[REM sleep behavior disorder as a prodromal stage of α-synucleinopathies: symptoms, epidemiology, pathophysiology, diagnosis and therapy]. / REM-Schlaf-Verhaltensstörung als prodromales Stadium von α-Synukleinopathien: Klinik, Epidemiologie, Pathophysiologie, Diagnose und Behandlung.

Rapid eye movement (REM) sleep behavior disorder (RBD) is defined as a parasomnia characterized by loss of REM sleep-associated atonia and the presence of motor activity during dreaming typically presenting with an aggressive dream content. Epidemiological data on the prevalence of RBD are insufficient but it can be idiopathic or symptomatic. A video-audio polysomnography is essential for diagnosis. Clonazepam and melatonin are available as pharmaceutical treatment. Recent studies demonstrated that individuals suffering from idiopathic RBD carry a high specific risk (up to 80 %) for developing a neurodegenerative disorder of the α-synucleinopathy type (e.g. Parkinson's disease, dementia with Lewy bodies and multiple system atrophy) within 10-20 years. The current article provides a short overview of symptoms, epidemiology, pathophysiology, diagnosis and therapy of RBD.

Tikhonov regularization and prior information in electrical impedance tomography.

The solution of impedance distribution in electrical impedance tomography is a nonlinear inverse problem that requires the use of a regularization method. The generalized Tikhonov regularization methods have been popular in the solution of many inverse problems. The regularization matrices that are usually used with the Tikhonov method are more or less ad hoc and the implicit prior assumptions are, thus, in many cases inappropriate. In this paper, we propose an approach to the construction of the regularization matrix that conforms to the prior assumptions on the impedance distribution. The approach is based on the construction of an approximating subspace for the expected impedance distributions. It is shown by simulations that the reconstructions obtained with the proposed method are better than with two other schemes of the same type when the prior is compatible with the true object. On the other hand, when the prior is incompatible with the true object, the method will still give reasonable estimates.