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Sensation Thresholds (sensation + threshold)
Selected AbstractsTear-film lipid layer morphology and corneal sensation in the development of blinking in neonates and infantsJOURNAL OF ANATOMY, Issue 3 2005John G. Lawrenson Abstract The aim of the study was to evaluate the role of lipid layer thickness and corneal sensation in the development of blinking in neonates. The study group comprised sixty-four neonates and infants (mean age 27.5 ± 15 (sd) weeks, range 3.4,52) whose mothers were attending a general practice healthy baby clinic. Spontaneous eye-blink activity was determined from digital videographic recordings; tear film lipid layer morphology wasexamined using interference patterns produced by the Keeler TearscopeÔ Plus over a five-point grading scale (higher grades are associated with thick and stable lipid films); corneal sensation threshold was assessed with the Non-Contact Corneal Aesthesiometer (NCCA), using the eye-blink response as an objective indication that the cooling stimulus had been felt; palpebral aperture dimensions were measured using calibrated digital still images of the eye in the primary position. The overall mean spontaneous blink-rate was found to be 3.6 (± 0.3) blinks min,1, and the mean interblink time was 21.6 (± 2.8) s. The lowest blink-rates were observed in the 0,17-week age group (average 2 blinks min,1). The blink-rate showed a highly significant correlation with age (r = 0.46, P < 0.01). The overall mean lipid layer grading was 3.6 (± 0.2 SE) arbitrary units. Higher grades were found in the newborn and the mean grading score reduced with age (P < 0.01). The mean sensation threshold to blink (TTB) was 0.69 (0.04 SE) mbar, which did not differ from a control group of older subjects (P > 0.05). There was a rapid increase in palpebral aperture length and width from birth to 1 year old, with surface area increasing by 50% over the same period. We concluded that the low rate of spontaneous eye blink activity in neonates is associated with a thick stable lipid layer that may be a function of a small palpebral aperture. Furthermore, neonates appear to have the capacity to detect ocular surface cooling, which is a major trigger for spontaneous blinking. [source] Extremely low frequency (ELF) electric and magnetic field exposure limits: Rationale for basic restrictions used in the development of an Australian standard,BIOELECTROMAGNETICS, Issue 6 2008Andrew W. Wood Abstract There are large disparities between basic restrictions for exposure to extremely low-frequency (0,3 kHz) Electric and Magnetic Fields set by two major international bodies. Both bodies agree that these basic restrictions should prevent neuro-stimulatory effects: the retinal phosphene at frequencies up to a few hundred Hertz and peripheral nervous stimulation (PNS) at higher frequencies. The disparity arises from differences in estimated thresholds and frequency dependence, and whether restrictions should be of tissue induced current density or electric field. This paper argues that the latter metric more directly relates to neurostimulatory processes. By analysing available literature, a threshold for retinal phosphenes occurrence is found to be 56 mV/m (95% Confidence Interval 2,1330 mV/m), with a characteristic frequency of 20 Hz. Similarly, the smallest PNS sensation threshold is identified at 2 V/m (characteristic frequency above 3 kHz). In the case of the former, the large range of uncertainty suggests a ,power of ten' value of 100 mV/m. For the latter, because of the small margin between sensation and pain threshold, and because of the large individual variation, the smallest estimate of sensation threshold (2 V/m) represents a basic restriction with precaution incorporated. Bioelectromagnetics 29:414,428, 2008. © 2008 Wiley-Liss, Inc. [source] Patterns Of Quantitative Sensation Testing Of Hypoesthesia And Hyperalgesia Are Predictive Of Diabetic Polyneuropathy,a Study Of Three CohortsJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 2 2000P.J. Dyck OBJECTIVE,To test quantitative sensation testing (QST) patterns of hypoesthesia and hyperalgesia as indicators of diabetic polyneuropathy (DPN) and its severity. RESEARCH DESIGN AND METHODS,We used Computer-Assisted Sensory Examination IV characterized the QST results of the foot of each patient in three diabetic cohorts (similar to 1,500 patients) as hyperesthetic (less than or equal to 2.5th percentile), low-normal (2.5th,50th percentiles), high-normal (50th,97.5th percentiles), or hypoesthetic (greater than or equal to 97.5th percentile), and tested associations with symptoms, impairments, and test abnormalities. RESULTS,Overall neuropathic impairment was most severe in the pancreas-renal transplant and nerve growth factor cohorts, but it was much less severe in the population-based Rochester Diabetic Neuropathy Study (RDNS) cohort. The frequency distribution of sensory abnormalities mirrored this difference. When the QST spectra of diabetic cohorts were compared with those of the control subject cohort for vibration and cooling sensations, the only abnormality observed was hypoesthesia, which was expressed as an increased number of subjects with values at or above the 97.5th percentile or by an increased percentage of cases with high-normal values. Symptoms and impairments of DPN were significantly more frequent in the subjects with Values at or above the 97.5th percentile than in the subjects whose values were between the 50th and 97.5th percentiles. For heat pain (HP) sensation thresholds (intermediate pain severity [HP:5], pain threshold [HP:0.5], and pain-stimulus response slope [HP:5-0.5]), an increased frequency of both hypoalgesia and hyperalgesia was observed (especially in the RDNS cohort). Steeper pain-stimulus response slopes were significantly associated with sensory symptoms, including severity of pain. CONCLUSIONS,1) Decreased vibratory sensation (hypoesthesia) appears to be characteristic of mild DPN, whereas pan-modality hypoesthesia is characteristic of severe DPN. 2) A shift of vibratory and cold detection thresholds and also of attributes of nerve conduction and a measure of autonomic dysfunction from low-normal (2.5th,50th percentiles) to high-normal (50th,37.5th percentiles) appears to precede overt expression of DPN and to thereby provide evidence of subclinical abnormality. 3) Heat stimulus-induced hyperesthesia (low thresholds) occurs especially in mild DPN, and, because it correlates with DPN symptoms and impairments, it must be attributed to hyperalgesia rather than to supersensitivity. Therefore, hypoalgesia or hyperalgesia may be an indicator of early DPN. [source] MULTIDISCIPLINARY PAIN ABSTRACTS: 12PAIN PRACTICE, Issue 1 2004Article first published online: 15 MAR 200 The purpose of this study was to investigate whether selective nerve fiber dysfunction, as assessed by quantitative sensory testing (QST), correlates with the effectiveness of epidural steroid injections (ESI) in patients with lumbar radiculopathy. Twenty patients with unilateral painful sciatica caused by disc herniation participated in this open study. Before ESI, quantitative thermal and mechanical sensory testing was conducted at the most painful dermatome and the contralateral dermatome. The primary outcome measure used was the self-recording of pain intensity twice daily with a 0,10 numerical pain scale (NPS). Secondary efficacy measures included the Short Form of the McGill Pain Questionnaire, the straight leg raising test, and the lumbar range of motion. A significant difference in all types of sensory thresholds between the affected and the contralateral dermatomes was detected at baseline. All outcome measures improved subsequent to the ESI. A significant positive correlation was found between the increase in cold sensation thresholds of the affected dermatome (Adelta-fiber dysfunction) and the improvement in NPS. The increase in touch and vibration thresholds (Abeta-fiber dysfunction) was found to be inversely correlated with the improvement in NPS. No correlation was found between heat sensation thresholds and any of the outcome measures. These results suggest that QST has the potential to be an important tool in the selection of the appropriate treatment for patients with sciatica and may assist in identifying the mechanisms of pain generation in these patients. [source] ORIGINAL RESEARCH,EJACULATORY DISORDERS: Quantitative Sensory Testing of Peripheral Thresholds in Patients with Lifelong Premature Ejaculation: A Case-Controlled StudyTHE JOURNAL OF SEXUAL MEDICINE, Issue 6 2009Andrea Salonia MD ABSTRACT Introduction., The main functional factors related to lifelong premature ejaculation (PE) etiology have been suggested to be penile hypersensitivity, greater cortical penile representation, and disturbance of central serotoninergic neurotransmission. Aims., To quantitatively assess penile sensory thresholds in European Caucasian patients with lifelong PE using the Genito-Sensory Analyzer (GSA, Medoc, Ramat Yishai, Israel) as compared with those of an age-comparable sample of volunteers without any ejaculatory compliant. Methods., Forty-two consecutive right-handed, fully potent patients with lifelong PE and 41 right-handed, fully potent, age-comparable volunteers with normal ejaculatory function were enrolled. Each man was assessed via comprehensive medical and sexual history; detailed physical examination; subjective scoring of sexual symptoms with the International Index of Erectile Function; and four consecutive measurements of intravaginal ejaculatory latency time with the stopwatch method. All men completed a detailed genital sensory evaluation using the GSA; thermal and vibratory sensation thresholds were computed at the pulp of the right index finger, and lateral aspect of penile shaft and glans, bilaterally. Main Outcome Measures., Comparing quantitatively assessed penile thermal and vibratory sensory thresholds between men with lifelong PE and controls without any ejaculatory compliant. Results., Patients showed significantly higher (P < 0.001) thresholds at the right index finger but similar penile and glans thresholds for warm sensation as compared with controls. Cold sensation thresholds were not significantly different between groups at the right index finger or penile shaft, but glans thresholds for cold sensation were bilaterally significantly lower (P = 0.01) in patients. Patients showed significantly higher (all P , 0.04) vibratory sensation thresholds for right index finger, penile shaft, and glans, bilaterally, as compared with controls. Conclusions., Quantitative sensory testing analysis suggests that patients with lifelong PE might have a hypo- rather than hypersensitivity profile in terms of peripheral sensory thresholds. The peripheral neuropathophysiology of lifelong PE remains to be clarified. Salonia A, Saccà A, Briganti A, Carro UD, Dehò F, Zanni G, Rocchini L, Raber M, Guazzoni G, Rigatti P, and Montorsi F. Quantitative sensory testing of peripheral thresholds in patients with lifelong premature ejaculation: A case-controlled study. J Sex Med 2009;6:1755,1762. [source] Paradoxical Vocal Fold Motion: A Sensory-Motor Laryngeal Disorder,THE LARYNGOSCOPE, Issue 2 2008Sabrina Cukier-Blaj SLP Abstract Objectives: The purpose of this study is to determine the laryngeal sensitivity (LS) thresholds and the ratings of laryngopharyngeal reflux symptoms in patients with paradoxical vocal fold motion (PVFM). Methods: This is a chart review following Institutional Review Board approval of 75 patients from January 2006 to June 2007. The patients were diagnosed with PVFM following case history, transnasal flexible laryngoscopy and spirometric testing. The data analyzed consisted of the reflux symptom index (RSI) and laryngopharyngeal sensitivity (LS). Laryngeal sensitivity and RSI were graded according to mild, moderate, or severe. Results: There were 12 (16%) patients with normal RSI scores, 37 patients (49.3%) with moderate RSI (RSI 11,22), and 26 patients (34.7%) with severe RSI (RSI >22). The right LS was normal in 11 patients (14.7%), moderately impaired in 16 patients (21.3%), and severely impaired in 48 (64%) patients. The left LS showed normal sensation in 11 patients (14.7%), moderately impaired LS in 13 patients (17.3%), and severe impairment in 51 patients (68%). Only one patient had both normal sensation and normal RSI, and 70.4% of patients had abnormal RSI and sensation thresholds. Conclusions: Patients diagnosed with PVFM had a high prevalence of symptoms related to LPR and markedly reduced LS. These findings suggest that PVFM may be triggered by reduced peripheral sensation or laryngeal inflammation. [source] | |||||||||||||