Clinical and genetic determinants of chronic visual pathway changes after methanol - induced optic neuropathy: four-year follow-up study

[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.

Case Reports Study on Methanol Poisoning in King Abdul Aziz Specialist Hospital, Taif, Saudi Arabia

Methanol poisoning is a challenging issue due to its inducing acute multiple organ failures, and especially due to a lack of preparedness, available antidotes, and management protocols. The current study presents six cases of methanol poisoning that attended the emergency department of King Abdul Aziz Specialist Hospital, Taif, Saudi Arabia, between March and November 2022. All of the patients suffered from severe metabolic acidosis and visual impairment following the ingestion of homemade alcoholic beverages and colonia. Three patients were comatose, suffered from post-cardiac pulmonary arrest, and, finally, died, while the other three were non-comatose and discharged from the ICU after improvement. Management was based on clinical symptoms and other laboratory findings due to a shortage of methanol level measurement resources. The antidote, fomepizole, was not given to all of the cases due to its deficiency, and ethanol was given only to one patient due to difficulties in administering it without monitoring its concentration. Methanol poisoning and its outbreak provide insights into the dangers of hazardous homemade alcohol and other pharmaceutical preparations that might be adulterated with methanol, particularly to the shortage of suitable diagnostic testing and antidotes in addition to poor resources for management of intoxicated patients in some regions of Saudi Arabia.

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.

Time course study of optical coherence tomography angiography in patients with methanol induced optic neuropathy

INTRODUCTION

In countries where alcoholic beverages are legally prohibited, methanol toxicity usually occurs due to ingesting homemade alcoholic drinks. The initial ophthalmologic symptoms of methanol toxicity typically appear 6-48 h after ingestion, and the severity of symptoms varies widely from mild and painless decreased vision to no-light perception vision.

METHODS

This prospective study examines 20 patients with acute methanol poisoning within 10 days of use. Patients underwent ocular examinations, BCVA (Best Corrected Visual Acuity) recording, and OCTA (Optical Coherence Tomography Angiography) of the macula and optic disc. BCVA measurement and imaging were repeated one month and three months after intoxication.

RESULTS

There was a statistically significant reduction in superficial parafoveal vascular density (P-value = 0.026), inner retinal thickness (P-value = 0.022), RNFL (Retinal Nerve Fiber Layer) thickness (P-value = 0.031), and an increase in cup to disc ratio (P-value < 0.001), and central visual acuity (P-value = 0.002) in this time course. However, there was no statistically significant difference in FAZ (Foveal Avascular Zone) area (P-value = 0.309), FAZ perimeter (P-value = 0.504), FD-300 (Foveal density, vascular density within a 300 μm wide region of the FAZ) (P-value = 0.541), superficial vascular density (P-value = 0.187), deep foveal vascular density (P-value = 0.889), deep parafoveal vascular density (P-value = 0.830), choroidal flow area (P-value = 0.464), total retinal thickness (P-value = 0.597), outer retinal thickness (P-value = 0.067), optic disc whole image vascular density (P-value = 0.146), vascular density inside the disc (P-value = 0.864), or peripapillary vascular density (P-value = 0.680) at different times.

CONCLUSION

Over time, methanol poisoning can cause changes in retinal layers thickness, vasculature, and optic nerve head. The most important changes include cupping of the optic nerve head, reduction in RNFL thickness, and inner retinal thickness.

Factors affecting the severity and prognosis of visual damage in inhalational methanol poisoning

Background/Aim

Inhalational methanol poisoning could cause severe damage to visual function. This study analyzed the prognosis of the correlation between the visual function and the relevant risk factors.

Methods

In this retrospective study, 14 patients had confirmed inhalational methanol poisoning, resulting in visual impairment in both eyes. The following tests were performed: laboratory tests, best corrected visual acuity (BCVA), intraocular pressure, slit lamp, fundus photography, visual field (VF), pattern visual evoked potential (P-VEP), flash electroretinogram (F-ERG), optical coherence tomography (OCT), and orbital or cranial magnetic resonance imaging (MRI).

Results

With active treatment, visual function improved to varying degrees in all 14 cases (28 eyes) in this study. The BCVA of 21 eyes declined to no light perception at the onset; 16 eyes showed different degrees of improvement after treatment, with the final BCVA (LogMar) mainly ranging from 2 to 3, and vision acuity stabilized after the 5th month. The VF pattern in the acute phase was mostly blind. Other VF patterns included the central visual island, large paracentral scotomas, hemipleural VF defects, and the temporal visual island. Retinal nerve fiber layer (RNFL) thickening was observed commonly in the acute phase (146.8 ± 33.2 μm), which subsided in the 1st month, showed dramatic thinning at the 3rd month, and then stabilized in the 5th month after onset. MRI showed that the main sites involved were optic nerve impairment, the optic disk, and retrobulbar segments. The basal ganglia region was the site most involved in the central nervous system (CNS).

Conclusion

Inhalational methanol poisoning could lead to severe impairment of visual function, and the prognosis of visual acuity (VA) was highly relevant to the risk factors of duration of toxic exposure, delayed admission, and degree of acidosis.

Clinical Characteristics of Methanol-Induced Optic Neuropathy: Correlation between Aetiology and Clinical Findings

PURPOSE

To show the clinical characteristics, identify the magnetic resonance imaging (MRI) and optical coherence tomography (OCT) features, and observe the visual outcome of methanol-induced optic neuropathy.

METHODS

Clinical data were retrospectively collected from in-patients diagnosed with methanol-induced optic neuropathy in the Neuro-Ophthalmology Department of the Chinese People's Liberation Army General Hospital from January 2016 to January 2021.

RESULTS

Eight patients were included in this study. The exposure time was 6-34 h for ingestion, 3-4 months for inhalation, and more than ten years for skin absorption. All patients demonstrated bilateral acute visual impairment. Seven of eight patients had other accompanying systemic symptoms. Seven of eight patients demonstrated optic nerve lesions in MRI, and five presented with a hyperintense T2 signal in a "central" type. OCT showed the macular ganglion cell layer and inner plexiform layer (mGCL-IPL) thinning before the peripapillary retinal nerve fiber layer (pRNFL) thinning. The visual improvement was achieved transiently for seven of eight patients after treatment. One patient with a mitochondrial DNA mutation maintained a bilateral no-light perception (NLP) from the onset to the last visit. All patients had poor visual prognoses, with either light perception or NLP.

CONCLUSIONS

Methanol-induced optic neuropathy is a rare bilateral optic neuropathy with a poor visual outcome. A centrally hyperintense T2 signal of the optic nerve is common in methanol-induced optic neuropathy. The thinning of the mGCL-IPL is more sensitive than that of the pRNFL for early diagnosis. A mitochondrial genetic defect may be a predisposing factor for methanol-induced optic neuropathy.

Clinical electrophysiology of the optic nerve and retinal ganglion cells

Clinical electrophysiological assessment of optic nerve and retinal ganglion cell function can be performed using the Pattern Electroretinogram (PERG), Visual Evoked Potential (VEP) and the Photopic Negative Response (PhNR) amongst other more specialised techniques. In this review, we describe these electrophysiological techniques and their application in diseases affecting the optic nerve and retinal ganglion cells with the exception of glaucoma. The disease groups discussed include hereditary, compressive, toxic/nutritional, traumatic, vascular, inflammatory and intracranial causes for optic nerve or retinal ganglion cell dysfunction. The benefits of objective, electrophysiological measurement of the retinal ganglion cells and optic nerve are discussed, as are their applications in clinical diagnosis of disease, determining prognosis, monitoring progression and response to novel therapies.

The APOE4 allele is associated with a decreased risk of retinopathy in type 2 diabetics

BACKGROUND

Common polymorphisms within the apolipoprotein E (APOE) gene are suggested to be associated with the development of type 2 diabetes mellitus (T2DM), but the potential association with T2DM complications (nephropathy, neuropathy and retinopathy) remains unclear. We perform the case-control study to analyse the association between the APOE polymorphism and risk of T2DM and to analysed the potential relationship between the APOE and T2DM complications.

METHODS AND RESULTS

APOE variants (rs429358 and rs7412) were genotyped by TaqMan assay in T2DM patients (N = 1274; N = 829 with complications including retinopathy, neuropathy and nephropathy status) and with PCR-RFLP in healthy nondiabetic controls (N = 2055). The comparison of subjects with genotypes associated with low plasma cholesterol (APOE2/E2 and APOE2/E3 carriers vs. others) did not show an association with T2DM (OR [95% CI] = 0.88 [0.71-1.08). The differences remained insignificant after adjusting for diabetes duration, sex and BMI. Carriers of at least one APOE4 allele (rs429358) are protected against T2DM related retinopathy (OR [95% CI] = 0.65 [0.42-0.99]. Protection against retinopathy is driven mostly by females (OR [95% CI] = 0.50 [0.25-0.99]); and remains significant (P = 0.044) after adjustment for diabetes duration and BMI.

CONCLUSION

Common APOE polymorphism was not associated with T2DM in the Czech population. Yet, APOE4 allele revealed an association with retinopathy. In particular, female T2DM patients with at least one APOE4 allele exhibit lower prevalence of retinopathy in our study subjects.

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.

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.

Lessons from a methanol poisoning outbreak in Egypt: Six case reports

BACKGROUND

Mass methanol poisonings are challenging, especially in regions with no preparedness, management guidelines and available antidotes.

CASE SUMMARY

Six Ukrainian patients were referred to our emergency department in Cairo, Egypt several hours after drinking an alcoholic beverage made of 70%-ethanol disinfectant bought from a local pharmacy. All patients presented with severe metabolic acidosis and visual impairments. Two were comatose. Management was based on the clinical features and chemistry tests due to deficient resources for methanol leveling. No antidote was administered due to fomepizole unavailability and the difficulties expected to obtain ethanol and safely administer it without concentration monitoring. One patient died from multiorgan failure, another developed blindness and the four other patients rapidly improved.

CONCLUSION

This methanol poisoning outbreak strongly highlights the lack of safety from hazardous pharmaceuticals sold in pharmacies and limitations due to the lack of diagnostic testing, antidote availability and staff training in countries with limited-resources such as Egypt.

Effects of adenosine triphosphate on methanol-induced experimental optic nerve damage in rats: biochemical and histopathological evaluation

PURPOSE

Acute methanol exposure leads to systemic intoxication and toxic optic neuropathy. In this experimental study, we aimed to determine the protective effects of intravenous administration of ATP in methanol-induced optic neuropathy.

MATERIALS AND METHODS

A total of 18 male albino Wistar rats weighing between 267 and 282 g were used for the experiment. The animals were divided into three groups as healthy control (HC), methanol (M), and methanol + ATP (M-ATP) groups. Distilled water was given to the healthy control group (n = 6) as the solvent, while 20% methanol was administered orally to the rats in M (n = 6) and M-ATP (n = 6) groups at a dose of 3 g/kg. Four hours after the administration of 20% methanol orally to the M-ATP group, ATP was injected intraperitoneally at a dose of 4 mg/kg. Eight hours after ATP injection, the animals were sacrificed by high-dose (50 mg/kg) thiopental anaesthesia and biochemical and histopathological examinations were performed on the removed optic nerve tissues. Malondialdehyde (MDA), total glutathione (tGSH), total oxidant status (TOS) and total anti-oxidant status (TAS) were analysed with biochemical tests.

RESULTS

MDA, TOS and OSI were significantly higher and tGSH and TAS levels were significantly lower in methanol administered group compared with the healthy controls or M-ATP group (p: 0.001). There was not any significant difference between healthy controls and M-ATP group regarding the oxidative stress parameters. There was a significant destruction and increase in thickness and astrocyte numbers and edema-vacuolization in methanol administered group compared with the healthy controls or M-ATP group (p: 0.001).

CONCLUSION

Intravenous ATP administration had a significant positive effect on the oxidative stress parameters and optic nerve structure in methanol-intoxicated rats. Antioxidant therapies should be considered in future studies as a possible therapy for methanol-induced toxic optic neuropathy.

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.