is the seventh member of the family of coronaviruses that infect humans (1) and induces coronavirus disease 2019 (COVID-19). Human coronaviruses have neuroinvasive capacities and may be neurovirulent by two main mechanisms (2-4): viral replication into glial or neuronal cells of the brain or autoimmune reaction with a misdirected host immune response (5). Thus, a few cases of acute encephalitislike syndromes with human coronaviruses were reported in the past 2 decades (5-8). In regard to COVID-19, current data on central nervous system involvement are uncommon but growing (9-17), demonstrating the high frequency of neurologic symptoms. However, the delineation of a large cohort of confirmed brain MRI parenchymal signal abnormalities (excluding ischemic infarcts) related to COVID-19 has never been performed, and the underlying pathophysiologic mechanisms remain unknown. The purpose of the current study was to describe the neuroimaging findings (excluding ischemic infarcts) in patients with severe COVID-19 and report the clinicobiologic profile of these patients. Materials and Methods This retrospective observational national multicenter study was initiated by the French Society of Neuroradiology in collaboration with neurologists, intensivists, and infectious disease specialists and brought together 16 hospitals. The study was approved by the ethical committee of Strasbourg University Hospital (CE-2020-37) and was in accordance with the 1964 Helsinki Declaration and its later amendments. Because of the emergency in the context of the COVID-19 pandemic responsible for

ObjectiveTo describe neuroimaging findings and to report the epidemiological and clinical characteristics of COVID-19 patients with neurological manifestations.MethodsIn this retrospective multicenter study (10 Hospitals), we included 64 confirmed COVID-19 patients with neurologic manifestations who underwent a brain MRI.ResultsThe cohort included 43 men (67%), 21 women (33%), and the median age was 66 years (range: 20-92). 36 (56%) brain MRIs were considered abnormal, possibly related to SARS-CoV-2. Ischemic strokes (27%), leptomeningeal enhancement (17%), and encephalitis (13%) were the most frequent neuroimaging findings. Confusion (53%) was the most common neurological manifestation, following by impaired consciousness (39%), presence of clinical signs of corticospinal tract involvement (31%), agitation (31%), and headache (16%). The profile of patients experiencing ischemic stroke was different from the other patients with abnormal brain imaging since the former had less frequently acute respiratory distress syndrome (p=0·006) and more frequently corticospinal tract signs (p=0·02). Patients with encephalitis were younger (p=0·007), whereas agitation was more frequent for patients with leptomeningeal enhancement (p=0·009).ConclusionsCOVID-19 patients may develop a wide range of neurological symptoms, which can be associated with severe and fatal complications, such as ischemic stroke or encephalitis. Concerning the meningoencephalitis involvement, even if a direct effect of the virus cannot be excluded, the pathophysiology rather seems to involve an immune and/or inflammatory process given the presence of signs of inflammation in both cerebrospinal fluid and neuroimaging but the lack of virus in cerebrospinal fluid.

Background Iodinated and gadolinium-based contrast media (ICM; GBCM) induce immediate hypersensitivity (IH) reactions. Differentiating allergic from non-allergic IH is crucial; allergy contraindicates the culprit agent for life. We studied frequency of allergic IH among ICM or GBCM reactors. Methods Patients were recruited in 31 hospitals between 2005 and 2009. Clinical symptoms, plasma histamine and tryptase concentrations and skin tests were recorded. Allergic IH was diagnosed by intradermal tests (IDT) with the culprit CM diluted 1:10, “potentially allergic” IH by positive IDT with pure CM, and non-allergic IH by negative IDT. Findings Among 245 skin-tested patients (ICM = 209; GBCM = 36), allergic IH to ICM was identified in 41 (19.6%) and to GBCM in 10 (27.8%). Skin cross-reactivity was observed in 11 patients with ICM (26.8%) and 5 with GBCM (50%). Allergy frequency increased with clinical severity and histamine and tryptase concentrations (p < 0.0001). Cardiovascular signs were strongly associated with allergy. Non-allergic IH was observed in 152 patients (62%) (ICM:134; GBCM:18). Severity grade was lower (p < 0.0001) and reaction delay longer (11.6 vs 5.6 min; p < 0.001). Potentially allergic IH was diagnosed in 42 patients (17.1%) (ICM:34; GBCM:8). The delay, severity grade, and mediator release were intermediate between the two other groups. Interpretation Allergic IH accounted for < 10% of cutaneous reactions, and > 50% of life-threatening ones. GBCM and ICM triggered comparable IH reactions in frequency and severity. Cross-reactivity was frequent, especially for GBCM. We propose considering skin testing with pure contrast agent, as it is more sensitive than the usual 1:10 dilution criteria.

Methanol, a highly toxic substance, is used as an industrial solvent and in automobile antifreeze. Acute methanol poisoning produces severe metabolic acidosis and serious neurologic sequelae. We describe a 50-year-old woman with accidental methanol intoxication who was in a vegetative state. MRI showed haemorrhagic necrosis of the putamina and oedema in the deep white matter.

IMPORTANCEVisual impairment in primary central nervous system lymphoma (PCNSL) is caused mostly by intraocular lymphomatous involvement (vitritis and retinal infiltration), whereas optic nerve infiltration (ONI) is a rare condition.OBJECTIVE To describe the clinical presentation of ONI, its imaging characteristics, and outcome. DESIGN, SETTING AND PARTICIPANTSA total of 752 patients diagnosed with PCNSL were retrospectively identified from the databases of 3 French hospitals from January 1, 1998, through December 31, 2014. Of these, 7 patients had documented ONI. Exclusion criteria were intraocular involvement, orbital lymphoma, or other systemic lymphoma. Clinical presentation, neuroimaging, biological features, treatment, and outcomes were assessed. MAIN OUTCOMES AND MEASURESTreatment response was evaluated clinically and radiologically on follow-up magnetic resonance imaging (MRI) according to the International PCNSL Collaborative Group response criteria. RESULTSThe 7 patients included 5 women and 2 men. Median age at diagnosis was 65 years (range, 49-78 years). Two patients had initial ONI at diagnosis, and 5 had ONI at relapse. Clinical presentation was marked by rapidly progressive and severe visual impairment for all patients. The MRI findings showed optic nerve enlargement in 3 patients and contrast enhancement of the optic nerve in all patients. Additional CNS lesions were seen in 4 patients. Examination of cerebrospinal fluid samples detected lymphomatous meningitis in 2 patients. Clinical outcome was poor and marked by partial recovery for 2 patients and persistent severe low visual acuity or blindness for 5 patients. Median progression-free survival after optic nerve infiltration was 11 months (95% CI, 9-13 months), and median overall survival was 18 months (95% CI, 9-27 months).CONCLUSIONS AND RELEVANCE Optic nerve infiltration is an atypical and challenging presentation of PCNSL. Its visual and systemic prognosis is particularly poor compared with vitreoretinal lymphomas even in response to chemotherapy. Although intraocular involvement is frequent in PCNSL and clinically marked by slowly progressive visual deterioration, lymphomatous ONI is rare and characterized by rapidly progressive severe visual impairment.