scholarly journals Robotic Stroking on the Face and Forearm: Touch Satiety and Effects on Mechanical Pain

2021 ◽  
Vol 2 ◽  
Author(s):  
Pankaj Taneja ◽  
Lene Baad-Hansen ◽  
Sumaiya Shaikh ◽  
Peter Svensson ◽  
Håkan Olausson

Background: Slow stroking touch is generally perceived as pleasant and reduces thermal pain. However, the tactile stimuli applied tend to be short-lasting and typically applied to the forearm. This study aimed to compare the effects of a long-lasting brushing stimulus applied to the facial region and the forearm on pressure pain thresholds (PPTs) taken on the hand. Outcome measurements were touch satiety and concurrent mechanical pain thresholds of the hand.Methods: A total of 24 participants were recruited and randomized to receive continuous stroking, utilizing a robotic stimulator, at C-tactile (CT) favorable (3 cm/s) and non-favorable (30 cm/s) velocities applied to the right face or forearm. Ratings of touch pleasantness and unpleasantness and PPTs from the hypothenar muscle of the right hand were collected at the start of stroking and once per minute for 5 min.Results: A reduction in PPTs (increased pain sensitivity) was observed over time (P < 0.001). However, the increase in pain sensitivity was less prominent when the face was stroked compared to the forearm (P = 0.001). Continuous stroking resulted in a significant interaction between region and time (P = 0.008) on pleasantness ratings, with a decline in ratings observed over time for the forearm, but not on the face. Unpleasantness ratings were generally low.Conclusion: We observed touch satiety for 5 min of continuous robotic brushing on the forearm confirming previous studies. However, we did not observe any touch satiety for brushing the face. Mechanical pain sensitivity, measured in the hand, increased over the 5-min period but less so when paired with brushing on the face than with brushing on the forearm. The differential effects of brushing on the face and forearm on touch satiety and pain modulation may be by the differences in the emotional relevance and neuronal pathways involved.

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Morten Pallisgaard Støve ◽  
Rogerio Pessoto Hirata ◽  
Thorvaldur Skuli Palsson

Abstract Objectives The effect of stretching on joint range of motion is well documented, and although sensory perception has significance for changes in the tolerance to stretch following stretching the underlining mechanisms responsible for these changes is insufficiently understood. The aim of this study was to examine the influence of endogenous pain inhibitory mechanisms on stretch tolerance and to investigate the relationship between range of motion and changes in pain sensitivity. Methods Nineteen healthy males participated in this randomized, repeated-measures crossover study, conducted on 2 separate days. Knee extension range of motion, passive resistive torque, and pressure pain thresholds were recorded before, after, and 10 min after each of four experimental conditions; (i) Exercise-induced hypoalgesia, (ii) two bouts of static stretching, (iii) resting, and (iv) a remote, painful stimulus induced by the cold pressor test. Results Exercise-induced hypoalgesia and cold pressor test caused an increase in range of motion (p<0.034) and pressure pain thresholds (p<0.027). Moderate correlations in pressure pain thresholds were found between exercise-induced hypoalgesia and static stretch (Rho>0.507, p=0.01) and exercise-induced hypoalgesia and the cold pressor test (Rho=0.562, p=0.01). A weak correlation in pressure pain thresholds and changes in range of motion were found following the cold pressor test (Rho=0.460, p=0.047). However, a potential carryover hypoalgesic effect may have affected the results of the static stretch. Conclusions These results suggest that stretch tolerance may be linked with endogenous modulation of pain. Present results suggest, that stretch tolerance may merely be a marker for pain sensitivity which may have clinical significance given that stretching is often prescribed in the rehabilitation of different musculoskeletal pain conditions where reduced endogenous pain inhibition is frequently seen.


2021 ◽  
pp. 1-8
Author(s):  
Daniel Viggiani ◽  
Jack P. Callaghan

Viscoelastic creep generated in the lumbar spine following sustained spine flexion may affect the relationship between tissue damage and perceived pain. Two processes supporting this altered relationship include altered neural feedback and inflammatory processes. Our purpose was to determine how low back mechanical pain sensitivity changes following seated lumbar spine flexion using pressure algometry in a repeated-measures, cross-sectional laboratory design. Thirty-eight participants underwent a 10-minute sustained seated maximal flexion exposure with a 40-minute standing recovery period. Pressure algometry assessed pressure pain thresholds and the perceived intensity and unpleasantness of fixed pressures. Accelerometers measured spine flexion angles, and electromyography measured muscular activity during flexion. The flexion exposure produced 4.4° (2.7°) of creep that persisted throughout the entire recovery period. The perception of low back stimulus unpleasantness was elevated immediately following the exposure, 20 minutes before a delayed increase in lumbar erector spinae muscle activity. Women reported the fixed pressures to be more intense than men. Sustained flexion had immediate consequences to the quality of mechanical stimulus perceived but did not alter pressure pain thresholds. Neural feedback and inflammation seemed unlikely mechanisms for this given the time and direction of pain sensitivity changes, leaving a postulated cortical influence.


Author(s):  
O. Ya. Mokryk

The lateral facial region including zygomatic, parotid and buccal regions is innervated by trigeminal nerve branches: zygomatic, auriculotemporal, buccal, mental nerves as well as by branches of cervical plexus: great auricular and transverse cervical nerves. According to the classical Brown’s method, great auricular and transverse cervical nerves can be blocked at Erb’s point on the posterior border of the sternocleidomastoid muscle.Anesthesia of the listed nerves is commonly attained in the contemporary surgical practice during superfi cial cervical plexus block. However, due to the high probability of local complications such as external jugular veindamaging by the injection needle this technique can’t be used in the outpatient surgical dental practice.The aim of the study – to develop methods of conduction anesthesia of facial branches of cervical plexus (great auricular and transverse cervical nerves) on patient’s face considering individual topographic anatomical peculiarities.Materias and Methods. Clinical observation was conducted in 39 sheduled patients of different sex and age (18–60 years old) that were being on stationary treatment. In case the localization of pathological processes (benign tumors, keloid scars, fi stulas of migrating granulomas) in the parotid region (21 cases) surgical interventions were conducted under local conduction anesthesia of auriculotemporal nerve as well as facial branches of great auricular and transverse cervical nerves. In case the localization of pathological processes in the buccal region (18 cases) surgical interventions were conducted under local conduction anesthesia of buccal, mental nerves and facial branches of transverse cervical nerve (if necessary). Facial branches of great auricular nerve were blocked along the posterior border of mandible ramus – from the gonial angle to the neck of mandibular condyle. Anesthesia of facial branches of transverse cervical nerve was conducted along the inferior border of mandible. Individual topographic anatomical peculiarities of the facial part of the head in patients were determined by computing the facial index of each patient using Garson’s algorithm. Tactile and pain sensitivity were explored. In order to assess objectively the developed method of great auricular nerve block it was used stimulating electromyography. It is established that pathological processes did not infl uence the sensory function (tactile and pain sensitivity) of the zygomatic, parotid and buccal regions in patients before the planned surgical interventions on the lateral facial region.Results and Discussion. After the block of facial branches of great auricular nerve according to the developed technique it is revealed that in all cases the posterior part of the parotid region adjoining the mandible angleand posterior part of mandible ramus became insensitive. In 19 cases (93.1 %) an absolute anesthesia of this topographic anatomical region occurred. In 7 cases (33.4 %) the conduction anesthesia of facial branches oftransverse cervical nerve was carried out when this nerve took part in the innervation of the parotid region. It is clinically confi rmed that there are three types of ramifying on the human face of branches of great auricular and transverse cervical nerves (Bruno Ella classifi cation, 2015). The fi rst type of the lateral facial region innervation by the rami of cervical plexus occurred the most frequently, in 11 cases (52.4 %), and prevailed in patients with mesoprosopic form of facial part of the head. The second type of ramifying was observed in 7 cases (33.4 %), in patients with euriprosopic and mesoprosopic face shapes. The third type occurred in 14. 3 % cases in patients with mesoprosopic and leptoprosopic face shapes. In those people a major part of the lateral facial region was innervated by auriculotemporal nerve. In 55. 6 % cases a scattered type of buccal nerve ramifying was found on the face in patients prevailing in leptoprosops. In three patients transverse cervical nerve took part in the buccal region innervation. In all cases they were individuals with euriprosopic face shape. The loss of tactile and pain sensitivity on the skin cover of both the parotid and buccal regions as well as temporary absence of conductance along the facial branches of great auricular nerve that was detected during stimulating electromyography absolutely confi rmed the effectiveness of the developed methods of local conduction anesthesia. During surgical treatment the effi ciency of used methods of local anesthesia was evaluated on 4.7 ± 0.5 points – it was observed a stable anesthesia, without psychosomatic peculiarities as well as local and general complications, in patients; sometimes weakly expressed affective reactions took place, but they didn’t infl uence the course of the operation.Conclusions. The results of clinical observations confi rm the signifi cant variability of sensitive innervation of soft tissues of the lateral facial area, it varies in patients depending on their individual anatomical features.There are three types of branching in the parietal-chewing area of the facial branches of the surface cervical nerve plexus, which can spread to the cheek area. The use of techniques, conductive anesthetics of the facial branches of the large anus and transverse nerve of the neck, in combination with the traditional methods of local anesthesia, which we developed, provided painless surgical interventions on the lateral face of the face.


Pain Medicine ◽  
2019 ◽  
Vol 20 (11) ◽  
pp. 2198-2207 ◽  
Author(s):  
Christopher Carey ◽  
Jonathan Saxe ◽  
Fletcher A White ◽  
Kelly M Naugle

AbstractBackground. Recent animal research suggests that mild traumatic brain injury (mTBI) facilitates abnormal endogenous modulation of pain, potentially underlying the increased risk for persistent headaches following injury. However, no human studies have directly assessed the functioning of endogenous facilitory and inhibitory systems in the early stages after an mTBI. Objective. The purpose of this exploratory study was to examine trigeminal sensitization and endogenous pain inhibitory capacity in mTBI patients in the acute stage of injury compared with matched controls. We also examined whether post-traumatic headache pain intensity within the mTBI sample was related to sensitization and pain inhibitory capacity. Methods. Twenty-four mTBI patients recruited from emergency departments and 21 age-, race-, and sex-matched controls completed one experimental session. During this session, participants completed quantitative sensory tests measuring trigeminal sensitization (pressure pain thresholds and temporal summation of pain in the head) and endogenous pain inhibition (conditioned pain modulation). Participants also completed validated questionnaires measuring headache pain, depression, anxiety, and pain catastrophizing. Results. The results revealed that the mTBI group exhibited significantly decreased pressure pain thresholds of the head and decreased pain inhibition on the conditioned pain modulation test compared with the control group. Furthermore, correlational analysis showed that the measures of trigeminal sensitization and depression were significantly associated with headache pain intensity within the mTBI group. Conclusions. In conclusion, mTBI patients may be at risk for maladaptive changes to the functioning of endogenous pain modulatory systems following head injury that could increase risk for post-traumatic headaches.


One of the important components of an intelligent Human computer Interface system is accurate classification of the various affect states. Such interface systems are however plagued by a recurring problem of image occlusion. The challenge hence is to be able to classify the various affect states accurately from whatever portions of the face are available to the system. This paper attempts to investigate if there are segments within the facial region which carry sufficient information about the affect states. In this paper we have used two pre-defined Convolutional Neural networks (CNN). We have implemented a ResNet-50 network and a modified version of ResNet-50 which has a Squeeze and Excitation network connected to ResNet-50. This is called SE-ResNet-50. We use these two networks to classify seven basic affect states of Angry, Contempt, Disgust, Fear, Happy, Sad and Surprise from various segments of the face. We partition the face into four regions with each region comprising of only 50% of the original data. The results obtained are compared with that obtained using the full face. The validation accuracy values are obtained for full face as well as the four segments of the face. The paper also calculates precision and recall for each partitioned area for each of the affect states using the two networks. Our evaluation shows that both, ResNet-50 as well as SE-ResNet-50 are successful in accurately classifying all the 7 affect state from the Right segment, Left segment Lower segment and Upper segment of the face. While ResNet-50 performs marginally better compared to the SE-ResNet-50 in identifying the various affect states form the right, left and lower segments of the face, SE-ResNet-50 performs better in identifying the affect states from the upper segment of the face. We can thus conclude that right segment, left segment, lower segment and upper segments of the face contain sufficient information to correctly classify the seven affect states. The experimental results presented in this paper show that pre-defined Convolutional Neural Networks gives us very high accuracy, precision and recall values and hence can be used to accurately classify affect states even when there are occlusions present in the image and only certain portions of the face are available for analysis.


2021 ◽  
Author(s):  
Maria Lalouni ◽  
Jens Fust ◽  
Johan Bjureberg ◽  
Granit Kastrati ◽  
Robin Fondberg ◽  
...  

Individuals who engage in nonsuicidal self-injury (NSSI) have demonstrated higher pain thresholds and tolerance compared with individuals without NSSI. The objective of the study was to assess which aspects of the pain regulatory system that account for this augmented pain perception. In a cross-sectional design, 81 women, aged 18-35 (mean [SD] age, 23.4 [3.9]), were included (41 with NSSI and 40 healthy controls). A quantitative sensory testing protocol, including heat pain thresholds, heat pain tolerance, pressure pain thresholds, conditioned pain modulation (assessing central down-regulation of pain), and temporal summation (assessing facilitation of pain signals) was used. Thermal pain stimuli were assessed during fMRI scanning and NSSI behaviors and clinical symptoms were self-assessed. NSSI participants demonstrated higher pain thresholds during heat and pressure pain compared to controls. During conditioned pain modulation, NSSI participants showed a more effective central down-regulation of pain for NSSI participants. Temporal summation did not differ between the groups. There were no correlations between pain outcomes and NSSI behaviors or clinical characteristics. The fMRI analyses revealed increased activity in the primary and secondary somatosensory cortex in NSSI participants, compared to healthy controls, which are brain regions implicated in sensory aspects of pain processing. The findings suggest segregated inhibitory mechanisms for pain and emotion in NSSI, as pain insensitivity was linked to enhanced inhibitory control of pain in spite of significant impairments in emotion regulation. This may represent an endophenotype associated with a greater risk for developing self-injurious behavior.


Cephalalgia ◽  
2021 ◽  
pp. 033310242110565
Author(s):  
Jan Petter Neverdahl ◽  
Martin Uglem ◽  
Dagfinn Matre ◽  
Johannes Orvin Hansen ◽  
Morten Engstrøm ◽  
...  

Objective There is an unexplained association between disturbed sleep and migraine. In this blinded crossover study, we investigate if experimental sleep restriction has a different effect on pain thresholds and suprathreshold pain in interictal migraineurs and controls. Methods Forearm heat pain thresholds and tolerance thresholds, and trapezius pressure pain thresholds and suprathreshold pain were measured in 39 interictal migraineurs and 31 healthy controls after two consecutive nights of partial sleep restriction and after habitual sleep. Results The effect of sleep restriction was not significantly different between interictal migraineurs and controls in the primary analyses. Pressure pain thresholds tended to be lower (i.e., increased pain sensitivity) after sleep restriction in interictal migraineurs compared to controls with a 48-hour preictal-interictal cut-off (p = 0.061). We found decreased pain thresholds after sleep restriction in two of seven migraine subgroup comparisons: heat pain thresholds decreased in migraineurs with lower pain intensity during attacks (p = 0.005) and pressure pain thresholds decreased in migraineurs with higher severity of photophobia during attacks (p = 0.031). Heat pain thresholds tended to decrease after sleep restriction in sleep-related migraine (p = 0.060). Sleep restriction did not affect suprathreshold pain measurements in either group. Conclusion This study could not provide strong evidence for an increased effect of sleep restriction on pain sensitivity in migraineurs compared to healthy controls. There might be a slightly increased effect of sleep restriction in migraineurs, detectable using large samples or more pronounced in certain migraine subgroups.


2018 ◽  
Vol 12 (4) ◽  
pp. 250-256 ◽  
Author(s):  
Theresa Wodehouse ◽  
Kavita Poply ◽  
Shankar Ramaswamy ◽  
Saowarat Snidvongs ◽  
Julius Bourke ◽  
...  

Background: Fibromyalgia is a chronic musculoskeletal pain condition that is often associated with sleep disturbances and fatigue. The pathophysiology of fibromyalgia is not understood, but indirect evidence suggests a central dysfunction of the nociceptive modulating system. The aim of this study was to evaluate whether quantitative sensory testing detects a change in pain thresholds in fibromyalgia patient receiving pregabalin treatment. Methods: A total of 25 patients were recruited for the study and received routine pregabalin, but only 14 patients completed the treatment. Assessment of pressure pain thresholds and changes in conditioned pain modulation using ischaemic pain as a conditioning stimulus were measured at baseline and every 4 weeks for 12 weeks. Fibromyalgia impact questionnaire, PainDETECT and SF-12 were also completed. Results: Patients with fibromyalgia demonstrated a less-efficient conditioned pain modulation at baseline. An efficient conditioned pain modulation was observed at 1 month and this was maintained until the final visit. Pressure pain thresholds (PPTs) showed a significant improvement from baseline. Patients also reported a similar magnitude of improvements in PainDETECT, fibromyalgia impact questionnaire (FIQ) and its impact on daily life and change in outcome for SF-12. Conclusion: This pilot study reports an increase in PPTs and improved conditioned pain modulation response after commencing pregabalin, which was maintained at 12 weeks, and this was supported by positive pain scores. Pregabalin is a licenced treatment for fibromyalgia in Europe, and its response to central sensitisation, particularly ‘dynamic responses’, has not been reported. We conclude that pregabalin has the potential to reduce peripheral and central sensitisation in patients with fibromyalgia, as measured using quantitative sensory testing.


Cephalalgia ◽  
2010 ◽  
Vol 30 (8) ◽  
pp. 904-909 ◽  
Author(s):  
Trond Sand ◽  
Kristian Bernhard Nilsen ◽  
Knut Hagen ◽  
Lars Jacob Stovner

Normal heat pain threshold (HPT) and cold pain threshold (CPT) repeatability should be estimated in order to identify thermal allodynia in longitudinal studies, but such data are scarce in the literature. The aim of our study was to estimate normal HPT and CPT repeatability in the face, forehead, neck and hand. In addition, we reviewed briefly normative studies of thermal pain thresholds relevant for headache research. Thermal pain thresholds were measured on three different days in 31 healthy headache-free subjects. Coefficients of repeatability and normal limits were calculated. HPT and CPT were lowest in the face. Pooled across regions, the lower repeatability limit for the test/retest ratio was 63% for HPT and 55% for CPT. The upper normal CPT limit varied between 24.5°C and 29.7°C. Lower HPT limits ranged between 35.5°C and 40.8°C. Quantitative sensory methods provide useful information about headache and pain pathophysiology, and it is important to estimate the normal test/retest repeatability range in follow-up studies.


2001 ◽  
Vol 16 (1) ◽  
pp. 68-70 ◽  
Author(s):  
H. Papezová ◽  
A. Yamamotová ◽  
J. Nedvídková

The objective of this study was to test the effect of melatonin on thermal pain threshold in female patients with eating disorders. Fourteen patients were included in the study. We found a parabolic relation between pain threshold and the content of urine sulfatoxymelatonin (r = 0.6299, P < 0.05). We can speculate that increase in severity of eating disorder pathology may decrease both the melatonin level and pain sensitivity. In contrast with expected melatonin analgesic effect, our results showed its possible normalizing influence as well on pathologically decreased pain sensitivity.


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