Since the outbreak of the COVID-19 pandemic, much has been learned regarding its clinical course, prognostic inflammatory markers, disease complications, and mechanical ventilation strategy. Clinically, three stages have been identified based on viral infection, pulmonary involvement with inflammation, and fibrosis. Moreover, low and high elastance phenotypes can be distinguished in mechanically ventilated patients, based on lung mechanics, ventilation-to-perfusion ratio, and CT scans; these two phenotypes have presumed differences in their underlying pathophysiology. Although essential for therapeutic guidance, the pathophysiology of COVID-19 is poorly understood. Here, we systematically reviewed published case reports and case series in order to increase our understanding of COVID-19 pathophysiology by constructing a timeline and correlating histopathological findings with clinical stages of COVID-19. Using PRISMA-IPD guidelines, 42 articles reporting 198 individual cases were included in our analysis. In lung samples (n = 131 cases), we identified three main histological patterns: epithelial (n = 110, 85%), with reactive epithelial changes and DAD; vascular (n = 76, 59%) with microvascular damage, (micro)thrombi, and acute fibrinous and organizing pneumonia; and fibrotic (n = 28, 22%) with interstitial fibrosis. The epithelial and vascular patterns can present in all stages of symptomatic COVID-19, whereas the fibrotic pattern presents starting at~3 weeks. Moreover, patients can present with more than one pattern, either simultaneously or consecutively. These findings are consistent with knowledge regarding clinical patterns of viral infection, development of hyperinflammation and hypercoagulability, and fibrosis. Close collaboration among medical staff is necessary in order to translate this knowledge and classification of pathophysiological mechanisms into clinical stages of disease in individual patients. Moreover, further research, including histopathological studies, is warranted in order to develop reliable, clinically relevant biomarkers by correlating these pathological findings with laboratory results and radiological findings, thus, increasing our understanding of COVID-19 and facilitating the move to precision medicine for treating patients.

Background Surgery on extraforaminal lumbar disc herniation (ELDH) is a commonly performed procedure. Operating on this type of herniation is known to come with more difficulties than on the frequently seen paramedian lumbar disc herniation (PLDH). However, no comparative data are available on the effectiveness and safety of this operation. We sought out to compare clinical outcomes at 1 year following surgery for ELDH and PLDH. Methods Data were collected through the Norwegian Registry for Spine Surgery (NORspine). The primary outcome measure was change at 1 year in the Oswestry Disability Index (ODI). Secondary outcome measures were quality of life measured with EuroQol 5 dimensions (EQ-5D); and numeric rating scales (NRSs). Results Data of a total of 1750 patients were evaluated in this study, including 72 ELDH patients (4.1%). One year after surgery, there were no differences in any of the patient reported outcome measurements (PROMs) between the two groups. PLDH and ELDH patients experienced similar changes in ODI (− 30.92 vs. − 34.00, P = 0.325); EQ-5D (0.50 vs. 0.51, P = 0.859); NRS back (− 3.69 vs. − 3.83, P = 0.745); and NRS leg (− 4.69 vs. − 4.46, P = 0.607) after 1 year. The proportion of patients achieving a clinical success (defined as an ODI score of less than 20 points) at 1 year was similar in both groups (61.5% vs. 52.7%, P = 0.204). Conclusions Patients operated for ELDH reported similar improvement after 1 year compared with patients operated for PLDH.