The Prevalence of Dizziness and Vertigo in COVID-19 Patients: A Systematic Review.

Clinical manifestations of COVID-19 include symptoms of vertigo and dizziness, which is rather unsurprising, since SARS-CoV-2 neurotropism may inflict a broad spectrum of neuropathic effects. The widespread nature of central and peripheral audiovestibular pathways suggests that there may be several probable pathophysiological mechanisms. The cytokine storm, CNS infiltration of the virus through ACE 2 receptors, and other systemic factors can be responsible for the significant number of COVID-19 patients reported to experience symptoms of vertigo and dizziness. In this paper, we present a systematic review of clinical studies reporting the detection of dizziness and vertigo as clinical manifestations of COVID-19 and discuss their etiopathogenesis.

Rituximab and multiple sclerosis.

B lymphocytes seem to have a fundamental role in multiple sclerosis, acting as sensors, coordinators, and regulators of the immune response. Furthermore, they are important in activating T cells and they can mediate tissue injury through diverse mechanisms. Such findings have important therapeutic implications in autoimmune central nervous system diseases in a fashion similar to other autoimmune processes. The best known monoclonal antibody targeting B cells that has been used as a novel therapy for various autoimmune conditions, as well as multiple sclerosis, is rituximab. This review summarizes the available data on the role of B cell in multiple sclerosis and further reports on current knowledge on the B-cell-depleting monoclonal antibody rituximab, its mechanism of action, and its efficacy on multiple sclerosis. Data presented were categorized in 3 groups based on the nature of data presented (radiological, clinical, and immunological data). Both case-control studies and case reports were included, while table classification was in chronological order.

TGF-ß/BMPs: crucial crossroad in neural autoimmune disorders.

Transforming growth factor beta (TGF-ß) has a crucial role in the differentiation of ectodermal cells to neural or epidermal precursors. TGF-ß and bone morphogenetic protein molecules (BMPs) are involved in many developmental processes, including cell proliferation and differentiation, apoptosis, mitotic arrest and intercellular interactions during morphogenesis. Additionally, the failure of central thymic tolerance mechanisms, leading to T cells with a skewed autoreactive response, is being described as a contributor in inflammatory processes in autoimmune diseases such as multiple sclerosis. Since TGF-ß and BMP proteins are crucial for the development of the neural system and the thymus, as well as for the differentiation of T cells, it is essential to further investigate their role in the pathophysiology of this disorder by using references from embryonic experimental research. Available literature in the TGF/BMP signalling cascade, mostly during embryonic development of the nervous system is being reviewed. An attempt is made to further elucidate a potential role of TGF/BMP signalling in the pathophysiology of MS. During demyelination, BMP signaling, through various molecular mechanisms, directs the development of the adult neural stem cell in the astrocyte rather than the oligodendrocyte direction, therefore inhibiting the repair process. Further understanding of the above relationships could lead to the development of potentially efficient therapies for MS in the future.

Human herpesvirus 6 infection as a trigger of multiple sclerosis.

We systematically reviewed the existing evidence to determine whether a relationship exists between infection with human herpesvirus 6 (HHV-6) and multiple sclerosis (MS) and, if so, to define the strength of that relationship. The following terms were used in searches of the Entrez-PubMed database (1966-2009): human herpes virus 6, HHV 6, demyelination, multiple sclerosis, pathogenesis, diagnosis, serology, cerebrospinal fluid, IgG antibodies, IgM antibodies, PCR, and lymphoproliferative techniques. Study quality was assessed using the criteria proposed by Moore and Wolfson and by the classification criteria used by the Canadian Task Force on the Periodic Health Examination. Studies were categorized both by experimental technique and by quality (high [A], intermediate [B], and low [C]) as determined by the Moore and Wolfson criteria. Overall, 25 (41%) of 61 studies, 15 (60%) of which were classified as A quality, reached a statistically significant result. According to the Canadian Task Force classification, all studies were categorized as evidence of quality II-1. Limitations of the available experimental techniques and perspectives for future research are discussed. The current review supports the need for further, objective, evidence-based examination of the relationship between HHV-6 infection and multiple sclerosis.

Gender hormones: role in the pathogenesis of central nervous system disease and demyelination.

Gender hormones are associated with the evolution of Multiple Sclerosis (MS) like changes in experimental models of MS. Several clinical studies have attempted to elucidate the role of gender hormones in the evolution of the clinical spectrum of the disease. We attempt to describe the currently known data regarding such associations emphasizing the potential clinical applications in different MS scenarios i.e. pregnancy, menstruation, use of oral contraceptives and hormonal replacement therapy. Moreover we discuss relevant effects of gender hormones on immunological parameters relating to MS pathogenesis. Beneficial neuroprotective effects were noted for elevated levels of estrogens, progesterone and elevated dosages of androgens. Some of these changes may be explained by a favorable immunological shift from a Th1 to Th2 response. Further elucidation of the clinical implications of such associations is necessary.