The Effect of ShotBlocker on Pain and Patient Satisfaction for Spinal Anesthesia: A Randomized Trial.

BACKGROUND: During spinal anesthesia, patients may experience pain and discomfort associated with dermal puncture. It may also cause involuntary movement, which often disturbs the patient's posture thus affecting the success of spinal anesthesia. Different methods have been studied to cope with needle-related pain. "ShotBlocker" is a flexible, plastic, U-shaped device, which has several blunt points. It is suggested that blunt points provide a nonnoxious physical stimulation and inhibit the transmission of injection pain. OBJECTIVES: The purpose of this study was to examine the effectiveness of the ShotBlocker for dermal puncture pain during spinal anesthesia. STUDY DESIGN: Prospective randomized trial. SETTING: University hospital, operating room. METHODS: Ninety-four patients aged 18 to 65 years with physical status American Society of Anesthesiologists (ASA) I or II scheduled for elective surgery under spinal anesthesia were randomly assigned to either a ShotBlocker (n = 47) or control group (n = 47). In the ShotBlocker group, lumbar punctures were performed with the application of ShotBlocker. Needle-associated pain score and patient satisfaction were assessed by the patient, immediately after completion of the spinal anesthesia using a 10-cm Visual Analog Scale (VAS) and a 5-point Likert scale for satisfaction. Patients were also closely observed for symptoms of discomfort such as spontaneous vocalization and involuntary movement. RESULTS: A total of 88 patients completed the study. There was no significant difference in VAS scores, patient satisfaction, or procedure time between groups (P > 0.05). Spontaneous vocalization did not occur in both groups. However, incidence of unintentional movement during dermal puncture was higher in the control group (6.8% vs. 31.8%; P < 0.05). LIMITATIONS: Study was conducted in a single-center with a relatively small population of patients. Only the attending anesthetist collecting data was blinded to the procedure. Patients older than age 65 years were also excluded from the study, thus our results cannot be generalized. CONCLUSIONS: ShotBlocker did not show any advantage on VAS scores but decreased the incidence of unintentional movement during dermal puncture.

Mechanical Nociception in Mice and Rats: Measurement with Automated von Frey Equipment.

von Frey hairs are important tools for the study of mechanisms of cutaneous stimulation-induced sensory input. Mechanical force is exerted via application of a particular hair to the cutaneous receptive field until buckling of the hair occurs. The most commonly used von Frey filaments are productive in evaluating behavioral responses of neuropathic pain in preclinical and clinical research. To reduce the potential experimenter bias, automated instruments are being developed for behavioral assessment.

A novel clinical applicable bed-side tool for assessing conditioning pain modulation: proof-of-concept.

Background and aims In recent years, focus on assessing descending pain modulation or conditioning pain modulation (CPM) has emerged in patients with chronic pain. This requires reliable and simple to use bed-side tools to be applied in the clinic. The aim of the present pilot study was to develop and provide proof-of-concept of a simple clinically applicable bed-side tool for assessing CPM. Methods A group of 26 healthy volunteers participated in the experiment. Pressure pain thresholds (PPT) were assessed as test stimuli from the lower leg before, during and 5 min after delivering the conditioning tonic painful pressure stimulation. The tonic stimulus was delivered for 2 min by a custom-made spring-loaded finger pressure device applying a fixed pressure (2.2 kg) to the index finger nail. The pain intensity provoked by the tonic stimulus was continuously recorded on a 0-10 cm Visual Analog Scale (VAS). Results The median tonic pain stimulus intensity was 6.7 cm (interquartile range: 4.6-8.4 cm) on the 10 cm VAS. The mean PPT increased significantly (P = 0.034) by 55 ± 126 kPa from 518 ± 173 kPa before to 573 ± 228 kPa during conditioning stimulation. When analyzing the individual CPM responses (increases in PPT), a distribution of positive and negative CPM responders was observed with 69% of the individuals classified as positive CPM responders (increased PPTs = anti-nociceptive) and the rest as negative CPM responders (no or decreased PPTs = Pro-nociceptive). This particular responder distribution explains the large variation in the averaged CPM responses observed in many CPM studies. The strongest positive CPM response was an increase of 418 kPa and the strongest negative CPM response was a decrease of 140 kPa. Conclusions The present newly developed conditioning pain stimulator provides a simple, applicable tool for routine CPM assessment in clinical practice. Further, reporting averaged CPM effects should be replaced by categorizing volunteers/patients into anti-nociceptive and pro-nociceptive CPM groups. Implications The finger pressure device provided moderate-to-high pain intensities and was useful for inducing conditioning stimuli. Therefore, the finger pressure device could be a useful bed-side method for measuring CPM in clinical settings with limited time available. Future bed-side studies involving patient populations are warranted to determine the usefulness of the method.

Association of dynamic and widespread mechanical sensitivity in cluster headache.

We investigated if dynamic pressure pain sensitivity in the symptomatic area is associated with pressure sensitivity in local and distant pain-free areas in cluster headache (CH). A pressure algometry set consisting of 8 rollers with fixed pressure levels ranging from 500 to 5300 g was used to assess dynamic pressure pain sensitivity in men with episodic CH. Each roller was moved from an anterior-to-posterior direction over the temporalis muscle. The load level of the first painful roller was considered the dynamic pain threshold (DPT). Further, pain elicited during DPT (roller evoked pain) was also assessed. We used a pressure algometer to determine pressure pain thresholds (PPTs) over the temporalis muscle, C5/C6 joint, second metacarpal, and tibialis anterior. Patients were assessed in an asymptomatic (remission) phase, at least 6 months after their last cluster period and without taking pharmacological treatment. Forty men with episodic CH (mean age 42 years) were included. Both outcomes, DPTs (r = 0.781, P < 0.001) and roller-evoked pain (r = 0.586; P < 0.001) were bilaterally correlated. Further, DPT, but not roller-evoked pain, was moderately associated with PPTs measured at the symptomatic (temporalis: r = 0.665, P < 0.001) and distant pain-free (C5-C6 joint: r = 0.389, P = 0.013; second metacarpal: r = 0.551, P < 0.001; and, tibialis anterior: r = 0.308, P = 0.035) points. Dynamic pressure sensitivity in the trigeminal area was correlated to pressure pain sensitivity at both symptomatic and distant pain-free areas in men with CH supporting the use of roller pressure algometry. Dynamic pressure algometry may be a new tool for assessing the status of sensitization in primary headaches.

Immediate effects of noxious and innocuous thermal stimulation on brain activation in patients with stroke.

Case-control studies have shown that noxious thermal stimulation (TS) can improve arm function in patients with stroke. However, the neural mechanisms underlying this improvement are largely unknown. We explored functional neural activation due to noxious and innocuous TS intervention applied to the paretic arm of patients with stroke. Sixteen participants with unilateral cortical infarctions were allocated to one of two groups: noxious TS (8 patients; temperature combination: hot pain 46°C to 47°C, cold pain 7°C-8°C) or innocuous TS (n = 8; temperature combination: hot 40°C-41°C, cold 20°C-21°C). All subjects underwent fMRI scanning before and after 30 min TS intervention and performed a finger tapping task with the affected hand. Immediate brain activation effects were assessed according to thermal type (noxious vs. innocuous TS) and time (pre-TS vs post-TS). Regions activated by noxious TS relative to innocuous TS (P < .05, adjusted for multiple comparisons) were related to motor performance and sensory function in the bilateral primary somatosensory cortices, anterior cingulate cortex, insula, thalamus, hippocampus and unilateral primary motor cortex, secondary somatosensory cortex at the contralateral side of lesion, and unilateral supplementary motor area at the ipsilateral side of lesion. Greater activation responses were observed in the side contralateral to the lesion, suggesting a significant intervention effect. Our preliminary findings suggest that noxious TS may induce neuroplastic changes unconstrained to the local area.Trial registration: NCT01418404.

Quantitative Sensory Testing in pain assesment and treatment. Brief review and algorithmic management proposal. / Test sensitivos cuantitativos («Quantitative Sensory Testing¼) en el diagnóstico y tratamiento del dolor. Breve revisión y propuesta de protocolización de empleo.

Quantitative Sensory Testing (QST) is used to globally analyze the nociceptive system in order to obtain a more objective understanding of pain perception. In recent years, QST has become a common tool in many pain clinics and anesthesiology departments worldwide. In 2013, the Neuropathic Pain Special Interest Group of the IASP put forward the first recommendations for conducting QST in clinical practice and research. However, the wide variety of QST methodologies and standards in the literature make it difficult to generalize the used of this tool in clinical practice. In this study, we present the basic concepts of QST, the type of tests and devices used, how they are applied, and the role of QST in anesthesiology and pain management.

Allodynography: Reliability of a New Procedure for Objective Clinical Examination of Static Mechanical Allodynia.

OBJECTIVE: There is a need for reliable and valid clinical assessment tools for quantifying allodynia in neuropathic pain. Allodynography has been proposed as a useful standardized procedure for clinical assessment of mechanical allodynia. This study (www.clinicaltrials.gov NCT02070367) undertook preliminary investigation of the measurement properties of allodynography, a new standardized clinical examination procedure for mapping the area of cutaneous allodynia. METHODS: Persons with pain in one upper extremity after complex regional pain syndrome, a peripheral nerve injury, or who had recently experienced a hand fracture were recruited for assessment of static mechanical allodynia (based on perception of a 15g force stimulus delivered by Semmes-Weinstein monofilament #5.18 as painful) by two raters at baseline; the assessment was repeated one week later. RESULTS: Single-measures estimates suggested inter-rater reliability for allodynography was excellent at an intraclass correlation coefficient (ICC) of 0.97 (N = 12); test-retest reliability was also excellent at ICC = 0.89 (N = 10) for allodynography (P < 0.001 for both). Confidence intervals' lower bounds confirm inter-rater reliability as excellent (0.90) but were less definitive for test-retest (0.59). CONCLUSIONS: This preliminary study supports the inter-rater and test-retest reliability of allodynography. Studies on larger samples in multiple contexts and reporting other measurement properties are warranted.

Phase I Safety Trial: Extended Daily Peripheral Sensory Stimulation Using a Wrist-Worn Vibrator in Stroke Survivors.

Peripheral sensory stimulation augments post-stroke upper extremity rehabilitation outcomes. Most sensory stimulations interfere with natural hand tasks and the stimulation duration is limited. We developed TheraBracelet, low-level random-frequency vibration applied via a wristwatch, to enable stimulation during hand tasks and potentially extend stimulation durations. To determine safety of prolonged exposure to TheraBracelet. Single-site double-blind crossover randomized controlled trial. Chronic stroke survivors were instructed to wear a device on the affected wrist for > 8 h/day everyday for 2 months while coming to the laboratory weekly for evaluations, with a 2-week break between each month. The device applied vibration at 60% and 1% of the sensory threshold for the real and sham month, respectively. The order of the real and sham months was randomized/balanced. Adverse events (AEs) were assessed weekly, including worsening of hand sensation, dexterity, grip strength, pain, or spasticity and occurrence of skin irritation or swelling. Device-related AE rates were compared between the real and sham month. Twenty-five participants completed the study. Six participants (24%) experienced mild AEs involving worsened sensory scores that may be related to the intervention with reasonable possibility. Two experienced them in the real stimulation month only, 3 in the sham month only, and 1 in both months. Therefore, less participants experienced device-related AEs in the real than sham month. Daily stimulation using the device for a month is safe for chronic stroke survivors. Future studies examining the efficacy of pairing TheraBracelet with therapy for increasing neurorehabilitation outcomes are a logical next step. Trial registration: NCT03318341.

Investigating the Feasibility of a Modified Quantitative Sensory Testing Approach to Profile Sensory Function and Predict Pain Outcomes Following Intrathecal Baclofen Implant Surgery in Cerebral Palsy.

OBJECTIVES: Intrathecal baclofen (ITB) pumps used to manage spasticity in children with cerebral palsy (CP) also improve pain outcomes for some but not all patients. The purpose of this clinical feasibility study was to explore whether a quantitative sensory testing approach could a) be modified and used to subgroup individuals into sensory profiles and b) test whether the profiles were related to postimplant pain outcomes (i.e., pain responsive or pain persistent). SUBJECTS: A purposeful clinical sample of nine children with CP (mean age = 12.5 years, male = 56%) and complex communication needs participated. METHODS: A prospective within-subject design was used to measure proxy-reported pain before and after ITB implant. Pain response status was determined by proxy-reported pain intensity change (>50% change in maximum rated intensity). A modified quantitative sensory testing (mQST) procedure was used to assess behavioral responsivity to an array of calibrated sensory (tactile/acute nociceptive) stimuli before surgery. RESULTS: Seven individuals with presurgical pain had mQST differentiated sensory profiles in relation to ITB pain outcomes and relative to the two individuals with no pain. Presurgically, the ITB pain responsive subgroup (N = 3, maximum rated pain intensity decreased >50% after ITB implant) showed increased behavioral reactivity to an acute nociceptive stimulus and cold stimulus, whereas the ITB pain persistent subgroup (N = 4) showed reduced behavioral reactivity to cold and repeated von Frey stimulation relative to the no pain individuals. CONCLUSION: Implications for patient selection criteria and stratification to presurgically identify individuals with CP "at risk" for persistent postprocedure pain are discussed.

The Effect of External Thermomechanical Stimulation and Distraction on Reducing Pain Experienced by Children During Blood Drawing.

This study aimed to investigate the sole and combined effects of external thermomechanical stimulation and distraction in pain relief of children during blood drawing.This is a randomized clinical trial. The sample consisted of 218 children aged 6 to 12 years who were randomly assigned to 4 groups: group 1 received no intervention, group 2 received external thermomechanical stimulation using Buzzy, group 3 received distraction via DistrACTION Cards, and group 4 received a combination of both external thermomechanical stimulation and distraction. Preprocedural anxiety was assessed through observers' observations using the Children's Anxiety and Pain Scale. Children's pain levels were assessed by themselves, observers, and parents, as reported using the Faces Pain Scale-Revised. Preprocedural anxiety did not differ significantly (P > 0.05). When the 3 study groups were compared with the control group, all 3 groups had significantly lower pain levels than the control group (P < 0.001). The lowest pain level was measured in the combined condition (Buzzy and DistrACTION Cards). The mean score of the device group was lower than the distraction group.

Controlled emotional tactile stimulation during functional magnetic resonance imaging and electroencephalography.

BACKGROUND: Tactile stimulation used to induce emotional responses is often not well-controlled. Replicating the same tactile stimulations across studies is difficult, compared to replicating visual and auditory modalities, which have standardized stimulus sets. Standardizing a stimulation method by replicating stimuli across studies is necessary to further elucidate emotional responses in neuroscience research using tactile stimulation. THE NEW METHOD: We developed a tactile stimulation device. The device's ultrasonic motor and optical force sensor have the following criteria: (1) controls the physical property of stimuli, pressure, and stroking speed; (2) measures actual touch timing; (3) is safe to use in a magnetic resonance imaging (MRI) scanner; and (4) produces low noise in electroencephalography (EEG) and MRI. RESULTS: The noise level of the device's drive was sufficiently low. For the EEG experiment, we successfully used signal processing to diminish the commercial power supply noise. For functional MRI (fMRI) scans, we found <5% signal loss occurred during device rotation. COMPARISON WITH EXISTING METHOD(S): We found no previous report about the noise level of a tactile stimulation device used to induce emotional responses during EEG and fMRI recordings. The signal loss rate was comparable with that of other robotic devices used in MRI scanners. Emotional feelings induced by this stimulation method were comparable with those elicited in other sensory modalities. CONCLUSIONS: The developed device could be used for cognitive-affective neuroscience research when conducting EEG and fMRI scans. The device should aid in standardizing affective tactile stimulation for research in psychology and cognitive neuroscience.

The Effect of Daily Use of Plantar Mechanical Stimulation Through Micro-Mobile Foot Compression Device Installed in Shoe Insoles on Vibration Perception, Gait, and Balance in People With Diabetic Peripheral Neuropathy.

OBJECTIVE: People with diabetic peripheral neuropathy (DPN) have impaired gait and balance performance. The aim of this study is to investigate therapeutic effectiveness of mechanical stimulation through a wearable foot compression device equipped in a shoe insole on vibration perception, balance control and gait performance in people with DPN. METHODS: Using a single-arm 4-week intervention study design, we examined effectiveness of daily use of shoes equipped with the foot compression device (Footbeat™, AVEX, Grand Junction, CO, USA) on improving vibration perception threshold (VPTmax), skin perfusion pressure (SPP), ankle brachial index (ABI), lower extremities edema (circumferences in the calf and ankle), and motor performance (postural sway with eyes open and closed conditions, and gait performance during normal, dual-task and fast walking). Thirty people with type 2 diabetes and symptoms of PN completed the experimental protocol. RESULTS: Improvements in VPTmax (before = 27.4 V, after = 23.3 V, P = .007, d = 0.33, where d denotes effect size), center-of-mass sway in the mediolateral direction with both eyes open and closed conditions (before = 0.94 cm, after = 0.76 cm, P = .020, d = 0.47; before = 1.10 cm, after = 0.83 cm, P = .033, d = 0.66, respectively), and stride velocity for normal walking, dual-task walking and fast walking tasks (before = 0.87 m/s, after = 0.96 m/s, P = .017, d = 0.41; before = 0.75 m/s, after = 0.91 m/s, P = .001, d = 0.77; before = 1.10 m/s, after = 1.20 m/s, P = .043, d = 0.33, respectively) were found post treatment. There was no significant improvement in SPP, ABI, and circumferences in the calf and ankle. CONCLUSIONS: Our findings suggest the wearable foot compression device may be effective for reducing neuropathic symptoms and enhancing motor performances in people with DPN.

Immediate improvement of speech-in-noise perception through multisensory stimulation via an auditory to tactile sensory substitution.

BACKGROUND: Hearing loss is becoming a real social and health problem. Its prevalence in the elderly is an epidemic. The risk of developing hearing loss is also growing among younger people. If left untreated, hearing loss can perpetuate development of neurodegenerative diseases, including dementia. Despite recent advancements in hearing aid (HA) and cochlear implant (CI) technologies, hearing impaired users still encounter significant practical and social challenges, with or without aids. In particular, they all struggle with understanding speech in challenging acoustic environments, especially in presence of a competing speaker. OBJECTIVES: In the current proof-of-concept study we tested whether multisensory stimulation, pairing audition and a minimal-size touch device would improve intelligibility of speech in noise. METHODS: To this aim we developed an audio-to-tactile sensory substitution device (SSD) transforming low-frequency speech signals into tactile vibrations delivered on two finger tips. Based on the inverse effectiveness law, i.e., multisensory enhancement is strongest when signal-to-noise ratio is lowest between senses, we embedded non-native language stimuli in speech-like noise and paired it with a low-frequency input conveyed through touch. RESULTS: We found immediate and robust improvement in speech recognition (i.e. in the Signal-To-Noise-ratio) in the multisensory condition without any training, at a group level as well as in every participant. The reported improvement at the group-level of 6 dB was indeed major considering that an increase of 10 dB represents a doubling of the perceived loudness. CONCLUSIONS: These results are especially relevant when compared to previous SSD studies showing effects in behavior only after a demanding cognitive training. We discuss the implications of our results for development of SSDs and of specific rehabilitation programs for the hearing impaired either using or not using HAs or CIs. We also discuss the potential application of such a set-up for sense augmentation, such as when learning a new language.

Vibrotactile piezoelectric stimulation system with precise and versatile timing control for somatosensory research.

BACKGROUND: Tactile stimulations systems are useful for studying the somatosensory system in children because they are innocuous and safe. Stimulators based on piezoelectric actuator are useful, but there is still a need for such systems capable of providing accurate and versatile control of timing and pattern of activation. NEW METHOD: We have implemented a vibrotactile stimulating system useful for behavioral and electroencephalography (EEG) and magnetoencephalography (MEG) research. Our design goal was to create a system capable of providing up to five independently controlled mechanical stimulations with precise timing. We developed a Graphic User Interface (GUI) in LabVIEW, which controls a commercially available piezoelectric braille stimulator using an Arduino based controller. We made a customized braille stimulator based on the Metec Braille device. RESULTS: Our system can control up to five tactile stimulators with independent timing control and negligible errors. Although it can be directly used for behavioral and EEG research, the piezoelectric stimulators in our system generate stimulus artifacts that interfere with MEG recordings. A moving averaging subtraction algorithm we developed can remove the artifact. The stimulator can be used to measure somatic evoked magnetic fields from the somatosensory cortex of a child without the artifact. COMPARISON TO EXISTING METHODS: Our system provides an accurate independent control of one or more piezoelectric actuators using a GUI-based easy-to-control programming approach based on recent advances in embedded systems and software. Versatility and precise stimulation timing distinguish our system compared to existing somatic stimulators. CONCLUSIONS: Our system may be useful for somatic research.

Noninvasive Ultrasonic Neuromodulation in Freely Moving Mice.

Neuromodulation is a fundamental method for obtaining basic information about neuronal circuits for use in treatments for neurological and psychiatric disorders. Ultrasound stimulation has become a promising approach for noninvasively inducing neuromodulation in animals and humans. However, the previous investigations were subject to substantial limitations, due to most of them involving anesthetized and fixed small-animal models. Studies of awake and freely moving animals are needed, but the currently used ultrasound devices are too bulky to be applied to a freely moving animal. This study is the first time to design and fabricate a miniature and lightweight head-mounted ultrasound stimulator for inducing neuromodulation in freely moving mice. The main components of the stimulator include a miniature piezoelectric ceramic, a concave epoxy acoustic lens, and housing and connection components. The device was able to induce action potentials recorded in situ and evoke head-turning behaviors by stimulating the primary somatosensory cortex barrel field of the mouse. These findings indicate that the proposed method can be used to induce noninvasive neuromodulation in freely moving mice. This novel method could potentially lead to the application of ultrasonic neuromodulation in more-extensive neuroscience investigations.

Tactile Display Design for Flight Envelope Protection and Situational Awareness.

Spatial disorientation and visual channel saturation are defined as critical situations encountered by military pilots. Such subjects are interesting research areas likely to create innovative systems able to surmount obstacles of this kind. The integration of new stimulation techniques (sensory substitute, adjunct for visual and audio feedback) may be considered to make the visual channel better. This contribution may help in integrating tactile stimulation to improve or substitute the visual channel. It may also help to better interpret the spatial disorientation awareness signals and the vestibulo-ocular response limitations. The innovation of the proposed approach translates in: (i) the development of the PI-Inverse dynamics controller to provide a time delay reduction of the low cost tactile actuator, and thus, high-performance tactile system; (ii) an approach based on fuzzy logic controller (FLC) is being used in order to translate the turn rate angle, the flight path climb angle and the warning messages into tactile signal features instead of a conventional approach based on direct coding of the pitch and bank angles; and (iii) the consideration of the flight envelope. The fuzzy set translation of flight parameters into tactile signals is also a pragmatic and useful way to design the system.

Experimental noxious stimulation of the right masseter muscle does not affect bilateral masseter and temporalis muscle activity and force parameters during standardised isometric biting tasks.

AIM: To determine if the electromyographic (EMG) activity of the left and right masseter and anterior temporalis muscles is altered by experimental right masseter muscle noxious stimulation during goal-directed isometric biting tasks in asymptomatic humans. METHODS: Isometric biting tasks (slow and fast ramp biting tasks, 2-step biting task) were performed on an intraoral force transducer in 18 participants during the following blocks: baseline block, hypertonic saline infusion into the right masseter muscle (painful block) and isotonic saline infusion into the right masseter (control block). Bipolar surface electrodes recorded EMG activity from the bilateral masseter and anterior temporalis muscles. A 100-mm visual analogue scale (VAS) quantified pain intensity, and the McGill Pain Questionnaire (MPQ), the Depression, Anxiety and Stress Scales-21 (DASS-21) and the Pain Catastrophizing Scale (PCS) were completed. Repeated measures ANOVA assessed the effects of pain on the force rates (N/s), force amplitudes (N) and the root mean square (RMS) jaw muscle EMG activity across blocks. Statistical significance accepted at P < 0.05. RESULTS: VAS scores were significantly (P < 0.001) higher during hypertonic than isotonic saline infusion blocks. There was no significant effect of pain on the force rates, or force levels or the RMS EMG activity of each masseter and anterior temporalis muscle. CONCLUSION: The findings suggest that experimentally induced right masseter muscle pain does not modify force or surface jaw muscle EMG activity during isometric biting tasks.

Reorganization of motor unit activity at different sites within the human masseter muscle during experimental masseter pain.

The aims were to test the hypotheses that experimental masseter muscle pain leads to recruitment and/or derecruitment of motor units at different sites within the masseter and that the patterns of change in motor unit activity differ between sites. Single motor unit (SMU) activity was recorded at two sites within the right masseter [superior/anterior, inferior/posterior (IP)] during isometric biting tasks (ramp, step level) on an intraoral force transducer in 17 participants during three experimental blocks comprising no infusion (baseline), 5% hypertonic saline infusion (pain), or isotonic saline infusion (control). A visual analog scale (VAS) was used to score pain intensity. The VAS scores were statistically significantly greater during infusion of hypertonic saline than during infusion of isotonic saline. No significant differences in force levels and rates of force change were found between experimental blocks. In comparison with isotonic saline infusion, SMUs could be recruited and derecruited at both sites during hypertonic saline infusion. The frequency of recruitment or derecruitment, in comparison with no change, was statistically significantly greater at the IP site than at the superior/anterior site. Experimental noxious masseter stimulation results in a reorganization of motor unit activity throughout the muscle, and the pattern of reorganization may be different in different regions of the muscle.

The tactile receptive fields of freely moving Caenorhabditis elegans nematodes.

Sensory neurons embedded in skin are responsible for the sense of touch. In humans and other mammals, touch sensation depends on thousands of diverse somatosensory neurons. By contrast, Caenorhabditis elegans nematodes have six gentle touch receptor neurons linked to simple behaviors. The classical touch assay uses an eyebrow hair to stimulate freely moving C. elegans, evoking evasive behavioral responses. This assay has led to the discovery of genes required for touch sensation, but does not provide control over stimulus strength or position. Here, we present an integrated system for performing automated, quantitative touch assays that circumvents these limitations and incorporates automated measurements of behavioral responses. The Highly Automated Worm Kicker (HAWK) unites a microfabricated silicon force sensor holding a glass bead forming the contact surface and video analysis with real-time force and position control. Using this system, we stimulated animals along the anterior-posterior axis and compared responses in wild-type and spc-1(dn) transgenic animals, which have a touch defect due to expression of a dominant-negative α-spectrin protein fragment. As expected from prior studies, delivering large stimuli anterior and posterior to the mid-point of the body evoked a reversal and a speed-up, respectively. The probability of evoking a response of either kind depended on stimulus strength and location; once initiated, the magnitude and quality of both reversal and speed-up behavioral responses were uncorrelated with stimulus location, strength, or the absence or presence of the spc-1(dn) transgene. Wild-type animals failed to respond when the stimulus was applied near the mid-point. These results show that stimulus strength and location govern the activation of a characteristic motor program and that the C. elegans body surface consists of two receptive fields separated by a gap.

Automated Mechanical Peripheral Stimulation Effects on Gait Variability in Individuals With Parkinson Disease and Freezing of Gait: A Double-Blind, Randomized Controlled Trial.

OBJECTIVE: To assess the effects of automated peripheral stimulation (AMPS) in reducing gait variability of subjects with Parkinson disease (PD) and freezing of gait (FOG) treated with AMPS and to explore the effects of this treatment on gait during a single task (walking) and a dual task (walking while attending the word-color Stroop test). DESIGN: Interventional, double-blinded, placebo-controlled, randomized trial. SETTING: Clinical rehabilitation. PARTICIPANTS: Thirty subjects were randomized into 2 groups: AMPS (n=15) and AMPS sham (n=15). INTERVENTIONS: Both groups received 2 treatment sessions a week for 4 consecutive weeks (totaling 8 treatment sessions). AMPS was applied by using a medical device (Gondola™) and consisted in mechanical pressure stimulations delivered by metallic actuators on 4 areas of the feet. Treatment parameters and device configuration were modified for AMPS sham group. MAIN OUTCOME MEASURES: Gait analyses were measured at baseline and after the first, fourth, and eighth treatment sessions. RESULTS: Interactions among groups and sessions were found for both conditions while off anti-Parkinsonian medications. AMPS decreased gait variability in subjects with PD and FOG for both single and dual task conditions. CONCLUSIONS: AMPS is an effective add-on therapy for treating gait variability in patients with PD and FOG.