Alcohol-Induced Neuropathy in Chronic Alcoholism: Causes, Pathophysiology, Diagnosis, and Treatment Options

Pain in comorbid alcohol use disorder and HIV: A network meta-analysis study

Alcohol use is prevalent among people with HIV (PWH). PWH often experience pain (said discomfort) and use alcohol to combat pain. We reported that short-term alcohol exposure exerts analgesic effect. Prolonged exposure is known to result in chronic pain. We hypothesize that alcohol exposure, either in-vivo for macaques or in-silico simulation exposure onto differentially expressed genes (DEGs) from HIV-1Tg rats and HIV patients, exacerbates discomfort in PWH. To substantiate this hypothesis, we analyzed genomic data collected from three brain datasets including the hippocampus of alcohol-exposed Macaca mulatta (GSE69685), HIV-1Tg rats (GSE47474), and post-mortem brain tissue of HIV-positive patients (GSE28160). Ingenuity Pathway Analysis (IPA)-Core Analysis revealed activation of neuroinflammation, neuropathic pain signaling pathways, and the inhibition of opioid signaling as well as in the increase of neuromuscular disease with neuropathy in Macaca mulatta exposed to binge EtOH and SIV infection. IPA-Core Analysis of the DEGs from HIV-1Tg rats, a rat model that mimics HIV patients on cART, possessing 7 of 9 HIV viral proteins, showed activation of neuroinflammation, neuropathic pain signaling pathways. IPA-Core Analysis of the DEGs from HIV patients showed activation of neuroinflammation and inhibition of neuropathic pain and increase in neuromuscular disease with neuropathy. To study the impact of alcohol exposure in HIV-1Tg rats and HIV patients, in-silico simulation of ethanol (EtOH) treatment mimicking exposure of alcohol onto the DEGs in response to HIV viral proteins in HIV-1Tg rats and HIV infection in HIV patients enhanced discomfort and increased neuromuscular diseases. These molecules showed significant modulation by simulated alcohol exposure, further supporting the link between alcohol use and heightened pain in PWH. Taking together, our findings suggest that alcohol consumption and HIV promote pain via modulating signaling pathways including neuroinflammation, and neuropathic pain signaling pathways and by disease like neuromuscular disease with neuropathy.

Adolescent alcohol exposure promotes mechanical allodynia and alters synaptic function at inputs from the basolateral amygdala to the prelimbic cortex

Binge drinking is common among adolescents despite mounting evidence linking it to various adverse health outcomes that include heightened pain perception. The prelimbic (PrL) cortex is vulnerable to insult from adolescent alcohol exposure and receives input from the basolateral amygdala (BLA) while sending projections to the ventrolateral periaqueductal gray (vlPAG) - two brain regions implicated in nociception. In this study, adolescent intermittent ethanol (AIE) exposure was carried out in male and female rats using a vapor inhalation procedure. Assessments of mechanical and thermal sensitivity revealed that AIE exposure-induced protracted mechanical allodynia. To investigate synaptic function at BLA inputs onto defined populations of PrL neurons, retrobeads and viral labeling were combined with optogenetics and slice electrophysiology. Recordings from retrobead labeled cells in the PrL revealed AIE reduced BLA-driven feedforward inhibition of neurons projecting from the PrL to the vlPAG, resulting in augmented excitation/inhibition (E/I) balance and increased intrinsic excitability. Consistent with this finding, recordings from virally tagged PrL parvalbumin interneurons (PVINs) demonstrated that AIE exposure reduced both E/I balance at BLA inputs onto PVINs and PVIN intrinsic excitability. These findings provide compelling evidence that AIE alters synaptic function and intrinsic excitability within a prefrontal nociceptive circuit.

Alcohol and alcoholism associated neurological disorders: Current updates in a global perspective and recent recommendations

Alcohol use disorder (AUD) is a medical condition that impairs a person's ability to stop or manage their drinking in the face of negative social, occupational, or health consequences. AUD is defined by the National Institute on Alcohol Abuse and Alcoholism as a "severe problem". The central nervous system is the primary target of alcohol's adverse effects. It is crucial to identify various neurological disorders associated with AUD, including alcohol withdrawal syndrome, Wernicke-Korsakoff syndrome, Marchiafava-Bignami disease, dementia, and neuropathy. To gain a better understanding of the neurological environment of alcoholism and to shed light on the role of various neurotransmitters in the phenomenon of alcoholism. A comprehensive search of online databases, including PubMed, EMBASE, Web of Science, and Google Scholar, was conducted to identify relevant articles. Several neurotransmitters (dopamine, gamma-aminobutyric acid, serotonin, and glutamate) have been linked to alcoholism due to a brain imbalance. Alcoholism appears to be a complex genetic disorder, with variations in many genes influencing risk. Some of these genes have been identified, including two alcohol metabolism genes, alcohol dehydrogenase 1B gene and aldehyde dehydrogenase 2 gene, which have the most potent known effects on the risk of alcoholism. Neuronal degeneration and demyelination in people with AUD may be caused by neuronal damage, nutrient deficiencies, and blood brain barrier dysfunction; however, the underlying mechanism is unknown. This review will provide a detailed overview of the neurobiology of alcohol addiction, followed by recent studies published in the genetics of alcohol addiction, molecular mechanism and detailed information on the various acute and chronic neurological manifestations of alcoholism for the Future research.

Proteomic Analysis of Chronic Binge Alcohol-Induced Hippocampal and Anterior Cingulate Cortex Neuroadaptations in Simian Immunodeficiency Virus (SIV)-Infected Female Rhesus Macaques

Human immunodeficiency virus (HIV) infection produces neurological comorbidities including HIV-associated neurocognitive disorder (HAND) and chronic pain. HIV also increases the risk of developing an alcohol use disorder (AUD). With the rising prevalence of AUD in women and people with HIV (PWH), understanding the neurobiological impact of alcohol in these populations is important. We examined proteomic alterations in the hippocampus and anterior cingulate cortex (ACC), brain regions critical for cognition and affective pain, in a female rhesus macaque model of chronic binge alcohol administration and SIV infection. Adult female rhesus macaques received either chronic binge alcohol (CBA, 13-14 g/kg/week of alcohol) or water (VEH) via gastric catheter. All animals were inoculated with simian immunodeficiency virus (SIVmac251) and treated with antiretroviral therapy (ART). Brain samples were processed for proteomic analysis, and quantitative discovery-based proteomics identified differentially expressed proteins in both brain regions comparing CBA treatment to VEH. Ingenuity Pathway Analysis (IPA) was also used to predict pathway activation. CBA significantly altered 147 proteins in the hippocampus and 176 proteins in the ACC. IPA revealed alterations in 39 canonical pathways in the hippocampus and 62 canonical pathways in the ACC. Fourteen common canonical pathways were enriched in both regions, including synaptogenesis and protein kinase A (PKA) signaling. These discoveries expand our understanding of how alcohol alters proteins of critical signaling pathways in vulnerable brain regions in the context of SIV/HIV infection and may lead to the development of new pharmacological treatment avenues for neurological dysfunction in women with HIV who use alcohol.

Adolescent alcohol exposure promotes mechanical allodynia and alters synaptic function at inputs from the basolateral amygdala to the prelimbic cortex

Binge drinking is common among adolescents despite mounting evidence linking it to various adverse health outcomes that include heightened pain perception. The prelimbic (PrL) cortex is vulnerable to insult from adolescent alcohol exposure and receives input from the basolateral amygdala (BLA) while sending projections to the ventrolateral periaqueductal gray (vlPAG) - two brain regions implicated in nociception. In this study, adolescent intermittent ethanol (AIE) exposure was carried out in male and female rats using a vapor inhalation procedure. Assessments of mechanical and thermal sensitivity revealed that AIE exposure induced protracted mechanical allodynia. To investigate synaptic function at BLA inputs onto defined populations of PrL neurons, retrobeads and viral labelling were combined with optogenetics and slice electrophysiology. Recordings from retrobead labelled cells in the PrL revealed AIE reduced BLA driven feedforward inhibition of neurons projecting from the PrL to the vlPAG, resulting in augmented excitation/inhibition (E/I) balance and increased intrinsic excitability. Consistent with this finding, recordings from virally tagged PrL parvalbumin interneurons (PVINs) demonstrated that AIE exposure reduced both E/I balance at BLA inputs onto PVINs and PVIN intrinsic excitability. These findings provide compelling evidence that AIE alters synaptic function and intrinsic excitability within a prefrontal nociceptive circuit.

Decrypting the multifaceted peripheral neuropathy based on molecular pathology and therapeutics: a comprehensive review

CONTEXT

Peripheral neuropathy (PN) is a multifaceted complication characterized by nerve damage due to oxidative stress, inflammatory mediators, and dysregulated metabolic processes. Early PN manifests as sensory changes that develop progressively in a "stocking and glove" pattern.

METHODS AND MECHANISMS

A thorough review of literature has been done to find the molecular pathology, clinical trials that have been conducted to screen the effects of different drugs, current treatments and novel approaches used in PN therapy. Diabetic neuropathy occurs due to altered protein kinase C activity, elevated polyol pathway activity in neurons, and Schwann cells-induced hyperglycemia. Other causes involve chemotherapy exposure, autoimmune ailments, and chronic ethanol intake.

CONCLUSION

Symptomatic treatments for neuropathic pain include use of tricyclic antidepressants, anticonvulsants, and acetyl-L-carnitine. Patients will have new hope if clinicians focus on novel therapies including gene therapy, neuromodulation techniques, and cannabidiol as an alternative to traditional medications, as management is still not ideal.

Prevalence of alcohol use among U.S. older adults with pain: A scoping review

The majority of older adults in the United States (U.S.) have been bothered by pain in the past month and over one-third report pain that has persisted or recurred for >3 months (i.e., chronic pain). Accumulating evidence indicates that behavioral factors, such as alcohol use, can influence the impact of pain on health and functioning in older adults. However, most studies exploring the prevalence of alcohol use among individuals with pain have not focused on older adults, specifically. Therefore, the goal of this scoping review was to examine what is known about the prevalence of alcohol use in older adults with pain. Relevant articles published prior to April 2024 were identified through a comprehensive search strategy, developed in collaboration with content experts and a medical librarian. A total of 13 studies met inclusion criteria for this paper. Results indicated that 53-64 % of older adults with pain reported alcohol consumption, 11-28 % engaged in hazardous patterns of alcohol use, and 1-10 % had a documented alcohol use diagnosis. Moreover, there is evidence that pain severity is positively associated with likelihood of alcohol consumption among older adults. These findings are worrisome given evidence that alcohol use has been shown to lead to poorer pain outcomes, and that older adults may be at risk for experiencing detrimental alcohol-related effects at comparatively low doses, given unique challenges faced by this population (e.g., high rates of multimorbidity/polypharmacy). Collectively, findings underscore the need for enhanced assessment and treatment of alcohol use in older adults with pain.

[Opticopathies in the differential diagnosis of retinal diseases - part 1]

Due to the close anatomical, functional and trophic relationships between the optic nerve and retina, a wide variety of diseases affecting both structures have reciprocal effects on each other, which must be considered in the differential diagnosis to avoid misdiagnosis. Therefore, it is essential to assess pathological changes in both structures in context to differentiate the type and location of the primary lesion from its consequences, as well as to correctly classify coincidences and disease-specific lesion patterns in both organ components.This article highlights the typical symptom constellations and lesion patterns of optic neuropathies and retinopathies. An attempt is made to identify the reciprocal characteristic relationships of the respective lesions in both structures in various disease groups, as well as to present their respective roles in the differential diagnosis.In the first part of the article, typical optic neuropathies in the context of various syndromic and non-syndromic retinal dystrophies are initially examined. Subsequently, the relationships between different hereditary and acquired mitochondriopathic optic neuropathies and possible accompanying retinal changes are analysed, and their pathogenesis and relevant differential diagnoses are discussed.It is demonstrated and exemplified how important it is in general, but also specifically in regard to the disease groups discussed in this article, to have a careful and targeted diagnostic approach in each case, considering both the retinal and optic nerve findings, in order to avoid misdiagnosis.

Communicating pain: emerging axonal signaling in peripheral neuropathic pain

Peripheral nerve damage often leads to the onset of neuropathic pain (NeuP). This condition afflicts millions of people, significantly burdening healthcare systems and putting strain on families' financial well-being. Here, we will focus on the role of peripheral sensory neurons, specifically the Dorsal Root Ganglia neurons (DRG neurons) in the development of NeuP. After axotomy, DRG neurons activate regenerative signals of axons-soma communication to promote a gene program that activates an axonal branching and elongation processes. The results of a neuronal morphological cytoskeleton change are not always associated with functional recovery. Moreover, any axonal miss-targeting may contribute to NeuP development. In this review, we will explore the epidemiology of NeuP and its molecular causes at the level of the peripheral nervous system and the target organs, with major focus on the neuronal cross-talk between intrinsic and extrinsic factors. Specifically, we will describe how failures in the neuronal regenerative program can exacerbate NeuP.

Diagnosing Peripheral Neuropathy in Patients With Alcohol Use Disorder

With the lack of distinctive features or diagnostic biomarkers, peripheral neuropathy in patients with excessive alcohol consumption is often misdiagnosed as alcohol-related neuropathy, influenced by underlying implicit and explicit bias against patients with an alcohol use disorder (AUD). Alcohol-related nerve toxicity has been attributed to various underlying mechanisms including altered trophic factor signaling, disrupted protein synthesis, free radical injury from oxidative stress, and nutritional deficiencies. Alcohol-related neuropathy has been most described as mild but painful, predominantly affecting small sensory fibers, without major functional limitations. This phenotype may be indistinguishable from a chronic idiopathic axonal neuropathy; hence, a causal relationship with AUD cannot be established with certainty. Searching for alternative causes is warranted, especially in patients with a more severe or rapidly progressive peripheral neuropathy. At the same time, there is underlying implicit and explicit bias in the medical field against patients with AUDs. Patients often experience devaluation and stigma, which can affect their adherence to medical advice and may lead to social reclusion. Addressing biases in health care workers is crucial to ensure that individuals receive proper care and are not subjected to stigmatization. In this article, we present a comprehensive narrative review of the literature on the clinical presentation and underlying pathomechanisms of alcohol-related peripheral neuropathy, raising awareness of the bias in the medical field against patients with AUD.

Etiological profile of peripheral neuropathies in an academic hospital in southern Morocco

Background

Peripheral neuropathies constitute a common complaint in general and neurology practice, and are a source of handicap to patients. Epidemiological data in the Middle East and North Africa region as well as in the African continent are sparse. Nevertheless, regional etiological profiles are crucial in navigating the diagnostic maze of neuropathies. This study outlines the etiological profile of peripheral neuropathies in an academic hospital in southern Morocco.

Results

A total of 180 cases were recorded in a span of 8 years (22.5 cases per year). The mean age of patients was 42.35 years. Male gender was predominant (68.88%), with a sex ratio of 2.2. Motor symptoms were the most frequently reported (86.6%). The axonal form (40.56%) was the most frequently encountered electrophysiologic form. The most frequent etiologies in the study were diabetes (26.7%), acute polyradiculoneuropathy (26.1%) and amyotrophic lateral sclerosis (16.1%). Alcohol neuropathy was found in 2.2% of the cohort. No cause was found in 5% of cases. Outcome was mostly favorable under treatment, although 10 deaths due to acute polyradiculoneuropathy were recorded (mortality = 21.3%).

Conclusions

Knowledge of the etiological profile of peripheral neuropathies should guide clinicians to an early diagnosis and aid in an adapted management of patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41983-022-00531-4.

Toxic and Nutritional Optic Neuropathies—An Updated Mini-Review

Optic neuropathies constitute a group of conditions with various etiologies and might be caused by different factors; we can distinguish the genetic and acquired causes of optic neuropathies. Even though the symptoms are not highly specific, this condition is primarily characterized by unilateral or bilateral vision loss with worsening color detection. The loss may be acute or gradual depending on the causation. In this article, we included a specification of toxic optic neuropathy (TON) mainly triggered by alcohol abuse and also the usage of other substances, including drugs or methanol, as well as intoxication by metals, organic solvents, or carbon dioxide. Nutritional deficiencies, vitamin absorption disorder, and anemia, which usually appear during excessive alcohol intake, and their effect on the etiology of the optic neuropathy have been likewise discussed.