RESUMO
The present series of experiments was designed to examine, in the anesthetized cat, the extent to which the synaptic efficacy of knee joint afferents is modified during the state of central sensitization produced by the injection of capsaicin into the hindlimb plantar cushion. We found that the intradermic injection of capsaicin increased the N2 and N3 components of the focal potentials produced by stimulation of intermediate and high threshold myelinated fibers in the posterior articular nerve (PAN), respectively. This facilitation lasted several hours, had about the same time course as the paw inflammation and was more evident for the N2 and N3 potentials recorded within the intermediate zone in the L6 than in the L7 spinal segments. The capsaicin-induced facilitation of the N2 focal potentials, which are assumed to be generated by activation of fibers signaling joint position, suggests that nociception may affect the processing of proprioceptive and somato-sensory information and, probably also, movement. In addition, the increased effectiveness of these afferents could activate, besides neurons in the intermediate region, neurons located in the more superficial layers of the dorsal horn. As a consequence, normal joint movements could produce pain representing a secondary hyperalgesia. The capsaicin-induced increased efficacy of the PAN afferents producing the N3 focal potentials, together with the reduced post-activation depression that follows high frequency autogenetic stimulation of these afferents, could further contribute to the pain sensation from non-inflamed joints during skin inflammation in humans. The persistence, after capsaicin, of the inhibitory effects produced by stimulation of cutaneous nerves innervating non-inflamed skin regions may account for the reported reduction of the articular pain sensations produced by trans-cutaneous stimulation.
Assuntos
Vias Aferentes/fisiopatologia , Artralgia/fisiopatologia , Pé/fisiopatologia , Inflamação/fisiopatologia , Articulações/fisiopatologia , Mecanorreceptores/fisiopatologia , Transmissão Sináptica/fisiologia , Potenciais de Ação/fisiologia , Animais , Artralgia/induzido quimicamente , Capsaicina/farmacologia , Gatos , Feminino , Pé/inervação , Inflamação/induzido quimicamente , Articulações/inervação , Masculino , Condução Nervosa/fisiologia , Inibição Neural/efeitos dos fármacos , Inibição Neural/fisiologia , Plasticidade Neuronal/fisiologia , Nociceptores/efeitos dos fármacos , Nociceptores/fisiologia , Propriocepção/fisiologia , Fármacos do Sistema Sensorial/farmacologia , Limiar Sensorial/fisiologia , Pele/inervação , Pele/fisiopatologia , Distúrbios Somatossensoriais/induzido quimicamente , Distúrbios Somatossensoriais/fisiopatologia , Fatores de TempoRESUMO
Abdominal skin hypesthesia may occur after abdominoplasty. The purpose of this study was to find out (1) which sensibility modalities are decreased and (2) which areas of the abdominal wall are affected, so that patients can be warned preoperatively about this condition. Forty patients were divided in two groups of 20 patients each. In the control group, patients had no previous abdominal incisions. The sensibility evaluation of patients from the experimental group was made from 12 to 60 months after abdominoplasty, with an average of 31.5 months. These patients were divided into two groups of 10 patients each, a short-term follow-up group (12 to 30 months postoperatively) and a long-term follow-up group (31 to 60 months postoperatively). The abdominal skin was divided into 12 areas; nine were above the abdominoplasty incision and three were below it. Sensibility to superficial touch, superficial pain, and hot and cold modalities was recorded as positive in all areas by a variable number of patients of the experimental group. However, in area 8 (hypogastric area), a statistically significant number of patients had decreased sensibility in all sensibility modalities (Fisher's test and t test). Patients in the experimental group also showed decreased sensibility to hot and cold temperature in area 11 (pubic area). Sensibility to pressure decreased significantly in all areas of the abdomen when compared with the control group (t test). When patients of the short-term follow-up group were compared with those of the long-term follow-up group, there was no statistically significant difference for all modalities of sensibility in the areas studied, except for area 5. In this area it was found that long-term follow-up patients recovered sensibility to cold and hot temperatures. These findings help plastic surgeons to orient their patients about possible risk of exposure to injuries in the areas with decreased sensibility after abdominoplasty. Most importantly, as these patients have decreased sensibility to pressure and hot temperature in a more extensive area of the abdomen, they are exposed to a higher risk of burn injury.
Assuntos
Parede Abdominal/inervação , Parede Abdominal/cirurgia , Hipestesia/diagnóstico , Procedimentos de Cirurgia Plástica , Complicações Pós-Operatórias/diagnóstico , Adulto , Feminino , Seguimentos , Humanos , Mecanorreceptores/fisiopatologia , Pessoa de Meia-Idade , Pressão , Valores de Referência , Limiar Sensorial/fisiologia , Pele/inervação , Sensação Térmica/fisiologiaRESUMO
The current knowledge regarding the pathophysiologic basis of the vasodepressor response was reviewed. The balance of evidence indicates that the mechanoreceptor hypothesis seems unlikely to be the sole afferent alteration that leads to the vasodepressor response. Alternative afferent mechanisms should include neurohumoral mediated sympathoinhibition triggered by opioid mechanisms as well as impaired endothelial and NO responses to orthostatic stress in susceptible individuals. It is possible that impaired cardiovagal and sympathetic outflow control of arterial baroreceptors is enhanced by the aforementioned mechanisms. The role of central sympathoinhibition and vagal excitation triggered directly from pathways within the temporal lobe or triggered by alterations in regional cerebral blood flow should be considered as potential alternative mechanisms. Efferent autonomic outflow during vasodepressor syncope include sympathetic neural outflow withdrawal in addition to activation of parasympathetic outflow to the heart and abdominal viscera. Further human research is needed to understand the underlying mechanisms that result in the described neural and vascular responses.
Assuntos
Homeostase/fisiologia , Síncope Vasovagal/fisiopatologia , Nervo Vago/fisiopatologia , Velocidade do Fluxo Sanguíneo , Encéfalo/irrigação sanguínea , Humanos , Hipotensão Ortostática/complicações , Hipotensão Ortostática/fisiopatologia , Mecanorreceptores/fisiopatologia , Sistemas Neurossecretores/metabolismo , Pressorreceptores/fisiopatologia , Síncope Vasovagal/etiologia , Síncope Vasovagal/metabolismo , Teste da Mesa Inclinada , VasodilataçãoRESUMO
From 1977 to 1988, 166 patients with median nerve paralysis of varied aetiology underwent opponensplasty. In 50 of these the extensor indicis was used, and in 116 the flexor digitorum superficialis of the ring finger. An analysis of these hands showed that the EI opponensplasty was best in supple hands and FDS opponensplasty was more suitable for less pliable hands. There were fewer complications seen after FDS opponensplasty if the detachment of the donor tendon was done through a volar oblique incision rather than the conventional lateral incision.