Background and purpose Hypertrophy/signal hyperintensity and/or gadolinium enhancement of plexus structures on magnetic resonance imaging (MRI) are observed in two‐thirds of cases of typical chronic inflammatory demyelinating polyneuropathy (CIDP). The objective of our study was to determine the additional benefit of plexus MRI in patients referred to tertiary centers with baseline clinical and electrophysiological characteristics suggestive of typical or atypical CIDP. Methods A total of 28 consecutive patients with initial suspicion of CIDP were recruited in nine centers and followed for 2 years. Plexus MRI data from the initial assessment were reviewed centrally. Physicians blinded to the plexus MRI findings established the final diagnosis (CIDP or neuropathy of another cause). The proportion of patients with abnormal MRI was analyzed in each group. Results Chronic inflammatory demyelinating polyneuropathy was confirmed in 14 patients (50%), as were sensorimotor CIDP (n = 6), chronic immune sensory polyradiculoneuropathy (n = 2), motor CIDP (n = 1) and multifocal acquired demyelinating sensory and motor neuropathy (n = 5). A total of 37 plexus MRIs were performed (17 brachial, 19 lumbosacral and 8 in both localizations). MRI was abnormal in 5/37 patients (14%), all of whom were subsequently diagnosed with CIDP [5/14(36%)], after an atypical baseline presentation. With plexus MRI results masked, non‐invasive procedures confirmed the diagnosis of CIDP in all but one patient [1/14 (7%)]. Knowledge of the abnormal MRI findings in the latter could have prevented nerve biopsy being performed. Conclusion Systematic plexus MRI in patients with initially suspected CIDP provides little additional benefit in confirming the diagnosis of CIDP.

Background New diagnostic tools have been developed to improve the diagnosis of infectious encephalitis. Using a prospective cohort of encephalitis patients, our objective was to identify possible clusters of patients with similar patterns among encephalitis of unknown cause, and to describe to what extent the patient’s initial presentation may be predictive of encephalitis etiology, particularly Herpes simplex virus (HSV) and Varicella-zona virus (VZV). Methods The national cohort of infectious encephalitis in France (ENCEIF) is an ongoing prospective cohort study implemented in France in 2016. Patients presenting with a documented or suspected acute infectious encephalitis were included. Focusing on the variables describing the initial presentation, we performed a factor analysis of mixed data (FAMD) to investigate a pattern of association between the initial presentation of the patient and the etiologic pathogen. Results As of 1st August 2018, data from 349 patients were analysed. The most frequent pathogens were HSV (25%), VZV (11%), Tick-borne encephalitis virus (6%), Listeria (5%), Influenza virus (3%), and encephalitis of unknown cause (EUC) (34%). Using the FAMD, it was not possible to identify a specific pattern related to the group of EUC. Age, temporal or haemorrhagic lesions, and cerebral spinal fluid lymphocytosis were significantly associated with HSV/VZV encephalitis. Conclusion No initial clinical/imaging/biology pattern was identified at admission among EUC, despite the improvement of diagnostic tools. In this context, the recommendation for a universal, early probabilistic initial treatment against HSV and VZV is still relevant, regardless of the initial clinical presentation of the encephalitis.

Background 5‐Fluorouracil (5‐FU) and its oral prodrug capecitabine have been rarely but consistently associated with acute central nervous system toxicity, including transient leukoencephalopathies involving the splenium of the corpus callosum. Methods We performed a retrospective search in the French Pharmacovigilance database (FPDB) (January 1985−July 2020) for adult patients affected by solid cancers who developed acute toxic leukoencephalopathies with splenial lesions following treatment with 5‐FU or capecitabine. A comprehensive review of the literature helped to circumstantiate our findings. Results Our research in the FPDB identified six patients who, within 3 days from their first cycle of 5‐FU or capecitabine, developed acute neurological symptoms, including gait ataxia (n = 4), dysarthria (n = 3), dysmetria (n = 2), headache (n = 2), and confusion (n = 2). Brain magnetic resonance imaging (MRI) showed T2/FLAIR (fluid‐attenuated inversion recovery) hyperintensities in the corpus callosum, with diffusion restriction and no contrast enhancement, generally accompanied by additional alterations in the bilateral supratentorial white matter (n = 5). All patients discontinued the agent supposedly responsible for the toxicity and experienced full recovery after a median of 8.5 days from symptom onset. Control MRI showed a progressive normalization of acute MRI abnormalities. Literature review identified 26 cases with similar clinical and paraclinical characteristics. A single patient from the literature resumed 5‐FU at a lower dose, with no recurrent toxicity. Conclusions 5‐FU and capecitabine might be responsible for acute leukoencephalopathies with transient splenial lesions that are generally reversible upon drug discontinuation. Resuming the agent responsible for toxicity might be feasible in selected cases, after having excluded dihydropyrimidine dehydrogenase deficiency, if expected benefits outweigh the risks.

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