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Results for “Sensory Thresholds”

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At least 19 recordsLinked to original sources
PubMed1992

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↗
PubMed1992

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↗
PubMedDate not supplied

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↗
PubMed1992

Study on the correlation between subjective perception of bladder filling and the sensory threshold towards electrical stimulation in the lower urinary tract.

In 426 urodynamic patients with or without a neuropathic bladder sensation in the lower urinary tract was determined with 2 different investigation methods. During medium-fill cystometry the perception of filling was evaluated. At each sensation the bladder volume and detrusor pressure were noted. The electrical threshold was determined at different areas of the lower urinary tract with constant current stimulation. No correlation was found between the volume and pressure variables at which filling perception occurred and the electrical sensory thresholds. The levels of sensory threshold of the bladder and urethra in sensory urgency and hyposensitive bladder cases were not different from those seen in the normosensitive patients. Of the patients with disturbed or absent electrosensation 18% had a normal filling perception. Filling perception and electrosensation seem to correspond with 2 different areas of the sensory innervation of the lower urinary tract. To gain a maximum of information on bladder sensation, electrosensation as part of exteroceptive perception and filling perception as part of proprioception should be studied.

Adolescent↗
PubMed1991

Studies on sensory threshold of different parts of the lower urinary tract measured electrically.

In 450 patients, sensory thresholds of bladder wall and of different parts of the urethra were determined with constant-current stimulation. These thresholds were compared with those of the skin of the forearm in the same patients. In both sexes, threshold of the bladder was higher than that of the urethra. Threshold of the female urethra did not differ much from skin threshold. In the male patients, the threshold of the prostatic urethra was higher than that of the penile urethra; the latter did not significantly differ from the skin threshold. In female patients, thresholds were usually lower than the corresponding thresholds in males. These data on exteroception give additional information on the sensory innervation of the different parts of the lower urinary tract.

Adolescent↗
PubMed1975

A health survey of granite workers in Finland: radiographic findings, respiratory function, hearing, electric sensory thresholds of the fingers and subjective symptoms.

Results from a health survey of 777 granite workers, exposed to quartz dust, noise and/or machine vibration, and 122 unexposed "controls" are reported. The survey included chest X-rays, pulmonary function tests, a hearing examination, the determination of the electric sensory thresholds of the fingers, and questionnaires on the subjective symptoms of the respiratory system and upper limbs. The exposed workers' radiographic findings (except for a 2.6 % rate of silicosis), respiratory functions, and sensory thresholds did not differ significantly from those of the controls. Granite drillers had a high prevalence of hearing defects. Respiratory symptoms were common among drillers and sandblasters, and subjective symptoms of the upper limbs due to vibration occurred among the granite dressing workers who used pneumatic hammers. Both primary and secondary measures of prevention are strongly recommended for the granite industry, primarlily for quartz dust exposure and its health effects.

Adult↗
PubMed1979

Trialwise tracking method for measuring drug-affected sensory threshold changes in animals.

Rats and rhesus monkeys were trained under a multiple schedule, the components of which were random ratio schedules for food presentation and for shock presentation. The discriminative stimulus for the shock presentation component was a pure tone for the rats and a light for the rhesus monkeys. In the test session under the extinction condition for the shock presentation component, the intensity of the discriminative stimulus was successively either decreased by fixed units when the conditioned suppression was observed or increased when the conditioned suppression was not observed. The levels finally oscillated within a narrow range around the threshold. The auditory thresholds of rats were increased by intramuscular administration of quinidine at 20 mg/kg and also by repeated intramuscular administration of kanamycin at 250 and 500 mg/kg/day. In rhesus monkeys, visual thresholds were raised by application of pilocarpine at 0.02-0.16 mg/kg to the eyes and also by subcutaneous administration of LSD-25 at 4-8 micrograms/kg in one monkey and at 20-30 micrograms/kg in another. The method used for tracking the animals' sensory thresholds was sensitive enough to test the selective effect of the drugs and was also a relatively easy way to obtain a stable behavioral baseline for experimental purposes.

Animals↗
PubMed1977

Mucosal sensory threshold of urinary bladder and urethra measured electrically.

Urodynamic investigation consists of evaluation of detrusor stretch responses, muscle strength and motor activities. The electrosensitivity test is the only method to evaluate mucosal sensory threshold of exteroceptive receptors in urinary bladder and posterior urethra thus checking integrity of sensory reflex arcs. A constant current square wave pulse of 0.5 msec duration and 10 msec interval is used with increasing amplitude from 0 to 25 mA until the patient registers sensation. Skin electrosensitivity is tested to start with, then perception threshold of urinary bladder and posterior urethra is recorded. Sensory deficits after segmental sacral nerve lesions or after peripheral nerve injuries postoperatively can be quantitated in terms of milliamperes. The urgency syndrome in adult women is characterized by a low perception threshold in the posterior urethra (below 1 mA) while the bladder electrosensitivity is within normal range (3--10 mA).

Adult↗
PubMed1977

[Stabilization of operant responses during a program of variable interval reinforcement as a preliminary investigation of sensory thresholds using conditioned suppression in the cat].

Cats were trained to press a key during a variable interval schedule of reinforcement with a limited hold contingency. The main modifications of the response rate were observed when the subject missed one reinforcement or obtained more than one reinforcement during the limited hold. The existence of a zone of lesser variability in the mean response rate is shown to be linked to the occurrence of the last reinforcement. This result suggests an original methodological contingency concerning the use of conditioned suppression in psychophysics. The schedule of sensory stimulation should be established for each subject during that period of lesser variability between two reinforcements.

Animals↗
PubMed1977

Sensory threshold measurements for electrical stimulation of the digits.

Repeated impedance measurements of electrical stimulation to the finger using the stimulator of an electromyograph were evaluated in seven normal subjects to determine whether reliable threshold values to perception of pain could be obtained. Stimuli were delivered through ring or disc electrodes separated by 3 cm and interfaced to the skin of the digit with EKG paste. Stimulation through these electrodes produced only relative values of threshold, expressed as a potentiometer dial setting. Such values proved to be meaningful only when repeated during a single session. A possible reason for the apparent unreliability of repeated measurements over time is discussed. When a constant current source was substituted, reliable and consistent threshold measurements were obtained. It is suggested that the clinician wishing to make accurate, repeatable and quantified measurements of patient thresholds to electrical stimulation of the finger employ a nonloading source, namely, a constant current or constant voltage stimulator.

Adult↗
PubMedDate not supplied

[A stochastic approach to solving the problem of sensory system thresholds].

On the basis of an analysis of mathematical models realizing concept of discrete and signal detection probability of the threshold it is shown that utilization for describing the discrete model concepts of probability and the apparatus of Dirac delta functions and root-mean-square of noise distribution being reduced to zero in the continuous model the analytical expressions of the models are identical. The evidence obtained shows inner unity of the examined thresholds models and universal nature of the thresholds model of Swets, Tanner and Birdsall built on the basis of the statistical theory of signal detectability. It provides solution of one of the central problems of psychophysics--that of the threshold of the sensory systems.

Models, Theoretical↗
PubMed1976

Sensory and reflex responses to tooth pulp stimulation in man.

Experiments have been carried out to investigate whether all tooth pulp afferent nerves are capable of producing pain. Monopolar and bipolar stimuli were applied to teeth in human subjects and sensory thresholds determined. EMGs were recorded from the masseter and the anterior digastric muscles. With stimuli up to three times the sensory threshold, no response could be detected in the digastric but at, or just above, the sensory threshold, inhibitory effects were produced in masseter muscle. The latency of the muscle response with bipolar stimulation was 18-22 msec. There was no evidence of stimulus spread to nerves outside the teeth. Bipolar and monopolar stimulation both produced the same sensation but this was not described as painful. It is concluded that some pulpal afferent nerves may not be capable of producing pain, and that the sensory and reflex responses at threshold were probably produced by the same fibres.

Adult↗
PubMed1991

Impaired anal sensation and early diabetic faecal incontinence.

Faecal incontinence develops in up to 20% of diabetic patients. To try to determine the relative contributions of sensory and motor neuropathy in this troublesome complication, anorectal function was examined in 10 male diabetic patients with early faecal incontinence (mucus leakage or faecal staining without the need to wear a pad), 10 asymptomatic male diabetic patients, and 10 normal control subjects. Motor function was tested using anal manometry to determine the resting and maximum squeeze pressure, and the functional anal canal length. No significant differences were found between the groups. Sensory function was tested by measuring the mucosal sensitivity to electrical stimulation, and the response to inflation of a balloon in the rectum. In the mid-anal canal position the symptomatic patients had a significantly higher sensory threshold at 6.6 +/- 2.8 mA compared with 3.0 +/- 1.2 mA in the normal control subjects (p less than 0.002), and in the high anal zone symptomatic patients had a significantly elevated sensory threshold at 9.1 +/- 2.0 mA compared with 4.6 +/- 1.6 mA in asymptomatic patients and 3.6 +/- 1.3 mA in the normal control subjects (both p less than 0.001). There were no significant differences in the first sensation of fullness, maximum tolerated volume or percentage fall from resting pressure between the groups on inflation of the balloon. Elevation of the sensory threshold in the upper anal canal is an early abnormality in the development of diabetic faecal incontinence.

Anal Canal↗