Widespread sensory neuropathy in diabetic patients hospitalized with severe COVID-19 infection

Identification of Differentially Expressed Genes and Protein-Protein Interaction in Patients With COVID-19 and Diabetes Peripheral Neuropathy: A Bioinformatics and System Biology Approach

The coronavirus disease 2019 (COVID-19) pandemic has had a significant impact globally, resulting in a higher death toll and persistent health issues for survivors, particularly those with pre-existing medical conditions. Numerous studies have demonstrated a strong correlation between catastrophic COVID-19 results and diabetes. To gain deeper insights, we analysed the transcriptome dataset from COVID-19 and diabetic peripheral neuropathic patients. Using the R programming language, differentially expressed genes (DEGs) were identified and classified based on up and down regulations. The overlaps of DEGs were then explored between these groups. Functional annotation of those common DEGs was performed using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Bio-Planet, Reactome, and Wiki pathways. A protein-protein interaction (PPI) network was created with bioinformatics tools to understand molecular interactions. Through topological analysis of the PPI network, we determined hub gene modules and explored gene regulatory networks (GRN). Furthermore, the study extended to suggesting potential drug molecules for the identified mutual DEG based on the comprehensive analysis. These approaches may contribute to understanding the molecular intricacies of COVID-19 in diabetic peripheral neuropathy patients through insights into potential therapeutic interventions.

Quantitative sensory testing defines the trajectory of sensory neuropathy after severe COVID-19

AIMS

To assess sensory neuropathy development after severe COVID-19.

METHODS

Patients with severe COVID-19 underwent assessment of neuropathic symptoms, tendon reflexes, and quantitative sensory testing to evaluate vibration (VPT), cold (CPT), warm (WPT) and heat perception thresholds (HPT) within 1-3 weeks of admission and after 1-year.

RESULTS

32 participants with severe COVID-19 aged 68.6 ± 12.4 (18.8 % diabetes) were assessed. At baseline, numbness and neuropathic pain were present in 56.3 % and 43.8 % of participants, respectively. On the feet, VPT, WPT, and HPT were abnormal in 81.3 %, CPT was abnormal in 50.0 % and HPT on the face was abnormal in 12.5 % of patients. At 1-year follow-up, the prevalence of abnormal VPT (81.3 % vs 50.0 %, P < 0.01), WPT (81.3 % vs 43.8 %, P < 0.01), and HPT (81.3 % vs 50.0 %, P < 0.01) decreased, with no change in CPT (P = 0.21) on the feet or HPT on the face (P = 1.0). Only participants without diabetes recovered from an abnormal VPT, CPT, and WPT. Patients with long-COVID (37.5 %) had comparable baseline VPT, WPT and CPT with those without long-COVID (P = 0.07-0.69).

CONCLUSIONS

Severe COVID-19 is associated with abnormal vibration and thermal thresholds which are sustained for up to 1 year in patients with diabetes. Abnormal sensory thresholds have no association with long-COVID development.

Exploration of the common pathogenic link between COVID-19 and diabetic foot ulcers: An in silico approach

Background and Aims

The Coronavirus Disease-19 (COVID-19) is posing an ongoing threat to human health. Patients of diabetic foot ulcer (DFU) are susceptible to COVID-19-induced adverse outcomes. Nevertheless, investigations into their mutual molecular mechanisms have been limited to date. In the present work, we tried to uncover the shared pathogenesis and regulatory gene targets of COVID-19 and DFU.

Methods

In this study, we chose GSE161281 as the COVID-19 data set, which contained severe acute respiratory syndrome coronavirus 2 infected human induced embryonic stem cell-derived peripheral neurons (n = 2) with uninfected controls (n = 2). The GSE134431 designated as the DFU data set, comprising full-thickness DFU (n = 13) and diabetic foot skin (n = 8) samples from diabetic patients. The differential expressed genes (DEGs) were identified from GSE161281 and GSE134431, and the common DEGs between COVID-19 and DFU were extracted. Multifactor regulatory network and co-expression network of the common DEGs were analyzed, along with candidate drug prediction.

Results

Altogether, six common DEGs (dickkopf-related protein 1 [DKK1], serine proteinase inhibitor A3 [SERPINA3], ras homolog family member D [RHOD], myelin protein zero like 3 [MPZL3], Claudin-11 [CLDN11], and epidermal growth factor receptor pathway substrate 8-like 1 [EPS8L1]) were found between COVID-19 and DFU. Functional analyses indicated that pathways of apoptotic and Wnt signaling may contribute to progression of COVID-19. Gene co-expression network implied the shared pathways of immune regulation and cytokine response participated collectively in the development of DFU and COVID-19. A multifactor regulatory network was constructed integrating the corresponding microRNAs (miRNAs) and transcription factors. Additionally, we proposed potential drug objects for the combined therapy.

Conclusion

Our study revealed the shared molecular mechanisms underlying COVID-19 and DFU. The identified pivotal targets and common pathways can provide new perspectives for further research and assist the development of management strategies in patients of DFU complicated with COVID-19.

Factors associated with hospitalisations and deaths of residential aged care residents with COVID-19 during the Omicron (BA.1) wave in Queensland

OBJECTIVE

To identify characteristics associated with the hospitalisation and death of people with COVID-19 living in residential aged care facilities (RACFs).

DESIGN

Retrospective cohort study.

SETTING, PARTICIPANTS

All confirmed (polymerase chain reaction testing) or probable SARS-CoV-2 infections (rapid antigen tests) in residents of the 86 RACFs in the Metro South Hospital and Health Service area (southeast Queensland), 13 December 2021 - 24 January 2022.

MAIN OUTCOME MEASURES

Hospitalisation within 14 days or death within 28 days of COVID-19 diagnosis.

RESULTS

Of 1071 RACF residents with COVID-19, 151 were hospitalised within 14 days and 126 died within 28 days of diagnosis. Likelihood of death increased with age (per five years: adjusted odds ratio [aOR], 1.38; 95% confidence interval [CI], 1.21-1.57), but not that of hospitalisation. Men were more likely to be hospitalised (aOR, 1.7; 95% CI, 1.2-2.4) or die (aOR, 2.5; 95% CI, 1.7-3.6) than women. The likelihood of hospitalisation was greater for those with dementia (aOR, 1.9; 95% CI, 1.2-3.0), heart failure (aOR, 1.7; 95% CI, 1.1-2.7), chronic kidney disease (aOR, 1.7; 95% CI, 1.1-2.5), or asthma (aOR, 2.2; 95% CI, 1.2-3.8). The likelihood of death was greater for residents with dementia (aOR, 2.2; 95% CI, 1.3-3.7), diabetes mellitus (aOR, 1.9; 95% CI, 1.3-3.0), heart failure (aOR, 2.0; 95% CI, 1.1-3.3), or chronic lung disease (aOR, 1.7; 95% CI, 1.1-2.7). The likelihood of hospitalisation and death were each higher for residents who had received two or fewer vaccine doses than for those who had received three doses.

CONCLUSIONS

Most characteristics that influenced the likelihood of hospitalisation or death of RACF residents with COVID-19 were non-modifiable factors linked with frailty and general health status. Having received three COVID-19 vaccine doses was associated with much lower likelihood of hospitalisation or death.

Peripheral Neuropathy in Diabetes Mellitus: Pathogenetic Mechanisms and Diagnostic Options

Diabetic neuropathy (DN) is one of the main microvascular complications of both type 1 and type 2 diabetes mellitus. Sometimes, this could already be present at the time of diagnosis for type 2 diabetes mellitus (T2DM), while it appears in subjects with type 1 diabetes mellitus (T1DM) almost 10 years after the onset of the disease. The impairment can involve both somatic fibers of the peripheral nervous system, with sensory-motor manifestations, as well as the autonomic system, with neurovegetative multiorgan manifestations through an impairment of sympathetic/parasympathetic conduction. It seems that, both indirectly and directly, the hyperglycemic state and oxygen delivery reduction through the vasa nervorum can determine inflammatory damage, which in turn is responsible for the alteration of the activity of the nerves. The symptoms and signs are therefore various, although symmetrical painful somatic neuropathy at the level of the lower limbs seems the most frequent manifestation. The pathophysiological aspects underlying the onset and progression of DN are not entirely clear. The purpose of this review is to shed light on the most recent discoveries in the pathophysiological and diagnostic fields concerning this complex and frequent complication of diabetes mellitus.

A systematic review and meta-analysis of neuropathic pain associated with coronavirus disease 2019

BACKGROUND AND OBJECTIVE

Neuropathic pain is an occasionally reported complication of coronavirus disease 2019 (COVID-19) that has received increased attention in scientific literature. In this systematic review and meta-analysis, we aimed to provide information on the frequency of neuropathic pain associated with COVID-19.

DATABASES AND DATA TREATMENT

We systematically reviewed and analysed literature regarding neuropathic pain associated with COVID-19. Literature searches were conducted in PubMed, EMBASE and Cochrane Library databases. We considered prospective and retrospective studies published up until September 2022 (limitations included English language, full-text publications and studies including at least 10 patients). A random effects meta-analysis was performed and heterogeneity and publication bias were assessed.

RESULTS

We identified 149 studies. We included 17 studies in the systematic review, and six studies reporting the frequency of neuropathic pain in the acute/subacute phase of COVID-19 in the meta-analysis. The estimated frequency of neuropathic pain ranged between 0.4 and 25%. Forest plot analysis showed that the random effect overall frequency was 10% (95% confidence interval: 5%-15%), with a high level of heterogeneity (Chi²  = 104; Tau²  = 0.004; df = 5; I²  = 95%; test for overall effect: Z = 3.584; p < 0.0005). The overall risk of bias was moderate in all studies selected, particularly due to the poor description of neuropathic pain diagnostic criteria.

CONCLUSIONS

The pooled estimated frequency of neuropathic pain associated with COVID-19 should be considered with caution due to the high heterogeneity across studies and the poor description of the neuropathic pain diagnostic criteria applied.

SIGNIFICANCE

Emerging evidence supports the development of neuropathic pain as a complication of COVID-19. However, longitudinal studies enrolling consecutive patients with COVID-19 that detail the diagnostic criteria for neuropathic pain are needed to better assess the frequency of this condition.

Update on Corneal Confocal Microscopy Imaging

In vivo corneal confocal microscopy (IVCM) is a non-invasive ophthalmic imaging technique that provides images of the cornea at the cellular level. Despite the uses in ocular surface pathologies, in the last decades IVCM has been used to provide more knowledge in refractive surgery wound healing, in neuropathies diagnosis, etc. The observation of the corneal cells, both normal and inflammatory, and the possibility of quantification of the corneal nerve density with manual or automated tools, makes IVCM have a significant potential to improve the diagnosis and prognosis in several systemic and corneal conditions.

Risks of Severe COVID-19 Outcomes Among Patients With Diabetic Polyneuropathy in the United States

CONTEXT

Diabetic neuropathy (DN) affects more than 50% of diabetic patients who are also likely to have compromised immune system and respiratory function, both of which can make them susceptible to the SARS-CoV-2 virus.

OBJECTIVE

To assess the risk of severe COVID-19 illness among adults with DN, compared with those with no DN and those with no diabetes.

SETTING

The analysis utilized electronic health records from 55 US health care organizations in the TriNetX research database.

DESIGN

A retrospective cohort study.

PARTICIPANTS

The analysis included 882 650 adults diagnosed with COVID-19 in January 2020 to June 2021, including 16 641 with DN, 81 329 with diabetes with no neuropathy, and 784 680 with no diabetes.

OUTCOME MEASURES

The presence of health care utilization (admissions to emergency department, hospital, intensive care unit), 30-day mortality, clinical presentation (cough, fever, hypoxemia, dyspnea, or acute respiratory distress syndrome), and diagnostic test results after being infected affected by COVID-19.

RESULTS

The DN cohort was 1.19 to 2.47 times more likely than the non-DN cohorts to utilize care resources, receive critical care, and have higher 30-day mortality rates. Patients with DN also showed increased risk (1.13-2.18 times) of severe symptoms, such as hypoxemia, dyspnea, and acute respiratory distress syndrome.

CONCLUSIONS

Patients with DN had a significantly greater risk of developing severe COVID-19-related complications than those with no DN. It is critical for the public health community to continue preventive measures, such as social distancing, wearing masks, and vaccination, to reduce infection rates, particularly in higher risk groups, such as those with DN.

Body Weight May Have a Role on Neuropathy and Mobility after Moderate to Severe COVID-19: An Exploratory Study

Background and Objectives: Among the extra-pulmonary manifestations of COVID-19, neuromuscular signs and symptoms are frequent. We aimed to assess the correlation between neuromuscular abnormalities (electrophysiological) and mobility measures (Berg Balance Scale and Timed-Up-and-Go test) twice, at least 6 weeks after hospital discharge and 6 months later, taking into account cognitive performance, nutrition, muscle strength, and submaximal exercise capacity. Materials and Methods: 43 patients (51.4 ± 9.3 years old) accepted to participate in the study; they had a dyspnea score ≤ 3 (Borg scale), and no history of neurology/neuromuscular/orthopedic disorders, but high frequency of overweight/obesity and weight loss during hospital stay. The two evaluations included physical examination, cognitive assessment, nutritional evaluation, muscle strength (hand-grip and quadriceps dynamometry), electromyography, Barthel Index, Six-Minute- Walk-Test (6MWT), Berg Balance Scale and Timed-Up-and-Go test. Bivariate and repeated measures covariance analyses were performed (significance level of 0.05). Results: Electrophysiological abnormalities were evident in 67% of the patients, which were associated with diminished performance on the 6MWT, the Berg Balance Scale and the Timed-Up-and-Go test. At each evaluation and between evaluations, scores on the Berg Balance Scale were related to the body mass index (BMI) at hospital admission and the 6MWT (MANCoVA R ≥ 0.62, p = 0.0001), while the time to perform the Timed-Up-and-Go test was related to the electrophysiological abnormalities, weight loss during hospital stay, sex, handgrip strength, and the 6MWT (MANCoVA, R ≥ 0.62, p < 0.0001). We concluded that, after hospital discharge, patients with moderate to severe COVID-19 may have neuromuscular abnormalities that can be related to BMI/weight loss, and contribute to mobility decrease. In patients with moderate to severe COVID-19 and high BMI/ large weight loss, neuromuscular and intended mobility assessments could be required to provide early rehabilitation. Apart from the 6MWT, handgrip dynamometry and the Timed-Up-and-Go test were useful tools to quickly assess fitness and mobility.

Abnormal quantitative pupillary light responses following COVID-19

Purpose

To characterize alterations in pupillary light reflex responses in subjects following coronavirus disease 2019 (COVID-19), especially those with long-COVID.

Methods

Thirty-five subjects with previous COVID-19 and 30 healthy control participants were enrolled in this cross-sectional comparative study. An infrared dynamic pupillometry system (MonPack One; Metrovision, France) was used to quantify pupillary light responses. The National Institute for Health and Care Excellence (NICE) long-COVID questionnaire was used to identify persisting symptoms at least 4 weeks after acute COVID-19.

Results

The median time after the diagnosis of acute COVID-19 was 4.0 (2.0–5.0) months. There was an increase in the latency of pupil contraction (P = 0.001) and a reduction in the duration of pupil contraction (P = 0.039) in post-COVID-19 subjects compared to healthy controls. No significant differences were observed in the initial pupil diameter, amplitude and velocity of pupil contraction or latency, velocity and duration of pupil dilation. Long-COVID was present in 25/35 (71%) subjects and their duration of pupil contraction was reduced compared to subjects without long-COVID (P = 0.009). The NICE long-COVID questionnaire total score (ρ = − 0.507; P = 0.002) and neurological score (ρ = − 0.412; P = 0.014) correlated with the duration of pupil contraction and the total score correlated with the latency of dilation (ρ = − 0.352; P = 0.038).

Conclusion

Dynamic pupillometry reveals significant alterations in contractile pupillary light responses, indicative of parasympathetic dysfunction after COVID-19.

Post-acute sensory neurological sequelae in patients with SARS-CoV-2 infection: the COVID-PN observational cohort study

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection can cause neurological sequelae after the resolution of symptomatic COVID-19 illness, but the occurrence of peripheral neuropathy symptoms and cranial nerve dysfunction is unknown. This study aimed to characterize the occurrence and severity of pain and peripheral neuropathy symptoms in patients with SARS-CoV-2 infection.An observational cohort study included adults tested for a SARS-CoV-2 infection at an academic medical center (assigned as CV+ or control, based on test results). 30-90 days after the index SARS-CoV-2 test, patients completed a web-based questionnaire assessing pain, peripheral neuropathy-related sensory symptoms, and symptoms in the distribution of cranial nerves (current symptoms, symptoms at testing and two weeks thereafter). Univariate analyses compared the outcomes between the groups. Multivariable analysis was used to determine the odds for neuropathy symptoms after adjusting for key baseline variables.1556 participants were included: 542 CV+ and 1014 controls. CV+ patients reported a higher occurrence of peripheral neuropathy symptoms in the extremities anytime within 90 days post-infection (28.8% vs 12.9%, OR [95%CI] =2.72 [2.10-3.54]), as well as such symptoms persisting up to 90 days after infection (6.1% vs 1.9%, OR=3.39 [1.91-6.03]). The occurrence of pain in the extremities was higher in the CV+ group (24.2% vs 9.8%, OR=2.95 [2.21-3.91]). SARS-CoV-2 infection was also associated with higher occurrence of peripheral neuropathy symptoms, after adjusting for the history of chronic pain and neuropathy (OR=3.19 [2.37-4.29]. The results suggest that SARS-CoV-2 infection was independently associated with an increased risk of pain and peripheral neuropathy symptoms.

Corneal Confocal Microscopy to Image Small Nerve Fiber Degeneration: Ophthalmology Meets Neurology

Neuropathic pain has multiple etiologies, but a major feature is small fiber dysfunction or damage. Corneal confocal microscopy (CCM) is a rapid non-invasive ophthalmic imaging technique that can image small nerve fibers in the cornea and has been utilized to show small nerve fiber loss in patients with diabetic and other neuropathies. CCM has comparable diagnostic utility to intraepidermal nerve fiber density for diabetic neuropathy, fibromyalgia and amyloid neuropathy and predicts the development of diabetic neuropathy. Moreover, in clinical intervention trials of patients with diabetic and sarcoid neuropathy, corneal nerve regeneration occurs early and precedes an improvement in symptoms and neurophysiology. Corneal nerve fiber loss also occurs and is associated with disease progression in multiple sclerosis, Parkinson's disease and dementia. We conclude that corneal confocal microscopy has good diagnostic and prognostic capability and fulfills the FDA criteria as a surrogate end point for clinical trials in peripheral and central neurodegenerative diseases.

What is the impact of microvascular complications of diabetes on severe COVID-19?

Evidence suggests severe coronavirus disease-19 (COVID-19) infection is characterised by pulmonary and systemic microvasculature dysfunction, specifically, acute endothelial injury, hypercoagulation and increased capillary permeability. Diabetes, which is also characterised by vascular injury in itself, confers an increased risk of adverse COVID-19 outcomes. It has been suggested that pre-existing endothelial dysfunction and microvascular disease in diabetes will exacerbate the vascular insults associated with COVID-19 and thus lead to increased severity of COVID-19 infection. In this article, we evaluate the current evidence exploring the impact of microvascular complications, in the form of diabetic retinopathy and nephropathy, in individuals with COVID-19 and diabetes. Future insights gained from exploring the microvascular injury patterns and clinical outcomes may come to influence care delivery algorithms for either of these conditions.

COVID-19 and the hidden threat of diabetic microvascular complications

The coronavirus disease 2019 (COVID-19) pandemic affected at least 200 million individuals worldwide and resulted in nearly 5 million deaths as of October 2021. According to the latest data from the International Diabetes Federation (IDF) in 2021, the diabetes pandemic has affected 537 million people and is associated with 6.7 million deaths. Given the high prevalence of both diabetes and COVID-19 and common pathological outcomes, a bidirectional relationship could have a catastrophic outcome. The increased risk of COVID-19 in those with obesity and diabetes and higher morbidity and mortality has received considerable attention. However, little attention has been given to the relationship between COVID-19 and microvascular complications. Indeed, microvascular complications are associated with an increased risk of cardiovascular disease (CVD) and mortality in diabetes. This review assesses the evidence for an association between diabetic microvascular complications (neuropathy, nephropathy, and retinopathy) and COVID-19. It draws parallels between the pathological changes occurring in the microvasculature in both diseases and assesses whether microvascular disease is a prognostic factor for COVID-19 outcomes in diabetes.

Small fiber neuropathy in the cornea of Covid-19 patients associated with the generation of ocular surface disease

Purpose

To describe the association between Sars-CoV-2 infection and small fiber neuropathy in the cornea identified by in vivo corneal confocal microscopy.

Methods

Twenty-three patients who had overcome COVID-19 were recruited to this observational retrospective study. Forty-six uninfected volunteers were also recruited and studied as a control group. All subjects were examined under in vivo confocal microscopy to obtain images of corneal subbasal nerve fibers in order to study the presence of neuroma-like structures, axonal beadings and dendritic cells. The Ocular Surface Disease Index (OSDI) questionnaire and Schirmer tear test were used as indicators of Dry Eye Disease (DED) and ocular surface pathology.

Results

Twenty-one patients (91.31%) presented alterations of the corneal subbasal plexus and corneal tissue consistent with small fiber neuropathy. Images from healthy subjects did not indicate significant nerve fiber or corneal tissue damage. Eight patients reported increased sensations of ocular dryness after COVID-19 infection and had positive DED indicators. Beaded axons were found in 82.60% of cases, mainly in patients reporting ocular irritation symptoms. Neuroma-like images were found in 65.22% patients, more frequently in those with OSDI scores >13. Dendritic cells were found in 69.56% of patients and were more frequent in younger asymptomatic patients. The presence of morphological alterations in patients up to 10 months after recovering from Sars-CoV-2 infection points to the chronic nature of the neuropathy.

Conclusions

Sars-CoV-2 infection may be inducing small fiber neuropathy in the ocular surface, sharing symptomatology and morphological landmarks with DED and diabetic neuropathy.

Neuropathy in COVID-19 associated with dysbiosis-related inflammation

Although COVID-19 affects mainly lungs with a hyperactive and imbalanced immune response, gastrointestinal and neurological symptoms such as diarrhea and neuropathic pains have been described as well in patients with COVID-19. Studies indicate that gut-lung axis maintains host homeostasis and disease development with the association of immune system, and gut microbiota is involved in the COVID-19 severity in patients with extrapulmonary conditions. Gut microbiota dysbiosis impairs the gut permeability resulting in translocation of gut microbes and their metabolites into the circulatory system and induce systemic inflammation which, in turn, can affect distal organs such as the brain. Moreover, gut microbiota maintains the availability of tryptophan for kynurenine pathway, which is important for both central nervous and gastrointestinal system in regulating inflammation. SARS-CoV-2 infection disturbs the gut microbiota and leads to immune dysfunction with generalized inflammation. It has been known that cytokines and microbial products crossing the blood-brain barrier induce the neuroinflammation, which contributes to the pathophysiology of neurodegenerative diseases including neuropathies. Therefore, we believe that both gut-lung and gut-brain axes are involved in COVID-19 severity and extrapulmonary complications. Furthermore, gut microbial dysbiosis could be the reason of the neurologic complications seen in severe COVID-19 patients with the association of dysbiosis-related neuroinflammation. This review will provide valuable insights into the role of gut microbiota dysbiosis and dysbiosis-related inflammation on the neuropathy in COVID-19 patients and the disease severity.

Corneal confocal microscopy identifies corneal nerve fibre loss and increased dendritic cells in patients with long COVID

Background/Aims

Long COVID is characterised by a range of potentially debilitating symptoms which develop in at least 10% of people who have recovered from acute SARS-CoV-2 infection. This study has quantified corneal sub-basal nerve plexus morphology and dendritic cell (DC) density in patients with and without long COVID.

Methods

Forty subjects who had recovered from COVID-19 and 30 control participants were included in this cross-sectional comparative study undertaken at a university hospital. All patients underwent assessment with the National Institute for Health and Care Excellence (NICE) long COVID, Douleur Neuropathique 4 (DN4) and Fibromyalgia questionnaires, and corneal confocal microscopy (CCM) to quantify corneal nerve fibre density (CNFD), corneal nerve branch density (CNBD), corneal nerve fibre length (CNFL), and total, mature and immature DC density.

Results

The mean time after the diagnosis of COVID-19 was 3.7±1.5 months. Patients with neurological symptoms 4 weeks after acute COVID-19 had a lower CNFD (p=0.032), CNBD (p=0.020), and CNFL (p=0.012), and increased DC density (p=0.046) compared with controls, while patients without neurological symptoms had comparable corneal nerve parameters, but increased DC density (p=0.003). There were significant correlations between the total score on the NICE long COVID questionnaire at 4 and 12 weeks with CNFD (ρ=−0.436; p=0.005, ρ=−0.387; p=0.038, respectively) and CNFL (ρ=−0.404; p=0.010, ρ=−0.412; p=0.026, respectively).

Conclusion

Corneal confocal microscopy identifies corneal small nerve fibre loss and increased DCs in patients with long COVID, especially those with neurological symptoms. CCM could be used to objectively identify patients with long COVID.

[Polyneuropathies during COVID-19 epidemics]

Our review article aimed for analysis of pathogenesis, diagnostyics and treatment of polyneuropathies manifesting in the course of COVID-19. The reasons for hyposmia and taste disturbances are considered in the subjects with this coronavirus infection as well as relationship between these clinical manifestations and severity of the viral infection. Special attention is given to description of autoimmune mechanisms of Guillain-Barré syndrome and polyneuropathies of critical conditions associated with COVID-19. Some data report about clinical deterioration of diabetic and alcoholic neuropathy during the SARS-CoV-2 infection. Inclusion of group B vitamins, together with C and D vitamins, is recommended to the schedules of combined treatment for polyneuropathies in these patients. Early diagnostics of polyneuropathies, especially, Guillain-Barré syndrome, is required during COVID-19 pandemics, thus helping to administer rational therapy and promoting better quality of life in the patients.

Association Between Olfactory Dysfunction and Critical Illness and Mortality in COVID-19: A Meta-analysis

LEVEL OF EVIDENCE

4.

SARS-CoV-2-Associated Guillain-Barre Syndrome Obscured by Diabetes Mellitus Peripheral Neuropathy

Multiple neurological complications, including Guillain-Barre syndrome (GBS), have been reported in association with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak. GBS has well-known associations with viruses such as influenza, human immunodeficiency virus, Zika, severe acute respiratory syndrome, Middle East respiratory syndrome, Epstein-Barr virus, and cytomegalovirus. Till date, there have been around 50 distinct published cases of GBS occurring concurrently or shortly after SARS-CoV-2 infection. This report describes the case of a 53-year-old male who presented with bilateral extremity paresthesias two weeks after a positive SARS-CoV-2 test. His symptoms were originally thought to be due to underlying diabetic peripheral neuropathy, but as they progressed, he was eventually diagnosed with SARS-CoV-2-associated GBS. Though GBS may not be a common sequelae of SARS-CoV-2 infection, the prevalence of diabetes mellitus-associated peripheral neuropathy is high enough to warrant awareness and prompt recognition of neurological symptoms that deviate from the baseline in individuals with recent, confirmed SARS-CoV-2 infection.