Methanol Poisoning as an Acute Toxicological Basal Ganglia Lesion Model: Evidence from Brain Volumetry and Cognition

Aspartame-induced cognitive dysfunction: Unveiling role of microglia-mediated neuroinflammation and molecular remediation

Aspartame, an artificial sweetener, is consumed by millions of people globally. There are multiple reports of aspartame and its metabolites affecting cognitive functions in animal models and humans, which include learning problems, headaches, seizures, migraines, irritable moods, anxiety, depression, and insomnia. These cognitive deficits and associated symptoms are partly attributed to dysregulated excitatory and inhibitory neurotransmitter balance due to aspartate released from aspartame, resulting in an excitotoxic effect in neurons, leading to neuronal damage. However, microglia, a central immunocompetent cell type in brain tissue and a significant player in inflammation can contribute to the impact. Microglia rapidly respond to changes in CNS homeostasis. Aspartame consumption might affect the microglia phenotype directly via methanol-induced toxic effects and indirectly via aspartic acid-mediated excitotoxicity, exacerbating symptoms of cognitive decline. Long-term oral consumption of aspartame thus might change microglia's phenotype from ramified to activated, resulting in chronic or sustained activation, releasing excess pro-inflammatory molecules. This pro-inflammatory surge might lead to the degeneration of healthy neurons and other glial cells, impairing cognition. This review will deliberate on possible links and research gaps that need to be explored concerning aspartame consumption, ecotoxicity and microglia-mediated inflammatory cognitive impairment. The study covers a comprehensive analysis of the impact of aspartame consumption on cognitive function, considering both direct and indirect effects, including the involvement of microglia-mediated neuroinflammation. We also propose a novel intervention strategy involving tryptophan supplementation to mitigate cognitive decline symptoms in individuals with prolonged aspartame consumption, providing a potential solution to address the adverse effects of aspartame on cognitive function.

Höffding step and beyond: The impact of visual sensory impairment on cognitive performance in neuropsychological testing of survivors of acute methanol poisoning

BACKGROUND

Sensory deficits can result in limitations regarding how well neuropsychological test findings can be interpreted. Only a few studies have investigated the influence of vision alteration on neuropsychological tests. In 2012 the Czech Republic experienced mass methanol poisoning. Methanol metabolites cause histotoxic hypoxia to the optic nerve.

OBJECTIVE

In the current study, the effect of the toxic damage on the parts of the visual pathway on visual and non-visual neuropsychological measures was investigated using electrophysiological methods (visual evoked potential (VEP) and optical coherence tomography (OCT) with retinal nerve fibre layer (RNFL) thickness measurement.

METHODS

53 individuals who experienced methanol poisoning participated in this research (76% men; ages 24 to 74 years, mean = 43.8±14.6 years; education 11.9±1.4 years). Each participant underwent comprehensive neurological, ophthalmological, and neuropsychological examinations.

RESULTS

The results of mixed-effect models revealed significant small to a medium association between the Stroop test weak interference and Grooved Pegboard with the left eye global, nasal and temporal RNFL thickness. Also, medium associations between the Finger Tapping test and the Stroop test weak interference and OS temporal RNFL, right eye temporal RNFL, and the latency P1 of VEP in the left eye were significant.

CONCLUSION

The results of this study found a small to medium association (r = .15- .33; p = .010- .046) between RNFL thickness and cognitive visual test performance. Careful interpretation is suggested regarding results obtained from visual tests of the executive or motor functioning with participants with RNFL decrease or other types of early visual processing damage.

Acute methanol poisoning with bilateral diffuse cerebral hemorrhage: A case report

BACKGROUND

Acute methanol poisoning (AMP) is a systemic disease that mainly affects the central nervous system and is characterized by ocular damage and metabolic acidosis. If appropriate treatments are inadequate or delayed, the mortality can exceed 40%. As the most serious complication, cerebral hemorrhage is rare with reported prevalence of 7%-19%.

CASE SUMMARY

A 62-year-old man drank liquor mixed with 45% methanol and 35% alcohol. His vision blurred 10 h later and he fell into coma in another 9 h. Serum toxicological tests were performed immediately, and continuous renal replacement therapy (CRRT) was carried out as the lactic acid exceeded 15 mmol/L and blood pH was 6.78. In addition, the toxicological report revealed 1300.5 μg/mL of methanol in serum and 1500.2 μg/mL in urine. After 59 h of CRRT, the methanol level decreased to 126.0 μg/mL in serum and 151.0 μg/mL in urine. However, the patient was still unconscious and his pupillary light reflex was slow. Computed tomography showed hemorrhage in the left putamen. After 16 d of life support treatment, putamen hemorrhage developed into diffuse symmetric intracerebral hemorrhage. In the end, his family gave up and the patient was discharged, and died in a local hospital.

CONCLUSION

Cerebral hemorrhage requires constant vigilance during the full course of treatment for severe cases of AMP.

MicroRNA-124 modulates neuroinflammation in acute methanol poisoning rats via targeting Krüppel-like factor-6

Microglia activation-stimulated neuroinflammation exerts functionally in neurodegenerative diseases like brain injury. Acute methanol poisoning (AMP) is a crucial cause of death and morbidity that possibly leads to neuroinflammation. Studies have manifested that miRNAs can modulate microglia activation to mediate neuroinflammation. Nevertheless, the role of miR-124 in AMP-stimulated neuroinflammation is uncertain. This research was to explore the action of miR-124 in AMP-stimulated neuroinflammation and its molecular mechanism. The study findings indicated that AMP accelerated microglia activation and stimulated inflammation and oxidative stress in brain tissue of rats. MiR-124 expression was lowered in AMP rats, while KLF6 expression was elevated. Elevated miR-124 or repressed KLF6 increased the number of CD206⁺ cells and decreased the number of CD68⁺ cells, as well as restrained inflammation and NF-κB phosphorylation and induced superoxide dismutase, Nrf2/HO-1, and M2 polarization. MiR-124 modulated microglia activation via targeting KLF6. AMP repressed neuronal viability and enhanced neuronal apoptosis. Suppression of miR-124 further promoted AMP-induced damage to neurons, while inhibition of KLF6 turned around this phenomenon. Anyway, our study demonstrated that miR-124 accelerates M2 polarization via targeting KLF6 to ameliorate AMP-stimulated neuronal damage.

Fatal methanol poisoning with different clinical and autopsy findings: Case report and literature review

Methanol poisoning is responsible for high morbidity and mortality, and the elevated concentration of methanol in the body is the major criteria for forensic diagnosis of methanol poisoning. However, in cases with lower methanol concentrations, diagnosis is mainly dependent on highly variable postmortem manifestations.Herein, we report a fatal methanol poisoning cases that two subjects ingested the same amount of methanol simultaneously, yet the subject one presented only non-specific gastrointestinal and mild central nervous system symptoms, while the other subject exhibited typical toxic manifestations with the exception of visual compromise. In autopsy, subject number 1 did not show typical pathological changes caused by methanol poisoning, except for the elevated levels of methanol in body fluids. On the contrary, bilateral basal ganglia hemorrhage and necrosis caused by methanol-induced brain lesion was observed in case number 2. Due to the complex and multifactorial process of methanol intoxication, many factors, including comprehensive autopsy, quantitative detection of methanol and formic acid, and genotype analysis, participate in its metabolism and toxicity, and can impact the clinical symptoms, prognosis and postmortem manifestations. Therefore, a combination of multiple diagnosis methods may more accurately contribute to the forensic diagnosis of methanol poisoning and should be tailored on an individual basis. This case report also reviews forensic diagnosis literature on methanol poisoning to provide a reference for forensic pathologists.

Cognitive changes after methanol exposure: Longitudinal perspective

BACKGROUND

From 2012 to 2013, there was a mass methanol poisoning outbreak in the Czech Republic. Methanol metabolites can cause specific lesions in the basal ganglia, subcortical white matter, and optic nerve. However, long-term sequelae of methanol poisoning on cognitive functioning have not yet been explored. The current study aimed to delineate the cognitive changes observed in methanol poisoning survivors in the seven years since 2012.

METHODS

We conducted longitudinal research with repeated measurements in 2013, 2015, 2017 and 2019 to evaluate the development of cognitive changes after acute methanol poisoning. A complex neuropsychological battery consisted of tests of global cognitive performance, auditory and visual attention, executive functioning, learning and memory, working memory and language. Motor performance measures and depression scale were also included.

RESULTS

Repeated measures ANOVA of four measurements with post-hoc tests showed a significant decline in the Mini-Mental State Examination (p = 0.007); however, other parameters were not significantly decreasing. In comparison to normative values, the z-scores for each test measure, in the memory domain, in particular, ranged from 43 to 60 % of participants below 1.5 SD. Mild to severe depression levels from the onset of poisoning improved during the seven years, returning to normal in up to 27 % of participants.

CONCLUSION

In the longitudinal perspective, methanol poisoning survivors manifest progressive global cognitive decline and overall persistent below-average cognitive performance with some improvements in the frequency of depressive symptoms.

Estimation of long-term costs of postacute care in survivors of the methanol poisoning outbreak

OBJECTIVES

To fill the existing research gap related to long-term costs of postacute care in methanol poisoning survivors, healthcare cost for 6 years after the outbreak has been modelled and estimated.

DESIGN

In a prospective longitudinal cohort study, data collected from 55 survivors of the Czech methanol mass poisoning outbreak in 2012 were collected in four rounds (5 months, then 2, 4 and 6 years after the discharge) in the General University Hospital in Prague according to the same predefined study protocol. The collected data were used to inform the cost model.

SETTING AND PARTICIPANTS

All 83 patients discharged from a hospital poisoning treatment after the 2012 methanol outbreak were informed about the study and invited to participate. Fifty-five patients (66%) gave their written informed consent and were followed until their death or the last follow-up 6 years later. The costs were modelled from the Czech healthcare service (general health insurance) perspective.

MAIN OUTCOME MEASURES

Long-term national budget impact of the methanol poisoning outbreak, frequencies of sequelae and their average costs.

RESULTS

The postacute cost analysis concentrated on visual and neurological sequelae that were shown to be dominant. Collected data were used to create process maps portraying gradual changes in long-term sequelae over time. Individual process maps were created for the central nervous system, peripheral nervous system, sequelae detected during eye examinations and sequelae concerning the visual evoked potentials. Based on the process maps the costs of the postacute outpatient care were estimated.

CONCLUSIONS

In 2013-2019 the highest costs per patient related to postacute care were found in the first year; the average costs decreased afterwards, and remained almost constant for the rest of the studied period of time. These costs per patient ranged from CZK4142 in 2013 to CZK1845 in 2018, when they raised to CZK2519 in 2019 again.

Inpatient Burden and Mortality of Methanol Intoxication in the United States

BACKGROUND

This study aimed to assess inpatient prevalence, characteristics, outcomes, and resource utilization of hospitalization for methanol intoxication in the United States.

MATERIALS AND METHODS

A total of 603 hospitalized patients with a primary diagnosis of methanol intoxication from 2003 to 2014 were identified in the National Inpatient Sample database. The inpatient prevalence, clinical characteristics, treatments, outcomes, resource utilization, were investigated. Multivariable logistic regression was performed to identify factors independently associated with in-hospital mortality.

RESULTS

The overall inpatient prevalence of methanol intoxication among hospitalized patients was 6.4 cases per 1,000,000 admissions in the United States. The mean age was 38±18 (range 0-86) years. 44% used methanol for suicidal attempts. 20% of admissions required mechanical ventilation, and 40% required renal replacement therapy. The three most common complications were metabolic acidosis (44%), hypokalemia (18%), and visual impairment or optic neuritis (8%). The three most common end-organ failures were renal failure (22%), respiratory failure (21%), and neurological failure (17%). 6.5% died in the hospital. Factors associated with increased in-hospital mortality included alcohol drinking, hypernatremia, renal failure, respiratory failure, circulatory failure, and neurological failure. The mean length of hospital stay was 4.0 days. The mean hospitalization cost per patient was $43,222 CONCLUSION: The inpatient prevalence of methanol intoxication in the United States was 6.4 cases per 1,000,000 admissions. The risk of in-hospital mortality mainly depended on the number of end-organ failures.

Efficiency of 123I-ioflupane SPECT as the marker of basal ganglia damage in acute methanol poisoning: 6-year prospective study

CONTEXT

Investigate whether ¹²³I-ioflupane SPECT (DaT SPECT) has the potential as a marker of basal ganglia damage in acute methanol poisoning.

METHODS

Prospective, single-centre, cohort study of patients with confirmed methanol poisoning was conducted. DaT SPECT was performed twice with semi-quantification using DaTQUANT^TM and MRI-based volumetry was calculated. Specific binding ratios (SBR) of striatum, caudate nucleus, and putamen were correlated with laboratory parameters of outcome, volumetric data, and retinal nerve fibres layer (RNFL) thickness measurements.

RESULTS

Forty-two patients (mean age 46.3 ± 4.2 years; 8 females), including 15 with MRI-detected putamen lesions (group I) and 27 patients with intact putamen (group II), underwent DaT SPECT. Volumetry was calculated in 35 of the patients assessed. SBR values for the left putamen correlated with putamen volume (r = 0.665; p < 0.001). Decreased bilateral SBR values were determined for the striatum and the putamen, but not for the nucleus caudate, in group I (p < 0.05). Significant correlation was observed between the SBR of the posterior putamen and arterial blood pH (r = 0.574; p < 0.001) and other toxicological parameters of severity of poisoning/outcome including serum lactate, glucose, and creatinine concentrations (p < 0.05). The SBR of the posterior putamen positively correlated with the global RNFL thickness (p < 0.05). ROC analysis demonstrated a significant discriminatory ability of SBR of the posterior putamen with AUC = 0.753 (95%CI 0.604-0.902; p = 0.007). The multivariate regression model demonstrated that arterial blood pH, age, and gender were the most significant factors associated with SBR of the posterior putamen.

CONCLUSION

DaT SPECT demonstrates significant potential for the diagnosis of methanol-induced basal ganglia damage.

MRI-based brain volumetry and retinal optical coherence tomography as the biomarkers of outcome in acute methanol poisoning

BACKGROUND

Basal ganglia lesions are typical findings on magnetic resonance imaging (MRI) of the brain in survivors of acute methanol poisoning. However, no data are available on the association between the magnitude of damaged brain regions, serum concentrations of markers of acute methanol toxicity, oxidative stress, neuroinflammation, and the rate of retinal nerve ganglion cell loss.

OBJECTIVES

To investigate the association between MRI-based volumetry of the basal ganglia, retinal nerve fibre layer (RNFL) thickness and prognostic laboratory markers of outcomes in acute methanol poisoning.

METHODS

MRI-based volumetry of putamen, nucleus caudatus and globus pallidus was performed and compared with laboratory parameters of severity of poisoning and acute serum markers of oxidative damage of lipids (8-isoprostan, MDA, HHE, HNE), nucleic acids (8-OHdG, 8-OHG, 5-OHMU), proteins (o-Thyr, NO-Thyr, Cl-Thyr) and leukotrienes (LTC4, LTD4, LTE4, LTB4), as well as with the results of RNFL measurements by optic coherence tomography (OCT) in 16 patients with acute methanol poisoning (Group I) and in 28 survivors of poisoning two years after discharge with the same markers measured within the follow-up examination (Group II). The control group consisted of 28 healthy subjects without methanol poisoning.

RESULTS

The survivors of acute methanol poisoning had significantly lower volumes of basal ganglia than the controls. The patients with MRI signs of methanol-induced toxic brain damage had significantly lower volumes of basal ganglia than those without these signs. A positive correlation was found between the volume of putamen and arterial blood pH on admission (r = 0.45; p = 0.02 and r = 0.44; p = 0.02 for left and right putamen, correspondingly). A negative correlation was present between the volumes of putamen and acute serum lactate (r = -0.63; p < 0.001 and r = -0.59; p = 0.01), creatinine (r = -0.53; p = 0.01 and r = -0.47; p = 0.01) and glucose (r = -0.55; p < 0.001 and r = -0.50; p = 0.01) concentrations. The volume of basal ganglia positively correlated with acute concentrations of markers of lipoperoxidation (8-isoprostan: r = 0.61; p < 0.05 and r = 0.59; p < 0.05 for left and right putamen, correspondingly) and inflammation (leukotriene LTB4: r = 0.61; p < 0.05 and r = 0.61; p < 0.05 for left and right putamen, correspondingly). The higher the volume of the basal ganglia, the higher the thickness of the RNFL, with the strongest positive association between global RNFL and the volume of putamen bilaterally (all p < 0.01). In the follow-up markers of oxidative stress and inflammation, only o-Thyr concentration negatively correlated with the volume of putamen bilaterally (r = -0.39; p < 0.05 and r = -0.37; p < 0.05 for left and right putamen, correspondingly).

CONCLUSION

In survivors of acute methanol poisoning with signs of toxic brain damage, the magnitude of affected areas correlated with acute parameters of severity of poisoning, markers of oxidative stress and neuroinflammation. There was a positive association between the basal ganglia volume and the thickness of RNFL, making OCT an important screening test and MRI-based volumetry the confirmative diagnostic method for the detection of CNS sequelae of methanol poisoning.

Health-related quality of life determinants in survivors of a mass methanol poisoning outbreak: six-year prospective cohort study

Purpose: The effect of acute methanol poisoning on the follow-up quality of life of survivors in mass poisoning outbreaks is not known. The objective of this is to study the impact of visual and central nervous system (CNS) sequelae of methanol poisoning on long-term health-related quality of life (QoL) of survivors, its clinical determinants, and dynamics.Materials and methods: A total of 54 patients with confirmed methanol poisoning (mean age 46.7 ± 13.4 years, 9 females) were examined consequently three times within six-year prospective cohort study and compared to 23 controls with the history of chronic alcohol abuse. The following tests were performed: SF-36 QoL questionnaire, visual evoked potentials (VEP) of optic nerve, ocular examination with retinal nerve fiber layer (RNFL) thickness measurement, brain magnetic resonance imaging (MRI), and biochemical and toxicological tests.Results: Acute methanol poisoning led to significant decrease in physical component summary (PCS) compared to PCS of age-adjusted controls (mean score with SD 46.8 ± 11.0 versus 52.3 ± 9.4 points; p = .003). In 17/40 (42.5%) patients with three rounds of examination, signs of severe disability (≤30 points in at least one score) were present six years after discharge, with negative dynamics of PCS score during the observation period. The patients with abnormal RNFL thickness had lower PCS (mean difference 10.5 points; 95%CI 3.5-17.5, p = .004) and mental component summary score (9.5 points; 95%CI 1.9-17.1, p = .015) compared to the patients with normal RNFL. Signs of physical and mental adaptation to long-term visual sequelae were registered with gradual reduction of difference in most of physical and mental components scores compared to the patients with normal RNFL during six years of observation. Signs of hemorrhagic brain lesions were associated with permanent decrease of PCS score (mean difference 7.4 points; 95%CI 0.6-14.0; p = .033), bodily pain (8.7 points; 95%CI 1.6-17.6; p = .018), and social functioning (8.2 points; 95%CI 3.0-17.4; p = .005) six years after discharge. No effect of type of antidote (fomepizole versus ethanol) and extracorporeal enhanced elimination modality (intermittent hemodialysis versus continuous renal replacement therapy) applied in hospital on long-term QoL was found (all p > .05).Conclusion: Acute methanol poisoning was associated with a significant decrease of health-related quality of life of survivors persisting for at least six years after discharge. The more pronounced decrease in QoL scores was observed in the patients with hemorrhagic brain lesions and visual sequelae of poisoning with abnormal RNFL thickness.