Early Guillain-Barré syndrome in coronavirus disease 2019 (COVID-19): a case report from an Italian COVID-hospital.

Guillain-Barré syndrome (GBS) is an acute polyradiculoneuropathy associated with dysimmune processes, often related to a previous infectious exposure. During Italian severe acute respiratory syndrome coronavirus-2 outbreak, a woman presented with a rapidly progressive flaccid paralysis with unilateral facial neuropathy after a few days of mild respiratory symptoms. Coronavirus was detected by nasopharyngeal swab, but there was no evidence of its presence in her cerebrospinal fluid, which confirmed the typical albumin-cytological dissociation of GBS, along with consistent neurophysiological data. Despite immunoglobulin infusions and intensive supportive care, her clinical picture worsened simultaneously both from the respiratory and neurological point of view, as if reflecting different aspects of the same systemic inflammatory response. Similar early complications have already been observed in patients with para-infectious GBS related to Zika virus, but pathological mechanisms have yet to be established.

Myositis and myasthenia during nivolumab administration for advanced lung cancer: a case report and review of the literature.

The immunotherapy significantly improved survival of non-small cell lung cancer patients, but it may cause immune-related adverse events, which are severe in less than 10% of cases. We report the case of one patient who developed myositis and myasthenia during nivolumab treatment for metastatic lung squamous carcinoma. Moreover, we reviewed literature data in order to identify similar cases in cancer patients treated with immune-checkpoints inhibitors. A 65-year-old patient, who had previously received a first-line platinum-based therapy, developed diplopia and ptosis 4 weeks after the start of nivolumab. Although antibodies associated with myositis, myasthenia gravis and paraneoplastic syndromes were absent, immune-related myositis and myasthenia were diagnosed. Corticosteroids, immunoglobulin and pyridostigmine showed poor efficacy and the patient died 7 weeks after the appearance of the first symptoms. Fifteen similar cases were found in the literature. A close collaboration between different specialists is essential to rapidly identify and treat severe immune-related adverse events.

k-Nearest neighbour local linear prediction of scalp EEG activity during intermittent photic stimulation.

The characterization of the EEG response to photic stimulation (PS) is an important issue with significant clinical relevance. This study aims to quantify and map the complexity of the EEG during PS, where complexity is measured as the degree of unpredictability resulting from local linear prediction. EEG activity was recorded with eyes closed (EC) and eyes open (EO) during resting and PS at 5, 10, and 15 Hz in a group of 30 healthy subjects and in a case-report of a patient suffering from cerebral ischemia. The mean squared prediction error (MSPE) resulting from k-nearest neighbour local linear prediction was calculated in each condition as an index of EEG unpredictability. The linear or nonlinear nature of the system underlying EEG activity was evaluated quantifying MSPE as a function of the neighbourhood size during local linear prediction, and by surrogate data analysis as well. Unpredictability maps were obtained for each subject interpolating MSPE values over a schematic head representation. Results on healthy subjects evidenced: (i) the prevalence of linear mechanisms in the generation of EEG dynamics, (ii) the lower predictability of EO EEG, (iii) the desynchronization of oscillatory mechanisms during PS leading to increased EEG complexity, (iv) the entrainment of alpha rhythm during EC obtained by 10 Hz PS, and (v) differences of EEG predictability among different scalp regions. Ischemic patient showed different MSPE values in healthy and damaged regions. The EEG predictability decreased moving from the early acute stage to a stage of partial recovery. These results suggest that nonlinear prediction can be a useful tool to characterize EEG dynamics during PS protocols, and may consequently constitute a complement of quantitative EEG analysis in clinical applications.

An identifiable model to assess frequency-domain granger causality in the presence of significant instantaneous interactions.

We present a new approach for the investigation of Granger causality in the frequency domain by means of the partial directed coherence (PDC). The approach is based on the utilization of an extended multivariate autoregressive (MVAR) model, including instantaneous effects in addition to the lagged effects traditionally studied, to fit the observed multiple time series prior to PDC computation. Model identification is performed combining standard MVAR coefficient estimation with a recent technique for instantaneous causal modeling based on independent component analysis. The approach is first validated on simulated MVAR processes showing that, in the presence of instantaneous effects, only the extended model is able to interpret the imposed Granger causality patterns, while the traditional MVAR approach may yield strongly biased PDC estimates. The subsequent application to multichannel EEG time series confirms the potentiality of the approach in real data applications, as the importance of instantaneous effects led to significant differences in the PDC estimated after traditional and extended MVAR identification.