Although severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a novel virus, many central and peripheral nervous system manifestations associated with coronavirus disease-19 (COVID-19) infection have been reported. Beyond the neurologic manifestations, we may still have much to learn about the neuropathologic mechanism of SARS-CoV-2 infection. Here we report a case of post-poliomyelitis syndrome (PPS) related to COVID-19 and attempt to predict the possible pathophysiologic mechanism behind this association.

[Acute-onset cerebrovascular diseases are connected to a number of immunological changes. Here, we summarize immune responses participating in the evolution of atherosclerotic plaques and poststroke local immune responses in the injured CNS as well as in the systemic circulation. Ischemic injury of the CNS alters the balanced neuroimmune modulation resulting in CIDS, the central nervous system injury-induced immune deficiency syndrome. Due to the immunodepression and reduced pro-inflammatory immune responses, the susceptibility for infection is increased; indeed, poststroke infection plays a major role in stroke-related mortality. On the other hand, CIDS may protect against damaging autoimmune responses elicited by exposed CNS antigens. Investigation of immune responses related to ischemic stroke may result in novel therapies indicated by an increasing number of experimental and clinical trials altering poststroke immune responses and preventing infections.]

Although vertigo is one of the most common complaints, intracranial malignant tumors rarely cause sudden asymmetry between the tone of the vestibular peripheries masquerading as a peripheral-like disorder. Here we report a case of simultaneous temporal bone infiltrating macro-metastasis and disseminated multi-organ micro-metastases presenting as acute unilateral vestibular syndrome, due to the reawakening of a primary gastric signet ring cell carcinoma. Purpose – Our objective was to identify those pathophysiological steps that may explain the complex process of tumor reawakening, dissemination. The possible causes of vestibular asymmetry were also traced. A 56-year-old male patient’s interdisciplinary medical data had been retrospectively analyzed. Original clinical and pathological results have been collected and thoroughly reevaluated, then new histological staining and immunohistochemistry methods have been added to the diagnostic pool. During the autopsy the cerebrum and cerebellum was edematous. The apex of the left petrous bone was infiltrated and destructed by a tumor mass of 2x2 cm in size. Histological reexamination of the original gastric resection specimen slides revealed focal submucosal tumorous infiltration with a vascular invasion. By immunohistochemistry mainly single infiltrating tumor cells were observed with Cytokeratin 7 and Vimentin positivity and partial loss of E-cadherin staining. The subsequent histological examination of necropsy tissue specimens confirmed the disseminated, multi-organ microscopic tumorous invasion. Discussion – It has been recently reported that the expression of Vimentin and the loss of E-cadherin is significantly associated with advanced stage, lymph node metastasis, vascular and neural invasion and undifferentiated type with p<0.05 significance. As our patient was middle aged and had no immune-deficiency, the promoting factor of the reawakening of the primary GC malignant disease after a 9-year-long period of dormancy remained undiscovered. The organ-specific tropism explained by the “seed and soil” theory was unexpected, due to rare occurrence of gastric cancer to metastasize in the meninges given that only a minority of these cells would be capable of crossing the blood brain barrier. Patients with past malignancies and new onset of neurological symptoms should alert the physician to central nervous system involvement, and the appropriate, targeted diagnostic and therapeutic work-up should be established immediately. Targeted staining with specific antibodies is recommended. Recent studies on cell lines indicate that metformin strongly inhibits epithelial-mesenchymal transition of gastric cancer cells. Therefore, further studies need to be performed on cases positive for epithelial-mesenchymal transition.