A simplified theoretical model of the structure and dynamics of polymer networks is successfully applied to the transversaland 2H-NMR relaxation in 1,4-cis-polybutadiene networks produced by crosslinking a mix of conventional and partially deuterated chains with thiuram. For both independent relaxation methods the relaxation curves are qualitatively equal and their analysis provides a consistent picture of the characteristic network parameters. Especially, the Afc values, which were determined by both relaxation methods, are in good agreement with one another and with values which were obtained from stress-strain measurements on the same samples. Taking into consideration similar results of our previous papers, the theoretical treatment and comparison of the NMR results to mechanical experiments provide a firm basis for the continuing use of the approach to characterize Mc.

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BackgroundThe differential diagnosis of pseudo-neurological symptoms often represents a clinical challenge. The Diagnostic and Statistical Manual of Mental Disorders, DSM-5, made an attempt to improve diagnostic criteria of conversion disorder (functional neurological symptom disorder). Incongruences of the neurological examination, i.e. positive neurological signs, indicate a new approach - whereas psychological factors are not necessary anymore. As the DSM-5 will influence the International Classification of Diseases, ICD-11, this is of importance. In the case presented, a history of psychological distress and adverse childhood experiences coexisted with a true neurological disorder. We discuss the relevance of an interdisciplinary assessment and of operationalized diagnostic criteria.Case presentationA 32-year-old man presented twice with neurological symptoms without obvious pathological organic findings. A conversion disorder was considered early on at the second admission by the neurology team. Sticking to ICD-10, this diagnosis was not supported by a specialist for psychosomatic medicine, due to missing hints of concurrent psychological distress in temporal association with neurological symptoms. Further investigations then revealed a deep vein thrombosis (though D-dimers had been negative), which had probably resulted in a crossed embolus.ConclusionThe absence of a clear proof of biological dysfunction underlying neurological symptoms should not lead automatically to the diagnosis of a conversion disorder. In contrast, at least in more complex patients, the work-up should include repeated psychological and neurological assessments in close collaboration. According to ICD-10 positive signs of concurrent psychological distress are required, while DSM-5 emphasizes an incongruity between neurological symptoms and neurophysiological patterns of dysfunction. In the case presented, an extensive medical work-up was initially negative, and neither positive psychological nor positive neurological criteria could be identified. We conclude, that, even in times of more sophisticated operationalization of diagnostic criteria, the interdisciplinary assessment has to be based on an individual evaluation of all neurological and psychosocial findings. Prospective studies of inter-rater reliability and validity of psychological factors and positive neurological signs are needed, as evidence for both is limited. With respect to ICD-11, we suggest that positive neurological as well as psychological signs for functional neurological symptom disorder should be considered to increase diagnostic certainty.

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When the diagnosis of dissociative seizures has been made, psychotherapy is indicated, possibly in combination with psychoactive medication, in the setting of long-term treatment provided in collaboration by the neurologist, psychiatrist, psychotherapist, and family physician. Further randomized trials are needed to determine which treatments are best for which subgroups of patients.