Modifying quantitative sensory testing to investigate behavioral reactivity in a pediatric global developmental delay sample: Relation to peripheral innervation and chronic pain outcomes.

Early tactile and nociceptive (pain) mechanisms in children with global developmental delay at risk for intellectual and developmental disability are not well understood. Sixteen children with global developmental delay (mean age = 5.1 years, SD = 1.4; 50% male) completed a modified quantitative sensory testing (mQST) protocol, an epidermal (skin) punch biopsy procedure, and parent-endorsed measures of pain. Children with reported chronic pain had significantly greater epidermal nerve fiber density (ENFd) compared to children without chronic pain. Based on the mQST trials, ENFd values were associated with increased vocal reactivity overall and specifically during the light touch and cool thermal stimulus trials. The findings support the feasibility of an integrative biobehavioral approach to test nociceptive and tactile peripheral innervation and behavioral reactivity during a standardized sensory test in a high-risk sample for which there is often sensory dysfunction and adaptive behavior impairments.

Pathophysiology of Gastroparesis Syndromes Includes Anatomic and Physiologic Abnormalities.

BACKGROUND: Factors underlying gastroparesis are not well defined. AIMS: We hypothesized that multiple systems may be involved in patients with gastroparesis symptoms and performed a comparative physiologic study. METHODS: We studied 43 consecutive eligible patients with gastroparetic symptoms categorized by GI symptoms, metabolic status, illness quantification, and gastric physiology. Patients were evaluated by two methods in each of five core areas: inflammatory, autonomic, enteric, electrophysiologic, and hormonal with abnormalities examined by correlations. RESULTS: Patients had similar GI symptoms regardless of baseline gastric emptying or diabetic/idiopathic status, and all patients demonstrated abnormalities in each of the 5 areas studied. Nearly all patients presented with elevated markers of serum TNFα (88%) and serum IL-6 (91%); elevated cutaneous electrogastrogram frequency (95%); and interstitial cells of Cajal count abnormalities (inner: 97%, outer: 100%). Measures of inflammation correlated with a number of autonomic, enteric anatomy, electrophysiologic and hormonal abnormalities. CONCLUSIONS: We conclude that patients with the symptoms of gastroparesis have multiple abnormalities, when studied by traditional, as well as newer, diagnostic assessments. Inflammation appears to be a fundamental abnormality that affects other organ systems in symptomatic patients. Future work on gastroparetic syndromes and their treatment may benefit from a focus on the diffuse nature of their illness, diverse pathophysiologic mechanisms involved, especially the possible causes of underlying inflammation and disordered hormonal status. TRAIL REGISTRY: This study is registered with Clinicaltrials.gov under study # NCT03178370 https://clinicaltrials.gov/ct2/show/NCT03178370 .

A clinical case-control comparison of epidermal innervation density in Rett syndrome.

INTRODUCTION: Rett syndrome (RTT), a rare neurodevelopmental disorder occurring primarily in females (1:10-15,000 female live births), is most often caused by loss-of-function mutations in the X-linked methyl-CpG-binding protein 2 gene (MECP2). Clinical observations and preclinical findings indicate apparent abnormal sensory and nociceptive function. There have been no direct investigations of epidermal sensory innervation in patients with RTT. METHODS: We compared 3 mm epidermal punch biopsy specimens from adolescent female RTT patients (N = 4, aged 12-19 years) against an archived approximate age-, sex-, body-site matched comparison sample of healthy adolescent females (N = 8, ages 11-17). RESULTS: Confocal imaging revealed, on average, statistically significant increased epidermal nerve fiber (ENF) peptidergic (co-stained calcitonin gene-related protein [CGRP]) innervation density compared with healthy female control individuals. CONCLUSIONS: Given the clinical phenotype of disrupted sensory function along with diagnostic criteria specific to cold hands/feet and insensitivity to pain, our preliminary observations of ENF peptidergic fiber density differences warrants further investigation of the peripheral neurobiology in RTT.

Gastroparesis syndromes: Response to electrical stimulation.

BACKGROUND AND AIMS: Factors underlying gastroparesis are not well defined, nor is the mechanism of action of gastric electrical stimulation (GES). We hypothesized that GES acts via several mechanisms related to underlying disordered pathophysiology. METHODS: We studied 43 consecutive eligible patients with gastroparetic symptoms, previously evaluated by two methods in each of five core areas: inflammatory, autonomic, enteric, electrophysiologic, and hormonal; and also categorized by GI symptoms, metabolic status, illness quantification, and gastric physiology. We then studied 41 patients who underwent temporary GES for 5-7 days. Thirty-six of those patients were implanted and 30 were followed up at 6 months after permanent GES. RESULTS: In previous but separately reported work, patients had similar GI symptoms regardless of baseline gastric emptying or diabetic/idiopathic status and all patients demonstrated abnormalities in each of the five areas studied. After GES, patients showed early and late effects of electrical stimulation with changes noted in multiple areas, categorized by improvement status. CONCLUSION: Patients with symptoms of gastroparesis have multiple abnormalities, including systemic inflammation and disordered hormonal status. GES affects many of these abnormalities. We conclude electrical stimulation improves symptoms and physiology with (a) an early and sustained anti-emetic effect; (b) an early and durable gastric prokinetic effect in delayed emptying patients; (c) an early anti-arrhythmic effect that continues over time; (d) a late autonomic effect; (e) a late hormonal effect; (f) an early anti-inflammatory effect that persists; and (g) an early and sustained improvement in health-related quality of life. This study is registered with Clinicaltrials.gov under study # NCT03178370 (https://clinicaltrials.gov/ct2/show/NCT03178370).

Comparison of Neurovascular Characteristics of Facial Skin in Patients After Primary and Revision Rhytidectomies.

IMPORTANCE: Wound healing influences both the cosmetic and functional outcomes of facial surgery. Study of cutaneous innervation may afford insight into patients' preoperative wound healing potential and aid in their selection of appropriate surgical procedures. OBJECTIVE: To present the quantitative and qualitative differences of epidermal nerve fibers (ENFs), neurotransmitters, vasculature, and mast cells in facial skin among patients after primary and revision rhytidectomies. DESIGN, SETTING, AND PARTICIPANTS: This pilot study collected cutaneous specimens from 8 female patients aged 42 to 66 years who underwent primary rhytidectomy (n = 5) and revision rhytidectomy (n = 3) at Centennial Lakes Surgery Center, Edina, Minnesota, from July 2010 to March 2014. Tissue was processed for confocal/epifluorescence microscopy and indirect immunofluorescent localization of several neural and tissue antigens as well as basement membrane and mast cell markers. INTERVENTION: Primary rhytidectomy vs revision rhytidectomy with selection of a small area of redundant, otherwise disposed of tissue anterior to the tragus for ENF study. MAIN OUTCOMES AND MEASURES: Demographic characteristics included smoking status; 10-point rating scales for facial sensation, pain, and paresthesias; and confocal/epifluorescence microscopy to quantify ENFs, neurotransmitters, vasculature, and mast cells. RESULTS: Patients in the primary rhytidectomy group had a mean (SD) of 54.4 (31.6) ENFs/mm (range, 14.2-99.2 ENFs/mm), and those in the revision rhytidectomy group had a mean (SD) of 18.6 (5.8) ENFs/mm (range, 13.8-25.0 ENFs/mm). A patient in the primary rhytidectomy group was a 25-pack-year smoker and had 14.2 ENFs/mm, the lowest in both groups. In addition to these structural neural changes, functional neural changes in revision rhytidectomy samples included qualitative changes in normal neural antigen prevalence (substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide). Capillary loops appeared less robust and were less common in dermal papilla among samples from both the primary and revision groups, and mast cells were more degranulated. No differences were found in subjective, self-reported postoperative facial sensation. CONCLUSIONS AND RELEVANCE: Previous skin elevation was associated with decreased epidermal nerve fiber density and qualitative changes in dermal nerves, capillaries, and mast cells in a clinical sample of patients undergoing rhytidectomy. Future research is needed to determine whether histological findings predict wound healing and to better understand the effects of surgery on regenerative capacity of epidermal nerve fibers. LEVEL OF EVIDENCE: NA.

Fast-adapting mechanoreceptors are important for force control in precision grip but not for sensorimotor memory.

Sensory feedback from cutaneous mechanoreceptors in the fingertips is important in effective object manipulation, allowing appropriate scaling of grip and load forces during precision grip. However, the role of mechanoreceptor subtypes in these tasks remains incompletely understood. To address this issue, psychophysical tasks that may specifically assess function of type I fast-adapting (FAI) and slowly adapting (SAI) mechanoreceptors were used with object manipulation experiments to examine the regulation of grip force control in an experimental model of graded reduction in tactile sensitivity (healthy volunteers wearing 2 layers of latex gloves). With gloves, tactile sensitivity decreased significantly from 1.9 ± 0.4 to 12.3 ± 2.2 µm in the Bumps task assessing function of FAI afferents but not in a grating orientation task assessing SAI afferents (1.6 ± 0.1 to 1.8 ± 0.2 mm). Six axis force/torque sensors measured peak grip (PGF) and load (PLF) forces generated by the fingertips during a grip-lift task. With gloves there was a significant increase of PGF (14 ± 6%), PLF (17 ± 5%), and grip and load force rates (26 ± 8%, 20 ± 8%). A variable-weight series task was used to examine sensorimotor memory. There was a 20% increase in PGF when the lift of a light object was preceded by a heavy relative to a light object. This relationship was not significantly altered when lifting with gloves, suggesting that the addition of gloves did not change sensorimotor memory effects. We conclude that FAI fibers may be important for the online force scaling but not for the buildup of a sensorimotor memory.

Peripheral Innervation in Children With Global Developmental Delay: Biomarker for Risk for Self-Injurious Behavior?

The relation between somatosensory mechanisms and self-injury among children with neurologic impairments associated with developmental delay is not well understood. We evaluated the feasibility of procuring skin biopsies to examine epidermal nerve fiber density and reported self-injury. Following informed parental consent, epidermal skin biopsies were obtained from a distal leg site with no pre-existing skin damage from 11 children with global developmental delay (55% male; mean age = 36.8 months, 17-63 months). Visual microscopic examination and quantitative analyses showed extremely high epidermal nerve fiber density values for some children. Children with reported self-injury (5/11) had significantly (P < .02) greater density values (138.8, standard deviation = 45.5) than children without self-injury (80.5, standard deviation = 17.5). Results from this novel immunohistologic analysis of skin in very young children with neurodevelopmental delays suggest it may be a useful tool to study peripheral innervation as a possible sensory risk factor for self-injury.

Skin and self-injury: a possible link between peripheral innervation and immune function?

The aim of this preliminary case study series was to investigate epidermal innervation in pediatric patients with significant neurological impairment and self-injurious behavior. We enrolled four pediatric patients with self-injury (two males, two females; mean age 12y, range 9-14y) and used archival specimens from healthy, age-matched children with typical development for comparison purposes. Epidermal nerve fiber density, peptide content, and mast cell degranulation patterns from non-damaged skin were tested between the patients and the comparison group. The male patients with self-injury had significantly increased epidermal nerve fiber densities, increased substance P positive fiber count and extensive mast cell degranulation compared with sex- and age-matched individuals with typical development. Our case series shows for the first time altered peripheral innervation from non-damaged tissue in children with significant self-injury and developmental disability compared with a healthy comparison group. Establishing the role of peripheral nociceptive and immune modulatory neural pathways may offer new treatment avenues for this devastating neurobehavioral disorder.

Epidermal innervation in healthy children and adolescents.

INTRODUCTION: Epidermal nerve fiber (ENF) density, morphology, and epidermal innervation patterns were examined in children using 2 different techniques, punch biopsy and suction blister. METHODS: Healthy children without symptoms or history of peripheral neuropathy and normal by neurologic examination were studied. Punch biopsy and suction blister specimens were collected from the lateral thigh and distal leg. ENFs were traced from confocal images of immunohistochemically stained samples. Statistical methods included repeated-measures analysis of covariance. RESULTS: Blister and biopsy nerve counts were associated. ENF density in children was dense, lower for older children (P<0.01) and with no difference between boys and girls (P=0.92). Many ENFs appeared multibranched and elongated. CONCLUSIONS: Epidermal innervation in the pediatric population is dense and age-dependent. Blister specimens are less invasive and may provide an alternative to punch biopsy for determining ENF density in children at risk for neuropathy.

A quantitative sensory analysis of peripheral neuropathy in colorectal cancer and its exacerbation by oxaliplatin chemotherapy.

Peripheral neuropathy caused by cytotoxic chemotherapy, especially platins and taxanes, is a widespread problem among cancer survivors that is likely to continue to expand in the future. However, little work to date has focused on understanding this challenge. The goal in this study was to determine the impact of colorectal cancer and cumulative chemotherapeutic dose on sensory function to gain mechanistic insight into the subtypes of primary afferent fibers damaged by chemotherapy. Patients with colorectal cancer underwent quantitative sensory testing before and then prior to each cycle of oxaliplatin. These data were compared with those from 47 age- and sex-matched healthy volunteers. Patients showed significant subclinical deficits in sensory function before any therapy compared with healthy volunteers, and they became more pronounced in patients who received chemotherapy. Sensory modalities that involved large Aß myelinated fibers and unmyelinated C fibers were most affected by chemotherapy, whereas sensory modalities conveyed by thinly myelinated Aδ fibers were less sensitive to chemotherapy. Patients with baseline sensory deficits went on to develop more symptom complaints during chemotherapy than those who had no baseline deficit. Patients who were tested again 6 to 12 months after chemotherapy presented with the most numbness and pain and also the most pronounced sensory deficits. Our results illuminate a mechanistic connection between the pattern of effects on sensory function and the nerve fiber types that appear to be most vulnerable to chemotherapy-induced toxicity, with implications for how to focus future work to ameloirate risks of peripheral neuropathy.

Subclinical peripheral neuropathy in patients with multiple myeloma before chemotherapy is correlated with decreased fingertip innervation density.

PURPOSE: The goal in this study was to determine the incidence of subclinical neuropathy in treatment-naive patients with multiple myeloma (MM) with no history of peripheral neuropathy using quantitative sensory tests (QSTs) and its correlation with innervation density of the extremities using noninvasive laser reflectance confocal microscopy. PATIENTS AND METHODS: QST results were collected for 27 patients with a diagnosis of MM and compared with data collected from 30 age- and sex-matched healthy volunteers. Skin temperature, sensorimotor function (grooved pegboard test), and detection thresholds for temperature, sharpness, and low-threshold mechanical stimuli (von Frey monofilaments and bumps detection test) were measured. Meissner's corpuscle (MC) density in the fingertips was assessed using in vivo laser reflectance confocal microscopy. RESULTS: Patients showed a high incidence (> 80%) of ≥ one subclinical QST deficit. These included increased von Frey, bumps, and warmth detection thresholds as compared with healthy volunteers. Patients also showed increases in cold pain, sensorimotor deficits (grooved pegboard test), and higher overall neuropathy scores. MC density was significantly lower in patients than controls and showed significant inverse correlation with bumps detection threshold. CONCLUSION: Patients with MM commonly present with sensory and sensorimotor deficits before undergoing treatment, and these deficits seem to result from disease-related decreases in peripheral innervation density.

Persistent chemoneuropathy in patients receiving the plant alkaloids paclitaxel and vincristine.

PURPOSE: Chemoneuropathy remains a painful, burdensome complication of cancer treatment for patients receiving a range of chemotherapeutics, yet the cause and persistence of this condition are not fully documented. This study was designed to quantify the longevity of and contributions to neuropathy following treatment with the plant alkaloids paclitaxel and vincristine. METHODS: Quantitative sensory testing was conducted approximately 18 months apart on 14 patients, seven of which had been treated with paclitaxel and seven with vincristine and compared to data from 18 healthy control subjects. In addition, skin biopsies were obtained to investigate changes in the density of Meissner's corpuscles and epidermal nerve fibers (ENFs), the loss of which is thought to contribute to multiple forms of neuropathy. RESULTS: Impairments in motor skills, as measured by a grooved peg-board, were found. Deficits in touch detection were observed using von Frey monofilaments, as were changes in sharpness detection using a weighted needle device. Using a Peltier device, warmth and heat detection were impaired. These deficits were consistent across time. Remarkably, the average length of time patients reported painful neuropathy was over four and a half years. Skin biopsies were found to be deficient in Meissner's corpuscles and ENFs. CONCLUSIONS: The combination of widespread deficits in sensory testing and decreases in skin innervation for cancer patients receiving paclitaxel or vincristine document a persistent polyneuropathy which severely impacts these patients. Decreases in Meissner's corpuscles and ENFs indicate a possible mechanism for the neuropathy.

Subclinical peripheral neuropathy is a common finding in colorectal cancer patients prior to chemotherapy.

PURPOSE: Of the numerous complications associated with cancer and cancer treatment, peripheral neuropathy is a deleterious and persistent patient complaint commonly attributed to chemotherapy. The present study investigated the occurrence of subclinical peripheral neuropathy in patients with colorectal cancer before the initiation of chemotherapy. EXPERIMENTAL DESIGN: Fifty-two patients underwent extensive quantitative sensory testing (QST) before receiving chemotherapy. Changes in multiple functions of primary afferent fibers were assessed and compared with a group of healthy control subjects. Skin temperature, sensorimotor function, sharpness detection, and thermal detection were measured, as was touch detection, using both conventional (von Frey monofilaments) and novel (Bumps detection test) methodology. RESULTS: Patients had subclinical deficits, especially in sensorimotor function, detection of thermal stimuli, and touch detection that were present before the initiation of chemotherapy. The measured impairment in touch sensation was especially pronounced when using the Bumps detection test. CONCLUSIONS: The patients with colorectal cancer in this study exhibited deficits in sensory function before undergoing chemotherapy treatment, implicating the disease itself as a contributing factor in chemotherapy-induced peripheral neuropathy. The widespread nature of the observed deficits further indicated that cancer is affecting multiple primary afferent subtypes. Specific to the finding of impaired touch sensation, results from this study highlight the use of newly used methodology, the Bumps detection test, as a sensitive and useful tool in the early detection of peripheral neuropathy.

Second-order spatial analysis of epidermal nerve fibers.

Breakthroughs in imaging of skin tissue reveal new details on the distribution of nerve fibers in the epidermis. Preliminary neurologic studies indicate qualitative differences in the spatial patterns of nerve fibers based on pathophysiologic conditions in the subjects. Of particular interest is the evolution of spatial patterns observed in the progression of diabetic neuropathy. It appears that the spatial distribution of nerve fibers becomes more 'clustered' as neuropathy advances, suggesting the possibility of diagnostic prediction based on patterns observed in skin biopsies. We consider two approaches to establish statistical inference relating to this observation. First, we view the set of locations where the nerves enter the epidermis from the dermis as a realization of a spatial point process. Secondly, we treat the set of fibers as a realization of a planar fiber process. In both cases, we use estimated second-order properties of the observed data patterns to describe the degree and scale of clustering observed in the microscope images of blister biopsies. We illustrate the methods using confocal microscopy blister images taken from the thigh of one normal (disease-free) individual and two images each taken from the thighs of subjects with mild, moderate, and severe diabetes and report measurable differences in the spatial patterns of nerve entry points/fibers associated with disease status.

Follow-up psychophysical studies in bortezomib-related chemoneuropathy patients.

UNLABELLED: Many frontline chemotherapeutic agents produce robust neuropathy as a dose-limiting side effect; however, the persistence of chemotherapy-related sensory disturbances and pain are not well documented. We have previously investigated the qualities of bortezomib-induced pain, and now seek to determine the ongoing nature of this pain. Twenty-six control subjects and 11 patients who had previously been treated with bortezomib and who were experiencing ongoing pain consented to recurring quantitative sensory testing. A pilot immunohistochemistry study of skin innervation was also performed on patient-obtained biopsies. Psychophysical testing in patients revealed persistent changes including decreased skin temperature in the area of pain, diminished touch and sharpness detection, increased pegboard completion times, and decreased sensitivity to skin heating. Additionally, the intensity of pain, as captured by the use of a visual analog scale and pain descriptors, was reported by patients to be unchanged during the retest despite similar morphine equivalent daily doses. The patient skin biopsies displayed a marked decrease in the density of epidermal nerve fibers and Meissner's corpuscles. These results signify a persistent and severe impairment of Aß, Aδ, and C fibers in patients with chronic bortezomib-induced chemoneuropathy. Further, this study reports a loss of both epidermal nerve fibers and Meissner's corpuscles. PERSPECTIVE: The results of this article indicate a persistent, painful peripheral neuropathy in patients treated with bortezomib. Pilot data indicates a loss of nerve fibers innervating the area of pain. This is the first paper to address the persistence, and potential contributing factors, of bortezomib chemoneuropathy.

Evidence for neural progenitor cells in the human adult enteric nervous system.

Putative neural stem cells have been identified within the enteric nervous system (ENS) of adult rodents and cultured from human myenteric plexus. We conducted studies to identify neural stem cells or progenitor cells within the submucosa of adult human ENS. Jejunum tissue was removed from adult human subjects undergoing gastric bypass surgery. The tissue was immunostained, and confocal images of ganglia in the submucosal plexus were collected to identify protein gene product 9.5 (PGP 9.5) - immunoractive neurons and neuronal progenitor cells that coexpress PGP 9.5 and nestin. In addition to PGP-9.5-positive/nestin-negative neuronal cells within ganglia, we observed two other types of cells: (1) cells in which PGP 9.5 and nestin were co-localized, (2) cells negative for both PGP 9.5 and nestin. These observations suggest that the latter two types of cells are related to a progenitor cell population and are consistent with the concept that the submucosa of human adult ENS contains stem cells capable of maintenance and repair within the peripheral nervous system.