An interesting case of small vessel pathology following coronavirus infection

Polyarteritis Nodosa: Old Disease, New Etiologies

Polyarteritis nodosa (PAN), also known as panarteritis nodosa, represents a form of necrotizing vasculitis that predominantly affects medium-sized vessels, although it is not restricted to them and can also involve smaller vessels. The clinical presentation is heterogeneous and characterized by a significant number of patients exhibiting general symptoms, including asthenia, fever, and unintended weight loss. Although PAN can involve virtually any organ, it preferentially affects the skin, nervous system, and the gastrointestinal tract. Orchitis is a rare but specific manifestation of PAN. The absence of granulomas, glomerulonephritis, and anti-neutrophil cytoplasmic antibodies serves to distinguish PAN from other types of vasculitis. Major complications consist of hemorrhagic and thrombotic events occurring in mesenteric, cardiac, cerebral, and renal systems. Historically, PAN was frequently linked to hepatitis B virus (HBV) infection, but this association has dramatically changed in recent years due to declining HBV prevalence. Current epidemiological research often identifies a connection between PAN and genetic syndromes as well as neoplasia. This article provides a comprehensive review of PAN, specifically focusing on the progression of its clinical manifestations over time.

COVID-19-Associated Cerebrovascular Events: A Case Series Study and a Literature Review of Possible Mechanisms

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects multiple body systems, including the nervous system. Cerebrovascular accidents can also occur. Patients with comorbid illnesses have severe manifestations and poor outcomes. Despite the proper mechanism of SARS-CoV-2 infection-associated stroke having not yet been settled, various possible mechanisms have been hypothesized. One possibility is that the virus causes endothelial dysfunction and immune-mediated injury. Another possibility is that the trans-neuronal spread of the virus affects brain tissue. In addition, hypercoagulability caused by SARS-CoV-2 infection could lead to a stroke. A virus-induced dysfunction of the renin-angiotensin system could also lead to a stroke. The immune response and vasculitis resulting from SARS-CoV-2 infection are also possible causes via a cytokine storm, immune dysfunction, and various inflammatory responses. SARS-CoV-2 infection may affect calcitonin gene-related peptides and cerebral blood flow and may lead to stroke. Finally, SARS-CoV-2 may cause hemorrhagic strokes via mechanisms stimulated by its interaction with angiotensin-converting enzyme 2 (ACE2), leading to arterial wall damage and blood pressure changes. In this article, we will present seven cases of stroke-associated SARS-CoV-2 infection.