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The locations and time-courses of the neural generators of the event-related P300 potential have been well described using intracranial recordings. However, this invasive method is not adequate for usage in healthy volunteers or psychiatric patients and not all brain regions can be covered well with this approach. With functional MRI, a non-invasive method with high spatial resolution, most of these locations could be found again. However, the time-course of these activations can only be roughly determined with this method, even if an event-related fMRI design has been chosen. Therefore, we have now tried to analyse the time-course of the activations using EEG data providing a better time resolution. We have used Low Resolution Electromagnetic Tomography (LORETA) in the analysis of P300 data (27 electrodes) of healthy volunteers (n = 50) in the time frame 230-480 ms and found mainly the same activations that have been described using intracranial recordings or fMRI, i. e. the inferior parietal lobe/temporo-parietal junction (TPJ), the supplementary motor cortex (SMA) and the anterior cingulate cortex (ACC), the superior temporal gyrus (STG), the insula and the dorsolateral prefrontal cortex. In these selected regions, an analysis of the activation time-courses has been performed.

BackgroundSleep disorders and fatigue are common in multiple sclerosis (MS). The underlying causes are not fully understood, and prospective studies are lacking. Therefore, we conducted a prospective, observational cohort study investigating sleep quality, fatigue, quality of life, and comorbidities in patients with MS.MethodsPatients with relapsing-remitting MS or clinically isolated syndrome treated with interferon beta-1b were followed over two years. The primary objective was to investigate correlations between sleep quality (PSQI), fatigue (MFIS), and functional health status (SF-36). Secondary objectives were to investigate correlations of sleep quality and daytime sleepiness (ESS), depression (HADS-D), anxiety (HADS-A), pain (HSAL), and restless legs syndrome (RLS). We applied descriptive statistics, correlation and regression analyses.Results139 patients were enrolled, 128 were available for full analysis. The proportion of poor sleepers (PSQI≥5) was 55.47% at the beginning and 37.70% by the end of the study (106 and 41 evaluable questionnaires, respectively). Poor sleepers performed worse in MFIS, SF-36, ESS, HADS-D, and HADS-A scores. The prevalence of patients with RLS was low (4.5%) and all were poor sleepers. Poor sleep quality was positively correlated with fatigue and low functional health status. These relationships were corroborated by multivariable-adjusted regression analyses. ESS values and poor sleep quality at baseline seem to predict sleep quality at the one-year follow-up. No variable predicted sleep quality at the two-year follow-up.ConclusionsOur results confirm the high prevalence of poor sleep quality among patients with MS and its persistent correlation with fatigue and reduced quality of life over time. They highlight the importance of interventions to improve sleep quality.Trial registrationThe study was registered at clinicaltrials.gov: NCT01766063 (registered December 7, 2012). Registered retrospectively (first patient enrolled December 6, 2012).Electronic supplementary materialThe online version of this article (10.1186/s12883-018-1113-5) contains supplementary material, which is available to authorized users.

This systematic review indicates that RLS prevalence amongst patients with MS ranges from 12.12% to 57.50% in different populations. Pooled analysis further indicates that the odds of RLS amongst patients with MS are fourfold higher compared to people without MS.