Cutaneous sensory threshold stimulation with high frequency square-wave current. I. The relationship of electrode dimensions to the sensory threshold.
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Electrodes↗
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Cutaneous sensory threshold stimulation with high frequency square-wave current. II. The relationship of body site and of skin diseases to the sensory threshold.
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Humans↗
Weighted needle pinprick sensory thresholds: a simple test of sensory function in diabetic peripheral neuropathy.
A simple device is described, consisting of 12 weighted 23 gauge disposable needles (0.2 to 5.2 g), for testing sensation in busy diabetic clinics. The pinprick sensory threshold (PPT) is the lightest weighted needle which consistently elicits a sharp sensation. The subjects were 48 healthy controls (hospital staff), 44 diabetic patients without neuropathic symptoms, and 35 diabetic patients with chronic painful neuropathy. In the controls, the mean PPT from the right hand and foot obtained on two test occasions a week apart did not differ significantly. In diabetic patients without symptomatic neuropathy, the mean PPT in the right hand and right foot were significantly higher than in the controls. The diabetic patients with painful neuropathy had clearly increased mean PPT in the right hand and foot compared with controls. Marstock thermal limen in diabetic patients with painful neuropathy correlated significantly with PPT determinations. PPT and thermal thresholds probably give comparable information on small fibre dysfunction in diabetic patients with symptomatic neuropathy. Compared with thermal threshold determinations however, the weighted needle apparatus is inexpensive, simple, and rapid to use.
Adolescent↗
Normal distributions of thermal and vibration sensory thresholds.
The distributions of sensory thresholds were estimated in a healthy population while controlling for potential covariates. Using the method of levels and the two-alternative forced choice, thermal and vibration thresholds respectively were measured in the hand and foot of 148 subjects. Age was uniformly distributed between 20 and 86 years. Independent effects of age, gender, height, and skin temperature were estimated using multiple linear regression. Parametric and nonparametric methods were used to estimate the distributions of interest. Significant age-related increases were observed for all vibration thresholds (P < 0.0001), and for thermal thresholds in the foot (P < 0.0002). Percentiles were estimated for thermal thresholds in the hand and age-adjusted continuous distributions were calculated for all other thresholds. Height was positively associated with vibration thresholds in the foot (P < 0.003), and appropriate corrections were made. Our results provide reference values for thermal and vibration sensory thresholds in a healthy population, allowing for the accurate diagnosis of disordered sensory function.
Adult↗
Acupuncture and sensory thresholds.
The effect of acupuncture on sensory thresholds was studied in 6 healthy subjects. The modes of acupuncture studied were: 1. manual stimulation, 2. electrical stimulation at 2 Hz, 3. electrical stimulation at 80 Hz. Superfiscial-acupuncture was used as placebo. Insertions of needles or application of electrodes were bilateral, at St 7 (intrasegmental) or Li 4 (extrasegmental). The study showed that manual or electro-acupuncture were effective when used intrasegmentally, raising pain threshold values 1.1 to 1.4 times that prior to stimulation. The pain threshold elevation obtained was not significantly related to plasma levels of beta-endorphin, ACTH or prolactin. Other sensory thresholds, thermal, vibrotactile and electrotactile were unaffected by such conditioned stimulation. Superfiscial-acupuncture had no significant effect on the sensory thresholds tested.
Acupuncture Analgesia↗
Sensory thresholds in the male urethra measured by electrical stimulation.
The sensory pathways innervating the male urethra were investigated by recording the sensory thresholds with electrical stimulation. Twenty-six male subjects (age 16 to 73 years) were included in the study. Ring-electrodes mounted on a Foley catheter were used for stimulation in proximal and distal urethra. Square wave pulses (duration 0.5 ms) were delivered with a constant current stimulator at different frequencies and the lowest intensity felt by the subject was defined as the threshold. The sensory thresholds were in the order of 0.5 to 5 mA and decreased with increasing stimulation frequency. All patients described a qualitative difference in the experienced sensation when comparing proximal and distal urethral stimulation. The reason for this is discussed. The possible use of this method as an adjunct to the urodynamic investigation in diagnosing neurogenic lesions is proposed.
Adolescent↗
Relationship between oral sensory thresholds and depressive moods.
AIMS: The aims were to compare the sensory thresholds on the tip of the tongue with on the dorsum of the hand, and to investigate the relationship between the sensory threshold and depressive mood with volunteers whose psychological conditions were normal. METHODS: Fifty-five subjects (28 women, 27 men) took psychiatric structured diagnostic interview and Self-rating Depression Scale (SDS). In the next step, the quantitative sensory tests (light touch sensation and thermal sensory test) were carried out on the tongue and the hand. Then we investigated the relationship between depressive moods and sensory thresholds on the tongue and the hand using logistic regression model. RESULT: The sensory thresholds on the tip of the tongues were significantly different from those on the dorsum of the hands. Only on tongue tip, increment of SDS had relation to the thresholds of innoxious thermal stimulation (OR=0.152, 95% CI. 0.049-0.478) and noxious heat stimulation (OR=0.352, 95% CI. 0.169-0.734). CONCLUSION: This finding might support for the idea that depressive mood had closer association with the tongue of the orofacial areas than the dorsum of the hand.
Adolescent↗
Sensory thresholds for vibration, perception and pain in diabetic patients aged 15-50 years.
The sensory thresholds for vibration, perception and pain were measured in 375/395 of all diabetic patients aged 15-50 years in Umeå county (population 118,500), 79% of whom had type 1 diabetes mellitus (DM). The results were compared with those from 100 healthy control subjects. Both type 1 and type 2 diabetic patients had significantly elevated sensory thresholds compared to control subjects. In multiple regression analysis, patients with type 1 DM had significant associations between elevated sensory thresholds and age, duration of diabetes, height but not with smoking. Type 2 diabetic patients had a significant association only with height and control subjects with age and height. Thresholds were significantly higher in men than in women with type 1 and type 2 DM and in control subjects but were no longer significant after normalizing for height. Thus, age, duration of DM and tall stature appear to be major risk factors and smoking a minor risk factor for elevation of sensory thresholds both in type 1 and type 2 DM and also in healthy control subjects. Gender differences depend on differences in height.
Adolescent↗
Variance of sensory threshold measurements: discrimination of feigners from trustworthy performers.
Sensory threshold measurements are criticized as subjective and therefore not to be relied upon in clinical diagnostic practice, particularly when deliberate deception by the patient is suspected. In an attempt to devise a method which permits dependable sensory threshold interpretation, individual variability of thresholds was examined in normal and neuropathic subjects. Normals were also instructed to feign sensory impairment resulting from hypothetical injury. For each subject, a number of threshold readings were averaged, yielding individual means and variances. Feigning normal subjects evidenced a larger variance compared to trustworthy normal and neuropathic subjects. Thus, alertness to variance reinforces the psychophysical analysis: small variance values suggest trustworthy normal or pathological results, whereas large variance calls the interpreter's attention to feigned results or inattentive test performance.
Cold Temperature↗
Elevation of sensory thresholds in the prostatic urethra after microwave thermotherapy.
OBJECTIVES: To determine whether transurethral microwave thermotherapy (TUMT) affects the sensory threshold in the posterior urethra and whether such an effect influences urinary storage symptoms. PATIENTS AND METHODS: The sensory threshold was measured before and at 3 and 12 weeks after TUMT in 13 men with minor obstructive symptoms caused by benign prostatic hyperplasia. Sensations were evoked by electrical stimulation at different frequencies, using a bipolar ring-electrode mounted on a urethral catheter. Changes in sensory thresholds were evaluated in the patients both as a group and individually. The patients were interviewed about their symptoms at each measurement. RESULTS: After TUMT, 12 patients were satisfied and reported decreased irritative symptoms, primarily less frequent nocturnal micturition; two patients were cured of urgency incontinence. In 11 of the satisfied patients, and the unsuccessful patient, decreased urge accompanied increased sensory thresholds. Thresholds elevated by >/= 30% were correlated with decreased irritative symptoms. CONCLUSIONS: TUMT decreases sensitivity in the posterior urethra, which may alleviate storage symptoms.
Electric Stimulation↗
Quantitative sensory testing in cluster headache: increased sensory thresholds.
To determine if recently reported changes in sensory thresholds during migraine attacks can also be seen in cluster headache (CH), we performed quantitative sensory testing (QST) in 10 healthy subjects and in 16 patients with CH. Eight of the patients had an episodic CH and the other eight a chronic CH. The tests were performed on the right and left cheeks and on the right and left side of the back of the hands to determine the subjects' perception and pain thresholds for thermal (use of a thermode) and mechanical (vibration, pressure pain thresholds, pin prick, von Frey hairs) stimuli. Six patients were examined in the attack-free period. Three were also willing to repeat the tests a second time during an acute headache attack, which was elicited with nitroglycerin. The healthy subjects performed the experiments in the morning and evening of the same day to determine if sensory thresholds are independent of the time of day. If they were, this would allow estimation of the influence of the endogenous cortisone concentration on these thresholds. The control group showed no influence of the time of day on the thresholds. There was a significant difference in pain sensitivity between the back of the hands and the cheeks (P<0.05): higher thresholds were found on the back of the hands. The thresholds generally exhibited little intersubject variability, indicating that QST is a reliable method. There was also a significant difference between the test areas in the patient group (P<0.001): the cheeks were also more sensitive than the back of the hands. In comparison with reference data of healthy volunteers, the detection thresholds were increased in the patients on both test areas. These were statistically significant for warmth, thermal sensory limen (TSL), heat and pressure on the back of the hands (P<0.04) and for the warmth and TSL thresholds on the cheeks (P<0.05). There were no differences in the thresholds regardless of whether the patients were examined in or outside of a cluster bout. Furthermore, we found no cutaneous allodynia in the three patients tested during an attack. The increased sensory thresholds on the cheeks as well as on the back of the hands are in agreement with an increased activation of the patients' antinociceptive system. The seasonal variation and the temporal regularity of single attacks as well as the findings in imaging studies indicate that the hypothalamus is involved in the pathophysiology of CH. In view of the strong connectivity between the hypothalamus and areas involved in the antinociceptive system in the brainstem, we hypothesize that this connection is the reason for the increased sensory thresholds in CH patients found in our study.
Adaptation, Physiological↗
Sensory thresholds of normal human feet.
HYPOTHESES/PURPOSE: Although several studies in the literature have evaluated the abnormal sensory thresholds of diabetic feet to Semmes-Weinstein monofilament testing, there is very limited data on the sensory thresholds of individuals without diabetes or peripheral neuropathy. The purpose of this study was to assess the dorsal and plantar sensation of the feet from 40 healthy, college-aged volunteers using Semmes-Weinstein monofilaments. CONCLUSIONS/SIGNIFICANCE: Semmes-Weinstein testing is a useful tool in predicting which diabetic patients may be at risk for ulceration of the feet. Several studies have determined 5.07 to be the threshold for protective sensation. Based on the normal values derived in this study, the inability to feel a Semmes-Weinstein monofilament of 5.07 (as in diabetic neuropathy) represents a sensory threshold that is more than 50 times greater than normal. This means that roughly 98% of the sensory ability has been lost. METHODS: 20 male and 20 female volunteers between the ages of 18 to 22 years old were selected. None had a history of any significant injury or previous surgery to the foot or ankle. There were no known medical conditions associated with decreased foot sensation, (e.g.- diabetes, syphilis, leprosy, myelomeningocele, syringomyelia, or hereditary neuropathy). Volunteers were also questioned regarding participation in athletic activities. The subjects were blindfolded with the leg resting comfortably on a chair as 14 plantar and 5 dorsal locations were tested on each foot. The right foot was always tested first. Each site on the foot had the Semmes-Weinstein monofilaments applied to it first, in an order of increasing stiffness, then repeated in decreasing order, using all twenty monofilaments in the set. A positive threshold response was recorded when the subject could feel the filament and could accurately locate where on the foot the stimulus had been applied. The left foot was then tested in an identical fashion. RESULTS: The mean sensitivity for all sites was 3.63 (0.0075 SEM). There were significant differences between sites, between using increasing or decreasing monofilament stiffness, between subjects, and in some instances, between right foot and left foot values. When testing was performed from the higher to lower monofilament stiffness, subjects were found to have significantly better sensitivity, which indicates the importance of a consistent testing protocol (either all up or all down). Sensation in the lesser toes and the arch were the most sensitive followed by the hallux and the plantar metatarsal heads. The least sensitive site was the heel, with 1/6th the sensitivity of the most sensitive toes.
Adolescent↗
Effect of radical prostatectomy on sensory threshold and pressure transmission.
PURPOSE: The mechanisms involved in post-radical prostatectomy incontinence remain unclear despite previous anatomical and functional studies. In addition, the factors responsible for the restoration of continence are not well studied. To improve our understanding of the alterations in continence mechanisms, we prospectively investigated the temporal changes in urodynamic parameters after radical prostatectomy. MATERIALS AND METHODS: Cystometry, urethral pressure profilometry and posterior urethral sensory threshold measurements were performed in patients undergoing radical prostatectomy. Preoperative pressure transmission was determined by the maximal urethral pressure divided by the maximal abdominal pressure during cough maneuvers at a bladder volume of 200 ml. Postoperative sensory threshold, pressure transmission (% of pressure transmission), maximal urethral closure pressure and functional sphincter length were measured 6 weeks and 6 months after prostatectomy. These parameters were compared between continent and incontinent patients. RESULTS: Preoperative and postoperative urodynamic studies were completed in 34 patients. The continence rate after 6 weeks was 18% (6 patients) and improved to 82% (28) after 6 months. Preoperatively sensory threshold was 16 +/- 11 mA. After 6 weeks and 6 months, respectively, sensory threshold was significantly higher in incontinent (84 +/- 11 mA., 70 +/- 8 mA.) compared to continent (65 +/- 8 mA., 41 +/- 12 mA.) patients. Preoperative proximal urethral sensory threshold was not correlated with degree of postoperative incontinence determined by pad tests. Pressure transmission was not different in continent and incontinent patients postoperatively. After 6 weeks and 6 months, respectively, pressure transmission was 77% and 91% in continent, and 37% and 58% in incontinent patients (p = 0.04, p = 0.03). Maximal urethral closure pressure was significantly higher in continent patients (35 +/- 6 cm. H2O) compared to incontinent patients (11 +/- 9 cm. H2O). Sphincter length decreased from 50 mm. preoperatively to 24 mm. after 6 weeks and 25 mm. after 6 months. There was no difference in sphincter length between continent and incontinent patients. CONCLUSIONS: Posterior urethral sensitivity and pressure transmission are impaired immediately after prostatectomy. An improvement in these parameters after 6 months is associated with the restoration of continence. These observations suggest that urinary continence after radical prostatectomy depends on the integrity of posterior urethral sensation and the efficiency of pressure transmission.
Humans↗
Standardization of barostat procedures for testing smooth muscle tone and sensory thresholds in the gastrointestinal tract. The Working Team of Glaxo-Wellcome Research, UK.
An international working team of 13 investigators met on two occasions to develop guidelines for standardizing the procedures used to test gastrointestinal muscle tone and sensory thresholds using a barostat. General recommendations were: (1) Use a thin-walled plastic bag that is infinitely compliant until its capacity is reached. Maximum diameter of the bag should be much greater than the maximum diameter of the viscus. (2) The pump should be able to inflate the bag at up to 40 ml/sec. (3) Pressure should be monitored inside the bag, not in the pump or inflation line. (4) Subjects should be positioned so that the bag is close to the uppermost surface of the body. (5) For rectal tests, bowel cleansing should be limited to a tap water enema to minimize rectal irritation. Oral colonic lavage is recommended for studies of the proximal colon, and magnesium citrate enemas for the descending colon and sigmoid. (6) If sedation is required for colonic probe placement, allow at least one hour for drug washout and clearance of insufflated air. Ten to 20 min of adaptation before testing is adequate if no air or drugs were used. (7) The volumes reported must be corrected for the compressibility of gas and the compliance of the pump, which is greater for bellows pumps than for piston pumps. (8) Subjects should be tested in the fasted state. For evaluation of muscle tone: (9) The volume of the bag should be monitored for at least 15 min. For evaluation of sensory thresholds; (10) It is recommended that phasic distensions be > or = 60 sec long and that they be separated by > or = 60 sec. (11) Sensory thresholds should be reported as bag pressure rather than (or in addition to) bag volume because pressure is less vulnerable to measurement error. (12) Tests for sensory threshold should minimize psychological influences on perception by making the amount of each distension unpredictable to the subject. (13) Pain or other sensations should be reported on a graduated scale; not "yes-no." The working team recommends verbal descriptor scales, containing approximately seven steps, or visual analog scales in which subjects place a mark on a straight line marked "none" on one end and "maximum" on the other end. (14) It is recommended that subjects should be asked to rate the unpleasantness of distensions separately from their intensity.
Animals↗
Sensory thresholds and motor responsiveness in thyroid disease: their responses to treatment and warming.
It has been our clinical observation that patients with hypothyroidism are relatively insensitive to the discomfort of venepuncture, whereas thyrotoxic patients seem to have a heightened sensitivity. In an initial study we have measured the sensory thresholds of perception along with motor responsiveness in hypothyroid, thyrotoxic and euthyroid subjects, employing a simple and readily reproducible technique. Sensory thresholds were elevated and motor responsiveness impaired in hypothyroid subjects as compared to euthyroid controls. In thyrotoxic subjects, motor responsiveness was significantly enhanced, but sensory thresholds did not differ from control values. In a subsequent study the threshold abnormalities of thyroid dysfunction were corrected by rendering the patients euthyroid with appropriate therapy. Warming a further group of untreated hypothyroid patients produced a similar improvement in motor responsiveness to that seen in the L-thyroxine-treated group, thus implying that this parameter is at least, in part, temperature dependent. Sensory thresholds would seem to be reliable reflectors of tissue thyroid status in hypothyroidism, whereas motor responsiveness seems the better guide to thyroid status across the whole spectrum of thyroid function.
Carbimazole↗
Normal values for sensory thresholds in the cervical dermatomes: a critical note on the use of Semmes-Weinstein monofilaments.
In many healthy subjects, sensory thresholds for touch using Semmes-Weinstein monofilaments appear to be higher than the 2.83 filament, which some authors have suggested as a screening instrument. The currently proposed normal values, the interpretation of results, as well as the calibration of the filaments are questioned. A normative study of 20 normal subjects using Semmes-Weinstein monofilaments was undertaken at a pain clinic in a university hospital. The main outcome measures were sensory thresholds (touch) in dermatomes C3 to C8. Per subject, 24 sites were tested and 50 sites in dermatome C5 left of one subject. The threshold distribution patterns were analyzed. The mean threshold expressed in log (10 x F; with F = force in milligrams) of all sites (n = 480) in normal subjects was 3.10 (95% confidence interval, 2.34-3.86). The mean threshold per subject was 3.10 (range, 2.70-3.50). The mean threshold of 50 sites in dermatome C5 left of one healthy subject was 3.22 (range, 2.42-4.02). In the study contained herein, sensory thresholds in the cervical dermatomes have been shown to be higher than the generally proposed normal values. The cervical dermatomes show thresholds from 0.13 to 8.47 mN. This concurs with other authors. Results depend on the testing method, which in this study was different from previous studies. The testing method must be described accurately. The distribution of thresholds within all tested sites, dermatomes, subjects, or even within one dermatome in one subject are comparable. Individual results have to be related to the mean of the subject to determine abnormality. Calibration of the monofilaments is important. When these terms are met, testing with Semmes-Weinstein monofilaments is an easy, reliable, and relatively inexpensive method of quantitative sensory testing and can be a useful tool in the process of rehabilitation.
Adult↗
Lowered oesophageal sensory thresholds in patients with symptomatic but not excess gastro-oesophageal reflux: evidence for a spectrum of visceral sensitivity in GORD.
Some patients undergoing ambulatory oesophageal pH monitoring to investigate symptoms suggestive of gastro-oesophageal reflux disease (GORD) are found to have oesophageal acid exposure within the physiological range but show a close correlation between their symptoms and individual reflux episodes. It is suggested that these patients might exhibit enhanced oesophageal sensation, akin to the heightened perception of both physiological and provocative stimuli in the gut that has been described in patients with functional gastrointestinal disorders. This study tested the hypothesis by measuring the sensory thresholds for oesophageal balloon distension and discomfort in 20 patients with symptoms of GORD, in whom ambulatory pH monitoring had shown normal acid exposure times, but in whom the symptom index for reflux events was 50% or greater, and compared these with 15 healthy volunteer controls, and with control groups with confirmed excess reflux. The study group showed lower thresholds both for initial perception of oesophageal distension, and for discomfort, compared with healthy controls (median ml (range)); 7.5 (2-19) v 12 (6-30) (p = 0.002) and 10 (5-20) v 16 (8-30) (p < 0.0001), respectively. Sensory thresholds in the study group were also significantly lower than in patients with excess reflux, and than patients with Barrett's oesophagus, who also exhibited significantly higher sensory thresholds than healthy controls. No differences in sensory thresholds for somatic nerve stimulation were found between the study group and health controls. The results show a spectrum of visceral sensitivity in GORD, with enhanced oesophageal sensation in patients with symptomatic but not excess gastro-oesophageal reflux, suggesting that their symptoms result from a heightened perception of normal reflux events.
Adolescent↗
The effect of subarachnoid lidocaine and combined subarachnoid lidocaine and epidural bupivacaine on electrical sensory thresholds.
Eight patients undergoing abdominal surgery received a combination of spinal anesthesia (catheter at L2-3 level) and epidural anesthesia (catheter at T10-11 level). Sensory thresholds to electrical stimulation were measured at the S1, L1, T10, and T5 levels before injection, after spinal anesthesia, and after the addition of epidural anesthesia. Subarachnoid injections with 5% lidocaine (without dextrose) were given until a T4 sensory level to pinprick was obtained (mean dose, 175 mg lidocaine). The mean sensory thresholds were increased from 2.2 +/- 0.3, 2.4 +/- 0.4, 2.9 +/- 0.4, and 3.8 +/- 0.4 mA to 21.3 +/- 4.3, 13.3 +/- 4.9, 10 +/- 4.4, and 10.6 +/- 4.3 mA, respectively (p less than 0.05 at all levels). The addition of 5 ml 0.5% epidural bupivacaine further increased the mean sensory thresholds to 26.9 +/- 3.1, 21.7 +/- 4.1, 21.3 +/- 4.1, and 17.5 +/- 4.7 mA, respectively (p less than 0.05 at all levels). Combined subarachnoid and epidural local anesthetics provide an enhanced afferent block not obtainable by either technique alone.
Aged↗