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At least 649 records · Page 36Linked to original sources
PubMed1996

Temporary threshold shift of vibratory sensation induced by a vibrating handle and its gripping force.

OBJECTIVE: This study examines the effect of the force with which a vibrating handle is gripped on the temporary threshold shift of vibratory sensation (TTSv) induced by hand-arm vibration. METHODS: Six healthy subjects gripped a handle vibrating with a 1.3 octave-band vibration, with a central frequency of 200 Hz and an intensity of 39.2 m/s2. Exposure was for 1 min and 10 min, respectively. Gripping forces for the 1-min exposure were 5 N, 10 N, 40 N and 80 N, respectively, with 0 N push-pull force. Gripping forces for the 10-min exposure were the same as for the 1-min exposure but omitting 80 N. The vibratory sensation threshold at 125 Hz was measured before and after exposure of an exposed fingertip to vibration. The differences measured determine TTSv.t at time t. TTSv.t determines TTSv.0, that is, the temporary threshold shift of vibratory sensation immediately after exposure to vibration according to the estimate made on the basis of the preceding study. The same experimental conditions were repeated 3 times on different days in a soundproof and thermoregulated room. RESULTS: Our findings show that TTSv increases significantly with increasing gripping force. We also determined the quantitative relationships between TTSv.0 and gripping force as described by the equation TTSv.0 = exp(kf x F + Cf). where kt and Cf are constants and F is gripping force. CONCLUSION: This study revealed the importance of ergonomic design in reducing the force with which a vibrating handle is gripped to prevent an adverse effect of local vibration. The equation devised may help in the quantitative assessment of the effect of reduced gripping force.

Adult↗
PubMed2006

The steel ball-bearing test: a new test for evaluating protective sensation in the diabetic foot.

AIMS/HYPOTHESIS: The aim of the study was to assess a new steel ball-bearing test as a means of evaluating protective sensation in the diabetic foot. METHODS: Subjects were enrolled for this study as follows: (1) 39 patients (mean age 61.3+/-9.7 years) with neuropathy and prior neuropathic ulcer (Group A); (2) 36 patients (mean age 63.7+/-10.1 years) with neuropathy without neuropathic ulcer (Group B); (3) 34 patients (mean age 52.1+/-10.4 years) without neuropathy (Group C); and (4) 21 healthy volunteers (mean age 46.7+/-8.7 years) (Group D). Neuropathy was diagnosed by means of neuropathy disability score (NDS). The plantar area over the second metatarsal head of each foot was examined with steel ball-bearings of varying diameters. The smallest diameter that the patient could feel was used to define the ball-bearing score (range 1-6). RESULTS: A high ball-bearing score was significantly more frequent in patients with neuropathic ulceration than in neuropathic patients without ulceration and in diabetic patients without neuropathy (p<0.001). A high score was also more frequent in neuropathic patients without ulceration, than in patients without neuropathy (p<0.001). The ball-bearing score was significantly (p=0.01) correlated with the NDS, the monofilament test, the vibration perception threshold and the thermal perception threshold. The ball-bearing test had a sensitivity of 84% and a specificity of 100% for impaired protective sensation due to neuropathy, and a sensitivity of 84.6% and a specificity of 86.1% for detection of patients with prior neuropathic ulceration. CONCLUSIONS/INTERPRETATION: The steel ball-bearing test has a high sensitivity and specificity both for the evaluation of protective sensation and for detection of patients with prior neuropathic ulceration.

Adult↗
PubMed2006

Individual differences in drug abuse vulnerability: d-amphetamine and sensation-seeking status.

RATIONALE: While the personality dimensions of novelty seeking and sensation seeking are associated with drug abuse vulnerability, the mechanisms associated with this vulnerability remain obscure. OBJECTIVE: This study examined the behavioral effects of d-amphetamine in healthy volunteers scoring in the upper and lower quartiles based on age- and gender-adjusted population norms on the impulsive Sensation-Seeking Scale (SSS) of the Zuckerman-Kuhlman personality questionnaire (ZKPQ). METHOD: Participants completed 7-day outpatient studies examining the subjective, performance, and cardiovascular effects of d-amphetamine (0, 7.5, and 15 mg/70 kg, p.o.) under double-blind conditions according to a randomized block design. Performance tasks included behavioral measures of impulsivity, including attention, inhibition, and risk-taking behavior. RESULTS: No differences in baseline performance or d-amphetamine effects on measures of attention, inhibition, and risk-taking behavior were observed. High impulsive sensation seekers reported greater increases on several subjective report measures associated with drug abuse potential, including visual analog scales feel drug, like drug, and high. CONCLUSIONS: Healthy adults scoring in the top quartile on the population of the impulsive SSS of the ZKPQ may be vulnerable to the abuse potential of d-amphetamine.

Adult↗
PubMed2004

The role of plantar cutaneous sensation in unperturbed stance.

Considerable evidence shows that sensation from the feet and ankles is important for standing balance control. It remains unclear, however, to what extent specific foot and ankle sensory systems are involved. This study focused on the role of plantar cutaneous sensation in quasi-static balance control. Iontophoretic delivery of anesthesia was used to reduce the sensitivity of the forefoot soles. In a follow-up experiment, subjects received intradermal injections of local anesthetic into the entire weight-bearing surface of the foot soles. Properties of the center-of-foot-pressure (COP) trajectories and ground reaction shear forces were analyzed using stabilogram-diffusion analysis and summary statistics. Effects of foot-sole anesthesia were generally small and mostly manifested as increases in COP velocity. Magnitude of COP displacement was unaffected by foot-sole anesthesia. Forefoot anesthesia mainly influenced mediolateral posture control, whereas complete foot-sole anesthesia had an impact on anteroposterior control. During bipedal stance, statistically significant effects of foot-sole anesthesia on COP were present only under eyes-closed conditions and included increases in COP velocity (11-12%) and shear force root-mean-square (13%), the latter indicating increases in body center-of-mass accelerations due to the foot-sole anesthesia. Similar effects were seen for unipedal stance in addition to an increase in anteroposterior COP median frequency (36%). Changes in stabilogram-diffusion parameters were confined to the short-term region suggesting that sensory information from the foot soles is mainly used to set a relevant background muscle activity for a given posture and support surface characteristic, and consequently is of little importance for feedback control during unperturbed stance. In general, this study demonstrates that plantar sensation is of moderate importance for the maintenance of normal standing balance when the postural control system is challenged by unipedal stance or by closing of the eyes. The impact of reduced plantar sensitivity on postural control is expected to increase with the loss of additional sensory modalities such as the concomitant proprioceptive deficits commonly associated with peripheral neuropathies.

Adult↗
PubMed2001

Determinants of the sensation of thirst in terminally ill cancer patients.

While a sensation of thirst causes severe distress for a certain proportion of cancer patients in the terminal stage, the factors contributing to this symptom have not been established. To clarify the association between sensation of thirst and medical factors, especially dehydration, a cross-sectional observational study was performed on terminally ill cancer patients receiving inpatient hospice care. On admission to a palliative care unit, 88 consecutive patients underwent blood sampling and were requested to rate the intensity of thirst on a visual analogue scale (VAS). Physicians prospectively evaluated factors that might potentially be contributing to the symptom. The mean VAS score for thirst was 5.0+/-2.8, and 18% of the patients complained of severe thirst with a VAS score of > or = 8. No significant correlations were observed between the VAS score for thirst and the values of total protein, blood urea nitrogen (BUN), creatinine, sodium, osmolality, hematocrit, atrial natriuretic peptide (ANP), and biochemical dehydration defined by the levels of BUN, creatinine, sodium and osmolality. On the other hand, dehydration defined by ANP level (< or = 15 pg/ml), hyperosmolality (> or = 300 mosmol/kg), gastrointestinal cancer, survival, performance status, oral intake, vomiting, and stomatitis were significantly associated with the severity of thirst. In addition, mouth breathing and opioids were determined to be a potential clinical cause of severe thirst when a retrospective chart review was carried out. In conclusion, sensation of thirst is a frequent symptom in terminally ill cancer patients and is associated with dehydration, hyperosmolality, poor general conditions, stomatitis, oral breathing, and opioids. Careful assessments and treatment of underlying causes is important to alleviate patients' distress.

Aged↗
PubMed2006

The restorative effects of pulsed infrared light therapy on significant loss of peripheral protective sensation in patients with long-term type 1 and type 2 diabetes mellitus.

Pulsed infrared light therapy (PILT) has been shown to increase peripheral sensation in diabetic patients with diabetic peripheral neuropathy (DPN). However, most studies last for very short periods, with the subjects receiving only 6-20 treatments. The purpose of this study was to evaluate the effectiveness of an eight-week course of PILT in reversing long-standing, profound DPN in patients with type 1 and type 2 diabetes. Twenty-two subjects with a diagnosis of type 1 (n=2) or type 2 (n=20) diabetes participated in the study. PILT was administered to one foot chosen at random with the other foot serving as a within-subject control (no treatment). Patients underwent 24 treatments (3 times/week, for eight weeks) for 30 min per treatment. Changes in peripheral protective sensation (PPS) were measured using Semmes-Weinstein monofilaments (SWM) ranging from 3.7 to 6.48. PILT improved PPS even in patients with long-standing chronic neuropathies whose initial pre-study sensation was not measurable with a 200-g SWM. PILT significantly improves PPS. While the exact mechanism of action is not understood, infrared light may improve peripheral neuropathies by improving foot perfusion by stimulating nitric oxide production.

Body Mass Index↗
PubMed2004

Functional constipation with impaired rectal sensation improved by electrical stimulation therapy: report of a case.

Patients with intractable constipation often complain of social, physical, and psychologic stress. Recently, biofeedback therapy has been widely used for the management of intractable constipation, particularly in cases of constipation associated with pelvic floor dyssynergia. However, some constipated patients often complain of absent or diminished sense of wanting to defecate. It is unclear whether impaired rectal sensation is a cause or outcome of constipation and what specific treatment is available for these patients. We treated a 25-year-old female patient who complained of intractable constipation for ten years. Colon transit time study and defecography showed nonspecific findings. Her anorectal manometric findings were within normal ranges with the exception of impaired rectal sensation. Rectal sensory threshold volumes for desire and urge to defecate and maximal tolerated volume were greatly increased. She was treated by electric stimulation therapy for the purpose of improving impaired rectal sensory function. After 14 sessions of electric stimulation therapy, her constipated symptoms improved dramatically. Furthermore, the desire and urge threshold volumes were remarkably decreased. We report this case of constipation with impaired rectal sensation possibly treated by electric stimulation therapy.

Adult↗
PubMed2006

Genetic analysis of sensation seeking with an extended twin design.

The heritability of sensation seeking is investigated in an extended twin design, including mono- and dizygotic twins and their siblings. Besides a comparison of the phenotypic resemblance between monozygotic twins and dizygotic twins, the design allows for an explicit test of the assumption that results from twins may be generalized to the singleton population. Secondly, the design offers the opportunity to investigate to what extent the influence of common environment is the same for males and females and for twins and siblings, i.e. allowing for explicit tests of a special twin environment and of a sex-specific common environment. The results indicate that individual variation in sensation seeking is heritable, with few differences between males and females in heritability estimates for the sensation seeking dimensions. In contrast to prior studies, evidence is found for common environmental influences for thrill and adventure seeking in males, and experience seeking and boredom susceptibility in females. Evidence for a special twin environment was limited to boredom susceptibility in females.

Adolescent↗
PubMed1984

Suppression of C-fibre discharges upon repeated heat stimulation may explain characteristics of concomitant pain sensations.

Nociceptors with unmyelinated axons were recorded from the superficial radial nerves of 7 volunteers. A sequence of uniform radiant heat stimuli of 18 s duration, starting from an individually adjusted adapting temperature were used to raise the skin surface temperature by 6 degrees C to a painful level (41-43 degrees C). These stimuli followed each other at 3 different interstimulus intervals of 35 s, 70 s and 105 s, occurring in a random order. The subjects were asked to track the time course of the stimulus-evoked sensation by manipulating the length of a light bar. Adaptation and stimulus temperatures were chosen to induce sensations of heat and/or pain. All nociceptors studied responded to these stimuli with a phasic response of 3-5 s duration, often followed by a low frequency tonic discharge, lasting as long as the stimulus. No discharges were seen in interstimulus periods. Discharge rates during the phasic responses were linearly related to interval duration, whereas tonic discharges were not influenced by the preceding interval. In parallel readings of pain responses were lower up to the 10th second of the stimulus after short rather than after long intervals. These results indicate that the suppression of C-fibre nociceptor discharges during repetitive stimulation may explain concomitant reductions in the magnitude of human pain sensations.

Adult↗
PubMed1989

Masseter inhibitory periods and sensations evoked by electrical tooth-pulp stimulation in subjects under hypnotic anesthesia.

Sensation and masseter inhibitory periods (MIP) to electrical tooth-pulp stimulation were recorded under hypnotic anesthesia and placebo to local anesthesia. In the first experiment, 8 subjects were tested for the effect of hypnotic anesthesia on sensory detection and MIP at non-painful stimulus levels (mean = 42.1 microA) and painful levels (mean = 86.5 microA). The percentage of detection for non-painful stimuli changed from 94.3% to 14.1% and for painful stimuli from 100% to 28%; both changes were significant (P less than 0.001). Hypnotic anesthesia blocked sensation without interrupting the initiation of the early component of the MIP, but did suppress its late component. In the second experiment, 8 subjects were tested for the perceived intensity of 5 levels of electrical tooth-pulp stimulation under hypnotic anesthesia and placebo. Sensory intensity was measured by the visual analog scale (VAS). Hypnotic anesthesia was significantly more effective than placebo (P less than 0.001) in reducing sensation. The differential effect of hypnotic anesthesia on the early and late component of the MIP lends further support to the hypothesis that hypnotic anesthesia operates primarily at suprasegmental, higher levels in the brain.

Adolescent↗
PubMed1989

Deficits of thermal sensation in patients with unilateral cerebral lesions.

Using a quantitative psychophysical test, the thresholds for detection of heat and cold were determined at both wrists in 16 hemiparetic patients with unilateral cerebral lesions and 1 patient with a unilateral frontal lesion but no hemiparesis. These data were compared with normal values for the absolute thermal thresholds and the symmetry of thermal thresholds in 25 age-matched control subjects. Significant elevation of thermal thresholds was found in all patients with clinically detectable deficits of nociceptive or thermal sensations. Thresholds were also elevated in 3 of 10 hemiparetic patients with no clinical evidence of impairment of nociceptive or thermal sensations. Deficits were found in patients with superficial cortical lesions as well as in those with extensive lesions involving deep structures, including thalamus. In patients with superficial lesions, the elevation of thermal threshold was slight (less than 1 degree C) and there was often little or no sensory deficit to clinical testing. In patients with very high thermal thresholds (greater than 6 degrees C), the lesions involved deep structures and there were clinically obvious deficits of thermal and nociceptive sensations.

Adolescent↗
PubMed1991

High incidence of esophageal motor disorders in consecutive patients with globus sensation.

Thirty consecutive patients with globus sensation who were referred to a psychosomatic clinic prospectively underwent otolaryngological, videokinematographic, and manometric examinations of pharynx and esophagus to evaluate whether morphological abnormalities or motility disorders underlay their symptom. When indicated by findings, 24-hour pH-metry, scintigraphy of bolus transport, and esophagogastroscopy were performed. Seven patients were shown to have achalasia, 10 had "hypochalasia" (lower esophageal sphincter relaxation less than 75% with esophageal contraction abnormalities but no complete distal aperistalsis), and 1 had diffuse esophageal spasms; 2 patients had also hyperplastic lingual tonsils, 1 had tonsillitis, and 1 had a cervical spondylophyte. Nutcracker esophagus and nonspecific contraction abnormalities were found in 7 patients, and gastroesophageal reflux with esophagitis and a low lower esophageal sphincter resting pressure was found in 1; only 3 patients had normal esophageal motility. None had volunteered dysphagic symptoms at primary evaluation. Psychometric investigations in consenting patients showed no higher mean scores for state and trait anxiety, depression, hysteria, and hypochondriasis than in general medical outpatients. Esophageal motor disorders may, before giving rise to dysphagia, be sensed more vaguely and induce the globus sensation. However, only disappearance of the sensation after treatment allows inferring an etiological significance of such a disorder.

Adult↗
PubMed1991

A taste illusion: taste sensation localized by touch.

Taste sensations appear to come from all over the inner surface of the mouth, yet the taste receptors are restricted to relatively small particular areas of the oral surface. In addition, even if a relatively large (e.g., one half) proportion of the taste field is damaged, subjective taste experience may be unaffected. The touch system contributes to this constancy because taste sensations appear to be localized by touch. If a taste solution is painted from the side of the tongue (an area of low receptor density) past the tip (an area of high receptor density) and on to the second side, the taste sensation begins weak, gets stronger at the tip, and retains much of its intensity. The strong taste from the tip follows the tactile path of the stimulus sweep. This illusion occurs for all four stimuli tested: sucrose, sodium chloride, citric acid, and quinine hydrochloride.

Adolescent↗
PubMed1996

The sensation of respiration in men experiencing high-altitude chronic hypoxia.

Respiratory sensation was studied in seven European lowlanders during a Himalayan expedition at over 6000 m. At rest, the ability to detect added inspiratory resistive loads can be used to create a sensitivity index P(A) taking response bias (B) into account based on Sensory Decision Theory. The data indicate that respiratory sensitivity may be involved in successful adaptation to hypoxia. Respiratory sensitivity improved during the first stages of exposure to altitude and returned to baseline after 17- and 27-day stays under chronic hypoxic conditions. The improvement in respiratory sensation could be a primary signal in the physiological and psychological adaptation to high altitude and change in sensation may reflect the degree of altitude adaptation.

Acclimatization↗
PubMed1991

Pain but no temperature sensations are evoked by thermal stimulation of cutaneous veins in man.

To test the hypothesis that the sensory innervation of veins subserves nociception exclusively, we studied pain and temperature sensations on intravenously applied thermal stimuli before and after blockade of either cutaneous or venous afferents in man. Intravenous cooling or warming of a cutaneous vein segment of the hand was associated with corresponding changes in skin temperature and evoked pain only after numbing the skin but temperatures sensations only after intravenous local anesthesia. Thus, the sensory elements of veins, probably polymodal nociceptors, convey pain only on thermal stimulation while coactivated cutaneous thermoreceptors are responsible for concomitant temperature sensations.

Afferent Pathways↗
PubMed1989

An association between phantom limb sensations and stump skin conductance during transcutaneous electrical nerve stimulation (TENS) applied to the contralateral leg: a case study.

This report describes a placebo-controlled study of transcutaneous electrical nerve stimulation (TENS) applied to the contralateral lower leg and outer ears of an amputee with non-painful phantom sensations. The subject received TENS or placebo stimulation on separate sessions in which baseline periods of no stimulation alternated with periods of TENS (or placebo). Throughout the two sessions, continuous measures of stump skin conductance, surface skin temperature and phantom intensity were obtained. The results showed that TENS applied to the contralateral leg was significantly more effective than a placebo in decreasing the intensity of phantom sensations, whereas stimulation of the outer ears led to a non-significant increase. The pattern of electrodermal activity on the TENS session was consistently linear during baseline periods, indicating a progressive increase in sympathetic sudomotor activity. In contrast, during periods of electrical stimulation the pattern of electrodermal activity was consistently curvilinear indicating an initial decrease followed by an increase in sudomotor responses. Changes in stump skin conductance correlated significantly with changes in phantom sensations both in TENS and placebo sessions suggesting a relationship between sympathetic activity at the stump and paresthesias referred to the phantom. Two hypotheses are presented to account for these findings.

Adult↗
PubMed1993

Flexion reflexes following anterolateral cordotomy in man: dissociation between pain sensation and nociceptive reflex RIII.

Nociceptive flexion reflexes (RIII response) of the lower limbs were recorded after unilateral cervico-thoracic anterolateral cordotomy (ALC) in 7 patients. Pre-operative recordings were also obtained in 1 patient and follow-up observations in 3 patients. Flexion reflexes ipsilateral to cordotomy remained normal after surgery. Conversely, responses contralateral to the cordotomy exhibited two consistent postoperative changes: first, the RIII reflex was always dissociated from subjective pain, i.e., it appeared in the absence of any pain sensation, and, second, the RIII was depressed in the limb contralateral to ALC in 5 of 7 patients. RIII attenuation ranged from slight reduction to total abolition, and proved to be reversible in 2 of 3 patients tested during the follow-up. The reappearance of withdrawal reflexes was never accompanied by a recovery of pain sensation in the stimulated limb. We conclude that the dissociation between flexion reflexes and pain sensation, which was evidenced even in case of depressed RIII responses, should be attributable to the surgical lesion of spinothalamic fibers. Dissociation between RIII and subjective pain is a landmark indicating a lesion of the spinothalamic fibers, and may be used for the clinical assessment of spinothalamic dysfunction. Conversely, RIII depression after ALC does not depend upon the surgical lesion to the spinothalamic axons, but may be secondary to interruption of ascending spinoreticular fibers in the anterolateral quadrant, and/or of descending excitatory axons in the ventral cord.

Adult↗
PubMed1994

The sensation of angina can be evoked by stimulation of the human thalamus.

We have performed single-neuron recording and microstimulation in the region of the thalamic principal sensory nucleus (ventrocaudal nucleus, Vc) prior to implantation of a deep brain-stimulating electrode in a patient with pain secondary to arachnoiditis and with a past history of unstable angina. Cells located in the 16 mm lateral plane had cutaneous receptive fields on the chest wall. At and posterior to the location of these cells stimulation coincided precisely with the sensation of angina (stimulation-associated angina). The description of stimulation-associated angina was measured using a questionnaire and was identical to the patient's usual angina except that it began and terminated suddenly. Stimulation-associated angina was coincident with a tingling sensation in the leg. Clinical, hemodynamic, electrophysiologic and biochemical measures of cardiac function showed no evidence of myocardial strain or injury related to stimulation-associated angina. Since cells in the region of the principle sensory nucleus of thalamus respond to cardiac injury in animals, the present results suggest that this region mediates the sensation of angina.

Aged↗