Dorsal Forearm Research Articles

Comparison of spatial summation properties at different body sites

Background and aimsThe nociceptive system appears to have evolved a range of protective characteristics that are of great interest in understanding both acute and chronic pain. Spatial summation is one important characteristic, whereby increasing area of a stimulus, or distance between multiple stimuli, results in more intense pain—not only greater area of pain. One of the mysteries of chronic pain is why spinal pain is so prevalent relative to pain at other sites. Since pathological tissue models have failed to fully explain spinal pain, we theorized that body region specific differences in sensory processing—such as a greater propensity for spatial summation—may help to explain its vulnerability. We aimed to examine this by comparing the properties of summation at different body parts: the dorsal forearm, neck, and back. MethodsSpatial summation of pain was investigated using noxious intra-dermal electrical stimuli in healthy pain-free adults (14 males, 6 females), and the perceived pain intensity was rated on a 0–100 pain scale. Area-based stimulation was investigated by doubling the stimulation area with the addition of a second electrode placed adjacent to the first. Distance-based summation was investigated by randomly varying the separation distance between paired noxious electrical stimuli at separations of 0, 10, 15, and 20cm. ResultsThis study demonstrated that the properties of area- and distance-based summation are uniform across the neck, back, and forearm in healthy adults. Spatial summation of pain was also found to be greatest at 15- and 20-cm paired separations for all body regions tested, confirming that noxious information can be integrated over an extensive anatomical area. ConclusionData from this investigation refutes the thesis that spatial summation of pain may be a contributing factor for the reported difference in chronicity rates between spinal and peripheral sites. It remains, however, a potentially important mechanism by which noxious inputs from multi-level pathology might integrate and contribute to pain. ImplicationsWhile data from this project suggest that there are no regional differences in the properties of spatial summation of noxious stimuli, regional differences in other characteristics of the nociceptive system may yet provide insight into why some spinal pain is so highly prevalent; nociceptive distance-based summation may be highly relevant where two or more conditions co-exist in close proximity.

In vivo confocal Raman spectroscopy for intrinsic aging and photoaging assessment

BackgroundIn vivo confocal Raman spectroscopy is a non-invasive method to assess either the epidermis or the dermis composition. Few studies have focused on dermis collagen alterations through intrinsic aging and photoaging. ObjectiveThis study evaluated the in vivo Raman spectra from the dermis of a photoexposed site versus a non-photoexposed region in different age groups, and evaluated the correlation between peak intensities and age, photoaging score and the amount of collagen assessed with histology and high frequency ultrasound (HFUS). MethodsFifteen volunteers aged 28–82 years were divided into three groups according to forearm photoaging degree. In vivo Raman spectra from the dermis were collected on the dorsal forearm (chronically photoexposed skin) and on the proximal medial arm (non-photoexposed skin). Cross-sectional images of the skin were obtained using a 20MHz ultrasound unit exactly on the same sites, which were further submitted to punch biopsies for histologic study (collagen I immunohistochemistry, picrosirius red staining and Verhoeff). Principal Component Analysis (PCA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) were taken in the spectral region of 796cm−1–996cm−1 to determine its potential to discriminate between different groups. The Spearman rank correlation coefficient of individual peak intensities and ratios with age, clinical score and the amount of collagen assessed by ultrasound and histology were calculated. ResultsPCA of pairs of groups and OPLS-DA could discriminate the intrinsically from the photoaged skin and the young group from the elderly one, with important contribution of the 938cm−1 and 855cm−1 peaks intensities. The intensity of the peaks in 855cm−1 and/or 938cm−1 presented moderate correlation with age (rho=0.579, p=0.049) and moderate to high inverse correlation with HFUS echogenicity (rho=−0.710, p=0.010) and collagen I immunohistochemistry (rho=−0.833, p=0.005) in the non-photoexposed region. The I1275/I1450 intensities ratio presented moderate to high correlation coefficients with age (rho=−0.730, p=0.007), photoaging score (rho=−0.594, p=0.042), HFUS echogenicity (rho=0.760, p<0.001) and histology (collagen I immunohistochemistry (rho=0.643, p=0.024), picrosirius (rho=0.773, p=0.005) and Verhoeff (rho=−0.727, p=0.011)) in the photoexposed site. ConclusionThe wavenumber region between 798 and 994cm−1 is useful for the analysis of dermal collagen alterations through the intrinsic aging process, while photoaging is better assessed by the I1275/I1450 intensities ratio. This is the first skin aging study to show a correlation between Raman peaks and the amount of collagen assessed by HFUS and histology.

Tactile motion lacks momentum.

The displacement of the final position of a moving object in the direction of the observed motion path, i.e. an overestimation, is known as representational momentum. It has been described both in the visual and the auditory domain, and is suggested to be modality-independent. Here, we tested whether a representational momentum can also be demonstrated in the somatosensory domain. While the cognitive literature on representational momentum suggests that it can, previous work on the psychophysics of tactile motion perception would rather predict an underestimation of the perceived endpoint of a tactile stimulus. Tactile motion stimuli were applied on the left and the right dorsal forearms of 32 healthy participants, who were asked to indicate the subjectively perceived endpoint of the stimulation. Velocity, length and direction of the trajectory were varied. Contrary to the prediction based on the representational momentum literature, participants in our experiment significantly displaced the endpoint against the direction of movement (underestimation). The results are thus compatible with previous psychophysical findings on the perception of tactile motion. Further studies combining paradigms from classical psychophysics and cognitive psychology will be needed to resolve the apparently paradoxical predictions by the two literatures.

Cutaneous Autonomic Pilomotor Testing to Unveil the Role of Neuropathy Progression in Early Parkinson's Disease (CAPTURE PD): Protocol for a Multicenter Study.

In Parkinson's disease (PD), alpha-synuclein accumulation in cutaneous autonomic pilomotor and sudomotor nerve fibers has been linked to autonomic nervous system disturbances even in the early stages of the disease. This study aims to assess the association between alpha-synuclein-mediated structural autonomic nerve fiber damage and function in PD, elucidate the role of neuropathy progression during the early disease stages, and test reproducibility and external validity of pilomotor function assessment using quantitative pilomotor axon-reflex test and sudomotor function via quantitative direct and indirect test of sudomotor function. A prospective controlled study will be conducted at four study sites in Europe and the USA. Fifty-two male and female patients with idiopathic PD (Hoehn and Yahr 1-2) and 52 age- and sex-matched healthy controls will be recruited. Axon-reflex-mediated pilomotor erection will be induced by iontophoresis of phenylephrine on the dorsal forearm. Silicone impressions of the response will be obtained, scanned, and quantified for pilomotor muscle impressions by number, impression size, and area of axon-reflex spread. Axon-reflex-mediated sweating following acetylcholine iontophoresis will be quantified for number and size of droplets and axon-reflex spread. Sympathetic skin responses, autonomic and motor symptoms will be evaluated. Tests will be performed at baseline, after 2 weeks, 1, 2, and 3 years. Skin biopsies will be obtained at baseline and after 3 years and will be analyzed for nerve fiber density and alpha-synuclein accumulation. We anticipate that progression of autonomic nerve dysfunction assessed via pilomotor and sudomotor axon-reflex tests is related to progression of autonomic symptom severity and alpha-synuclein deposition. Potential applications of the techniques include interventional studies evaluating disease-modifying approaches and clinical assessment of autonomic dysfunction in patients with PD. TRN NCT03043768.

Cutaneous exposure to hypoxia does not affect skin perfusion in humans.

Experiments have indicated that skin perfusion in mice is sensitive to reductions in environmental O2 availability. Specifically, a reduction in skin-surface PO2 attenuates transcutaneous O2 diffusion, and hence epidermal O2 supply. In response, epidermal HIF-1α expression increases and facilitates initial cutaneous vasoconstriction and subsequent nitric oxide-dependent vasodilation. Here, we investigated whether the same mechanism exists in humans. In a first experiment, eight males rested twice for 8h in a hypobaric chamber. Once, barometric pressure was reduced by 50%, while systemic oxygenation was preserved by O2 -enriched (42%) breathing gas (HypoxiaSkin ), and once barometric pressure and inspired O2 fraction were normal (Control1 ). In a second experiment, nine males rested for 8h with both forearms wrapped in plastic bags. O2 was expelled from one bag by nitrogen flushing (AnoxiaSkin ), whereas the other bag was flushed with air (Control2 ). In both experiments, skin blood flux was assessed by laser Doppler on the dorsal forearm, and HIF-1α expression was determined by immunohistochemical staining in forearm skin biopsies. Skin blood flux during HypoxiaSkin and AnoxiaSkin remained similar to the corresponding Control trial (P=0.67 and P=0.81). Immunohistochemically stained epidermal HIF-1α was detected on 8.2±6.1 and 5.3±5.7% of the analysed area during HypoxiaSkin and Control1 (P=0.30) and on 2.3±1.8 and 2.4±1.8% during AnoxiaSkin and Control2 (P=0.90) respectively. Reductions in skin-surface PO2 do not affect skin perfusion in humans. The unchanged epidermal HIF-1α expression suggests that epidermal O2 homoeostasis was not disturbed by HypoxiaSkin /AnoxiaSkin , potentially due to compensatory increases in arterial O2 extraction.

Pilot study on the correlation between skin auto-fluorescence and serum antioxidant enzyme: skin auto-fluorescence is negatively associated with levels of malondialdehyde.

Various methods have been used to objectively record skin changes. However, estimating the intrinsic and extrinsic aging of skin remains a challenge. Our objective was to study intrinsic skin aging with respect to patient age and extrinsic photo-aging of human dorsal (photo-exposed) and volar (photo-protected) forearm in vivo through skin auto-fluorescence (AF). We also examined the correlations between serum antioxidant enzyme, malondialdehyde(MDA), and skin AF. 37 healthy volunteers were enrolled. We measured skin AF and its heterogeneity on the dorsal and volar forearms. We also examined serum concentration of catalase, superoxide dismutase, vitamin E, and MDA levels in every participant. In photo-protected areas, skin AF intensity in the 40 years or older group was significantly higher compared to the group less than 40 years-old. On the other hand, heterogeneity value was significantly higher in the less than 40 years-old group in photo-protected area. With respect to serum antioxidant enzyme and MDA level, only MDA level showed a negative correlation with skin AF intensity in photo-exposed area. We determined that skin AF intensity of the photo-protected area reflects intrinsic skin aging. In addition, degree of photo-aging could be indirectly inferred by skin AF of photo-exposed area and serum MDA level.

Pilomotor function is impaired in patients with Parkinson's disease: A study of the adrenergic axon-reflex response and autonomic functions

IntroductionAutonomic nervous system disturbances including sweating abnormalities and cardiovascular symptoms are frequent in Parkinson's disease (PD) and often precede motor involvement. Cholinergic vasomotor and sudomotor skin nerves are impaired in patients with PD even at early disease stages. We hypothesized that adrenergic pilomotor nerve function is similarly impaired in early PD and might constitute a novel diagnostic target. MethodsWe conducted a study in 12 PD patients (Hoehn&Yahr 1–2) and 12 healthy control subjects. Pilomotor function was evaluated after iontophoresis of phenylephrine on the dorsal forearm to elicit axon-reflex mediated pilomotor erection (goose bumps). Silicone impressions were obtained, scanned and quantified for pilomotor muscle impressions by number, area and axon-reflex spread. Vasomotor function was evaluated using laser Doppler flowmetry and sudomotor function via sympathetic skin response. Cardiac autonomic function was assessed via heart rate variability. Severity of autonomic symptoms was evaluated using the Scales for Outcomes in Parkinson's disease–Autonomic questionnaire. ResultsPilomotor response was reduced in PD patients compared to control subjects (impression number: 12.2 ± 8.2 vs. 16.5 ± 5.9, p < 0.05; impression area: 10.8 ± 2.2 mm2 vs. 24.8 ± 3.1 mm2, p < 0.01; axon-reflex spread: 89.0 ± 10.6 mm2 vs. 185.9 ± 10.8 mm2, p < 0.01) and correlated negatively with severity of autonomic symptoms (p < 0.01). Similarly, sudomotor (p < 0.01) and vasomotor (p < 0.05) but not cardiac autonomic (p = n.s.) function were reduced in PD patients versus control subjects. ConclusionPilomotor function is impaired in early stages of PD. Pilomotor axon-reflex assessment might be useful in the investigation of disease related pathology and supplement other clinical markers of autonomic neuropathy in PD.

High frequency ultrasound to assess skin thickness in healthy adults

BackgroundIntradermal immunization is gaining increased attention due to multiple factors: (1) intradermal (ID) vaccination has been shown to induce improved immunogenicity compared to intramuscular (IM) vaccination; (2) ID vaccination has been shown to have a dose-sparing potential over IM leading to a reduced vaccine cost and an increased availability of vaccines worldwide. However, the currently used Mantoux technique for ID injection is difficult to standardize and requires training.The aim of the study was (1) to assess the epidermal and dermal thickness at the proximal ventral and dorsal forearm (PVF & PDF) and deltoid in adults aged 18–65years (2) to determine the maximum penetration depth and needle characteristics for the development of a platform of medical devices suited for intradermal injection, VAX-ID™. Materials and methodsMean thickness of the PVF, PDF and deltoid were measured using high-frequency ultrasound of healthy adults aged 18–65years. Correlation with gender, age and BMI was assessed using Mann-Whitney U Test, Spearman correlation and Wilcoxon Signed Ranks Test, respectively. ResultsResults showed an overall mean skin thickness of 1.19mm (0.65–1.55mm) at the PVF, 1.44mm (0.78–1.84mm) at the PDF, and 2.12mm (1,16–3.19mm) at the deltoid. Thickness of PVF & PDF and deltoid were significantly different for men vs women (pmean<0.001, <0.001, <0.001, and pmin<0.001, 0.012, <0.001, respectively). A significant association was found for age at the deltoid region (p<0.001). Skin thickness for PVF, PDF & deltoid was significantly associated to BMI (p<0.001). ConclusionSignificant differences in skin thickness were seen for the PVF, PDF and deltoid region for gender, and BMI. Age only influenced the skin thickness at deltoid region. A needle length of 1.0mm is best option for intradermal injection at the dorsal forearm (NCT02363465).

Histopathology and reflectance confocal microscopy features of photodamaged skin and actinic keratosis.

Actinic keratosis (AK) usually co-exists in areas of severe photodamage, but the clinical applicability of reflectance confocal microscopy (RCM) in diagnosing AK currently depends on a set of parameters yet to be defined in comparison to photodamaged skin (PD). To correlate the RCM features of PD and AK with histopathology. Twenty participants with a mean age of 64years and skin phototype I and II were studied. RCM was performed on two PD and one AK within a field of 25cm2 on the left dorsal forearm, followed by shave biopsies. Blinded evaluation of the histopathological and RCM images using established parameters in AK were performed retrospectively in consensus with an expert confocalist, correlated with the histopathological diagnosis by a board-certified dermatopathologist. A total of 57/60 areas were included. There were 43/57 (75%) and 14/57 (25%) histopathologically confirmed PD and AK respectively. Individual corneocytes, stratum corneum disruption, dermal inflammatory cells, increased vascularity/dilated vessels and solar elastosis were detected in PD and AK upon histopathology and RCM. The features in favour of AK were parakeratosis, hyperkeratosis, more severe keratinocyte pleomorphism and architectural disruption, and the presence of epidermal inflammatory cells. PD also demonstrated keratinocyte pleomorphism and architectural disruption though this was generally less severe than AK. A small subset of PD exhibited a comparable degree of keratinocyte pleomorphism and architectural disruption to the AKs in the cohort. The viable epidermis demonstrates PD and AK to be part of a disease continuum corresponding to field cancerization. Individual corneocytes, stratum corneum disruption, dermal inflammatory cells, increased vascularity/dilated vessels and solar elastosis may be present in PD; whereas, parakeratosis and hyperkeratosis may represent the key to distinguishing AK from PD using RCM. The significance of epidermal inflammatory cells in the RCM diagnosis of AK remains to be elucidated.

BODY DISTRIBUTION OF HANNEMANIA SP. (ACARI: LEEUWENHOEKIIDAE) IN RHINELLA SPINULOSA, PLEURODEMA BUFONINA, AND PLEURODEMA THAUL FROM CHILE.

Hannemania larvae are parasites of amphibians in North and South America. In Chile, only one species of Hannemania has been reported from Batrachyla taeniata (banded wood frog). The objective of the study was to determine the abundance and body distribution of Hannemania among three amphibians from Antuco (Biobío Region, Chile): Pleurodema thaul (13 adults; Chile four-eyed frog), Pleurodema bufonina (5 adults; large four-eyed frog), and Rhinella spinulosa (15 adults and 16 juveniles; warty toad). Amphibians (82.75 %; n = 49) were infested with Hannemania. The infestation rate in R. spinulosa juveniles was lower than in adults (68 versus 100%, respectively; mean larval intensity: juvenile = 3.2 ± 2.5 and adult = 17.3 ± 16.3). Mean intensity of larval infestation in P. bufonina (63.2 ± 47.9) was higher than in the other two species of amphibians (R. spinulosa adult: 17.3 ± 16.3; R. spinulosa juvenile: 3.2 ± 2.5; P. thaul: 11.62 ± 7.8). There was no significant association between body size and mean intensity of infestation. The inguinal region, ventrum, and dorsal forearm region were the most parasitized. These body zones would be in direct contact with the substrate making the infestation easier for the larvae. This study represents the first record of Hannemania sp. in P. bufonina, R. spinulosa, and P. thaul in Chile.

Developmental Changes in Skin Barrier and Structure during the First 5 Years of Life

The structure of the stratum corneum (SC) and the corresponding skin barrier develops from before birth up to about 4 years of age. Large subject-to-subject variability within an age group requires a large population to observe trends in skin barrier properties over time. Barrier function, quantified by transepidermal water loss (TEWL) and SC thickness, was measured on the upper inner arm and dorsal forearm in subjects aged 3 months to 4 years (n = 171) and a subset of mothers (n = 44). The rate of skin surface area expansion as a function of age peaked before birth (∼90 cm²/week) and declined to a steady plateau (∼10 cm²/week) by 1 year of age. SC thickness increased and TEWL decreased, but did not reach adult values until 3-4 years of age. A better understanding of how skin hydration changes after birth suggests that barrier function may be related mechanistically to skin surface area expansion.

(184) Pain sensitivity is associated with vigorous physical activity and high cardiorespiratory fitness

Current activity recommendations are based primarily on epidemiologic evidence of an inverse relationship between volume of physical activity (PA) and overall risk of chronic disease, disability, and ultimately, mortality. Although exercise is often recommended to prevent and treat chronic pain conditions, whether or not greater physical activity reduces pain sensitivity remains unclear. Thus, the primary goal of this study was to compare pain sensitivity in highly active and sedentary adults. We assessed pain sensitivity, 7-day PA, and cardiorespiratory fitness in 59 pain-free adults (29F, 30M; 18-45 yrs). Pain sensitivity was assessed using pressure pain thresholds (PPTs) of the middle deltoid, pressure temporal summation (TS) of the dorsal forearm, and conditioned pain modulation (CPM) using middle deltoid PPTs before and after contralateral cold water hand immersion. PA was assessed via self-report (International Physical Activity Questionnaire) and wrist-worn accelerometry (Actigraph; ± 6g triaxial). Cardiorespiratory fitness was estimated using a submaximal step test to classify participants as having low, average, or high fitness. PPTs were highest (lowest sensitivity) in the high fitness group (p ≤ 0.01) while no differences were noted between fitness groups for TS (p = 0.21) or CPM (p = 0.97). Pressure pain sensitivity decreased with increasing levels of self-reported and measured (accelerometry) vigorous PA (rs = 0.44, p ≤ 0.01). Less TS was observed with increasing vigorous self-reported PA only (rs = -0.29, p < 0.05), while CPM was not associated with activity level. These results suggest that PPTs are more sensitive to physical activity and fitness differences than pressure TS or CPM in a young, healthy cohort. Supported in part by University of Iowa Physical Therapy & Rehabilitation Science Department, University of Iowa, Carver College of Medicine NIH Training Grant, and NIH CTSA U54TR001013.

An Unusual Cause for Intersection Syndrome

Intersection syndrome is a rare local inflammatory disorder of the dorsal distal forearm at the cross point between the first compartment and the second compartment. The most common pathological change is the tenosynovitis of the second compartment at the intersection. It is usually related to acute or chronic overuse of the upper extremities, which may cause constant friction between the two compartments leading to synovial sheath injury and followed by inflammation. This case of intersection syndrome is induced by physical blunt injury. One feature of this case is that the inflammatory condition involves not only the second compartment, but also the first compartment. Another feature is that the tenosynovitis of the second compartment extends down to the wrist. Based on this case and literature review, another mechanism for the syndrome is proposed.

Increased cortical activation upon painful stimulation in fibromyalgia syndrome

BackgroundFibromyalgia syndrome (FMS) is a chronic condition characterized by widespread pain and associated symptoms. We investigated cerebral activation in FMS patients by functional near-infrared spectroscopy (fNIRS).MethodsTwo stimulation paradigms were applied: a) painful pressure stimulation at the dorsal forearm; b) verbal fluency test (VFT). We prospectively recruited 25 FMS patients, ten patients with unipolar major depression (MD) without pain, and 35 healthy controls. All patients underwent neurological examination and all subjects were investigated with questionnaires (pain, depression, FMS, empathy).ResultsFMS patients had lower pressure pain thresholds than patients with MD and controls (p < 0.001) and reported higher pain intensity (p < 0.001). Upon unilateral pressure pain stimulation fNIRS recordings revealed increased bilateral cortical activation in FMS patients compared to controls (p < 0.05). FMS patients also displayed a stronger contralateral activity over the dorsolateral prefrontal cortex in direct comparison to patients with MD (p < 0.05). While all three groups performed equally well in the VFT, a frontal deficit in cortical activation was only found in patients with depression (p < 0.05). Performance and cortical activation correlated negatively in FMS patients (p < 0.05) and positively in patients with MD (p < 0.05).ConclusionOur data give further evidence for altered central nervous processing in patients with FMS and the distinction between FMS and MD.Trial registrationISRCTN registry ID ISRCTN15015327 (24.09.2015).Electronic supplementary materialThe online version of this article (doi:10.1186/s12883-015-0472-4) contains supplementary material, which is available to authorized users.

Reliable assessment of forearm photoageing by high-frequency ultrasound: a cross-sectional study.

High-frequency ultrasound is a non-invasive tool used in skin ageing research to assess dermis thickness and echogenicity. This study evaluated the reliability of a range of high-frequency ultrasound parameters and tested their correlation with age and a validated clinical scale for the assessment of forearm skin photoageing; the difference between two body sites according to environmental exposition patterns was also investigated. Twenty-three volunteers aged 28-82 years were divided into three groups according to forearm photoageing degree. A 20 MHz ultrasound unit was used to obtain cross-sectional images of the skin by two trained investigators on two different sites: the dorsal forearm (chronically photoexposed skin) and the proximal medial arm (non-photoexposed skin). Several echogenicity parameters were studied for each skin compartment: total dermis, upper dermis and lower dermis, and the ratio between upper and lower dermis. The intraclass correlation coefficient (for complete agreement) between investigators was higher for upper and total dermis echogenicity measures compared with the lower dermis. At the non-photoexposed site, the upper and lower dermis parameter ratio was better correlated with age. At the photoexposed area, total dermis parameters demonstrated higher correlations with clinical score. The authors discuss the choice of parameters for forearm photoageing assessment using high-frequency ultrasound.

The impact of object weight, reach distance, discomfort and muscle activation on the location of preferred critical boundary during a seated reaching task

Successful performance of a goal-directed action requires the prospective actor to perceive the environment relative to their action capabilities and tailor their movements accordingly. The current study examined the roles of reach distance, object (power drill) weight, gender, discomfort, and muscle activation (anterior deltoid, upper trapezius, biceps, ventral and dorsal forearm) in determining the location of the transition between an arm-only and an arm-and-torso reach (preferred critical boundary) during a seated reach task in which participants had to direct a power drill toward a target. Generalized Estimating Equations (GEE) used extrinsic (independent of the participant) and intrinsic measures (relative to the biodynamic properties of the participant) of reach distance and drill weight, discomfort judgments, and EMG integral recordings for the five muscles to identify factors that best predicted the type of reach used. GEE revealed that intrinsic measures of reach distance and drill weight were superior predictors compared to extrinsic measures. Discomfort judgment and upper trapezius activity were also significant predictors of the location of the preferred critical boundary.

Exploration of sensory impairments associated with C6 and C7 radiculopathies

Cervical radiculopathy is a common disorder caused by compression of the cervical nerve roots and is characterized by arm pain and altered sensory-motor function. Incongruity in the locations of C6 and C7 dermatomes in competing versions of historical dermatome maps has plagued interpretation of impaired sensation associated with C6 and C7 radiculopathies. Magnetic resonance imaging (MRI) allows accurate identification of the C6 or C7 nerve root compression and therefore makes it possible to explore sensory findings that are associated with compression of specific nerve root. This study compared the locations of impaired sensation in subjects with cervical radiculopathy from MRI-confirmed C6 and C7 nerve root compression. Case series was used for this study. A total of 122 subjects with symptoms suggestive of cervical radiculopathy were recruited by 11 spine specialist from 5 practice locations. Of these, 30 subjects had MRI-confirmed C6 and 40 subjects C7 radiculopathy. Standardized pinprick sensory examination of the forearm and hand of every subject was performed, and the locations of sensory impairments were recorded. Sensory examination was performed before reviewing MRI results or performing motor or reflex examination. Areas of impaired sensation were recorded on drawings of the palmar and dorsal forearm and hand, and translated using a grid into 36 specific areas for analysis. Chi-square was used to compare frequencies of findings for each grid area for C6 and C7 radiculopathies. Power analysis suggested that a minimum of 27 subjects in each group were needed to detect a 30 percentage point difference in frequency of sensory impairments. Significance was set at ≤.05. Approximately 80% of subjects had impaired sensation in at least 1 grid area, most often in the distal forearm and hand, and many had findings in multiple areas. There was nearly complete overlap for locations of impaired sensation for C6 and C7 radiculopathy, and the frequencies of impaired sensation differed only in the dorsal aspect of the distal radial forearm where it was twice as common in C6 radiculopathy (p=.02). The location of sensory impairments associated with symptomatic C6 and C7 nerve root compression overlap to the extent that caution should be exercised when predicting compression of either the C6 or C7 nerve roots based on locations of impaired sensation. Impaired sensation in the radial aspect of the distal forearm is more common in C6 radiculopathies.

Panniculitis With Necrotizing Granulomata in a Patient on BRAF Inhibitor (Dabrafenib) Therapy for Metastatic Melanoma

There have been major developments in targeted therapeutics with the clinical development of selective BRAF inhibitors (BRAFi) for patients with metastatic BRAF V600E mutant melanoma. Objective response rate of almost 50% has been witnessed in BRAFi clinical trials. Frequent side effects range from squamoproliferative lesions, including hyperplasia, keratoacanthomas, and squamous cell carcinomas to second primary melanomas. We describe a 50-year-old Hispanic woman with BRAF V600E mutant metastatic melanoma who was treated with surgery, radiation therapy, interleukin-2, and was enrolled on a BRAFi (dabrafenib) trial. Two months after initiation, she developed multiple erythematous, indurated, tender subcutaneous nodules bilaterally on the anterior thighs, posterior arms, and left dorsal forearm without overlying epidermal change. Punch biopsy revealed panniculitis with necrotizing granulomata. Infectious and other causes for panniculitis were excluded. We believe the histology likely represents a reaction to BRAFi therapy based on the temporal relationship of its onset to initiation of BRAFi therapy and previously reported cases of neutrophilic panniculitis associated with BRAFi therapy. Panniculitis has been emerging as an important unusual side effect of BRAFi therapy. Our case illustrates a unique presentation of BRAFi-associated panniculitis demonstrating necrotizing granulomata.

A transcranial direct current stimulation over the sensorimotor cortex modulates the itch sensation induced by histamine

ObjectiveItching can be suppressed by scratching. However, scratching may aggravate itch symptoms by damaging the skin. Therefore, identifying an alternative approach to suppress itching is of clinical importance. The aim of the present study was to determine whether a transcranial direct current stimulation (tDCS) was useful for itch relief. MethodsThe present study was performed on a double-blind, Sham-controlled, and cross-over experimental design. A histamine-induced itch was evoked on the left dorsal forearms of healthy participants, who were asked to report the subjective sensation of itching every 30s for 23min. tDCS was applied over the sensorimotor cortex (SMC) according to a bi-hemispheric stimulation protocol during the itch stimuli; one electrode was placed over the right SMC, while the other was placed over the left SMC. The peak and lasting sensations of itching were compared between R-A/L-C (anodal electrode placed over the right and cathodal electrode over the left), L-A/R-C (anodal electrode placed over the left and cathodal electrode over the right), and Sham interventions. ResultsThe peak and lasting itch sensation were significantly suppressed during the R-A/L-C intervention than during the Sham intervention. On the other hand, the L-A/R-C intervention suppressed the peak itch sensation, but the effects did not last for more than a few minutes. ConclusionsThese results suggest that a bi-hemispheric tDCS intervention, especially when the anodal electrode was placed over the SMC of the contralateral side, was a potentially useful method for relieving lasting itch sensations. SignificanceThe present study demonstrated that a tDCS intervention may be an alternative approach for suppressing unpleasant itch sensations in healthy participants. Since tDCS has some advantages, namely, its easy application and safety in a clinical setting, it may become a useful method for the treatment of itching.

Radial Tunnel Syndrome, Diagnostic and Treatment Dilemma.

Radial tunnel syndrome is a disease which we should consider it in elbow and forearm pains. It is diagnosed with lateral elbow and dorsal forearm pain may radiate to the wrist and dorsum of the fingers. The disease is more prevalent in women with the age of 30 to 50 years old. It occurs by intermittent compression on the radial nerve from the radial head to the inferior border of the supinator muscle, without obvious extensor muscle weakness. Compression could happen in five different sites but the arcade of Frose is the most common area that radial nerve is compressed. To diagnosis radial tunnel syndrome, clinical examination is more important than paraclinic tests such as electrodiagnsic test and imaging studies. The exact site of the pain which can more specified by rule of nine test and weakness of the third finger and wrist extension are valuable physical exams to diagnosis. MRI studies my show muscle edema or atrophy along the distribution of the posterior interosseous nerve. Although non-surgical treatments such as rest, NSAIDs, injections and physiotherapy do not believe to have permanent relief, but it is justify undergoing them before surgery. Surgery could diminish pain and symptoms in 67 to 93 percents of patients completely.