A dor neuropática decorre do acometimento das vias somatossensitivas por lesão ou doença e afeta 7% da população geral. No entanto, apenas uma proporção dos doentes com neuropatia desenvolve este tipo de dor. Diversos estudos tentaram comparar doentes acometidos por lesões aparentemente semelhantes do sistema somatossensitivo em busca dos fatores determinantes para a ocorrência e características da dor neuropática, com resultados conflitantes. Parte deste insucesso deriva do fato de que indivíduos diferentes podem ter lesões de nervo semelhantes, mas diferem quanto ao perfil psicológico, epigenético, de polimorfismos de receptores de neurotransmissores, e de catastrofismo. Estas características e uma série de outros fatores interindividuais podem enviesar a interpretação dos achados locais sobre a área de neuropatia e dor. Assim, o estudo de um mesmo indivíduo que possua áreas diferentes de neuropatia com e sem dor neuropática concomitantes serviria para reduzir os vieses interindividuais nas suas avaliações, e poderia revelar alterações locais que se relacionem com a ocorrência de dor neuropática. A hanseníase é uma doença que afeta o sistema nervoso periférico com o padrão de mononeuropatia múltipla frequente. Uma grande proporção de doentes apresenta dor neuropática crônica que ocorre, na maior parte das vezes, após o fim do tratamento farmacológico antibioticoterápico, e que representa intenso impacto negativo na qualidade de vida. Assim, a hanseníase é um modelo de estudo em que um mesmo doente apresenta neuropatia periférica com dor neuropática (D+) em uma área do corpo (n+d+) e em outra parte do corpo (contralateral homóloga) pode apresentar neuropatia sem dor neuropática (n+d-). Ainda, há indivíduos que podem compor um grupo controle de doentes acometidos pela hanseníase, mas que não tem dor neuropática (D-), apresentando áreas de neuropatia sem dor neuropática (n+d-) e áreas corpóreas sem neuropatia (n-d-). O objetivo do presente estudo foi investigar fatores periféricos que poderiam implicar na ocorrência de dor neuropática avaliando doentes com antecedente de hanseníase e mononeuropatia múltipla como modelo. Foram avaliados 37 doentes com hanseníase e dor crônica (D+) e 22 doentes com hanseníase sem dor crônica (D-), grupo-controle. Realizou-se a caracterização sociodemográfica e clínica, exame neurológico padronizado e utilizou-se escalas de avaliação da dor padronizadas e validadas (Inventário Breve de Dor - IBD, Questionário de dor neuropática 4 (DN4), Questionário Breve de Dor McGill e Inventário de Sintomas de Dor Neuropática - ISDN). Sobre cada uma das quatro áreas presentes possíveis (n+d+; n+d-; n+d-; n-d-), realizou-se aferição da sensibilidade exteroceptiva e proprioceptiva por meio de limiares de sensibilidade dolorosa e não dolorosa pelo teste quantitativo de sensibilidade (TQS) e análise morfológico-quantitativa da densidade de fibras nervosas intraepidérmicas (DFNIE), associados à aferição da presença de fatores inflamatórios na neuropatologia cutânea. As formas paucibacilar e dimorfa da hanseníase apresentaram menor limiar de dor ao quente (LDoQ) em comparação com a forma multibacilar (-2,66?C e -4,25?C, p = 0,002, respectivamente). As áreas com dor neuropática apresentaram sinais de disfunção de fibras nervosas do tipo C e hiperestesia em comparação com áreas com neuropatia sem dor neuropática. O LDoQ foi maior em áreas com neuropatia e dor neuropática (47,5 ± 3,4) em comparação com áreas com neuropatia sem dor neuropática (45,9 ± 3,6), p = 0,010, enquanto o limiar de detecção mecânica (LDM) foi menor (1,5 ± 3,6) em áreas com neuropatia e dor neuropática em comparação com áreas com neuropatia sem dor neuropática (5,8 ± 29,6), p = 0,047. Os doentes hansênicos apresentaram diagnóstico de neuropatia de fibras finas grave em todas as áreas de pele amostradas, a média das densidades variaram entre 2,1 a 3,2 fibras por milímetro (abaixo do percentil 5%). Não houve diferença estatisticamente significativa entre as quatro diferentes áreas quanto à DFNIE e quanto a fatores inflamatórios como contagens de macrófagos, linfócitos, células de Langerhans e medida da citocina fator de necrose tumoral alfa. Na modelagem matemática das variáveis significativas, as áreas com neuropatia sem dor tiveram LDoQ 2,30?C mais altos do que as áreas sem neuropatia e sem dor (n-d-). As áreas com neuropatia com dor (n+d+) tiveram LDoQ 3,45 C mais altos do que as áreas sem neuropatia e sem dor (n-d-). Nas análises de modelagem da relação dos dados entre LDoQ e DFNIE, verificou-se que áreas totalmente desnervadas (DFNIE = 0/mm apresentaram aumento do LDoQ estimada de 4,03 C, enquanto as amostras parcialmente inervadas (DFNIE = 1-5fibras/mm) apresentaram um aumento estimado de LDoQ de 1,54 C em comparação às áreas de referência (DFNIE >- 5fibras/mm). Encontrou-se uma relação entre o tempo e o agravamento da neuropatia. A cada mês, decorrido entre o término do tratamento com antibióticos da hanseníase e a avaliação atual, o LDoQ aumentou em 0,03?C, reforçando teorias de que a presença de debris bacterianos podem estar relacionados à ocorrência de neuropatia ativa e vigente, assim como, um potencial papel das reações hansênicas na ocorrência de neuropatia e dor neuropática a longo prazo. As alterações do LDoQ e do LDM foram relacionadas à ocorrência da dor neuropática no presente estudo e podem ter valor prognóstico e de rastreio se esses achados forem replicados em coortes maiores no futuro / Neuropathic pain arises from a lesion or disease of the somatosensory system and affects 7% of the general population. However, only a proportion of patients with neuropathy develop this type of pain. Several studies have attempted to compare patients with apparently similar lesions to the somatosensory system in search of the factors determining the occurrence and characteristics of neuropathic pain, yielding conflicting results. Part of the challenge in such assessment stems from the fact that different individuals may have similar nerve lesions, but may differ in their psychological, epigenetic, neurotransmitter receptor polymorphisms and catastrophism profiles. These features and several other interindividual factors may bias the interpretation of local findings in the area of neuropathy and pain. Thus, the study of the same individual who presents with different areas of neuropathy with and without neuropathic pain concomitantly would reduce the interindividual bias of these assessments, and could reveal local changes related to the occurrence of neuropathic pain. Leprosy is a disease that affects the peripheral nervous system with the frequent pattern of multiple mononeuropathy distribution. A large proportion of patients present chronic neuropathic pain, which occurs most often after the end of the antibiotic therapy drug treatment, and which poses an intense negative impact on the quality of life. Thus, leprosy is a \"model\" in which the same patient presents peripheral neuropathy with neuropathic pain (P+) in one area of the body (n+p+) and in another part of the body (contralateral homologous) presents neuropathy without neuropathic pain (n+p-). In addition, there are individuals who may constitute a control group, who are affected by leprosy but who do not have neuropathic pain (P-), and have body areas with neuropathy without neuropathic pain (n+p-) and body areas without neuropathy (n-p-). The aim of the present study was to investigate peripheral factors that could be related to the occurrence of neuropathic pain by assessing patients with leprosy and multiple mononeuropathy. We evaluated 37 patients with leprosy and chronic pain (P+) and 22 patients with leprosy without chronic pain (P-) (control group). Sociodemographic and clinical characterization were performed, as well as, standardized neurological examination and assessment of pain and related symptoms with validated pain assessment scales (Brief Pain Inventory - BPI, Neuropathic Pain Questionnaire 4 - DN4, McGill Brief Pain Questionnaire and Neuropathic Pain Symptom Inventory - NPSI). On each of the four possible body areas (n+p+; n+p-; n+p-; n-p-), exteroceptive and proprioceptive sensitivity were assessed by means of thresholds of painful and non-painful sensory stimuli by quantitative sensitivity test (QST), as well as, morphological-quantitative analysis of intraepidermal nerve fiber density (IENFD), and assessment of inflammatory factors in cutaneous neuropathology. Paucibacillary and dimorphic forms of leprosy presented lower heat pain threshold (HPT) compared to the multibacillary form (-2.66?C and -4.25 C, p=0.002; respectively). Areas with neuropathic pain had signs of defective C nerve fiber dysfunction and hyperesthesia compared to areas with neuropathy without neuropathic pain. HPT was higher in areas with neuropathy and neuropathic pain (47.5 ± 3.4) compared to areas with neuropathy without neuropathic pain (45.9 ± 3.6), p=0.010), while mechanical detection threshold (MDT) was lower (1.5 ± 3.6) in areas with neuropathy and neuropathic pain compared to areas with neuropathy without neuropathic pain (5.8 ± 29.6), p=0.047. Leprosy patients had a diagnosis of severe small-fiber neuropathy in all areas of skin sampled, the mean densities ranged from 2.1 to 3.2 fibers per millimeter (below 5% percentile). There was no statistically significant difference between the four different areas concerning IEFND and for inflammatory factors such as presence of number of macrophages, lymphocytes, Langerhans cells and cytokine tumor necrosis factor alpha. In the mathematical modeling of significant variables, areas with painless neuropathy (n+p-) had a HPT 2.30?C higher than areas without neuropathy and without pain (n-p-). Areas with neuropathy with pain (n+p+) had a HPT 3.45 C higher than areas without neuropathy and without pain (n-p-). In the modeling analyses between the relationship of HPT and IEFND data, it was found that totally denervated areas (IEFND=0/mm) presented an increase in estimated HPT of 4.03 C, while scarcely innervated samples (IEFND=1-5fibers/mm) presented an estimated increase of HPT of 1.54?C compared to reference areas (IEFND >- 5fibers/mm). We found a relationship between time and worsening of neuropathy. Each month between the termination of the leprosy antibiotic treatment and the present assessment, HPT increased by 0.03°C, supporting theories relating the presence of bacterial debris and the occurrence of active and ongoing neuronal damage, as well as, a potential role of leprosy reactions in the occurrence of neuropathy and neuropathic pain in the long-term. HPT and MDT changes were related to the occurrence of neuropathic pain in the present study and may have prognostic and screening value should these findings be replicated in larger cohorts in the future

Les relations entre douleur, dysautonomie et atteinte des petites fibres nerveuses sont complexes. Notre travail a porté sur les relations entre le phénotypage clinique de la douleur d’une part, et sur la caractérisation neurophysiologique des atteintes autonomes d’autre part, dans le contexte d’atteinte des petites fibres nerveuses. Ceci a fait l’objet de 5 études. La première étude a montré que plusieurs variables cliniques permettaient de caractériser la douleur de façon différentielle entre des patients atteints de neuropathie des petites fibres idiopathique ou secondaire à un syndrome de Sjögren. La deuxième étude a montré que la lésion ou la perte de fonction des petites fibres entraînait plutôt une majoration de la sensibilisation centrale et des anomalies liées aux grosses fibres sensitives chez des patients ayant un syndrome de Sjögren douloureux associé à une neuropathie des petites fibres. La troisième étude a montré que, dans le syndrome du canal carpien, les troubles sensitifs, en dehors des sensations de brûlure, étaient aussi liés de façon prédominante aux grosses fibres, avec cependant une sensibilité diagnostique particulière de l’étude des fibres autonomes vasomotrices par le test à l'EMLA. La quatrième étude a porté sur l’intérêt de la mesure des conductances cutanées par Sudoscan ® dans le suivi des neuropathies amyloïdes et de leur traitement. Enfin, la cinquième étude a permis d’analyser la sensibilité diagnostique respective de deux tests sudoromoteurs (Sudoscan® et Neuropad®) dans le cadre de la détection précoce de la neuropathie amyloïde et aussi pour le suivi des patients, au moins en ce qui concerne le Sudoscan®. Avec tous ces aspects, ce travail a permis de mieux comprendre les relations entre troubles sensitifs et atteinte des petites fibres sensitives et autonomes dans des contextes neuropathiques cliniques, comme le syndrome de Sjögren, le syndrome du canal carpien et la neuropathie amyloïde. / The relationships between pain, autonomic dysfunction and involvement of small nerve fibers are complex. Our work focused on the relationships between clinical phenotyping of pain on the one hand, and the neurophysiological characterization of autonomic disorders on the other hand, in the context of small nerve fiber involvement. This has been the subject of 5 studies. The first study showed that several clinical variables differentially characterize pain between patients with idiopathic small fiber neuropathy or secondary to Sjögren's syndrome. The second study showed that the lesion or loss of function of small fibers led to an increase in central sensitization and abnormalities related to large sensory fibers in patients with painful Sjögren's syndrome associated with small fiber neuropathy. The third study showed that, in carpal tunnel syndrome, sensory disturbances, apart from burning sensations, were also predominantly related to large fibers, with however a particular diagnostic sensitivity of the study of autonomic vasomotor fibers by the EMLA test. The fourth study focused on the interest of measuring electrochemical skin conductance with Sudoscan ® in the monitoring of amyloid neuropathies and their treatment. Finally, the fifth study analyzed the respective diagnostic sensitivity of two sudoromotor tests (Sudoscan® and Neuropad®) in the context of early detection of amyloid neuropathy and also for patient follow-up, at least with Sudoscan®. With all these aspects, this work has led to a better understanding of the relationships between sensory disturbances and small sensory and autonomic fibre disorders in clinical neuropathic contexts, such as Sjögren's syndrome, carpal tunnel syndrome and amyloid neuropathy.

A dor neuropática decorre do acometimento das vias somatossensitivas por lesão ou doença e afeta 7% da população geral. No entanto, apenas uma proporção dos doentes com neuropatia desenvolve este tipo de dor. Diversos estudos tentaram comparar doentes acometidos por lesões aparentemente semelhantes do sistema somatossensitivo em busca dos fatores determinantes para a ocorrência e características da dor neuropática, com resultados conflitantes. Parte deste insucesso deriva do fato de que indivíduos diferentes podem ter lesões de nervo semelhantes, mas diferem quanto ao perfil psicológico, epigenético, de polimorfismos de receptores de neurotransmissores, e de catastrofismo. Estas características e uma série de outros fatores interindividuais podem enviesar a interpretação dos achados locais sobre a área de neuropatia e dor. Assim, o estudo de um mesmo indivíduo que possua áreas diferentes de neuropatia com e sem dor neuropática concomitantes serviria para reduzir os vieses interindividuais nas suas avaliações, e poderia revelar alterações locais que se relacionem com a ocorrência de dor neuropática. A hanseníase é uma doença que afeta o sistema nervoso periférico com o padrão de mononeuropatia múltipla frequente. Uma grande proporção de doentes apresenta dor neuropática crônica que ocorre, na maior parte das vezes, após o fim do tratamento farmacológico antibioticoterápico, e que representa intenso impacto negativo na qualidade de vida. Assim, a hanseníase é um modelo de estudo em que um mesmo doente apresenta neuropatia periférica com dor neuropática (D+) em uma área do corpo (n+d+) e em outra parte do corpo (contralateral homóloga) pode apresentar neuropatia sem dor neuropática (n+d-). Ainda, há indivíduos que podem compor um grupo controle de doentes acometidos pela hanseníase, mas que não tem dor neuropática (D-), apresentando áreas de neuropatia sem dor neuropática (n+d-) e áreas corpóreas sem neuropatia (n-d-). O objetivo do presente estudo foi investigar fatores periféricos que poderiam implicar na ocorrência de dor neuropática avaliando doentes com antecedente de hanseníase e mononeuropatia múltipla como modelo. Foram avaliados 37 doentes com hanseníase e dor crônica (D+) e 22 doentes com hanseníase sem dor crônica (D-), grupo-controle. Realizou-se a caracterização sociodemográfica e clínica, exame neurológico padronizado e utilizou-se escalas de avaliação da dor padronizadas e validadas (Inventário Breve de Dor - IBD, Questionário de dor neuropática 4 (DN4), Questionário Breve de Dor McGill e Inventário de Sintomas de Dor Neuropática - ISDN). Sobre cada uma das quatro áreas presentes possíveis (n+d+; n+d-; n+d-; n-d-), realizou-se aferição da sensibilidade exteroceptiva e proprioceptiva por meio de limiares de sensibilidade dolorosa e não dolorosa pelo teste quantitativo de sensibilidade (TQS) e análise morfológico-quantitativa da densidade de fibras nervosas intraepidérmicas (DFNIE), associados à aferição da presença de fatores inflamatórios na neuropatologia cutânea. As formas paucibacilar e dimorfa da hanseníase apresentaram menor limiar de dor ao quente (LDoQ) em comparação com a forma multibacilar (-2,66?C e -4,25?C, p = 0,002, respectivamente). As áreas com dor neuropática apresentaram sinais de disfunção de fibras nervosas do tipo C e hiperestesia em comparação com áreas com neuropatia sem dor neuropática. O LDoQ foi maior em áreas com neuropatia e dor neuropática (47,5 ± 3,4) em comparação com áreas com neuropatia sem dor neuropática (45,9 ± 3,6), p = 0,010, enquanto o limiar de detecção mecânica (LDM) foi menor (1,5 ± 3,6) em áreas com neuropatia e dor neuropática em comparação com áreas com neuropatia sem dor neuropática (5,8 ± 29,6), p = 0,047. Os doentes hansênicos apresentaram diagnóstico de neuropatia de fibras finas grave em todas as áreas de pele amostradas, a média das densidades variaram entre 2,1 a 3,2 fibras por milímetro (abaixo do percentil 5%). Não houve diferença estatisticamente significativa entre as quatro diferentes áreas quanto à DFNIE e quanto a fatores inflamatórios como contagens de macrófagos, linfócitos, células de Langerhans e medida da citocina fator de necrose tumoral alfa. Na modelagem matemática das variáveis significativas, as áreas com neuropatia sem dor tiveram LDoQ 2,30?C mais altos do que as áreas sem neuropatia e sem dor (n-d-). As áreas com neuropatia com dor (n+d+) tiveram LDoQ 3,45 C mais altos do que as áreas sem neuropatia e sem dor (n-d-). Nas análises de modelagem da relação dos dados entre LDoQ e DFNIE, verificou-se que áreas totalmente desnervadas (DFNIE = 0/mm apresentaram aumento do LDoQ estimada de 4,03 C, enquanto as amostras parcialmente inervadas (DFNIE = 1-5fibras/mm) apresentaram um aumento estimado de LDoQ de 1,54 C em comparação às áreas de referência (DFNIE >- 5fibras/mm). Encontrou-se uma relação entre o tempo e o agravamento da neuropatia. A cada mês, decorrido entre o término do tratamento com antibióticos da hanseníase e a avaliação atual, o LDoQ aumentou em 0,03?C, reforçando teorias de que a presença de debris bacterianos podem estar relacionados à ocorrência de neuropatia ativa e vigente, assim como, um potencial papel das reações hansênicas na ocorrência de neuropatia e dor neuropática a longo prazo. As alterações do LDoQ e do LDM foram relacionadas à ocorrência da dor neuropática no presente estudo e podem ter valor prognóstico e de rastreio se esses achados forem replicados em coortes maiores no futuro / Neuropathic pain arises from a lesion or disease of the somatosensory system and affects 7% of the general population. However, only a proportion of patients with neuropathy develop this type of pain. Several studies have attempted to compare patients with apparently similar lesions to the somatosensory system in search of the factors determining the occurrence and characteristics of neuropathic pain, yielding conflicting results. Part of the challenge in such assessment stems from the fact that different individuals may have similar nerve lesions, but may differ in their psychological, epigenetic, neurotransmitter receptor polymorphisms and catastrophism profiles. These features and several other interindividual factors may bias the interpretation of local findings in the area of neuropathy and pain. Thus, the study of the same individual who presents with different areas of neuropathy with and without neuropathic pain concomitantly would reduce the interindividual bias of these assessments, and could reveal local changes related to the occurrence of neuropathic pain. Leprosy is a disease that affects the peripheral nervous system with the frequent pattern of multiple mononeuropathy distribution. A large proportion of patients present chronic neuropathic pain, which occurs most often after the end of the antibiotic therapy drug treatment, and which poses an intense negative impact on the quality of life. Thus, leprosy is a \"model\" in which the same patient presents peripheral neuropathy with neuropathic pain (P+) in one area of the body (n+p+) and in another part of the body (contralateral homologous) presents neuropathy without neuropathic pain (n+p-). In addition, there are individuals who may constitute a control group, who are affected by leprosy but who do not have neuropathic pain (P-), and have body areas with neuropathy without neuropathic pain (n+p-) and body areas without neuropathy (n-p-). The aim of the present study was to investigate peripheral factors that could be related to the occurrence of neuropathic pain by assessing patients with leprosy and multiple mononeuropathy. We evaluated 37 patients with leprosy and chronic pain (P+) and 22 patients with leprosy without chronic pain (P-) (control group). Sociodemographic and clinical characterization were performed, as well as, standardized neurological examination and assessment of pain and related symptoms with validated pain assessment scales (Brief Pain Inventory - BPI, Neuropathic Pain Questionnaire 4 - DN4, McGill Brief Pain Questionnaire and Neuropathic Pain Symptom Inventory - NPSI). On each of the four possible body areas (n+p+; n+p-; n+p-; n-p-), exteroceptive and proprioceptive sensitivity were assessed by means of thresholds of painful and non-painful sensory stimuli by quantitative sensitivity test (QST), as well as, morphological-quantitative analysis of intraepidermal nerve fiber density (IENFD), and assessment of inflammatory factors in cutaneous neuropathology. Paucibacillary and dimorphic forms of leprosy presented lower heat pain threshold (HPT) compared to the multibacillary form (-2.66?C and -4.25 C, p=0.002; respectively). Areas with neuropathic pain had signs of defective C nerve fiber dysfunction and hyperesthesia compared to areas with neuropathy without neuropathic pain. HPT was higher in areas with neuropathy and neuropathic pain (47.5 ± 3.4) compared to areas with neuropathy without neuropathic pain (45.9 ± 3.6), p=0.010), while mechanical detection threshold (MDT) was lower (1.5 ± 3.6) in areas with neuropathy and neuropathic pain compared to areas with neuropathy without neuropathic pain (5.8 ± 29.6), p=0.047. Leprosy patients had a diagnosis of severe small-fiber neuropathy in all areas of skin sampled, the mean densities ranged from 2.1 to 3.2 fibers per millimeter (below 5% percentile). There was no statistically significant difference between the four different areas concerning IEFND and for inflammatory factors such as presence of number of macrophages, lymphocytes, Langerhans cells and cytokine tumor necrosis factor alpha. In the mathematical modeling of significant variables, areas with painless neuropathy (n+p-) had a HPT 2.30?C higher than areas without neuropathy and without pain (n-p-). Areas with neuropathy with pain (n+p+) had a HPT 3.45 C higher than areas without neuropathy and without pain (n-p-). In the modeling analyses between the relationship of HPT and IEFND data, it was found that totally denervated areas (IEFND=0/mm) presented an increase in estimated HPT of 4.03 C, while scarcely innervated samples (IEFND=1-5fibers/mm) presented an estimated increase of HPT of 1.54?C compared to reference areas (IEFND >- 5fibers/mm). We found a relationship between time and worsening of neuropathy. Each month between the termination of the leprosy antibiotic treatment and the present assessment, HPT increased by 0.03°C, supporting theories relating the presence of bacterial debris and the occurrence of active and ongoing neuronal damage, as well as, a potential role of leprosy reactions in the occurrence of neuropathy and neuropathic pain in the long-term. HPT and MDT changes were related to the occurrence of neuropathic pain in the present study and may have prognostic and screening value should these findings be replicated in larger cohorts in the future

L’existence de douleurs neuropathiques et/ou de perte de la sensibilité douloureuse sont souvent le reflet d’une neuropathie sensitive affectant plus particulièrement les fibres nerveuses sensitives amyélinique Aδ et C, dites neuropathie des petites fibres (NPF). Ces fibres innervent, notamment, le derme et l’épiderme de la peau. Elles communiquent la sensibilité thermique et algique au système nerveux central et contribuent à l’homéostasie cutanée, entre autres, par la libération de neuropeptides en périphérie. De nombreuses pathologies sont associées à une altération de ces petites fibres dans la peau. Deux pathologies impliquant une NPF ont été étudiées au cours de ce travail : les escarres et la maladie de Charcot-Marie-Tooth type 1A. Un travail expérimental a été réalisé chez la souris pour répondre à la question suivante ; est-ce qu’une seule atteinte des fibres nociceptives, responsables de la perte de sensibilité peut entraîner un déséquilibre de l’homéostasie cutanée, responsable de l’apparition des escarres ? La mise en place d’un modèle de neuropathie sensitive fonctionnelle réversible a permis de mettre en en évidence l’implication des neuropeptides, substance P (SP) et « calcitonin gene-related peptide » (CGRP), libérés par les fibres nerveuses cutanées, dans la formation d’ulcères de pression. Un traitement préventif à la rhEPO (Recombinant Human Erythropoietin) dans ce modèle associant une neuropathie et des plaies de pression, protège la peau contre une pression ischémiante induisant une escarre par son effet neuroprotecteur sur les petites fibres cutanées. L’association CMT1A et NPF a été étudiée à partir de biopsies cutanées humaines. La quantification des fibres intraépidermiques révèle que 48% des patients CMT1A sont atteints d’une NPF. L’analyse des biopsies cutanées révèle également une altération du nombre et de la morphologie de cellules de Langerhans dans la maladie de CMT1A. L'ensemble de ces résultats confirme l'intérêt de l'étude des petites fibres dans des pathologies variées et confirme le potentiel thérapeutique neuroprotecteur de l'EPO / The neuropathic pain and/or hypoalgesia often reflect a sensory neuropathy that affects particularly sensory, Aδ (thinly myelinated) and C (unmyelinated) nerve fibers. This kind of neuropathy is named "small fiber neuropathy" (SFN). These small fibers innervate the dermis and epidermis. C and Aδ free nerve endings respond to a variable range of stimuli including mechanical, thermal and pain stimuli. They conduct nociceptive signals to central nervous system and contribute to skin homeostasis, among others, by the release of neuropeptides in the periphery. Many diseases are associated with an alteration of these cutaneous small fibers. Two pathologies involving SFN were studied in this work: pressure ulcers and Charcot-Marie-Tooth disease Type 1A (CMT1A). Experimental studies on mice were performed to determine if impairment of nociceptive fibers could lead to an imbalance of skin homeostasis and could be involved in development of pressure ulcers, apart from its role in pain signal transduction. A functional reversible sensory neuropathy mouse model was set up and helped to demonstrate the involvement of the neuropeptides, substance P (SP) and "calcitonin gene-related peptide" (CGRP), released by cutaneous nerve fibers in the formation of pressure ulcers. By its neuroprotective effect on small nerve fibers, a preventive rhEPO (Recombinant Human Erythropoietin) treatment in this model protects the skin against an ischemic pressure-induced Stage 2 ulcer. The CMT1A and SFN association has been studied from human skin biopsies. Quantification of intraepidermal nerve fibers reveals that 48% of CMT1A patients have a SFN. The analysis of skin biopsies also revealed an alteration in the number and morphology of Langerhans cells in CMT1A disease. All these results confirm the interest of the study of small fibers in various pathologies and confirm the neuroprotective therapeutic potential of EPO.