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American Journal of Rhinology & Allergy May 2021Post-viral olfactory dysfunction is a common cause of both short- and long-term smell alteration. The coronavirus pandemic further highlights the importance of...
BACKGROUND
Post-viral olfactory dysfunction is a common cause of both short- and long-term smell alteration. The coronavirus pandemic further highlights the importance of post-viral olfactory dysfunction. Currently, a comprehensive review of the neural mechanism underpinning post-viral olfactory dysfunction is lacking.
OBJECTIVES
To synthesize the existing primary literature related to olfactory dysfunction secondary to viral infection, detail the underlying pathophysiological mechanisms, highlight relevance for the current COVID-19 pandemic, and identify high impact areas of future research.
METHODS
PubMed and Embase were searched to identify studies reporting primary scientific data on post-viral olfactory dysfunction. Results were supplemented by manual searches. Studies were categorized into animal and human studies for final analysis and summary.
RESULTS
A total of 38 animal studies and 7 human studies met inclusion criteria and were analyzed. There was significant variability in study design, experimental model, and outcome measured. Viral effects on the olfactory system varies significantly based on viral substrain but generally include damage or alteration in components of the olfactory epithelium and/or the olfactory bulb.
CONCLUSIONS
The mechanism of post-viral olfactory dysfunction is highly complex, virus-dependent, and involves a combination of insults at multiple levels of the olfactory pathway. This will have important implications for future diagnostic and therapeutic developments for patients infected with COVID-19.
Topics: Animals; COVID-19; Humans; Olfaction Disorders; Olfactory Bulb; Olfactory Mucosa; Olfactory Pathways; SARS-CoV-2; Species Specificity; Post-Acute COVID-19 Syndrome
PubMed: 32915650
DOI: 10.1177/1945892420957853 -
American Journal of Rhinology & Allergy Sep 2022Patients with acquired, idiopathic olfactory dysfunction (OD) commonly undergo magnetic resonance imaging (MRI) evaluation to rule out intracranial pathologies. This...
BACKGROUND
Patients with acquired, idiopathic olfactory dysfunction (OD) commonly undergo magnetic resonance imaging (MRI) evaluation to rule out intracranial pathologies. This practice is highly debated given the expense of MRI relative to the probability of detecting a treatable lesion. This, combined with the increasing use of MRI in research to investigate the mechanisms underlying OD, provided the impetus for this comprehensive review.
OBJECTIVE
The purpose of this systematic review was to both assess the utility of MRI in diagnosis of idiopathic OD and to describe MRI findings among mixed OD etiologies to better understand its role as a research tool in this patient population.
METHODS
A literature search of PubMed, Embase, Cochrane, Web of Science, and Scopus for studies with original MRI data for patients with OD was completed. Studies exclusively investigating patients with neurocognitive deficits or those studying traumatic or congenital etiologies of OD were excluded.
RESULTS
From 1758 candidate articles, 33 studies were included. Four studies reviewed patients with idiopathic OD for structural pathologies on MRI, of which 17 of 372 (4.6%) patients had a potential central cause identified, and 3 (0.8%) had an olfactory meningioma or olfactory neuroblastoma. Fourteen studies (42.4%) reported significant correlation between olfactory bulb volume and olfactory outcomes, and 6 studies (18.8%) reported gray matter volume reduction, specifically in the orbitofrontal cortex, anterior cingulate cortex, insular cortex, parahippocampal, and piriform cortex areas, in patients with mixed OD etiologies. Functional MRI studies reported reduced brain activation and functional connectivity in olfactory network areas.
CONCLUSION
MRI uncommonly detects intracranial pathology in patients with idiopathic OD. Among patients with mixed OD etiologies, reduced olfactory bulb and gray matter volume are the most common abnormal findings on MRI. Further research is required to better understand the role of MRI and its cost-effectiveness in patients with acquired, idiopathic OD.
Topics: Gray Matter; Humans; Magnetic Resonance Imaging; Olfaction Disorders; Olfactory Bulb; Olfactory Cortex; Smell
PubMed: 35585698
DOI: 10.1177/19458924221096913 -
Environmental Research May 2022Air pollution is one of the most serious environmental problems that afflict our planet and one of the greatest risk factors for human health. In particular, PM is able...
Air pollution is one of the most serious environmental problems that afflict our planet and one of the greatest risk factors for human health. In particular, PM is able to cross the blood-alveolar and blood-brain barriers, thus increasing the onset of respiratory, cardiovascular and neurodegenerative diseases. Neurodegenerative disease is a progressive neuronal dysfunction that leads to neuronal lesions in both structure and function, and includes several diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), vascular dementia (VaD), multiple sclerosis (MS), and others. We carried out a systematic review using PRISMA approach to investigate on the possible association between exposure to PM and neurodegenerative diseases. The international databases (PubMed, Science Direct, Web of Sciences) were used to find published studies on the topic. The search period was between January 2011 and June 2021. About 2000 full research articles were selected, and finally, we included 20 full-research articles. Selected studies have highlighted how PM exposure can be associated with the onset of neurodegenerative diseases (AD, PD, MS, VaD). This association depends not only on age, PM levels and exposure time, but also on exposure to other air pollutants, proximity to areas with high vehicular traffic, and the presence of comorbidities. Exposure to PM promotes neuroinflammation processes, because through breathing the particles can reach the nasal epithelial mucosa and transferred to the brain through the olfactory bulb. Furthermore, exposure to PM has been associated with an increased expression of markers of neurodegenerative diseases (e.g. alpha-synuclein or beta-amyloid), which can contribute to the etiopathogenesis of neurodegenerative diseases. Although many studies have revealed the pathological relationship between PM exposure and cognitive impairment, the potential cellular and molecular mechanisms of PM leading to neurodegenerative disease remain not entirely clear, and then, further studies need to be carried out on the topic.
Topics: Air Pollutants; Air Pollution; Alzheimer Disease; Environmental Exposure; Humans; Neurodegenerative Diseases; Particulate Matter
PubMed: 34979121
DOI: 10.1016/j.envres.2021.112581 -
American Journal of Rhinology & Allergy Jul 2024Endoscopic sinus surgery (ESS) could significantly improve olfactory function among patients with chronic rhinosinusitis (CRS). This study aimed to perform a... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Endoscopic sinus surgery (ESS) could significantly improve olfactory function among patients with chronic rhinosinusitis (CRS). This study aimed to perform a meta-analysis to evaluate the effect of ESS on the olfactory bulb volume (OBV) among patients with CRS.
METHODS
A systemic search of PubMed, Medline, Embase, Web of Science, and other databases was conducted to identify studies assessing OBV changes in patients with CRS after ESS utilizing magnetic resonance imaging.
RESULTS
A total of four studies with 168 participants were included. Comparing the changes in OBV of patients with CRS before and after surgery within 3-6 months, the ESS significantly improved the overall OBV ( = 0.005, I= 66%), with the left OBV increased by 5.57mm ( = 0.84, I= 0%), and the right OBV increased by 8.63mm ( = 0.09, I= 53%). A difference in OBV persists between healthy controls and patients with CRS 3-6 months after ESS. The overall OBV of patients with CRS after ESS was significantly smaller than controls (mean difference = -3.84, = 0.04), with a mean difference of 4.13mm on the left side ( = 0.72, I= 0%), and a mean difference of 3.22mm on the right side ( = 0.0001, I= 89%).
CONCLUSIONS
ESS significantly increases the OBV among patients with CRS.
Topics: Sinusitis; Rhinitis; Humans; Olfactory Bulb; Chronic Disease; Endoscopy; Paranasal Sinuses; Magnetic Resonance Imaging; Treatment Outcome; Organ Size; Rhinosinusitis
PubMed: 38549395
DOI: 10.1177/19458924241241874 -
Korean Journal of Radiology Nov 2021Central nervous system involvement in coronavirus disease 2019 (COVID-19) has been increasingly reported. We performed a systematic review and meta-analysis to evaluate... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
Central nervous system involvement in coronavirus disease 2019 (COVID-19) has been increasingly reported. We performed a systematic review and meta-analysis to evaluate the incidence of radiologically demonstrated neurologic complications and detailed neuroimaging findings associated with COVID-19.
MATERIALS AND METHODS
A systematic literature search of MEDLINE/PubMed and EMBASE databases was performed up to September 17, 2020, and studies evaluating neuroimaging findings of COVID-19 using brain CT or MRI were included. Several cohort-based outcomes, including the proportion of patients with abnormal neuroimaging findings related to COVID-19 were evaluated. The proportion of patients showing specific neuroimaging findings was also assessed. Subgroup analyses were also conducted focusing on critically ill COVID-19 patients and results from studies that used MRI as the only imaging modality.
RESULTS
A total of 1394 COVID-19 patients who underwent neuroimaging from 17 studies were included; among them, 3.4% of the patients demonstrated COVID-19-related neuroimaging findings. Olfactory bulb abnormalities were the most commonly observed (23.1%). The predominant cerebral neuroimaging finding was white matter abnormality (17.6%), followed by acute/subacute ischemic infarction (16.0%), and encephalopathy (13.0%). Significantly more critically ill patients had COVID-19-related neuroimaging findings than other patients (9.1% vs. 1.6%; = 0.029). The type of imaging modality used did not significantly affect the proportion of COVID-19-related neuroimaging findings.
CONCLUSION
Abnormal neuroimaging findings were occasionally observed in COVID-19 patients. Olfactory bulb abnormalities were the most commonly observed finding. Critically ill patients showed abnormal neuroimaging findings more frequently than the other patient groups. White matter abnormalities, ischemic infarctions, and encephalopathies were the common cerebral neuroimaging findings.
Topics: Brain; COVID-19; Humans; Magnetic Resonance Imaging; Neuroimaging; SARS-CoV-2
PubMed: 34269530
DOI: 10.3348/kjr.2021.0127 -
International Journal of Infectious... Jan 2024Symptoms from SARS-CoV-2 infection can involve multiple organ systems. Several reviews discussed the neurologic involvement and neuroimaging findings in adults but...
OBJECTIVES
Symptoms from SARS-CoV-2 infection can involve multiple organ systems. Several reviews discussed the neurologic involvement and neuroimaging findings in adults but research on children is lacking. This study aimed to analyze the incidence of neurologic involvement in patients diagnosed with pediatric inflammatory multisystem syndrome temporally associated with COVID-19 (PIMS-TS) or multisystem inflammatory syndrome in children (MIS-C); and also to summarize current literature on possible neuroimaging findings in SARS-CoV-2 infected children.
METHODS
A literature search in six electronic databases was performed to retrieve case series, cohort studies, and cross-sectional studies on neurologic involvement in COVID-19 patients younger than 21 years of age published between December 2019 to September 2023, including COVID-19 patients.
RESULTS
A total of 2224 patients with MIS-C from 10 cohorts and cross-sectional studies suggested that neurologic involvement in these subsets ranges from 8.5% to 32.1%. Symptoms included acute encephalitis, seizures, stroke, cranial nerve palsy, nausea/vomiting, and intracranial hypertension. Neuroradiology findings of 114 children from 50 case reports included splenial or acute disseminated encephalomyelitis (ADEM)-like lesions, cytotoxic brain edema, autoimmune demyelinating diseases, ischemic stroke and arteritis, venous thrombosis, intracranial hemorrhage, meningitis, posterior reversible encephalopathy syndrome, anti-N-methyl-D-aspartate receptor autoimmune encephalitis, acute hemorrhagic leukoencephalitis, hydrocephalus, olfactory bulb atrophy, cerebellitis, and acute necrotizing encephalitis.
CONCLUSION
Radiologic findings of SARS-CoV-2 infection in the pediatric population are diverse. Neuroimaging studies should be considered in critically ill patients to rule out neurologic involvement and facilitate early interventions.
Topics: Adult; Humans; Child; COVID-19; SARS-CoV-2; Cross-Sectional Studies; Posterior Leukoencephalopathy Syndrome; Neuroimaging; Systemic Inflammatory Response Syndrome
PubMed: 37944584
DOI: 10.1016/j.ijid.2023.11.006 -
Phytomedicine : International Journal... May 2024Intranasal administration has been adopted in traditional medicine to facilitate access to the bloodstream and central nervous system (CNS). In modern medicine, nasal...
BACKGROUND
Intranasal administration has been adopted in traditional medicine to facilitate access to the bloodstream and central nervous system (CNS). In modern medicine, nasal drug delivery systems are valuable for disease treatment because of their noninvasiveness, good absorption, and fast-acting effects.
OBJECTIVE
This study aimed to systematically organize preclinical and clinical studies on intranasal herbal medicines to highlight their potential in drug development.
METHODS
A comprehensive search for literature until February 2023 was conducted on PubMed and the Web of Science. From the selected publications, we extracted key information, including the types of herbal materials, target diseases, intranasal conditions, methods of toxicity evaluation, main outcomes, and mechanisms of action, and performed quality assessments for each study.
RESULTS
Of the 45 studies, 13 were clinical and 32 were preclinical; 28 studies used herbal extracts, 9 used prescriptions, and 8 used natural compounds. The target diseases were rhinosinusitis, influenza, fever, stroke, migraine, insomnia, depression, memory disorders, and lung cancer. The common intranasal volumes were 8-50 µl in mice, 20-100 µl in rats, and 100-500 µl in rabbits. Peppermint oil, Ribes nigrum folium, Melia azedarach L., Elaeocarpus sylvestris, Radix Bupleuri, Da Chuan Xiong Fang, Xingnaojing microemulsion, and Ginsenoside Rb1 emerged as potential candidates for rapid intranasal therapy. The in vivo toxicity assessments were based on mortality, body weight, behavioral changes, mucociliary activity, histopathology, and blood tests. Most intranasal treatments were safe, except for Cyclamen europaeum, Jasminum sambac, Punica granatum L., and violet oil, which caused mild adverse effects. At lower doses, intranasal herbal treatments often show greater effects than oral administration. The actions of intranasal herbal medicine mainly involve regulating inflammation and neurotransmission, with the olfactory bulb and anterior cingulate cortex to be relevant brain regions.
CONCLUSION
Intranasal delivery of herbal materials holds promise for enhancing drug delivery efficacy and reducing treatment duration, offering a potential future perspective for developing intranasal therapies for various diseases.
Topics: Animals; Administration, Intranasal; Brain; Fever; Plant Extracts; Humans
PubMed: 38442431
DOI: 10.1016/j.phymed.2024.155484 -
Frontiers in Neurology 2020There is emerging evidence that Guillain-Barré syndrome (GBS) may be associated with coronavirus disease 2019 (COVID-19) infection. The aim of this review was to...
There is emerging evidence that Guillain-Barré syndrome (GBS) may be associated with coronavirus disease 2019 (COVID-19) infection. The aim of this review was to investigate the strength of the evidence. The review was registered in PROSPERO (CDR42020184822). Three electronic databases, MEDLINE, PubMed, and Web of Science, and three preprint servers, MedRvix, ChemRvix, and BioRvix, were searched from December 2019 to 24th September 2020. Studies were included if they were on COVID-19 and of any design. Articles that are reviews or opinion were excluded. The selection process was carried out using EndNote and Rayyan software. The main outcomes in the study were study design, sample size, sex, age, overall GBS symptoms, other COVID-19 symptoms, comorbidity, timing between infection and the onset of neurological symptoms, CT, MRI, and EMG results. Methodological quality of the studies was assessed using the McMaster Critical Review Form. The collected data was analyzed using qualitative synthesis. Fifty-one high-quality studies (mostly) consisting of 83 patients were included in the study. All of the patients (except in a very few) in the included studies had confirmed diagnosis of COVID-19. Similarly, the diagnosis of GBS was based on standard clinical, electrophysiological, and cerebrospinal fluid (CSF) criteria. GBS may be associated with COVID-19, and therefore, testing for COVID-19 is recommended in patients presenting with GBS during this pandemic.
PubMed: 33519663
DOI: 10.3389/fneur.2020.566308 -
Clinical Neurology and Neurosurgery Jul 2020Increasing research reports neurological manifestations of COVID-19 patients. SARS-CoV-2 shares homology with other human coronaviruses that have also had nervous system...
BACKGROUND
Increasing research reports neurological manifestations of COVID-19 patients. SARS-CoV-2 shares homology with other human coronaviruses that have also had nervous system involvement.
OBJECTIVE
To review the neurological aspects of SARS-cov2 and other coronavirus, including transmission pathways, mechanisms of invasion into the nervous system, and mechanisms of neurological disease.
METHODS
We conducted a systematic review of articles in PubMed, SCOPUS and EMBASE data bases. Reviewed evidence is presented in sections of this manuscript which includes pathogenesis, neuro-invasion, encephalitis, Guillain-Barré, ADEM, multiple sclerosis, polyneuropathy, and cerebrovascular disease.
RESULTS
A total 67 studies were included in the final analysis of experimental studies, case reports, series of cases, cohort studies, and systematic reviews related to neurological manifestations of SARS- CoV-2 and other human coronavirus infections. The SARS-CoV-2 receptor is expressed in the nervous system. Common reported symptoms included hyposmia, headaches, weakness, altered consciousness. Encephalitis, demyelination, neuropathy, and stroke have been associated with COVID-19. Infection through the cribriform plate and olfactory bulb and dissemination through trans-synaptic transfer are some of the mechanisms proposed. Invasion of the medullary cardiorespiratory center by SARS-CoV-2 may contribute to the refractory respiratory failure observed in critically-ill COVID-19 patients.
CONCLUSION
An increasing number of reports of COVID-19 patients with neurological disorders add to emergent experimental models with neuro-invasion as a reasonable concern that SARS-CoV-2 is a new neuropathogen. How it may cause acute and chronic neurologic disorders needs to be clarified in future research.
Topics: Betacoronavirus; Brain; COVID-19; Coronavirus Infections; Humans; Nervous System Diseases; Observational Studies as Topic; Pandemics; Pneumonia, Viral; SARS-CoV-2
PubMed: 32422545
DOI: 10.1016/j.clineuro.2020.105921 -
Spinal Cord Aug 2020Spinal cord injury (SCI) is associated with significant and life-long disability. Yet, despite decades of research, no regenerative treatment has reached clinical...
INTRODUCTION
Spinal cord injury (SCI) is associated with significant and life-long disability. Yet, despite decades of research, no regenerative treatment has reached clinical practice. Cell-based therapies are one possible regenerative strategy beginning to transfer to human trials from a more extensive pre-clinical basis.
METHODS
We therefore conducted a scoping review to synthesise all cell-based trials in SCI to consider the current state of the field and the cell transplant type or strategy with greatest promise. A search strategy of MEDLINE returned 1513 results. All clinical trials including adult human patients with acute or chronic, compete or incomplete SCI and a recorded ASIA score were sought. Exclusion criteria included non-traumatic SCI, paediatric patients and animal studies. A total of 43 studies, treating 1061 patients, were identified. Most trials evaluated cells from the bone marrow (22 papers, 660 patients) or the olfactory bulb (10 papers, 245 patients).
RESULTS
Cell transplantation does appear to be safe, with no serious adverse effects being reported in the short-term. 86% of trials described efficacy as a primary outcome. However, varying degrees of outcome reporting prevented meta-analysis. No emerging cell type or technique was identified. The majority of trials, 53%, took place in developing countries, which may suggest more stringent regulatory requirements within Western countries.
CONCLUSION
We believe cell-based transplantation translation remains in its infancy and that, although further robust clinical research is required, it is an important strategy to consider in the treatment of SCI.
Topics: Cell Transplantation; Humans; Outcome Assessment, Health Care; Spinal Cord Injuries
PubMed: 32249830
DOI: 10.1038/s41393-020-0455-1