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 left eye 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.

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 DaTQUANTTM 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.

The impact of co-morbidities on a 6-year survival after methanol mass poisoning outbreak: possible role of metabolic formaldehyde.

Context: The influence of co-morbid conditions on the outcome of acute methanol poisoning in mass poisoning outbreaks is not known.Objective: The objective of this is to study the impact of burden of co-morbidities, complications, and methanol-induced brain lesions on hospital, follow-up, and total mortality.Methods: All patients hospitalized with methanol poisoning during a mass poisoning outbreak were followed in a prospective cohort study until death or final follow-up after 6 years. The age-adjusted Charlson co-morbidity index (ACCI) score was calculated for each patient. A multivariate Cox regression model was used to calculate the adjusted hazards ratio (HR) for death. The survival was modeled using the Kaplan-Meier method.Results: Of 108 patients (mean age with SD 50.9 ± 2.6 years), 24 (54.4 ± 5.9 years) died during hospitalization (mean survival with SD 8 ± 4 days) and 84 (49.9 ± 3.0 years; p = .159) were discharged, including 27 with methanol-induced brain lesions. Of the discharged patients, 15 (56.3 ± 6.8 years) died during the follow-up (mean survival 37 ± 11 months) and 69 (48.5 ± 3.3 years; p = .044) survived. The hospital mortality was 22%, the follow-up mortality was 18%; the total mortality was 36%. Cardiac/respiratory arrest, acute respiratory failure, multiorgan failure syndrome, and arterial hypotension increased the HR for hospital and total (but not follow-up) mortality after adjustment for age, sex, and arterial pH (all p < .05). All patients who died in the hospital had at least one complication. A higher ACCI score was associated with greater total mortality (HR 1.22; 1.00-1.48 95% CI; p = .046). Of those who died, 35 (90%) had a moderate-to-high ACCI. The Kaplan-Meier curve demonstrated that patients with a high ACCI had greater follow-up mortality compared to ones with low (p = .027) or moderate (p = .020) scores. For the patients who died during follow-up, cancers of different localizations were responsible for 7/15 (47%) of the deaths.Conclusions: The character and number of complications affected hospital but not follow-up mortality, while the burden of co-morbidities affected follow-up mortality. Methanol-induced brain lesions did not affect follow-up mortality. Relatively high cancer mortality rate may be associated with acute exposure to metabolic formaldehyde produced by methanol oxidation.

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

CONTEXT: Methanol poisoning induces acute optic neuropathy with possible long-term visual damage. OBJECTIVE: To study the dynamics and key determinants of visual pathway functional changes during 4 years after acute methanol poisoning. METHODS: A total of 42 patients with confirmed methanol poisoning (mean age 45.7 ± 4.4 years) were examined 4.9 ± 0.6, 25.0 ± 0.6, and 49.9 ± 0.5 months after discharge. The following tests were performed: visual evoked potential (VEP), retinal nerve fiber layer (RNFL) measurement, brain magnetic resonance imaging (MRI), complete ocular examination, biochemical tests, and apolipoprotein E (ApoE) genotyping. RESULTS: Abnormal VEP P1 latency was registered in 18/42 right eyes (OD) and 21/42 left eyes (OS), abnormal N1P1 amplitude in 10/42 OD and OS. Mean P1 latency shortening during the follow-up was 15.0 ± 2.0 ms for 36/42 (86%) OD and 14.9 ± 2.4 ms for 35/42 (83%) OS, with maximum shortening up to 35.0 ms. No significant change of mean N1P1 amplitude was registered during follow-up. A further decrease in N1P1 amplitude ≥1.0 mcV in at least one eye was observed in 17 of 36 patients (47%) with measurable amplitude (mean decrease -1.11 ± 0.83 (OD)/-2.37 ± 0.66 (OS) mcV versus -0.06 ± 0.56 (OD)/-0.83 ± 0.64 (OS) mcV in the study population; both p < .001). ApoE4 allele carriers had lower global and temporal RNFL thickness and longer initial P1 latency compared to the non-carriers (all p < .05). The odds ratio for abnormal visual function was 8.92 (3.00-36.50; 95%CI) for ApoE4 allele carriers (p < .001). The presence of ApoE4 allele was further associated with brain necrotic lesions (r = 0.384; p = .013) and brain hemorrhages (r = 0.395; p = .011). CONCLUSIONS: Improvement of optic nerve conductivity occurred in more than 80% of patients, but evoked potential amplitude tended to decrease during the 4 years of observation. ApoE4 allele carriers demonstrated lower RNFL thickness, longer P1 latency, and more frequent methanol-induced brain damage compared to non-carriers.

Peripapillary microcirculation in Leber hereditary optic neuropathy.

PURPOSE: In this prospective observational comparative case series, we aimed to study the peripapillary capillary network with spectral-domain optical coherence tomography angiography (OCT-A) in Leber hereditary optic neuropathy (LHON). METHODS: Twelve eyes of six individuals, of these three males (five eyes) after clinical onset of visual impairment were imaged by OCT-A with scans centred on optic discs. Control group consisted of 6 eyes with no visual impairment. RESULTS: The three affected individuals lost vision 6 years (at age 22 years), 2 years and 3 months (at age 26 years) and 1 year and 2 months (at age 30 years) prior to OCT-A examination. All five affected eyes had alterations in density of the radial peripapillary microvascular network at the level of retinal nerve fibre layer, including an eye of a patient treated with idebenone that underwent almost full recovery (best corrected visual acuity 0.87). Interestingly, the other eye showed normal ocular findings 14 months after onset. Results of OCT-A examination in this eye were unfortunately inconclusive due to a delineation error. At the level of the ganglion cell layer differences could be also noted, but only in two severely affected individuals. There were no differences between unaffected mutation carriers and control eyes. CONCLUSION: Optical coherence tomography angiography scans confirmed that the peripapillary microvascular network is highly abnormal in eyes manifesting visual impairment due to LHON. These findings support the hypothesis that microangiopathy contributes to the development of vision loss in this mitochondrial disorder.

Neuroinflammation markers and methyl alcohol induced toxic brain damage.

Methyl alcohol intoxication is a global problem with high mortality and long-term visual sequelae and severe brain damage in survivors. The role of neuroinflammation in the mechanisms of methyl alcohol-induced toxic brain damage has not been well studied. We measured the acute concentrations and dynamics of lipoxins LxA4 and LxB4 and the interleukins IL-4, IL-5, IL-9, IL-10, and IL-13 in the serum of patients treated with methyl alcohol poisoning and the follow-up concentrations in survivors two years after discharge from the hospital. A series of acute measurements was performed in 28 hospitalized patients (mean age 54.2 ±â€¯5.2 years, mean observation time 88 ±â€¯20 h) and the follow-up measurements were performed in 36 subjects who survived poisoning (including 12/28 survivors from the acute group). Visual evoked potentials (VEP) and magnetic resonance imaging of the brain (MRI) were performed to detect long-term visual and brain sequelae of intoxication. The acute concentrations of inflammatory mediators were higher than the follow-up concentrations: LxA4, 62.0 ±â€¯6.0 vs. 30.0 ±â€¯5.0 pg/mL; LxB4, 64.0 ±â€¯7.0 vs. 34.0 ±â€¯4.0 pg/mL; IL-4, 29.0 ±â€¯4.0 vs. 15.0 ±â€¯1.0 pg/mL; IL-5, 30.0 ±â€¯4.0 vs. 13.0 ±â€¯1.0 pg/mL; IL-9, 30.0 ±â€¯4.0 vs. 13.0 ±â€¯1.0 pg/mL; IL-10, 38.0 ±â€¯5.0 vs. 16.0 ±â€¯1.0 pg/mL; IL-13, 35.0 ±â€¯4.0 vs. 14.0 ±â€¯1.0 pg/mL (all p < 0.001). The patients with higher follow-up IL-5 concentration had prolonged latency P1 (r = 0.413; p = 0.033) and lower amplitude N1P1 (r = -0.498; p = 0.010) of VEP. The higher follow-up IL-10 concentration was associated with MRI signs of brain necrotic damage (r = 0.533; p = 0.001) and brain hemorrhage (r = 0.396; p = 0.020). Our findings suggest that neuroinflammation plays an important role in the mechanisms of toxic brain damage in acute methyl alcohol intoxication.

Progressive Chronic Retinal Axonal Loss Following Acute Methanol-induced Optic Neuropathy: Four-Year Prospective Cohort Study.

PURPOSE: To study the dynamics and clinical determinants of chronic retinal nerve fiber layer thickness (RNFL) loss after methanol-induced optic neuropathy. DESIGN: Prospective cohort study. METHODS: All patients underwent complete ophthalmic evaluation including spectral-domain optical coherence tomography 3 times during 4 years of observation: 4.9 (±0.6), 25.0 (±0.6), and 49.9 (±0.5) months after discharge. PARTICIPANTS: Eighty-four eyes of 42 survivors of methanol poisoning, mean age (standard deviation) of 45.7 (±4.4) years; and 82 eyes of 41 controls, mean age 44.0 (±4.2) years. MAIN OUTCOME MEASURES: Global and temporal RNFL loss. RESULTS: Abnormal RNFL thickness was registered in 13 of 42 (31%) survivors of methanol poisoning and chronic axonal loss in 10 of 42 (24%) patients. Significant decrease of global/temporal RNFL thickness during the observation period was found in the study population compared to the controls (P < .001). The risk estimate of chronic global RNFL loss for arterial blood pH < 7.3 at admission was 11.65 (95% confidence interval 1.91-71.12) after adjusting for age and sex. The patients with chronic axonal degeneration demonstrated progressive visual loss in 7 of 10 cases. The patients with abnormal RNFL thickness had magnetic resonance signs of brain damage in 10 of 13 vs 8 of 29 cases with normal RNFL thickness (P = .003). Signs of brain hemorrhages were present in 7 of 13 patients with abnormal RNFL thickness vs 5 of 29 cases with normal RNFL thickness (P = .015). CONCLUSIONS: Methanol-induced optic neuropathy may lead to chronic retinal axonal loss during the following years. Arterial blood pH on admission is the strongest predictor of chronic RNFL thickness decrease. Chronic retinal neurodegeneration is associated with the progressive loss of visual functions and necrotic brain lesions.

Role of activation of lipid peroxidation in the mechanisms of acute methanol poisoning.

CONTEXT: The role of activation of lipid peroxidation in the mechanisms of acute methanol poisoning has not been studied. OBJECTIVE: We measured the concentrations of lipid peroxidation markers in acutely intoxicated patients with known serum concentrations of methanol and leukotrienes. METHODS: Blood serum samples were collected from 28 patients hospitalized with acute intoxication and from 36 survivors 2 years after discharge. In these samples, concentrations of 4-hydroxy-trans-2-hexenal (HHE), 4-hydroxynonenal (HNE), and malondialdehyde (MDA) were measured using the method of liquid chromatography-electrospray ionization-tandem mass spectrometry. RESULTS: The maximum acute serum concentrations of all three lipid oxidative damage markers were higher than the follow-up serum concentrations: HNE 71.7 ± 8.0 ng/mL versus 35.4 ± 2.3 ng/mL; p < .001; HHE 40.1 ± 6.7 ng/mL versus 17.7 ± 4.1 ng/mL; p < .001; MDA 80.0 ± 7.2 ng/mL versus 40.9 ± 1.9 ng/mL; p < .001. The survivors without methanol poisoning sequelae demonstrated higher acute serum concentrations of the markers than the patients with sequelae. A correlation between measured markers and serum leukotrienes was present: HNE correlated with LTC4 (r = 0.663), LTD4 (r = 0.608), LTE4 (r = 0.771), LTB4 (r = 0.717), HHE correlated with LTC4 (r = 0.713), LTD4 (r = 0.676), LTE4 (r = 0.819), LTB4 (r = 0.746), MDA correlated with LTC4 (r = 0.785), LTD4 (r = 0.735), LTE4 (r = 0.814), LTB4 (r = 0.674); all p < .001. Lipid peroxidation markers correlated with anion gap (r= -0.428, -0.388, -0.334; p = .026, .045, .080 for HNE, HHE, MDA, respectively). The follow-up serum concentrations of lipid oxidation markers measured in survivors with and without visual/neurological sequelae 2 years after discharge did not differ. CONCLUSION: Our results demonstrate that lipid peroxidation plays a significant role in the mechanisms of acute methanol poisoning. The acute concentrations of three measured biomarkers were elevated in comparison with the follow-up concentrations. Neuronal membrane lipid peroxidation seems to activate leukotriene-mediated inflammation as a part of the neuroprotective mechanisms. No cases of persistent elevation were registered among the survivors 2 years after discharge.

Diabetes, Cardiovascular Disorders and 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Body Burden in Czech Patients 50 Years After the Intoxication.

The correlation between 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) intoxication and the parameters of metabolic impairment was examined in the last eight male survivors of 80 workers exposed to TCDD during the production of herbicides in a chemical factory in 1965-1967. Their median TCDD blood level was 112 (46-390) pg/g lipids, and the median TCDD body deposit was 3.9 (0.8-11.7) µg. This puts these patients into the most severely intoxicated group of subjects, according to back-calculated levels of TCDD. The median TCDD blood level in eight controls was 12 pg/g (<0.10 to 22.2 pg/g). Markers of metabolic impairment - diabetes, dyslipidaemia, arterial hypertension, carotid artery plaque, skin microvascular reactivity, eye fundus hypertensive angiopathy and history of coronary heart disease - were assessed and compared to a general male population of comparable age. Measured parameters compared with a population of comparable age were as follows: prevalence of diabetes (62.5% versus 17.6%), arterial hypertension (87.5% versus 71.8%), dyslipidaemia (87.5% versus 88.8%), history of coronary heart disease (62.5% versus 26.0%) and eye fundus hypertension angiopathy (50% versus 14%). All eight patients (100% versus 43%) developed plaques in carotid arteries, six had stenosis >50% and two had a carotid intervention (stenting or endarterectomy). Total cholesterol levels decreased compared to the earlier study this patient group in 2008, most likely due to a more intensive use of lipid-lowering drugs. Several metabolic parameters were higher (diabetes as much as 3.5-fold) in the group of severely TCDD-intoxicated subjects than in a general population of comparable age. This suggests that TCDD plays a role in the development of metabolic impairment and vascular changes.

Leukotriene-mediated neuroinflammation, toxic brain damage, and neurodegeneration in acute methanol poisoning.

CONTEXT: The role of neuroinflammation in methanol-induced toxic brain damage has not been studied. OBJECTIVE: We studied acute concentrations and the dynamics of leukotrienes (LT) in serum in hospitalized patients with acute methanol poisoning and in survivors. METHODS: Series of acute cysteinyl-LT and LTB4 concentration measurements were performed in 28/101 hospitalized patients (mean observation time: 88 ± 20 h). In 36 survivors, control LT measurements were performed 2 years after discharge. RESULTS: The acute maximum (Cmax) LT concentrations were higher than concentrations in survivors: Cmax for LTC4 was 80.7 ± 5.6 versus 47.9 ± 4.5 pg/mL; for LTD4, 51.0 ± 6.6 versus 23.1 ± 2.1 pg/mL; for LTE4, 64.2 ± 6.0 versus 26.2 ± 3.9 pg/mL; for LTB4, 59.8 ± 6.2 versus 27.2 ± 1.4 pg/mL (all p < 0.001). The patients who survived had higher LT concentrations than those who died (all p < 0.01). Among survivors, patients with CNS sequelae had lower LTE4 and LTB4 than did those without sequelae (both p < 0.05). The LT concentrations increased at a rate of 0.4-0.5 pg/mL/h and peaked 4-5 days after admission. The patients with better outcomes had higher cys-LTs (all p < 0.01) and LTB4 (p < 0.05). More severely poisoned patients had lower acute LT concentrations than those with minor acidemia. The follow-up LT concentrations in survivors with and without CNS sequelae did not differ (all p > 0.05). The mean decrease in LT concentration was 30.9 ± 9.0 pg/mL for LTC4, 26.3 ± 8.6 pg/mL for LTD4, 37.3 ± 6.4 pg/mL for LTE4, and 32.0 ± 8.8 pg/mL for LTB4. CONCLUSIONS: Our findings suggest that leukotriene-mediated neuroinflammation may play an important role in the mechanisms of toxic brain damage in acute methanol poisoning in humans. Acute elevation of LT concentrations was moderate, transitory, and was not followed by chronic neuroinflammation in survivors.

Is Chelation Therapy Efficient for the Treatment of Intravenous Metallic Mercury Intoxication?

The efficacy of treatment for intravenous elemental mercury intoxication has not been fully studied with regard to clinical outcome, and treatment recommendations vary. We treated a 41-year-old man with a history of drug abuse and depression who attempted suicide using 1 mL (13.53 g) metallic Hg i.v. He was admitted to the hospital 2 months later for dyspnoea and thoracic pain and was diagnosed with pneumonia. Hg deposits were seen in the lungs and extra-pulmonary organs. His blood level (372 µg/L) exceeded the population level of 5 µg/L by more than 70 times. Dimercaptopropane sulphonate sodium (DMPS; 600 mg/day orally) was administered for 14 days. One year later, the patient presented with dyspnoea on exertion, fatigue, depression and impaired sleep. His chest X-ray showed multiple opacities (size up to 2.8 cm), and psychological testing revealed a selective cognitive deficit in the area of visual attentiveness, flexibility, source memory and impairment of the motor speed of the dominant upper extremity. Mercury blood level was 158 µg/L and mercury urine output was 1380 µg/24 hr. DMPS (800 mg/day orally) was administered for 40 days; the patient eliminated up to 18 mg Hg/day. His Hg blood level and Hg urine output belong to the highest among reported cases. In spite of the therapy, the patient's blood Hg, complaints and psychological tests showed no improvement. This case report confirms that DMPS does not effectively remove intravenous deposits of metallic Hg.

Phenotypic features of CRB1-associated early-onset severe retinal dystrophy and the different molecular approaches to identifying the disease-causing variants.

PURPOSE: The aim of this study was to determine the molecular genetic basis of an early-onset severe retinal dystrophy in three unrelated consecutive patients of Czech origin and to describe their ocular phenotype. METHODS: DNA samples from two probands were analyzed using a genotyping microarray (Asper) followed by either target analysis of 43 genes implicated in retinal disorders by next generation sequencing or whole-exome sequencing, respectively. The third proband underwent conventional Sanger sequencing of CRB1 based on her ocular findings. RESULTS: All three probands harboured a known disease-causing mutation c.2843G>A; p.(Cys948Tyr) in the CRB1 gene. One individual was homozygous for this mutation, while in the other two probands c.2308G>A; p.(Gly770Ser) and c.3121A>G; p.(Met1041Val) were also identified in the heterozygous state, respectively. Both variants were novel and evaluated by in silico analysis as pathogenic. A false-negative result was observed in one of the two samples examined by the genotyping microarray. Disease onset in all patients was before the age of 7 years. Hypermetropic refractive error, bilateral nummular retinal pigmentation, retinal thickening and cystoid spaces in the macula were observed in two probands, aged 6 and 7 years. The third proband, aged 28 years, had bone spicule-like pigmentary changes associated with increased retinal nerve fiber layer. CONCLUSIONS: The first study reporting on the molecular genetic cause of non-syndromic early-onset severe retinal dystrophy in Czech patients identified one homozygous and two compound heterozygote probands with CRB1 mutations. Retina nerve fibre layer measurements should be considered an integral part of the clinical evaluation of retinal dystrophies. Detailed clinical examination and imaging can both direct molecular screening and help to confirm or refute disease causation of identified variants.

Visual evoked potentials in patients after methanol poisoning.

OBJECTIVES: We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. MATERIAL AND METHODS: The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. RESULTS: The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. CONCLUSIONS: The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae.

Use of Out-of-Hospital Ethanol Administration to Improve Outcome in Mass Methanol Outbreaks.

STUDY OBJECTIVE: Methanol poisoning outbreaks are a global public health issue, with delayed treatment causing poor outcomes. Out-of-hospital ethanol administration may improve outcome, but the difficulty of conducting research in outbreaks has meant that its effects have never been assessed. We study the effect of out-of-hospital ethanol in patients treated during a methanol outbreak in the Czech Republic between 2012 and 2014. METHODS: This was an observational case-series study of 100 hospitalized patients with confirmed methanol poisoning. Out-of-hospital ethanol as a "first aid antidote" was administered by paramedic or medical staff before the confirmation of diagnosis to 30 patients; 70 patients did not receive out-of-hospital ethanol from the staff (12 patients self-administered ethanol shortly before presentation). RESULTS: The state of consciousness at first contact with paramedic or medical staff, delay to admission, and serum methanol concentration were similar among groups. The median serum ethanol level on admission in the patients with out-of-hospital administration by paramedic or medical staff was 84.3 mg/dL (interquartile range 32.7 to 129.5 mg/dL). No patients with positive serum ethanol level on admission died compared with 21 with negative serum ethanol level (0% versus 36.2%). Patients receiving out-of-hospital ethanol survived without visual and central nervous system sequelae more often than those not receiving it (90.5% versus 19.0%). A positive association was present between out-of-hospital ethanol administration by paramedic or medical staff, serum ethanol concentration on admission, and both total survival and survival without sequelae of poisoning. CONCLUSION: We found a positive association between out-of-hospital ethanol administration and improved clinical outcome. During mass methanol outbreaks, conscious adults with suspected poisoning should be considered for administration of out-of-hospital ethanol to reduce morbidity and mortality.

Long-term visual damage after acute methanol poisonings: Longitudinal cross-sectional study in 50 patients.

CONTEXT: Visual disturbances due to the toxic effect of formic acid in acute methanol poisonings are generally transient. The subjective symptoms of visual toxicity may resolve within few weeks and fundoscopic signs of acute optic neuropathy subside within 1-2 months; therefore, the prevalence of long-term visual sequelae in the population of survivors of poisonings may be underestimated. OBJECTIVE: To study the prevalence and character of long-term visual sequelae of acute methanol poisonings based on the data from the Czech mass methanol outbreak in 2012. PATIENTS AND METHODS: A total of 50 patients with confirmed methanol poisoning were included in this longitudinal cross-sectional study, median age: 48 (range, 23-73) years. The following tests were performed: optical coherence tomography or OCT with evaluation of the retinal nerve fibers layer (RNFL), visual evoked potentials (VEP), magnetic resonance imaging (MRI) of brain, complete ocular examination (visual acuity/field, color vision, contrast sensitivity, and fundus), neurological examinations, and biochemical tests. RESULTS: Of 50 patients, 7/50 (14%) were discharged with diagnosed visual sequelae and 6/50 (12%) were discharged with both visual and central nervous system sequelae of poisoning. On the follow-up examination, 20/50 (40%) of the patients had long-term visual sequelae, with 8% of blindness. A total of 38% of the patients had abnormal (28% borderline) findings on RNFL, and 40% had abnormal (18% borderline) VEP. Among the patients discharged without detected visual sequelae, 8/37 (22%) had abnormal RNFL and VEP. Patients with visual sequelae had brain lesions more often (70% vs. 27%, p < 0.01). MRI identified optic nerve lesions in 2/20 cases with abnormal VEP only. The groups with and without visual sequelae differed in serum methanol, ethanol, HCO3-, formate, pH, anion gap, and base deficit (all p < 0.01). Visual disturbances on admission and coma were more prevalent in the patients with visual sequelae (p < 0.05). Patients with positive serum ethanol on admission were 93% less likely to have optical axonal damage (OR: 0.07 (95% CI: 0.01-0.8); p < 0.05). No association was found between visual sequelae and type of antidote administered, mode of hemodialysis, or folate substitution. Pre-hospital administration of ethanol seemed beneficial: these patients were 90% less likely to have abnormal RNFL findings (OR: 0.10 (95% CI: 0.02-0.52); p < 0.01). CONCLUSIONS: The long-term visual sequelae were clearly underestimated on discharge, suggesting a significantly higher amount of patients with long-term sequelae than earlier reported. Thorough examinations before discharge and during follow-up will likely uncover a higher morbidity also after methanol poisonings in general.

Successful Use of Hydroxocobalamin and Sodium Thiosulfate in Acute Cyanide Poisoning: A Case Report with Follow-up.

Hydroxocobalamin is an effective first-line antidote used mainly in monotherapy of cyanide poisonings, while the opinions are different on the effects of its combination with sodium thiosulfate. A 58-year-old male committed a suicide attempt by ingesting of 1200-1500 mg of potassium cyanide; he was unconscious for 1-1.5 min. after ingestion with the episode of generalized seizures. On admission to the ICU, the patient was acidotic (pH 7.28; HCO3 14.0 mmol/L, base excess -12.7 mmol/L, saturation O2 0.999) with high serum lactate (12.5 mmol/L). Hydroxocobalamin was administered 1.5 hr after ingestion in two subsequent intravenous infusions at a total dose of 7.5 g. The infusion was followed by continuous intravenous administration of 1 mL/hr/kg of 10% sodium thiosulfate at a total dose of 12 g. No complications and adverse reactions were registered. Serum lactate decreased to 0.6 mmol/L the same day, and arterial blood gases became normal (pH 7.49; HCO3 27.2 mmol/L, base excess 2.2 mmol/L, saturation O2 0.994). The follow-up examination 5 months later revealed no damage of basal ganglia and cerebellum on magnetic resonance imaging. The neurological examination revealed no pathological findings. On the ocular coherence tomography, the retinal nerve fibres layer was normal. In visual evoked potentials, there was a normal evoked complex on the left eye and minor decrease in amplitude on the right eye. Combination of hydroxocobalamin and sodium thiosulfate can have a positive effect on the survival without long-term neurological and visual sequelae in the cases of massive cyanide poisonings due to the possibility of a potentiation or synergism of hydroxocobalamin effects by sodium thiosulfate. This synergism can be explained by the different time-points of action of two antidotes: the initial and immediate effect of hydroxocobalamin, followed by the delayed, but more persistent effect of sodium thiosulfate.

Imaging findings after methanol intoxication (cohort of 46 patients).

OBJECTIVES: Our goal is to demonstrate the variability of imaging findings, primarily in the MRI, in 46 patients who survived acute methanol poisoning. This cohort of patients is the largest such sample group examined by MRI. METHODS: Patients were examined by means of imaging methods (42 patients by MRI and 4 by CT). All had an identical protocol of MR examination (T2WI, FLAIR, T1WI with or without application of contrast medium and T2WI/FFE, DWI in the transversal plane of the scan, and with focus on the optic nerves in the coronal plane of the scan in T2WI-SPIR). RESULTS: Imaging methods revealed a positive finding associated with methanol intoxication in 21 patients (46%). These consisted of symmetrical lesions in the putamen--13 patients (28%), haemorrhage--13 cases (28%), deposits in white matter with localization primarily subcortically--4 cases (9%), lesions in the region of the globus pallidus--7 cases (15%) (in 6 cases without combination with the lesions in the putamen), lesions in the brainstem afflicted 6 patients (13%), and lesion in the cerebellum was found in one case. A pathological finding was found only in the patients examined by MRI. CONCLUSION: Almost half of the patients who survived acute methanol poisoning had pathological findings by MRI. The most common finding concerned an affliction of the putamen, which is a predilection area. An interesting finding was the relatively frequent occurrence of selective lesion of the globus pallidus, which is more usually associated with other types of intoxication.