Corneal confocal microscopy in patients with distal symmetric polyneuropathy compared to controls.

BACKGROUND: Diabetic neuropathy (DN) is a very common clinical condition throughout the world. The diagnostic tests currently recommended have low sensitivity, such as electromyography, or are invasive, such as skin biopsy. New techniques have been developed to identify the early involvement of the peripheral nerve. With the advent of corneal confocal microscopy (CCM), a reduction in corneal innervation in patients with DN has been observed. OBJECTIVE: To compare, through CCM, diabetic patients with symptomatic distal symmetric polyneuropathy (DSP) and controls. METHODS: In the present study, through CCM, we compared the morphological changes in the sub-basal epithelial corneal plexus of 35 diabetic patients with symptomatic DSP with 55 controls. Moreover, we sought to determine a pattern of change regarding the severity stages of DSP, comparing the clinical, laboratory, and nerve-conduction (NC) variables. RESULTS: Differences between the control and diabetic groups were observed for the following variables, respectively: age (44.9 ± 13.24 years versus 57.02 ± 10.4 years; p < 0.001); fiber density (29.7 ± 10.2 versus 16.6 ± 10.2; p < 0.001); number of fibers (4.76 ± 1.30 versus 3.14 ± 1.63; p < 0.001); number of Langerhans cells (4.64 ± 8.05 versus 7.49 ± 10.3; p = 0.035); tortuosity (p < 0.05); and thickness (p < 0.05). Furthermore, inverse relationships were found regarding fiber density and age (p < 0.01) and fiber density and the severity of the disease (p < 0.05). A positive relationship between the conduction velocity of the fibular nerve and fiber density (p < 0.05) was also observed. CONCLUSION: Corneal confocal microscopy proved to be a fast, noninvasive and reproducible method for the diagnosis, staging, and monitoring of diabetic DSP.

ANTECEDENTES: A neuropatia diabética (ND) é condição clínica muito frequente no mundo inteiro. Os testes diagnósticos atualmente preconizados são pouco sensíveis, como a eletroneuromiografia, ou invasivos, como a biópsia de pele. Novas técnicas de investigação complementares têm sido desenvolvidas a fim de identificar o acometimento precoce do nervo periférico. Com o advento da microscopia confocal de córnea (MCC), observou-se redução da inervação da córnea em pacientes com ND. OBJETIVO: Comparar, por meio da MCC, pacientes diabéticos com polineuropatia simétrica distal (PSD) sintomática e controles. MéTODOS: Neste estudo, por meio da MCC, comparamos as alterações morfológicas do plexo sub-basal epitelial da córnea de 35 pacientes diabéticos com PSD sintomática com 55 indivíduos controles. Além disso, buscamos determinar um padrão de alteração entre os estágios de gravidade da PSD, comparando variáveis clínicas, laboratoriais e de neurocondução. RESULTADOS: Diferenças entre os grupos controle e diabéticos foram verificadas com relação às seguintes variáveis, respectivamente: idade (44,9 ± 13,24 anos versus 57,02 ± 10,4 anos; p < 0,001); densidade das fibras (29,7 ± 10,2 versus 16,6 ± 10,2; p < 0,001); número de fibras (4,76 ± 1,30 versus 3,14 ± 1,63; p < 0,001); número de células de Langerhans (4,64 ± 8,05 versus 7,49 ± 10,3; p = 0,035); tortuosidade (p < 0,05), e espessura (p < 0,05). Além disso, relações inversamente proporcionais foram verificadas entre a densidade das fibras e a idade (p < 0,01), e entre a densidade das fibras e a gravidade da doença (p < 0,05). Observou-se ainda uma relação positiva entre a velocidade de condução do nervo fibular e a densidade das fibras (p < 0,05). CONCLUSãO: A MCC constitui um método rápido, não invasivo e reprodutível para o diagnóstico, o estadiamento, e o acompanhamento da PSD diabética.

Corneal confocal microscopy in patients with distal symmetric polyneuropathy compared to controls / Microscopia confocal de córnea em pacientes com polineuropatia simétrica distal comparados a controles

Abstract Background Diabetic neuropathy (DN) is a very common clinical condition throughout the world. The diagnostic tests currently recommended have low sensitivity, such as electromyography, or are invasive, such as skin biopsy. New techniques have been developed to identify the early involvement of the peripheral nerve. With the advent of corneal confocal microscopy (CCM), a reduction in corneal innervation in patients with DN has been observed. Objective To compare, through CCM, diabetic patients with symptomatic distal symmetric polyneuropathy (DSP) and controls. Methods In the present study, through CCM, we compared the morphological changes in the sub-basal epithelial corneal plexus of 35 diabetic patients with symptomatic DSP with 55 controls. Moreover, we sought to determine a pattern of change regarding the severity stages of DSP, comparing the clinical, laboratory, and nerve-conduction (NC) variables. Results Differences between the control and diabetic groups were observed for the following variables, respectively: age (44.9 ± 13.24 years versus 57.02 ± 10.4 years; p< 0.001); fiber density (29.7 ± 10.2 versus 16.6 ± 10.2; p< 0.001); number of fibers (4.76 ± 1.30 versus 3.14 ± 1.63; p< 0.001); number of Langerhans cells (4.64 ± 8.05 versus 7.49 ± 10.3; p= 0.035); tortuosity (p< 0.05); and thickness (p< 0.05). Furthermore, inverse relationships were found regarding fiber density and age (p< 0.01) and fiber density and the severity of the disease (p< 0.05). A positive relationship between the conduction velocity of the fibular nerve and fiber density (p< 0.05) was also observed. Conclusion Corneal confocal microscopy proved to be a fast, noninvasive and reproducible method for the diagnosis, staging, and monitoring of diabetic DSP.

Resumo Antecedentes A neuropatia diabética (ND) é condição clínica muito frequente no mundo inteiro. Os testes diagnósticos atualmente preconizados são pouco sensíveis, como a eletroneuromiografia, ou invasivos, como a biópsia de pele. Novas técnicas de investigação complementares têm sido desenvolvidas a fim de identificar o acometimento precoce do nervo periférico. Com o advento da microscopia confocal de córnea (MCC), observou-se redução da inervação da córnea em pacientes com ND. Objetivo Comparar, por meio da MCC, pacientes diabéticos com polineuropatia simétrica distal (PSD) sintomática e controles. Métodos Neste estudo, por meio da MCC, comparamos as alterações morfológicas do plexo sub-basal epitelial da córnea de 35 pacientes diabéticos com PSD sintomática com 55 indivíduos controles. Além disso, buscamos determinar um padrão de alteração entre os estágios de gravidade da PSD, comparando variáveis clínicas, laboratoriais e de neurocondução. Resultados Diferenças entre os grupos controle e diabéticos foram verificadas com relação às seguintes variáveis, respectivamente: idade (44,9 ± 13,24 anos versus 57,02 ± 10,4 anos; p< 0,001); densidade das fibras (29,7 ± 10,2 versus 16,6 ± 10,2; p< 0,001); número de fibras (4,76 ± 1,30 versus 3,14 ± 1,63; p< 0,001); número de células de Langerhans (4,64 ± 8,05 versus 7,49 ± 10,3; p= 0,035); tortuosidade (p< 0,05), e espessura (p < 0,05). Além disso, relações inversamente proporcionais foram verificadas entre a densidade das fibras e a idade (p< 0,01), e entre a densidade das fibras e a gravidade da doença (p< 0,05). Observou-se ainda uma relação positiva entre a velocidade de condução do nervo fibular e a densidade das fibras (p< 0,05). Conclusão A MCC constitui um método rápido, não invasivo e reprodutível para o diagnóstico, o estadiamento, e o acompanhamento da PSD diabética.

A Single Administration of OC-01 (Varenicline Solution) Nasal Spray Induces Short-Term Alterations in Conjunctival Goblet Cells in Patients with Dry Eye Disease.

INTRODUCTION: Dry eye disease is characterized by a persistently unstable or deficient tear film causing discomfort or visual impairment. Varenicline is a small-molecule nicotinic acetylcholine receptor agonist recently approved for use as a preservative-free nasal spray (OC-01 [varenicline solution] nasal spray [OC-01 VNS]) to treat signs and symptoms of dry eye disease, but its effect on conjunctival goblet cells has not been studied. METHODS: In this phase 2, single-center, vehicle-controlled study, patients aged 18 years or more with a diagnosis of dry eye disease and Ocular Surface Disease Index© score of at least 23 were randomized 2:1 to receive a 50-µL single dose of OC-01 0.06 mg VNS or vehicle nasal spray in each nostril. Image assessments for area and perimeter were performed pre and 10 min post treatment for goblet cells by in vivo confocal microscopy and for meibomian glands by infrared meibography. Non-parametric Wilcoxon signed-rank test compared pre- and post-treatment measurements for each treatment group. Treatment-emergent adverse events (TEAEs) were assessed. RESULTS: The study randomized 18 patients (mean age 61 years); 6 received vehicle (3/6 [50%] female) and 12 patients received OC-01 VNS (11/12 [92%] female). OC-01 VNS treatment decreased mean goblet cell area (pre-treatment, 106.4 µm2; post-treatment, 67.6 µm2; p = 0.02) and perimeter (pre-treatment, 38.9 µm; post-treatment, 31.2 µm; p = 0.03) but not vehicle did not (p = 0.25). There were no significant changes in mean meibomian gland area with either treatment (p ≥ 0.05). All TEAEs were non-ocular, non-serious, and mild. CONCLUSIONS: This study demonstrated that a single administration of OC-01 0.06 mg VNS in patients with dry eye disease reduced conjunctival goblet cell area and perimeter, suggesting goblet cell degranulation and associated release of lubricating mucin. By activating the natural tear film, OC-01 VNS may provide benefits over topical medications. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03688802.

Neuropathic corneal pain and dry eye: a continuum of nociception.

Throughout the body, damage to peripheral nerves normally involved in nociception may produce a constellation of symptoms-including irritation, itchiness and pain. The neurobiological processes involved in corneal symptoms of dry eye (DE) and neuropathic corneal pain (NCP) have not been clearly considered in terms of nociceptive processing. The conventional underlying presumption is that a labelled line principle is responsible; that these distinct perceptions are hard coded by primary afferent inputs to the central nervous system. This presumption oversimplifies the neurobiological mechanisms underlying somatosensory perception. The labelled line perspective that DE represents a chronic pain condition does not make intuitive sense: how can an eye condition that is not painful in most cases be considered a pain condition? Does not chronic pain by definition require pain to be present? On the other hand, NCP, a term that clearly denotes a painful condition, has historically seemed to resonate with clinical significance. Both DE and NCP can share similar features, yet their differentiation is not always clear. As is often the case, clinical terms arise from different disciplines, with DE evolving from ophthalmological findings and NCP inspired by pain neurophysiology. This review evaluates the current definition of these terms, the rationale for their overlap and how the neurophysiology of itch impacts our understanding of these conditions as a continuum of the same disease. Despite the complexity of nociceptive physiology, an understanding of these mechanisms will allow us a more precise therapeutic approach.

Low-dose naltrexone is effective and well-tolerated for modulating symptoms in patients with neuropathic corneal pain.

PURPOSE: Neuropathic corneal pain (NCP) is caused by damage or disease of the somatosensory nervous system that innervates the cornea and presents with symptoms of pain or persistent unpleasant sensations, such as burning, dryness, or light sensitivity. This retrospective study aims to assess the efficacy and tolerability of low-dose naltrexone (LDN) in refractory NCP patients. METHODS: Fifty-nine NCP patients with a centralized component treated with oral LDN 4.5  mg at bedtime for at least four weeks were identified. Thirty out of 59 patients who had a baseline pain score ≥4 on the visual analogue scale had completed the ocular pain assessment survey (OPAS) and presented persistent pain, despite instillation of topical anesthetic drops, were included. Changes in pain scores, comorbidities, side effects, among others, were analyzed. Change in ocular pain scores (scale 0-10) and quality of life (QoL) scores (scale 0-100%) were the main endpoints. RESULTS: Mean age (years ± SD) was 45.60 ± 19.30 with a white (80.00%) female (73.33%) predominance. Duration of LDN use was 14.87 ± 11.25 months, and the duration of NCP before treatment was 17.53 ± 17.29 months. Eight patients used LDN as a monotherapy, whereas the remaining used it as an adjunct therapy. LDN resulted in a 49.22% decrease in mean pain score from 6.13 ± 1.93 to 3.23 ± 2.60 (p < 0.001). Mean QoL scores by the OPAS were 5.84 ± 2.57 at the first visit and improved to 3.77 ± 2.91 at the last visit (p = 0.023). Common side effects were vivid dreams, headaches, and stomachache. CONCLUSION: LDN was effective and well-tolerated for NCP treatment.

The utility of anterior segment optical coherence tomography angiography for the assessment of limbal stem cell deficiency.

PURPOSE: To determine the utility of anterior segment optical coherence tomography angiography (AS-OCTA) in assessing limbal stem cell deficiency (LSCD). METHODS: Twenty-six eyes of 24 LSCD patients, classified clinically into stage I, II and III, and 12 eyes of 12 healthy subjects were included. AS-OCTA images were analyzed by two masked observers, measuring the maximum corneal vascular extension (CoVE) from the limbus to the furthest vessel over the cornea, and corneal vascular thickness (CoVT) from the most superficial to the deepest corneal vessel. RESULTS: CoVE was 0.27 ± 0.10, 0.79 ± 0.21, 1.68 ± 0.89 and 2.53 ± 0.82 mm in controls, stage I, II and III LSCD, respectively (p < 0.001). The CoVT was 51.0 ± 19.4, 113.7 ± 36.6, 129.7 ± 39.3 and 336.0 ± 85.0 µm, respectively (p < 0.001). There was a significant difference in CoVE and CoVT between all stages compared to controls, and between stage I and III LSCD (p < 0.001). Further, CoVE showed a significant difference between stage I and II, whereas CoVT showed a significant difference between stage II and III LSCD (p < 0.001). BCVA showed strong correlation with CoVT (r = 0.765, p < 0.001) and moderate correlation with CoVE (r = 0.547, p = 0.001). AS-OCTA parameters showed excellent intra- and inter-class correlation coefficients (>0.900). CONCLUSION: LSCD demonstrates significant changes in CoVE and CoVT as early as stage I LSCD in comparison to controls. CoVE and CoVT strongly correlate to both disease severity and BCVA. AS-OCTA may provide novel quantitative and non-invasive parameters to assess LSCD.

Efficacy and tolerability of nortriptyline in the management of neuropathic corneal pain.

PURPOSE: Neuropathic corneal pain (NCP) is a recently acknowledged disease entity. However, there is no consensus in potential treatment strategies, particularly in patients with a centralized component of pain. This study aims to assess the efficacy and tolerability of the tricyclic antidepressant, nortriptyline, among NCP patients. METHODS: Patients with clinically diagnosed NCP and a centralized component of pain, treated with oral nortriptyline, who had recorded pain scores as assessed by the ocular pain assessment survey at the first and last visit were included. Patients were excluded if they had any other ocular pathology that might result in pain or had less than 4 weeks of nortriptyline use. Demographics, time between visits, concomitant medications, systemic and ocular co-morbidities, duration of NCP, side effects, ocular pain scores, and quality of life (QoL) assessment were recorded. RESULTS: Thirty patients with a mean age of 53.1 ± 18.5 were included. Male to female ratio was 8:22. Mean ocular pain in the past 24 h improved from 5.7 ± 2.1 to 3.6 ± 2.1 after 10.5 ± 9.1 months (p < 0.0001). Twelve patients (40.0%) had equal to or more than 50% improvement, 6 patients (20.0%) had 30-49% improvement, 6 patients (20.0%) had 1-29% improvement, 4 patients (13.3%) did not improve, while 2 patients (6.7%) reported increase in pain levels. Mean QoL improved from 6.0 ± 2.5 to 4.3 ± 2.4 (p = 0.019). Eight patients (26.6%) discontinued treatment due to persistent side effects, despite improvement by 22.4%. CONCLUSION: Nortriptyline was effective in relieving NCP symptoms in patients with centralized component and insufficient response to other systemic and topical therapies who tolerated the drug for at least 4 weeks. Nortriptyline may be used in the management of patients with NCP.

Visualization of microneuromas by using in vivo confocal microscopy: An objective biomarker for the diagnosis of neuropathic corneal pain?

PURPOSE: The diagnosis of neuropathic corneal pain (NCP) is challenging, as it is often difficult to differentiate it from conventional dry eye disease (DED). In addition to eye pain, NCP can present with similar signs and symptoms of DED. The purpose of this study is to find an objective diagnostic sign to identify patients with NCP, using in vivo confocal microscopy (IVCM). METHODS: This was a comparative, retrospective, case-control study. Patients with clinical diagnosis of NCP (n = 25), DED (n = 30), and age- and sex-matched healthy controls (n = 16), who underwent corneal imaging with IVCM (HRT3/RCM) were included. Central corneal IVCM scans were analyzed by 2 masked observers for nerve density and number, presence of microneuromas (terminal enlargements of subbasal corneal nerve) and/or nerve beading (bead-like formation along the nerves), and dendritiform cell (DC) density. RESULTS: There was a decrease in total nerve density in both NCP (14.14 ± 1.03 mm/mm2) and DED patients (12.86 ± 1.04 mm/mm2), as compared to normal controls (23.90 ± 0.92 mm/mm2; p < 0.001). However, total nerve density was not statistically different between NCP and DED patients (p = 0.63). Presence of nerve beading was not significantly different between patients and normal controls (p = 0.15). Interestingly, microneuromas were observed in all patients with NCP, while they were not present in any of the patients with conventional DED (sensitivity and specificity of 100%). DC density was significantly increased in both NCP (71.89 ± 16.91 cells/mm2) and DED patients (111.5 ± 23.86 cells/mm2), as compared to normal controls (24.81 ± 4.48 cells/mm2 (p < 0.05). However, there was no significant difference in DC density between DED and NCP patients (p = 0.31). CONCLUSION: IVCM may be used as an adjunct diagnostic tool for the diagnosis of NCP in the presence of neuropathic symptoms. Microneuromas may serve as a sensitive and specific biomarker for the diagnosis of NCP.

Comparison of clinical characteristics of post-refractive surgery-related and post-herpetic neuropathic corneal pain.

PURPOSE: To compare the clinical characteristics and in vivo confocal microscopy (IVCM) findings of patients with neuropathic corneal pain (NCP) due to refractive surgery (RS-NCP) and herpetic eye disease (H-NCP) to controls. METHODS: Sixteen patients with RS-NCP and 7 patients with H-NCP, and 37 healthy reference age- and sex-matched healthy controls were included to the study. The medical records were reviewed for demographic features, detailed disease history, ocular surface disease index (OSDI), ocular pain assessment survey (OPAS) scores. IVCM images of patients were analyzed and compared to reference controls by two masked observers. RESULTS: The mean pain intensity score for the last 24 h (5.1 ± 2.4 vs. 3.9 ± 1.2; p = 0.27), last 2 weeks (6.1 ± 2.5 vs. 4.8 ± 2.3; p = 0.13) for RS-NCP vs. H-NCP respectively, and quality of life scores (p = 0.23) were similar in both groups. Quality of life, especially mood (p = 0.06) and enjoying life/relations to others (p = 0.10) were affected in both groups, but were not statistically significant between groups. The mean total nerve density was lower in RS-NCP (5,702.4 ± 4,599.0 µm/mm2) compared to their respective controls (26,422.8 ± 4,491.0; p < 0.001) and in the H-NCP group (2,149.5 ± 2,985.9) compared to their respective controls (22,948.8 ± 3,169.0; p < 0.001). Alterations in DC density were similar between all groups (38.3 ± 48.0 cells/mm2 in RS-NCP, 61.0 ± 76.9 in H-NCP, p = 0.95). CONCLUSION: Neuropathic corneal pain patients due to refractive surgery show similar clinical characteristics, pain levels, quality of life impact, and IVCM findings as patients with NCP due to herpetic eye disease.

Infrared meibography allows detection of dimensional changes in meibomian glands following intranasal neurostimulation.

PURPOSE: Patients with dry eye disease (DED) may suffer from decreased tear break-up time due to meibomian gland (MG) dysfunction. Infrared meibography (IR Meibography) uses infrared wavelength light to visualize meibomian glands in vivo. We aimed to explore the feasibility of using serial IR Meibography imaging to assess morphological changes in MGs as an indirect measure of functionality, following intranasal neurostimulation (ITN). METHODS: Fifteen DED subjects were prospectively enrolled in a single-center, single-arm study. Changes in MGs were captured using IR meibography (RTVUE-XR, Optovue, Inc. Fremont, CA, USA) on the lower eyelids before and after 3 min of ITN (TrueTear®, Allergan, Dublin, Ireland) use that delivers a microcurrent to sensory neurons of the nasal cavity. The same MGs were selected pre- and post-stimulation, and MG area and perimeter were analyzed by two masked observers. RESULTS: Mean (±SD) pre- and post-stimulation MG areas were 2,187.60 ± 635.88 µm2 and 1,933.20 ± 538.55 µm2, respectively. The mean change in area, 254.49 µm2, representing an 11.6% reduction following ITN use, was statistically significant (p = 0.001). Mean (±SD) pre- and post-stimulation MG perimeters were 235.9 ± 51.38 µm and 222.2 ± 47.72 µm, respectively. The mean change in perimeter, 13.7 µm, representing a 5.81% reduction following ITN use, was statistically significant (p = 0.012). CONCLUSIONS: Our study shows that IR meibography can be used to detect immediate changes in gland area and perimeter, an indirect measure of MG activity following intervention by ITN.

Corneal pain and experimental model development.

The cornea is a valuable tissue for studying peripheral sensory nerve structure and regeneration due to its avascularity, transparency, and dense innervation. Somatosensory innervation of the cornea serves to identify changes in environmental stimuli at the ocular surface, thereby promoting barrier function to protect the eye against injury or infection. Due to regulatory demands to screen ocular safety of potential chemical exposure, a need remains to develop functional human tissue models to predict ocular damage and pain using in vitro-based systems to increase throughput and minimize animal use. In this review, we summarize the anatomical and functional roles of corneal innervation in propagation of sensory input, corneal neuropathies associated with pain, and the status of current in vivo and in vitro models. Emphasis is placed on tissue engineering approaches to study the human corneal pain response in vitro with integration of proper cell types, controlled microenvironment, and high-throughput readouts to predict pain induction. Further developments in this field will aid in defining molecular signatures to distinguish acute and chronic pain triggers based on the immune response and epithelial, stromal, and neuronal interactions that occur at the ocular surface that lead to functional outcomes in the brain depending on severity and persistence of the stimulus.

Neurostimulation in dry eye disease-past, present, and future.

Neuromodulation is a novel approach that utilizes electrical signals, pharmaceutical agents, or other forms of energy to modulate abnormal neural function through neurostimulation. Neurostimulation is a novel technique that uses electrical currents to stimulate the nervous system. During the recent few decades, neuromodulation has gained significant attention, in particular for the treatment of chronic neurological diseases, due to its success in treating patients unresponsive to conventional pharmacological therapies. Dry eye disease (DED) is a chronic, multifactorial disease that affects millions of people worldwide. Recent data have demonstrated that neurosensory abnormalities contribute to the pathogenesis of DED. Current mainstays of dry eye therapy include lubrication, tear retention, and anti-inflammatory therapies, among others. The recent development of intranasal neurostimulation therapy for DED utilizes the nasolacrimal reflex as an alternative pathway, not only to increase tear production via increased lacrimation, but also to target other tear film components, such as mucin and meibum secretion, promoting tear film homeostasis. This review aims to describe the different types of neuromodulation devices available and their application for non-ocular diseases, as well as to review recent advances and literature on ocular neurostimulation.

Neuropathic Corneal Pain: Approaches for Management.

Neuropathic pain is caused by a primary lesion or dysfunction of the nervous system and can occur in the cornea. However, neuropathic corneal pain (NCP) is currently an ill-defined disease. Patients with NCP are extremely challenging to manage, and evidence-based clinical recommendations for the management of patients with NCP are scarce. The objectives of this review are to provide guidelines for diagnosis and treatment of patients with NCP and to summarize current evidence-based literature in this area. We performed a systematic literature search of all relevant publications between 1966 and 2017. Treatment recommendations are, in part, based on methodologically sound randomized controlled trials (RCTs), demonstrating superiority to placebo or relevant control treatments, and on the consistency of evidence, degree of efficacy, and safety. In addition, the recommendations include our own extensive experience in the management of these patients over the past decade. A comprehensive algorithm, based on clinical evaluation and complementary tests, is presented for diagnosis and subcategorization of patients with NCP. Recommended first-line topical treatments include neuroregenerative and anti-inflammatory agents, and first-line systemic pharmacotherapy includes tricyclic antidepressants and an anticonvulsant. Second-line oral treatments recommended include an opioid-antagonist and opiate analgesics. Complementary and alternative treatments, such as cardiovascular exercise, acupuncture, omega-3 fatty acid supplementation, and gluten-free diet, may have additional benefits, as do potential noninvasive and invasive procedures in recalcitrant cases. Medication selection should be tailored on an individual basis, considering side effects, comorbidities, and levels of peripheral and centralized pain. Nevertheless, there is an urgent need for long-term studies and RCTs assessing the efficacy of treatments for NCP.

Corneal confocal microscopy in a healthy Brazilian sample / Microscopia confocal em córneas de brasileiros saudáveis

ABSTRACT Objective This study aims to evaluate the characteristics of the corneal sub-basal plexus by performing in vivo confocal microscopy of healthy Brazilians to provide reference values for the Brazilian population. Method This study is an observational, cross-sectional, descriptive study comparing corneas from 55 healthy Brazilian individuals across the age span of 20-70 years. Results The average number of fibers was 5.35 ± 1.36, fiber density was 33.4 ± 8.5 fibers per field, and the mean number of Langerhans cells was 5.13 ± 8.10. A correlation between the average number of fibers and age showed an inverse relationship between the number and density of fibers and age for women (p < 0.05). In the multivariate analysis, each annual increase of age showed an average increase of 1.017 (95%CI: 1.008 to 1.026) in the number of Langerhans cells, adjusting for sex and thickness. Conclusion Compared to other samples, this Brazilian population showed a higher average number of fibers, though further studies with a larger sample should be performed.

RESUMO Objetivo Este estudo tem como objetivo avaliar as características morfológicas do plexo sub-basal da córnea por microscopia confocal in vivo com indivíduos brasileiros saudáveis para fornecer uma referência para a população brasileira. Método Este trabalho é um estudo observacional, descritivo, transversal comparativo com microscopia confocal de córnea a partir de 55 indivíduos brasileiros saudáveis na faixa etária de 70 ± 20 anos de idade. Resultados Número médio de fibras foi 5,35 ± 1,36, a densidade foi de 33,4 ± 8,5 fibras por campo e de células de Langerhans foi 5,13 ± 8,10. Uma correlação entre o número médio de fibras e da idade dos indivíduos mostrou uma relação inversa entre o número e densidade de fibras, e idade para as mulheres, (p < 0,05). Na análise multivariada, cada aumento anual de idade apresentou um aumento médio de 1,017 (IC95%: 1,008-1,026) no número de células de Langerhans, ajustado para sexo e espessura. Conclusão Em comparação com outras amostras, esta população brasileira apresentou um maior número médio de fibras embora estudos com número maior de amostras necessitem ser realizados.

Corneal confocal microscopy in a healthy Brazilian sample.

OBJECTIVE: This study aims to evaluate the characteristics of the corneal sub-basal plexus by performing in vivo confocal microscopy of healthy Brazilians to provide reference values for the Brazilian population. METHOD: This study is an observational, cross-sectional, descriptive study comparing corneas from 55 healthy Brazilian individuals across the age span of 20-70 years. RESULTS: The average number of fibers was 5.35 ± 1.36, fiber density was 33.4 ± 8.5 fibers per field, and the mean number of Langerhans cells was 5.13 ± 8.10. A correlation between the average number of fibers and age showed an inverse relationship between the number and density of fibers and age for women (p < 0.05). In the multivariate analysis, each annual increase of age showed an average increase of 1.017 (95%CI: 1.008 to 1.026) in the number of Langerhans cells, adjusting for sex and thickness. CONCLUSION: Compared to other samples, this Brazilian population showed a higher average number of fibers, though further studies with a larger sample should be performed.