No description available.

Recent evidence appears to indicate that neurons, responsible for our perception of the world around us, are not only electrically excitable, but may have mechanical triggers as well. This is well supported through the growing number of observations of focused ultrasound (FUS) perturbations of the neurons located in our central nervous system (CNS). However, while the CNS is largely responsible for turning electrical signals from the periphery into thoughts and understanding, less is known about the effect of which FUS has upon the peripheral signals themselves: our peripheral nervous system (PNS). Given the non-invasive nature of FUS - were it be discovered to influence neuronal signaling, FUS would become a powerful tool for therapy and medicine, especially in conditions involving pain. Thus, we ponder the question, "How can FUS modulate nerve activity and furthermore, what are the interactions on pain signaling?" In this dissertation, a road-map is described for translating insights acquired through pre-clinical study of ultrasound PNS stimulation to clinical investigation on neuropathic pain modulation in humans. More specifically, methods and tools to study excitation of the sciatic nerve bundle and the dorsal root ganglia (DRG) were built and optimized in rodent models. In turn, these methods and findings enabled investigation into pain signaling and translation to human studies. Finally, FUS was shown to mitigate pain sensations in human patients with neuropathic pain. First, using a newly developed in vivo nerve displacement imaging technique, mechanical deformations of the nerve from FUS stimulation were noninvasively mapped in a two-dimensional plane centered at the sciatic nerve. Nerve displacements were positively correlated with downstream compound muscle activation from FUS sciatic nerve stimulation. Furthermore, by focusing ultrasound waves to the DRGs directly in an ex vivo preparation, additional parameters were identified to modulate spike transmission, effectively regulating high frequency signaling. Next, we investigated the feasibility translating FUS nerve stimulation to clinical studies. We first looked at effects on upstream cortical activity and pain signaling from somatosensory stimuli using high-frequency functional ultrasound (fUS) imaging. FUS was shown to both stimulate somatosensation and suppress pain signaling in the cortex. Secondly, nerve displacement imaging was scaled-up for human investigation, essential for in-procedure localization and stimulation of the targeted nerve bundle. Using a combination of imaging and therapeutic excitation, simultaneous nerve targeting, stimulation, and monitoring was established at pressures required for stimulation. Lastly, clinical feasibility was investigated using previously optimized FUS pulse schemes and scaled-up neuromodulation technologies. Specifically, we applied simultaneous FUS to the median nerve and thermal stimulation to the corresponding dermatome in healthy human subjects. Furthermore, patients with robust and repeatable mechanically-assessed neuropathic pain were similarly stimulated with FUS to assess pain suppression. Based on the findings presented herein, noninvasive FUS peripheral stimulation has the potential for radically shifting the traditional pharmaceutical paradigms in chronic and acute pain treatment by altering signals before being processed in the spinal cord and ultimately the brain. The studies outlined herein serve to elucidate mechanisms of FUS in the PNS, as well as provide the starting foundations for further development of FUS as an effective pain treatment.

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No description available.

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Yes / Diabetic Peripheral Neuropathy (DPN) is one of the most common types of diabetes that can affect the cornea. An accurate analysis of the nerve structures can assist the early diagnosis of this disease. This paper proposes a robust, fast and fully automatic nerve segmentation and morphometric parameter quantification system for corneal confocal microscope images. The segmentation part consists of three main steps. First, a preprocessing step is applied to enhance the visibility of the nerves and remove noise using anisotropic diffusion filtering, specifically a Coherence filter followed by Gaussian filtering. Second, morphological operations are applied to remove unwanted objects in the input image such as epithelial cells and small nerve segments. Finally, an edge detection step is applied to detect all the nerves in the input image. In this step, an efficient algorithm for connecting discontinuous nerves is proposed. In the morphometric parameters quantification part, a number of features are extracted, including thickness, tortuosity and length of nerve, which may be used for the early diagnosis of diabetic polyneuropathy and when planning Laser-Assisted in situ Keratomileusis (LASIK) or Photorefractive keratectomy (PRK). The performance of the proposed segmentation system is evaluated against manually traced ground-truth images based on a database consisting of 498 corneal sub-basal nerve images (238 are normal and 260 are abnormal). In addition, the robustness and efficiency of the proposed system in extracting morphometric features with clinical utility was evaluated in 919 images taken from healthy subjects and diabetic patients with and without neuropathy. We demonstrate rapid (13 seconds/image), robust and effective automated corneal nerve quantification. The proposed system will be deployed as a useful clinical tool to support the expertise of ophthalmologists and save the clinician time in a busy clinical setting.

The group of chemicals designated organophosphorus compounds have had a significant impact on modern life, including use as pesticides, industrial plasticizers and chemical warfare agents. Exposure to certain organophosphates produces a delayed degeneration of the longest and largest nerve fibers, including those of the ascending and descending tracts of the spinal cord, a condition termed organophosphorus ester-induced delayed neuropathy (OPIDN). Recorded incidents of such an effect in humans have led to research regarding this neurological disease. Among the OPIDN-inducing agents is mipafox, an organophosphate insecticide, the compound we chose to employ in our studies. Although the hen is the primary experimental model in the safety assessment of organophosphates, current research has suggested that the rat may have some validity as an experimental model. We examined the sequential neuropathic effects of a single dose of mipafox (30mg/kg) in rats and hens on a comparative basis to determine the better experimental model. / Master of Science

The contribution of the cardiovascular system. to organophosphate-induced delayed neuropathy (OPIDN) was examined using in situ and in vitro models for demonstration of response to vasoactive agents (e.g., the cholinergic agonist, acetylcholine; the α1 agonist, phenylephrine; and the β2 agonist, salbutamol). These responses were compared before and 1, 3, 7, and 21 days after hens were administered cyclic phenyl saligenin phosphate (PSP, 2.5 mg/kg i.m.), an OP that induces OPIDN but does not significantly inhibit acetylcholinesterase activity, and paraoxon (PXN, 0.1 mg/kg i.m.), an OP that inhibits acetylcholinesterase activity but does not induce OPIDN. The capability of verapamil, a calcium channel blocker, to attenuate these responses was examined, as this agent ameliorates OPIDN. For the in situ study, the ischiadic artery was cannulated and alterations in pressure measured at a constant flow used to indicate changes in vascular resistance. Changes in vascular resistance in response to acetylcholine, phenylephrine, and salbutamol that were different from those in control and PXN-treated hens were noted 1 and 3 days after administration of PSP. These changes were attenuated in hens given PSP and verapamil. Vascular segments from the ischiadic artery were used to provide an in vitro model to determine if OPs caused direct vascular damage that was responsible for effects seen in the in situ model. In the in vitro model, however, responses of PSP and PXN were similar and not modified in vascular segments from hens given verapamil as well as the OPs. This indicated that the contribution of the cardiovascular system to OPIDN was due to more than a direct effect on relatively large caliber vessels. The contribution of the cardiovascular system to OPIDN also did not appear to relate to morphological changes induced by administration of OPs, as no changes in vascular morphology were noted. An OP-induced effect that could contribute to vascular effects noted are levels of plasma catecholamines. These levels were altered in hens given PSP or PXN, with increases seen after administration of PSP and decreases seen after administration of PXN. These alterations in plasma catecholamine levels were attenuated in hens given both verapamil and OP. / Ph. D.

Organophosphorus compounds are widely used in agriculture as pesticides and in industry as petroleum additives and modifiers of plastics. Some of these compounds are capable of inducing an irreversible neuropathy developing weeks to months after exposure, yet there is no effective treatment. This may be due in part to the lack of knowledge of how this neuropathy develops. In this dissertation, it is proposed that as a consequence of a triggering event, peripheral nerves may be predisposed to an increase in calcium (Ca⁺⁺) mobilization and the neuronal accumulation of this cation. This increase in Ca could thereby initiate a cascade of events, in both nerve and muscle, that may account for some of the detrimental changes occurring during organophosphorus-induced delayed neuropathy (OPIDN). The involvement of Ca⁺⁺ in the pathogenesis of OPIDN was tested using functional, morphological, and biochemical techniques in the domestic hen, the recognized animal model of OPIDN. The isolated biventer cervicis nerve-muscle preparation was developed for quick assessment of the time course of OPIDN deficits and validated by comparison to in vivo preparations. This preparation proved more sensitive by functional and morphological evaluation indicating early damage at 4 days following exposure and before appearance of clinical signs. Regeneration was detected after 21 days. OPIDN was modified by using Ca⁺⁺ channel blockers, nifedipine, and verapamil, in the presence of phenyl saligenin phosphate, an active neurotoxicant. Attenuation of OPIDN by these compounds was revealed by clinical assessment, by changes in nerve excitability denoted by strength-duration relationships in response to electrical stimulation, by denervation hypersensitivity to neurotransmitter, and by morphology. These modifiers attenuated all degenerative responses. Furthermore, it was revealed that the activity of Ca⁺⁺-activated neutral protease (CANP), an enzyme responsible for neurofilament degradation, was increased in OPIDN. Such increases were ameliorated by modifiers of Ca movement. This study strongly suggests that Ca⁺⁺, possibly through activation of CANP, may contribute to functional and morphological deficits of OPIDN. / Ph. D.

Introdução: perda da sensibilidade axial é bem descrita nas polineuropatias axonais comprimento-dependentes (PACD). O padrão da perda de sensibilidade axial nas polineuropatias desmielinizantes adquiridas (PDA) é menos reconhecido na prática clínica e tem sido descrito como um padrão não-comprimentodependente. Nas PDAs, a perda de sensibilidade axial pode, somada às alterações da sensibilidade nos membros, envolver as regiões anteriores do tronco, da face, do couro cabeludo e do períneo. Eventualmente, pode ocorrer apenas no eixo do corpo sem o envolvimento dos membros. O padrão da perda de sensibilidade axial observado ao exame físico neurológico pode auxiliar no diagnóstico diferencial entre as PACDs e as PDAs. Objetivos: analisar as diferentes apresentações clínicas das alterações da sensibilidade axiais nos indivíduos acometidos por neuropatias desmielinizantes adquiridas. Analisar a resposta de curto prazo das alterações da sensibilidade nas porções axiais e suas relações com o gênero, idade, diagnóstico e com a presença ou não e comorbidades. Analisar se a resposta das alterações de sensibilidade axiais acompanham a resposta da força muscular ao tratamento, a fim de agilizar a avaliação clinica, o início do tratamento e o estabelecimento de prognóstico, visto não haver dados prévios na literatura médica a este respeito. Métodos: trata-se de estudo observacional analítico por meio de coorte retrospectiva não-controlada. Foram revisados 460 prontuários médicos de indivíduos com possíveis diagnósticos de PDAs. Dentre os 460, foram selecionados 284 prontuários de indivíduos que preencheram critérios diagnósticos recomendados para polirradiculoneuropatia inflamatória desmielinizante crônica (PIDC) ou para síndrome de Guillain-Barré (SGB) na sua forma de polirradiculoneuropatia inflamatória 5 desmielinizante aguda (PIDA). Registros médicos de indivíduos com comorbidades que poderiam cursar com neuropatias axonais, como a diabetes mellitus, por exemplo, não foram incluídos para avaliação. Deste modo, foram selecionados para a análise estatística 49 indivíduos. Após a revisão, foram analisadas a prevalência e as alterações clínicas da sensibilidade superficial, tátil e dolorosa, e força muscular que ocorreram durante e após o tratamento, a fim de avaliar a influência de dados demográficos, tais como a idade, o gênero, a presença ou não de comorbidades e o diagnóstico dos indivíduos sobre as variáveis clínicas acima descritas. Resultados: alterações da sensibilidade axial ocorreram em 64 (22,5%) dos 284 indivíduos que preencheram os critérios diagnósticos de PIDC e SGB. Destes, 49 (17,25%) foram selecionados por apresentarem alteração da sensibilidade axial, em algum momento da doença, e não preencherem os critérios de não-inclusão. 31 indivíduos (63,26%) eram do gênero masculino e 18 (36,74%) do gênero feminino, com mediana de idade em 45 anos (variando de 11 a 75 anos). Alteração da sensibilidade axial foi observada acometendo a região central do abdome (n=48, 97,9%), couro cabeludo (n=11, 22,4%), porção central da face (n=18, 36,7%), do dorso (n=3, 6,2%), da linha média anterior do tórax (n=2, 4,1%) ou do períneo (n=4, 8,2%). A perda de sensibilidade nos membros acometeu as regiões distais desses, embora o padrão da perda de sensibilidade não tenha ocorrido de forma comprimento-dependente. Após o primeiro curso de tratamento (com imunoglobulina humana ou plasmaférese nos casos de SGB, e corticoide, imunoglobulina humana ou plasmaférese, nos casos de PIDC), 29 (59,18%) dos indivíduos apresentaram melhora da perda da sensibilidade axial e 32 (61,5%) obtiveram melhora na força muscular. Em adição aos critérios clínicos recomendados, atualmente, para o diagnóstico destas doenças, a ausência do padrão comprimento-dependente de acometimento da sensibilidade pode auxiliar no diagnóstico clínico de ambas PDAs avaliadas. Conclusões: perda de sensibilidade axial ocorre em cerca de um a cada 5 indivíduos acometidos de PDAs. A ausência de relação da perda de sensibilidade com o comprimento do nervo acometido pode ser de suporte ao diagnóstico das neuropatias desmielinizantes adquiridas. A resolução das alterações da sensibilidade axial foi observada em 60,8% dos indivíduos após o tratamento. Esta melhora foi mais expressiva em casos de indivíduos com SGB (com 80% de melhora) do que em indivíduos com PIDC (com 33,3% de melhora). Por outro lado, indivíduos com menos de 45 anos de idade e acometidos por SGB apresentaram 6 a pior resposta ao tratamento. Assim, recomenda-se a busca ativa e sistemática por alterações da sensibilidade axial, visto que não são alterações frequentemente relatadas pelos pacientes no contexto do atendimento medico / Background: axial sensory loss (ASL) is well known in length-dependent axonal polyneuropathies (LDAP). The pattern of ASL in acquired demyelinating polyneuropathies (ADP) is less known in clinical practice but it was referred as a nonlength dependent. In ADPs, ASLs may, in addition to the upper and lower limbs, involve the anterior region of the trunk, face, scalp, and perineum. Eventually, it occurs only in the body axis without limbs involvement. The ASLs pattern could help in the differential diagnosis between ADPs and LDAP. Objectives: this study aims to analyze the different clinical presentation of the ASL in ADP patients; to analyze the clinical response in a short time to treatment of ASL and their relation with the gender, age, diagnosis and the presence, or not, of comorbidities; and to analyze the relation between the improvement of the ASL\'s and the improvement of the muscular weakness after treatment, in order to expedite the clinical evaluation, the beginning of the treatment and the evaluation of the prognosis, since there is no previous data in the medical literature in this regard. Methods: it is a observational, analytical and uncontrolled study using a retrospective cohort. Were reviewed 460 medical records with possible ADPs and selected 284 with the recommended diagnostic criteria for chronic inflammatory demyelinating polyneuropathies (CIDP) or Guillain-Barré syndrome (GBS), in acute inflammatory demyelinating polyneuropathy (AIDP) form. Medical records of patients with comorbidities that could course with neuropathies, like diabetes mellitus, were excluded. Thus, 49 subjects were enrolled for the statistical analysis. We checked the prevalence and the changes that happened with ASL (pain and tactile sensitivity), during and after treatment and then we analyzed the influence of demographic data, such as age at the onset, gender, diagnosis and comorbidities over the clinical variables described above. Results: partial ASL occurred in 64 8 (22,5%) of the 287 subjects who met the diagnostic criteria for CIDP and SGB. Of there, 49 subjects (17,25%) were accepted for the present study because they had ASL and did not fulfilled the non-inclusion criteria. 31 subjects (63,26%) were male and 18 (36,74%) were female with median age of 45 years old (11 - 75 years old). ASLs were found in the periumbilical region of the abdomen (n=48, 97,9%), scalp (n=11, 22,4%), central portion of the face (n=18, 36,7%), dorsum (n=3, 6,2%), anterior portion of the thorax (n=2, 4,1%) and perineum (n=4, 8,2%). The sensory loss in the patients\' limbs were very distal, though non-length-dependent. After the first course of treatment (intravenous human immunoglobulin - IgIV - or plasmapheresis for GBS, and steroids or IgIV for CIDP), 29 (59,18%) subjects showed improvement of ASL after treatment and 32 (61,5%) got a better motor strength. In addition to the clinical criteria recommended for diagnosis of CIDP or GBS, the absence of length dependency also supported the clinical diagnosis of both ADPs. Conclusions: ASLs occur in about one among five patients with ADPs and its non-length-dependent pattern can support their diagnosis. The absence of relationship between the sensory loss and the length of the nerve can be supportive to the diagnosis of ADPs. In 60,8% of the subjects, resolution of ASL were observed after the treatment. This was more expressive in GBS than in CIDP (80% after 33,3%). On the other hand, subjects with GBS younger than 45 years old showed poorer response to treatment. Yet, it is recommended to look for ASL since it is not frequently reported complaints by patients in the context of medical care