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Sensation and action during active and passive movement.

In order to determine the cause of active or passive sensation and action, we studied the effect of perception on gaze and posture control. Normal adults and a patient with bilateral labyrinthine loss underwent whole body rotation seated in a chair (120 degrees/s) or standing on a platform (60 degrees/s), while tilting their head with their vision normal or covered. Eye movements were recorded by a CCD video camera and body sways by a force platform. In normal subjects, gaze and posture became ataxic when head tilting with their vision covered, but they remained skilled under conditions of normal vision. The patient with bilateral labyrinthine loss did not undergo the effect of head tilting with no vision. It seems likely that sensation and action, whether they are skilled or ataxic, are controlled by the perception of an outer world which is integrated from visual and vestibular inputs and functions as a vector in the head.

Adult↗

Combined effects of fabric air permeability and moisture absorption on clothing microclimate and subjective sensation during intermittent exercise at 27 degrees C.

The present paper aimed at determining the combined effects of two different levels of air permeability and moisture absorption, in terms of clothing microclimate and subjective sensation, in resting and exercising subjects at an ambient temperature of 27 degrees C, a relative humidity of 50% and an air velocity of 0.14 m s-1. Three kinds of clothing ensemble were investigated: (1) polyester clothing with low moisture absorption and low air permeability (A), (2) polyester clothing with low moisture absorption and high air permeability (B), and (3) cotton clothing with high moisture absorption and high air permeability (C). The subjects exercised for 10 min on a cycle ergometer at an intensity of 30% maximal oxygen uptake and then had a 10 min rest. This sequence was repeated four times. The main findings are summarized as follows: (1) The clothing microclimate humidity in the back area was significantly higher in A than in B, and in C than in B. (2) The clothing microclimate temperature in the chest area was significantly higher in B than in A, and in B than in C. (3) The clothing microclimate temperature in the back area was significantly higher in C than in B. (4) The clothing surface temperature was significantly higher in C than in B. (5) Although the positive relationships between the microclimate humidity and forearm sweat rate was significantly confirmed in all three kinds of clothing, the microclimate humidity at chest for the same sweat rate was lower in C than in A and B. (6) Although the positive relationships between subjective sensation and forearm sweat rates were significantly confirmed in all three kinds of clothing, the subjective discomfort seemed to be reduced more effectively in C than in A and B for the same sweat rate. These results were discussed in terms of thermal physiology and combined effects of air permeability and moisture absorbency of the fabrics.

Absorption↗

Distant referral of cutaneous sensation (Mitempfindung). Observations on its normal and pathological occurrence.

Certain normal individuals when scratching a small area of skin often experience simultaneously an additional punctate sensation (Mitempfindung) at a remote site on the body. Four patients are described with acquired Mitempfindungen, the sensation being referred to the region that had been rendered abnormal by damage to the nervous system. The differences between normal and pathological Mitempfindungen and other patterns of cutaneous referral are considered, and mechanisms underlying Mitempfindungen, including the possible role of the spinocervical tract, are discussed.

Adult↗

The psychophysical relationship between bitter taste and burning sensation: evidence of qualitative similarity.

Although it has long been studied as a pure sensory irritant, the ability of capsaicin to evoke, mask, and desensitize bitter taste suggests that burning sensations and bitter taste might be closely related perceptually. The current study investigated the psychophysical relationship between bitterness and burning using 2 different approaches. In Experiment 1, spatial discrimination of 4 taste stimuli was measured in the presence or absence of capsaicin. The subjects' task was to report which of 3 swabs, spaced 1 cm apart and presented to the tongue tip, contained a taste stimulus when 1) water was presented on the other 2 swabs or 2) when 10 muM capsaicin was presented on all 3 swabs. The presence of capsaicin did not change performance on the 3 alternative forced-choice (3-AFC) task for sweet, sour, and salty stimuli, while the localization error for 1.8 mM quinine sulfate (QSO(4)) increased significantly. In Experiment 2, the perceptual similarity/dissimilarity of taste stimuli and capsaicin was measured directly using pairs of stimuli applied to opposite sides of the tongue tip on swabs separated by 2 cm. Multidimensional scaling analyses showed that capsaicin fell nearer to QSO(4) than to any other taste stimulus. Cluster analysis corroborated this finding: capsaicin was closely linked with QSO(4) and the capsaicin-QSO(4) group was separated from the other taste stimuli. The latter result indicated that bitterness was more similar to burning than to the other tastes. These findings imply that despite being mediated by different sensory modalities, bitterness and burn are qualitatively similar. We speculate that this similarity reflects a common function of these 2 sensations as sensory signals of potentially harmful stimuli.

Adolescent↗

Warm air sensation for assessment of block after spinal anaesthesia.

We have evaluated a new method of assessing dermatomal sensory levels after regional anaesthesia based on warm sensation. Sensory levels were assessed in 30 patients after spinal anaesthesia using a respiratory gas humidifier, adapted to deliver a constant flow of warm air at 40 +/- 0.2 degrees C. This was compared with the cold sensation from ethyl chloride spray. The frequency distribution of the dermatomal differences showed 96.6% of the comparisons were between +1 and -1 dermatomes. The median difference in dermatomal levels between the two methods of assessment was 0 (interquartile range 0-1) (P = 0.65). We conclude that the warm air method compares favourably with ethyl chloride spray and both can be used interchangeably.

Adolescent↗

Tissue expansion of sensate skin for pressure sores.

The surgical treatment of pressure sores has improved with the development of many techniques to provide coverage of these defects. Few deliver sensate coverage. This report describes tissue expansion of back skin to provide definitive sensate coverage of a pressure sore, thereby preventing its recurrence. Follow-up of 5.5 years is presented with a review of the literature.

Adult↗

Cortical processing of esophageal sensation is related to the representation of swallowing.

The esophagus plays a major role in the act of swallowing. The aim of the present investigation was to apply whole-head magnetoencephalography in order to study the cortical processing of esophageal sensation in healthy humans in whom the cortical representation of swallowing had been established previously. The proximal esophagus was stimulated in nine participants by intermittent 5 ml water infusion. Submental EMG recording was used to identify trials, which were contaminated by subsequent swallowing. Esophageal stimulation led to changes in rhythmic activity of the brain that were localized in the left lateral primary sensorimotor cortex. The pattern of cortical activation showed the same hemispheric lateralization as that of volitional swallowing, however, being localized more lateral. The close anatomical vicinity of these two functions points to an important physiological link between the cortical processing of esophageal sensation and the cortical control of swallowing.

Adult↗

Selective restoration of sensation by peripheral nerve grafts directly implanted into the contralateral C7 dorsal root ganglion: an experimental study in rat brachial plexus.

OBJECTIVE: In brachial plexus injuries, when the dorsal root ganglion (DRG) is avulsed from the spinal cord there is no possibility of direct repair. Therefore, in the present report the median nerve was connected directly to the contralateral C7 DRG, to restore forepaw sensation. METHODS: The ulnar nerve was sectioned, and a 15-mm segment of nerve was removed. The median nerve was sectioned, transposed dorsally, and repaired using a sural nerve graft directly implanted into the C7 contralateral DRG. Rats were then assessed 6 and 12 months later by behavioral, histological, and plasma extravasion techniques. RESULTS: All animals recovered sensation in the forepaw. Retrogradely labeled sensory neurons were demonstrated in the C7 DRG, and the whole forepaw was labeled after plasma extravasion induction by median nerve antidromic stimulation. Several myelinated and positively neurofilament-stained fibers were demonstrated in the grafted median nerve. CONCLUSION: The surgical strategy proposed might be a useful alternative to selective sensory repair in the emerging field of brachial plexus reconstruction by direct spinal cord surgery.

Animals↗

Improved infant swallowing after gastroesophageal reflux disease treatment: a function of improved laryngeal sensation?

OBJECTIVE: The objective of this study was to describe improvements in pediatric swallowing after gastroesophageal reflux treatment. STUDY DESIGN: The authors conducted a retrospective database and chart review at two tertiary care children's hospitals. PARTICIPANTS: Patients (21 males, 7 females) ranged in age from 1 to 32 months. All patients had clinical evidence of gastroesophageal reflux disease (GERD) as well as evidence of dysphagia with aspiration (laryngeal vestibule and/or trachea) or hypopharyngeal pooling on flexible endoscopic evaluation of swallowing and sensation testing (FEESST) or videofluoroscopic swallow study (VSS). INTERVENTION: Each child underwent either medical or surgical intervention for control of their GERD. OUTCOME MEASURES: Outcome measures were change in laryngopharyngeal sensation and swallowing function with repeat swallow evaluation after GERD treatment. RESULTS: A significant improvement in both swallow function and sensory testing was demonstrated after GERD treatment. CONCLUSIONS: GERD may result in decreased laryngopharyngeal sensitivity, which may contribute to pediatric swallowing dysfunction. Control of GERD may improve swallow function. These findings have important clinical implications that need further study.

Child, Preschool↗

Surgical treatment of chronic phantom limb sensation and limb pain after lower limb amputation.

BACKGROUND: Therapy for phantom sensation and phantom limb pain following amputation is still difficult, because pathophysiologic mechanisms have not been clarified. This report illustrates a simple and useful surgical intervention. The authors propose that changes at the peripheral nerve site can influence the central feeling of phantom sensation and pain. METHODS: Fifteen patients (mean age, 56 years) with lower limb amputation were included in the study. In all patients, the sciatic nerve was split at a point approximately 3 cm proximal to the popliteal fossa, and the two parts were reconnected in a sling fashion using an epiperineurial technique under microscopic vision. The nerves were covered with a fibrin patch and anesthetics were applied by means of a local pain catheter. Frequency, duration, intensity, and quality of phantom pain were compared preoperatively and 1 week, 3 months, 6 months, and 1 year postoperatively. RESULTS: Fourteen of 15 patients defined the procedure as very helpful. Average, maximum, and minimum pain intensity were significantly reduced 1 week, 3 months, 6 months, and 1 year postoperatively (p < 0.001). Pain intensity scores decreased significantly over the long term after surgical intervention (median visual analogue scale score: preoperatively, 7; 1 year postoperatively, 4) (p < 0.001). The duration of pain attack shortened from approximately 120 minutes to 5 to 10 minutes. CONCLUSIONS: This study shows that accurate treatment of the peripheral nerve can help to successfully reduce phantom limb pain. The authors feel encouraged to perform future investigations to test their operative method in a prospective, randomized, matched control study including electrophysiologic tests for more objective pain assessment.

Adult↗

The role of mucosal receptors in the nasal sensation of airflow.

50 subjects were admitted into a randomized double-blind placebo controlled cross-over trial with 4% lignocaine as the active drug and normal saline as the placebo. Each subject had 2 ml of solution sprayed into each nasal cavity and all subjects had both sprays but on different occasions. The order in which the sprays were administered was randomized. The subjective sensation of nasal airflow was measured using a visual analogue scale before and after the spray. These measurements were made under conditions of the same airflow rate, which was monitored throughout the experiment using a reprogrammed NR6 rhinomanometer. Objective nasal patency was measured as peak nasal inspiratory flow rate. It was found that the nasal sensation of airflow decreased slightly after both lignocaine (difference between medians 5.0; 95% confidence interval -2.91 to 6.11) and normal saline (difference between medians 6.0; 95% confidence interval -1.02 to 7.21). Nonparametric analysis of variance showed this difference to be non-significant (P = 0.73). In addition there was no significant change in objective nasal patency. The results suggest that nerve endings in the nasal mucosa play no part in sensing nasal airflow during respiration.

Adolescent↗

Self-esteem, types of attributional style and sensation and distress pain ratings in males.

This descriptive study focused on self-esteem and types of attributional style, and their relationship to sensation and distress pain ratings. Negative correlations were hypothesized between self-esteem and each pain rating, between positive internal type of attributional style and each pain rating, and between negative external type of attributional style and each pain rating. One hundred and nine healthy, non-institutionalized males, aged 21-50 years, participated in this study. The Tennessee Self-Concept Scale and revised Attributional Style Questionnaire were administered prior to the cold pressor test, a safe, short duration cold water hand immersion procedure for pain induction. Sensation and distress pain ratings were measured using visual analogue scales, and a pain history was obtained. The predicted relationship between self-esteem and distress pain ratings was supported. All other correlations were not statistically significant. A pain history question, asking subjects to rate their pain tolerance as compared with other people, was significantly related to both pain ratings, the correlations being negative.

Adult↗

Human respiratory muscles: sensations, reflexes and fatiguability.

1. Given the importance of the ventilatory 'pump' muscles, it would not be surprising if they were endowed with both sensory and motor specializations. The present review focuses on some unexpected properties of the respiratory muscle system in human subjects. 2. Although changes in blood gas tension were long held not to influence sensation directly, studies in subjects who are completely paralysed show that increases in arterial CO2 levels elicit strong sensations of respiratory discomfort. 3. Stretch reflexes in human limb muscles contain a monosynaptic spinal excitation and a long-latency excitation. However, inspiratory muscles show an initial inhibition when tested with brief airway occlusions during inspiration. This inhibition does not depend critically on input from pulmonary or upper airway receptors. 4. Human inspiratory muscles (including the diaphragm) have been considered to fatigue during inspiratory resistive loading. However, recent studies using phrenic nerve stimulation to test the force produced by the diaphragm show that carbon dioxide retention (hypoventilation) and voluntary cessation of loading occur before the muscles become overtly fatigued.

Carbon Dioxide↗

Tuning fork (128 Hz) versus neurothesiometer: a comparison of methods of assessing vibration sensation in patients with diabetes mellitus.

The current study compared the effectiveness of the graduated tuning fork (128 Hz) and the neurothesiometer in assessing vibration sensation perception in patients presenting with type II diabetes mellitus. A quota sample of patients (n = 21; age range 43-73 years) were assessed using the neurothesiometer and tuning fork by two investigators at five sites on both feet. There was a positive correlation between the results for the two methods of assessment for both investigators, and also between the results for both tools at three individual sites. Overall, there was 66.2% agreement between the results obtained from the two investigators using the tuning fork at each site; however, Kappa values only reached statistical significance at one site, indicating variability between the results from the two tools. This study suggests that assessment of vibration sensation with the tuning fork may be unreliable. These preliminary findings are based on a small sample size; thus further research is warranted.

Adult↗

Social context, sensation seeking, and teen-age alcohol abuse.

An anonymous questionnaire was administered to more than 1,200 seventh to 12th grade students in four rural public schools in western New York State. The questionnaire measured alcohol use, the social contexts of drinking, and the personality trait known as "sensation seeking." A majority (57%) were drinkers, and discriminant function analyses were performed on their scores on these measures to determine if they could distinguish between different levels of alcohol use intensity, alcohol-impaired driving, and riding with an impaired driver. Results indicated social context measure were effective in distinguishing among levels on each indicant of abuse. In particular, high-intensity drinkers, impaired drivers, and riders of impaired drivers were more likely to drink in a context of social facilitation, stress control, and defiance of school and adult authority. The drinking context of peer acceptance was important only in distinguishing teen-agers who ride with drunk drivers from those who do not. Overall, the sensation seeking trait was of moderate importance in distinguishing among different alcohol abuse practices. Implications of these findings for assessment as well as school-based prevention programs are discussed.

Adolescent↗

A comparison between the discharges of human nociceptive nerve fibres and the subject's ratings of his sensations.

1. Impulses in cutaneous nerve fibres were recorded percutaneously with tungsten micro-electrodes from the superficial radial nerve of adult human subjects. 2. Eight units studied had conduction velocities below 1.5 m/sec, and thus belong to the class of C fibres. On the basis of their responsiveness to mechanical and to thermal stimuli the units were classified as 'polymodal nociceptors'. 3. Units were tested with 12 sec heat pulses starting from a base line temperature of 43.0-43.5 degrees C. Heat stimuli reaching three different maximal levels were applied in randomized order, the subjects being blind with respect to stimulus size. Each of the eight units studied was tested with more tha 20 stimuli and with four of them were 80-125 stimulus repetitions. 4. After each stimulus the subjects had to rate his sensations on a six-point rating scale extending from 'just noticeable' to 'very hot, painful'. 5. Discrimination between the three stimulus levels by the integtated spike discharges and by the ratings of the subject was compared using the P(A) measure of the Signal Detection Theory. It was found that both the neurophysiological and the psychophysical measurements provided about equal discrimination. 6. In addition it has been found that spike discharges and ratings share a common variance beyond their common dependence on the stimulus level. Among the factors contributing to this interdependence a 'temporal position effect' was the most significant. 7. In spite of this interdependence between discharge rates and subjective ratings, the latter gave a better estimation of the stimulus size than of the discharge rates of the individual C fibre under study. 8. It was concluded that the polymodal C-nociceptors might be instrumental for the quantitative aspects of heat pain sensation. The hypothesis was derived from the present results that, under the conditions of cour experiments, the loss of information in the course of central processing might be about equal to the gain by the parallel processing in a population of nociceptors excited by a stimulus.

Action Potentials↗

Oesophageal sensation assessed by electrical stimuli and brain evoked potentials--a new model for visceral nociception.

Sensory thresholds and brain evoked potentials were determined in 12 healthy volunteers using electrical stimulation of the oesophagus 28 and 38 cm from the nares. The peaks of the evoked potentials were designated N for negative deflections and P for positive. Continuous electrical stimulation (40 Hz) at the 38 cm position resembled heartburn (five of 12 subjects) while non-specific ('electrical') sensations were provoked at 28 cm (10 of 12). Thresholds of sensation and of pain were lower at the initial than the second determination, but did not differ with respect to stimulation site. The pain summation threshold to repeated stimuli (2 Hz, 5 stimuli) was determined for the first time in a viscus. This threshold was lower than the pain threshold to single stimuli at 38 cm (p < 0.02). Evoked potential latencies did not change significantly over a six month period while the N1/P2 amplitude was higher at the first measurement (p < 0.05). P1 and N1 latencies were significantly shorter 38 cm (medians 100 and 141 ms) than 28 cm from the nares (102 and 148 ms) (p = 0.04 and p = 0.008). Electrical stimulation of the oesophagus may serve as a human experimental model for visceral pain. Longer evoked potential latencies from the proximal compared with distal stimulations provide new information about the sensory pathways of the oesophagus.

Adult↗

Respiratory sensation during bronchial challenge testing with methacholine, sodium metabisulphite, and adenosine monophosphate.

BACKGROUND: There is some evidence that the perception of bronchoconstriction may very according to the nature of the provoking stimulus. The aims of this study were, firstly, to develop a method for measuring dyspnoea during induced bronchoconstriction in patients with asthma and, secondly, to apply this method to testing differences between directly and indirectly acting bronchoconstricting stimuli. METHODS: Descriptive terms suitable for quantifying respiratory discomfort due to bronchoconstriction in patients with asthma were identified in a preliminary investigation. The relation between reduction in forced expiratory volume in one second (FEV1) and respiratory discomfort, measured using a visual analogue scale (VAS), was then studied during challenges with three different inhaled stimuli: methacholine (MCH), sodium metabisulphite (MBS), and adenosine monophosphate (AMP). Three indices were calculated to describe the relation: the VAS value associated with a 20% fall in FEV1 (FEV20 VAS); the ratio of the final VAS value to the final percentage fall in FEV1 (VAS-FEV1 ratio); and the regression coefficient for predicting VAS from the percentage fall in FEV1 within each challenge (beta VAS FEV1). RESULTS: "Difficulty in breathing" and "chest tightness" were selected as suitable terms for quantifying respiratory discomfort. There were no differences between the three agonists in the qualitative aspects of the respiratory sensation. In paired challenges with the same agonist the three indices were all found to be reproducible for both sensations measured. MCH induced less intense difficulty in breathing and chest tightness for a given fall in FEV1 than did AMP. There was a trend in the same direction for the comparison between MCH and MBS. There were no differences between AMP and MBS. FEV20 VAS was less powerful in discriminating between agonists than the two slope indices. CONCLUSIONS: The relation between induced reduction in FEV1 and the intensity of respiratory discomfort can be measured reliably. The indirectly acting bronchoconstricting agonists AMP and MBS induced more intense respiratory discomfort for a given fall in FEV1 than the direct agonist MCH. This may be due to differences in unmeasured mechanical changes in the lungs or to an additional action on airway sensory nerves.

Adenosine Monophosphate↗