabetes.This study suggests that at least four different frequencies (4, 8, 64 and 125 Hz) should be included in any examination in order to obtain a complete evaluation of the risk factors for diabetic neuropathy and diabetic foot ulcers.

Vibrotactile and thermal perception and its relation to finger skin thickness

ObjectiveQuantitative measurements of vibrotactile and thermotactile perception thresholds (VPT and TPT, respectively) rely on responses from sensory receptors in the skin when mechanical or thermal stimuli are applied to the skin. The objective was to examine if there is a relation between skin thickness (epidermis and dermis) and VPT or TPT. MethodsPerception thresholds were measured on the volar side of the fingertip on 148 male subjects, out of which 116 were manual workers exposed to hand-transmitted vibration and 32 were white-collar (office) workers. Skin thickness was measured using a high-frequency ultrasonic derma scanner system. ResultsThe difference in age, perception thresholds and skin thickness between manual and office workers was small and non-significant except for the perception of cold, which was decreased by vibration exposure. Skin thickness for both subgroups was mean 0.57 mm (range 0.25–0.93 mm). Increased age was associated with decreased perception of warmth and vibration. Lifetime cumulative exposure to vibration, but not age, was associated with decreased perception of cold. ConclusionNo association (p > .05) was found between finger skin thickness in the range of about 0.1–1 mm and vibration perception threshold for test frequencies from 8 to 500 Hz and thermotactile perception thresholds for warmth and cold. Increasing age was associated with reduced perception of vibration and warmth. Vibration exposure was associated with decreased perception of cold. SignificanceSkin thickness is a factor that may affect the response from sensory receptors, e.g., due to mechanical attenuation and thermal insulation. Thus, to evaluate perception threshold measurements, it is necessary to know if elevated thresholds can be attributed to skin thickness. No previous studies have measured skin thickness as related to vibrotactile and thermotactile perception thresholds. This study showed no association between skin thickness and vibrotactile perception or thermotactile perception.

Thermal perception thresholds among workers in a cold climate

PurposeTo investigate whether exposure to cold could influence the thermal perception thresholds in a working population.MethodsThis cross-sectional study was comprised of 251 males and females and was carried out at two mines in the northern part of Norway and Sweden. The testing included a baseline questionnaire, a clinical examination and measurements of thermal perception thresholds, on both hands, the index (Digit 2) and little (Digit 5) fingers, for heat and cold.ResultsThe thermal perception thresholds were affected by age, gender and test site. The thresholds were impaired by experiences of frostbite in the fingers and the use of medication that potentially could affect neurosensory functions. No differences were found between the calculated normative values for these workers and those in other comparative investigations conducted in warmer climates.ConclusionsThe study provided no support for the hypothesis that living and working in cold climate will lead to impaired thermal perception thresholds. Exposure to cold that had caused localized damage in the form of frostbite was shown to lead to impaired thermal perception.

Is there a connection between postprandial hyperglycemia and IGT related sensory nerve dysfunction?

Background and aimsTo assess the risk factors for sensory nerve dysfunction in subjects with isolated impaired glucose tolerance (IGT). Methods and resultsSeventy-two people with isolated IGT (WHO 1999 criteria) and 39 gender and age-matched healthy volunteers underwent detailed clinical and neurological assessment including quantitative sensory testing using the Neurometer device (current perception threshold measurement on four limbs at three different frequencies). Sensory nerve dysfunction was defined as at least two abnormalities on any frequencies on the upper or lower limbs.Sensory nerve dysfunction was more prevalent among subjects with IGT compared to controls (58.3 vs. 10.3%, OR: 11.23, 95%CI: 3.57–35.35). This association was not influenced by BMI, systolic and diastolic blood pressure, heart rate and autonomic neuropathy (multiple adjusted OR: 13.87, 95%CI: 3.18–60.58), but further adjustment for glycaemic measures abolished the association (OR: 1.58, 95%CI: 0.07–35.68). Assessing the components of glycaemic measures separately, the association between sensory nerve dysfunction and IGT was not affected by HbA1c (OR: 13.94, 95%CI: 1.84–105.5). It was, however, substantially attenuated by fasting plasma glucose (OR: 6.75, 95%CI: 1.33–34.27) while the significance was lost after adjustment for 120 min postload glucose level (OR: 3.76, 95%CI: 0.26–54.10). In the pooled population assessed, independent determinants of sensory nerve dysfunction were older age, 120 min glucose, higher height and cardiovascular autonomic neuropathy at near significance. ConclusionsSensory nerve dysfunction amongst subjects with IGT was not explained by cardiovascular covariates, only by glycaemic measures. In addition to 120 min glucose, cardiovascular autonomic neuropathy at borderline significance, age, and height were the independent determinants of sensory nerve dysfunction.

Efficacy of Administration of an Angiotensin Converting Enzyme Inhibitor for Two Years on Autonomic and Peripheral Neuropathy in Patients with Diabetes Mellitus.

Aim. To evaluate the effect of quinapril on diabetic cardiovascular autonomic neuropathy (CAN) and peripheral neuropathy (DPN). Patients and Methods. Sixty-three consecutive patients with diabetes mellitus [43% males, 27 with type 1 DM, mean age 52 years (range 22–65)], definite DCAN [abnormal results in 2 cardiovascular autonomic reflex tests (CARTs)], and DPN were randomized to quinapril 20 mg/day (group A, n = 31) or placebo (group B, n = 32) for 2 years. Patients with hypertension or coronary heart disease were excluded. To detect DPN and DCAN, the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE), measurement of vibration perception threshold with biothesiometer (BIO), and CARTs [R-R variation during deep breathing [assessed by expiration/inspiration ratio (E/I), mean circular resultant (MCR), and standard deviation (SD)], Valsalva maneuver (Vals), 30 : 15 ratio, and orthostatic hypotension (OH)] were used. Results. In group A, E/I, MCR, and SD increased (p for all comparisons < 0.05). Other indices (Vals, 30 : 15, OH, MNSIQ, MNSIE, and BIO) did not change. In group B, all CART indices deteriorated, except Vals, which did not change. MNSIQ, MNSIE, and BIO did not change. Conclusions. Treatment with quinapril improves DCAN (mainly parasympathetic dysfunction). Improved autonomic balance may improve the long-term outcome of diabetic patients.

Measurement of perception thresholds for electrical noise stimuli.

In previous research, the application of sub-threshold electrical nerve stimulation (SENS) to peripheral nerves has been shown to improve tactile sensitivity. SENS has applications in the symptomatic treatment of a wide array of conditions that result in the loss of peripheral nerve function. These include diabetes, stroke, and age related peripheral neuropathy. The technology is dependent on careful control of the amplitude of the intervention stimulation relative to the user's perception threshold. However, little is known about the factors that influence the perception threshold and whether it can be treated as a constant. Here we present a study where we applied a two alternate forced choice paradigm to determine electrical perception threshold. We investigated participant, noise frequency characteristics, electrode location, electrode type, and electrode impedance characteristics as explanatory factors for the variability seen in the threshold outcome. We find that the electrical perception threshold is dependent on the frequency characteristics of the signal applied, but varies widely without correlation to the remaining variables. It was also highly variable when re-tested under identical conditions. Our results cast doubt on the ability to treat the electrical threshold as a single value that holds constant for a particular participant and electrode placement. This finding has significant implications in SENS applications.

Sensory function assessment of the human male lower urinary tract using current perception thresholds

To evaluate the feasibility and reliability of current perception threshold (CPT) measurement for sensory assessment of distinct locations in the male lower urinary tract (LUT). Twelve male subjects (>18 years) without LUT symptoms or medical comorbidities were eligible. CPTs were determined twice (interval: 7-20 days) at the bladder dome, trigone and the proximal, membranous, and distal urethra. Square wave electrical stimulation of 3 Hz/0.2 ms and 0.5 Hz/1 ms was applied using a transurethral 8F catheter placed under fluoroscopic control. Bladder volume was kept constant (60 mL) using a second 10F catheter. Repetitive measurements and reliability were assessed by analysis of variance (ANOVA) and intraclass correlation coefficient (ICC). The ANOVA revealed significant main effects for stimulation site (P = 0.008) and type of stimulation (P < 0.001) with lower CPTs for 0.5 Hz/1 ms compared to 3 Hz/0.2 ms. There was no significant effect for visit number (P = 0.061). CPTs were higher for bladder dome than for proximal (0.5 Hz/1 ms: P = 0.022; 3 Hz/0.2 ms: P = 0.022) and distal urethra (0.5 Hz/1 ms: P = 0.026; 3 Hz/0.2 ms: P = 0.030). Reliability of CPT measurements was excellent to good (ICC = 0.67-0.96) except for the bladder dome (5 Hz/1 ms: ICC = 0.45; 3 Hz/0.2 ms: ICC = 0.20) and distal urethra (3 Hz/0.2 ms: ICC = 0.57). CPTs can be reliably detected at different LUT locations. However, alert and compliant subjects are essential. CPTs of LUT may become a complementary assessment method providing information on responsiveness and sensitivity of afferent LUT nerves. This is especially relevant for urethral afferents, which are not covered by standard urodynamic investigations. Neurourol. Urodynam. 36:469-473, 2017. © 2016 Wiley Periodicals, Inc.