We present a first-principles CFT calculation corresponding to the spherical collapse of a shell of matter in three dimensional quantum gravity. In field theory terms, we describe the equilibration process, from early times to thermalization, of a CFT following a sudden injection of energy at time t = 0. By formulating a continuum version of Zamolodchikov's monodromy method to calculate conformal blocks at large central charge c, we give a framework to compute a general class of probe observables in the collapse state, incorporating the full backreaction of matter fields on the dual geometry. This is illustrated by calculating a scalar field two-point function at time-like separation and the time-dependent entanglement entropy of an interval, both showing thermalization at late times. The results are in perfect agreement with previous gravity calculations in the AdS 3 -Vaidya geometry. Information loss appears in the CFT as an explicit violation of unitarity in the 1/c expansion, restored by nonperturbative corrections.

Objectives:The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is considered to have potential neuro-invasiveness that might lead to acute brain disorders or contribute to respiratory distress in patients with coronavirus disease 2019 (COVID-19). This study investigates the occurrence of structural brain abnormalities in non-survivors of COVID-19 in a virtopsy framework.Methods:In this prospective, monocentric, case series study, consecutive patients who fulfilled the following inclusion criteria benefited from an early postmortem structural brain MRI: death <24 hours, SARS-CoV-2 detection on nasopharyngeal swab specimen, chest computerized tomographic (CT) scan suggestive of COVID-19, absence of known focal brain lesion, and MRI compatibility.Results:Among the 62 patients who died from COVID-19 from 31/03/2020 to 24/04/2020 at our institution, 19 decedents fulfilled the inclusion criteria. Parenchymal brain abnormalities were observed in 4 decedents: subcortical micro- and macro-bleeds (2 decedents), cortico-subcortical edematous changes evocative of posterior reversible encephalopathy syndrome (PRES, one decedent), and nonspecific deep white matter changes (one decedent). Asymmetric olfactory bulbs were found in 4 other decedents without downstream olfactory tract abnormalities. No brainstem MRI signal abnormality was observed.Conclusions:Postmortem brain MRI demonstrates hemorrhagic and PRES-related brain lesions in non-survivors of COVID-19. SARS-CoV-2-related olfactory impairment seems to be limited to olfactory bulbs. Brainstem MRI findings do not support a brain-related contribution to respiratory distress in COVID-19.

ImportanceThe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is considered to have potential neuro-invasiveness that might lead to acute brain disorders or contribute to respiratory distress in patients with coronavirus disease 2019 (COVID-19). Brain magnetic resonance imaging (MRI) data in COVID-19 patients are scarce due to difficulties to obtain such examination in infected unstable patients during the COVID-19 outbreak.ObjectiveTo investigate the occurrence of structural brain abnormalities in non-survivors of COVID-19 in a virtopsy framework.DesignProspective, case series study with postmortem brain MRI obtained early (<24h) after death.SettingMonocentric study.ParticipantsFrom 31/03/2020 to 24/04/2020, consecutive decedents who fulfilled the following inclusion criteria were included: death <24 hours, SARS-CoV-2 detection on nasopharyngeal swab specimen, chest computerized tomographic (CT) scan suggestive of COVID-19, absence of known focal brain lesion, and MRI compatibility.Main Outcome(s) andMeasure(s)Signs of acute brain injury and MRI signal abnormalities along the olfactory tract and brainstem were searched independently by 3 neuroradiologists, then reviewed with neurologists and clinicians.ResultsAmong the 62 patients who died from COVID-19 during the inclusion period, 19 decedents fulfilled inclusion criteria. Subcortical micro- and macro-bleeds (2 decedents), cortico-subcortical edematous changes evocative of posterior reversible encephalopathy syndrome (PRES, one decedent), and nonspecific deep white matter changes (one decedent) were observed. Asymmetric olfactory bulbs were found in 4 other decedents without downstream olfactory tract abnormalities. No brainstem MRI signal abnormality.Conclusions and RelevancePostmortem brain MRI demonstrates hemorrhagic and PRES-related brain lesions in non-survivors of COVID-19 that might be triggered by the virus-induced endothelial disturbances. SARS-CoV-2-related olfactory impairment seems to be limited to olfactory bulbs. The absence of brainstem MRI abnormalities does not support a brain-related contribution to respiratory distress in COVID-19.Key PointsQuestionIs there common brain MRI abnormalities patterns in non-survivors of coronavirus disease 2019 ?FindingsIn a case series of 19 non-survivors of severe COVID-19 disease, early postmortem brain MRI demonstrated patterns evocative of intracranial vasculopathy in 4 decedents: subcortical micro- and macro-bleeds (2 decedents), cortico-subcortical edematous changes evocative of posterior reversible encephalopathy syndrome (PRES, one decedent), and nonspecific deep white matter changes (one decedent). Asymmetric olfactory bulbs were found in 4 other decedents but without downstream olfactory tract abnormalities.MeaningPostmortem brain MRI demonstrates hemorrhagic and PRES-related brain lesions in non-survivors of COVID-19 that might be triggered by virus-induced endothelial disturbances.