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Methanol Poisoning

Methyl Alcohol Poisoning

Methanol poisoning results from accidental or voluntary ingestion of methyl alcohol, a compound used in the chemical industry and as fuel. Methanol is in no case suitable for consumption.


Presentation

Methanol causes inebriation similar to ethanol and patients may merely appear drunk, lose their inhibitions and become ataxic. At the same time, gastrointestinal symptoms manifest. MP patients typically suffer from nausea, vomiting, diarrhea and abdominal pain. If they are examined that early, tachypnea, tachycardia, and hypertension may already be detected. They result from metabolic acidosis. In severe cases, fatal respiratory or cardiac failure may occur.

The stage described above is usually followed by a latency period of several hours, generally 12 to 24 hours. Only then, neurological symptoms can be observed. The more methanol has been ingested, the earlier additional symptoms set in. Simultaneous consumption of ethanol delays onset of further deficits since both alcohols are competitive substrates for alcohol dehydrogenase.

Progressive vision loss is characteristic for MP and patients may claim blurred vision, scotomas, scintillations, visual field restriction and eventually complete blindness. Seizures may be registered. Patients show increasingly reduced levels of awareness and may fall into a coma.

Tachypnea
  • Tachypnea was seen in 8 patients (28.6%).[apjmt.mums.ac.ir]
  • […] acid Thiamine Glycine ¿ Oxalic acid Formic acid a Hydroxy- b Ketoadipate Stage I (30 minutes to 12 hours) Intoxicated patient with no alcohol odor Nausea and vomiting Metabolic acidosis Crystalluria Myoclonus Seizure and death Stage II (12 to 24 hours) Tachypnea[doctorniruprasad.com]
  • Physical examination may show tachypnea , and ophthalmologic examination may show dilated pupils with hyperemia of the optic disc and retinal edema . Cause [ edit ] Methanol has a high toxicity in humans.[en.wikipedia.org]
  • As symptoms develop, most signs are related to metabolic acidosis; these are manifested as tachycardia, tachypnea, hypertension, and altered mental status. Pulmonary edema and acute respiratory distress may ensue, requiring intubation.[emedicine.medscape.com]
Kussmaul Respiration
  • Patients A and C were severely acidotic, obtunded and had Kussmaul’s respiration. All three patients were haemodynamically stable.[academic.oup.com]
Fatigue
  • Symptoms of methanol poisoning can include fatigue, headaches and nausea, similar to the effects as excessive drinking but with pronounced vision problems that may include blurred vision, flashes of light, tunnel vision, changes in colour perception,[smartraveller.gov.au]
  • Symptoms of methanol poisoning can include fatigue, headaches and nausea, and are associated with increasing vision problems such as heightened sensitivity to light and blurred or reduced vision.[safetravel.govt.nz]
  • Patients can present with a variety of devastatingly disabling clinical features, often after a 12-24 hour latency: visual disturbances characterised by optic neuritis and eventual blindness 1,3 CNS features such as a headache, dizziness, fatigue, and[radiopaedia.org]
  • Other symptoms of this condition are difficulty breathing, signs of low oxygen levels through blue fingernails and lips, complete fatigue and cramps in the legs.[wisegeekhealth.com]
  • : Bluish-colored lips and fingernails Stomach and intestines: Abdominal pain (severe) Diarrhea Liver problems, including jaundice (yellow skin) and bleeding Nausea Pancreatitis (nausea, vomiting, and abdominal pain) Vomiting, sometimes bloody Other: Fatigue[nlm.nih.gov]
Gastric Lavage
  • Additional treatment options including correcting metabolic acidosis with intravenous sodium bicarbonate, gastric lavage, and haemodialysis 1,4 .[radiopaedia.org]
  • Gastric lavage and emesis if ingestion is within two hours. 2. Activated charcoal for multi-drug ingestion 3. I.V. Fluids to correct high anion gap acidosis and hypoglycemia 4.[doctorniruprasad.com]
  • Other therapeutic procedures include gastric lavage, correction of acidosis with sodium bicarbonate, folic acid, and secondary detoxication with hemodialysis.[ajnr.org]
Vomiting
  • A 31-year-old male alcoholic had headache, impaired consciousness, neck stiffness, roving eyes with dilated unreactive pupils, papilloedema, abdominal pain, vomiting, and severe metabolic acidosis after a binge.[ncbi.nlm.nih.gov]
  • (by using ipecac syrup) If the individual vomits, turn them on one side to prevent from choking Try to locate the poison (or pill) container and take it to the hospital DO NOT give anything orally to the person Unless directed by the physician, DO NOT[dovemed.com]
  • Methanol poisoning typically induces nausea, vomiting, abdominal pain, and mild central nervous system depression.[ncbi.nlm.nih.gov]
  • If treatment is not started, the symptoms worsen to include blurred vision and blindness; difficulty breathing and respiratory failure; muscle weakness; stomach pain, pancreatitis, nausea, and vomiting; low blood pressure; and confusion, seizures, and[sharecare.com]
Nausea
  • Methanol poisoning typically induces nausea, vomiting, abdominal pain, and mild central nervous system depression.[ncbi.nlm.nih.gov]
  • If treatment is not started, the symptoms worsen to include blurred vision and blindness; difficulty breathing and respiratory failure; muscle weakness; stomach pain, pancreatitis, nausea, and vomiting; low blood pressure; and confusion, seizures, and[sharecare.com]
  • Symptoms of methanol poisoning can include fatigue, headaches and nausea, similar to the effects as excessive drinking but with pronounced vision problems that may include blurred vision, flashes of light, tunnel vision, changes in colour perception,[smartraveller.gov.au]
  • Methanol poisoning is a rare poisoning resulting in elevated anion gap metabolic acidosis, due to the alcohol dehydrogenase (ADH)-mediated production of formic acid (which is poisonous to the central nervous system), and characterized by dizziness, nausea[orpha.net]
Abdominal Pain
  • A 31-year-old male alcoholic had headache, impaired consciousness, neck stiffness, roving eyes with dilated unreactive pupils, papilloedema, abdominal pain, vomiting, and severe metabolic acidosis after a binge.[ncbi.nlm.nih.gov]
  • Methanol poisoning typically induces nausea, vomiting, abdominal pain, and mild central nervous system depression.[ncbi.nlm.nih.gov]
  • pain (severe) Diarrhea Liver problems, including jaundice (yellow skin) and bleeding Nausea Pancreatitis (nausea, vomiting, and abdominal pain) Vomiting, sometimes bloody Other: Fatigue Leg cramps Weakness Seek immediate medical help.[nlm.nih.gov]
  • pain (severe) Diarrhea Liver problems, including jaundice (yellow skin) and bleeding Nausea Pancreatitis (nausea, vomiting, and abdominal pain) Vomiting, sometimes bloody Other: Fatigue Leg cramps Weakness Home Care Seek immediate medical help.[mountsinai.org]
Epigastric Pain
  • The initial symptoms of methanol intoxication are similar to those of ethanol intoxication, i.e. disinhibition and ataxia; however, these patients then proceed to develop dizziness, headache, nausea, vomiting and epigastric pain; they may progress on[prognosisapp.com]
  • Acute methanol poisoning is characterized by weakness, nausea, vomiting, headache and epigastric pain, but not typically inebriation. Metabolic acidosis occurs.[library.med.utah.edu]
  • Following a latent period, patients may develop headache, nausea, vomiting, or epigastric pain. In later stages, drowsiness may rapidly progress to obtundation and coma.[emedicine.medscape.com]
Jaundice
  • Nervous system: Agitated behavior Coma (unresponsiveness) Confusion Difficulty walking Dizziness Headache Seizures Skin and nails: Bluish-colored lips and fingernails Stomach and intestines: Abdominal pain (severe) Diarrhea Liver problems, including jaundice[nlm.nih.gov]
Leg Cramp
Muscle Weakness
  • If treatment is not started, the symptoms worsen to include blurred vision and blindness; difficulty breathing and respiratory failure; muscle weakness; stomach pain, pancreatitis, nausea, and vomiting; low blood pressure; and confusion, seizures, and[sharecare.com]
Blurred Vision
  • Initial symptoms of blurred vision, elongated anion gap and metabolic acidosis are typically delayed and may not at first be recognised as methanol-related complaints. Once diagnosed, treatment must be prompt and definitive.[ncbi.nlm.nih.gov]
  • A 60-year-old man was admitted with blurred vision and changes in color perception 18 hours after ingesting 100 ml methanol. Fomepizole was chosen for antidotal therapy in combination with hemodialysis.[ncbi.nlm.nih.gov]
  • There is then a latent period lasting approximately 12-24 hours, depending, in part, on the methanol dose ingested, following which an uncompensated metabolic acidosis develops and visualfunction becomes impaired, ranging from blurred vision and altered[ncbi.nlm.nih.gov]
  • If treatment is not started, the symptoms worsen to include blurred vision and blindness; difficulty breathing and respiratory failure; muscle weakness; stomach pain, pancreatitis, nausea, and vomiting; low blood pressure; and confusion, seizures, and[sharecare.com]
  • Symptoms of methanol poisoning can include fatigue, headaches and nausea, similar to the effects as excessive drinking but with pronounced vision problems that may include blurred vision, flashes of light, tunnel vision, changes in colour perception,[smartraveller.gov.au]
Photophobia
  • Methanol Intoxication General Mental Confusion Metabolic acidosis Long latent period, often 12 to 24 hours Gastrointestinal Nausea Vomiting Severe abdominal pain Neurologic Headache Dizziness Seizures, stupor, coma Visual Diminished sensation of light Photophobia[doctorniruprasad.com]
  • SIGNS AND SYMPTOMS CNS – CONVULSIONS, PROGRESSING TO COMA RETINAL - BLURRED VISION, PHOTOPHOBIA, VISUAL ACUITY LOSS, DILATED NON-REACTIVE PUPILS, OPTIC NERVE BECOMES OEDEMATOUS GIT - NAUSEA, VOMITING CARDIAC - TACHYCARDIA, HYPERTENSION PROGRESSING TO[slideshare.net]
  • Hyperemia of optic disc and reduced papillary response to light, Looking into a snow field, blurred vision, decreased visual acuity, diplopia, and photophobia. Nausea, vomiting, abdominal pain.[mnpoison.org]
  • His blurring of vision was also associated with decreased visual acuity, photophobia, and “feeling of being in a snow field.[omicsonline.org]
  • Ocular findings can be prominent and may include photophobia, central scotoma, visual field defects, fixed pupils and difficulty with light adaptation. Pupillary dysfunction has also been shown to be a strong predictor of mortality.[renalandurologynews.com]
Central Scotoma
  • However, a right central scotoma persisted, and bilateral optic atrophy was present. No reason for the exceptional delay before recovery and degree of recovery could be deduced, although throughout his convalescence he frequently chewed betel nut.[ncbi.nlm.nih.gov]
  • scotoma, reduced visual acuity, loss of color vision, and blindness [ 7 , 11 ].[omicsonline.org]
  • Ocular findings can be prominent and may include photophobia, central scotoma, visual field defects, fixed pupils and difficulty with light adaptation. Pupillary dysfunction has also been shown to be a strong predictor of mortality.[renalandurologynews.com]
Diplopia
  • Hyperemia of optic disc and reduced papillary response to light, Looking into a snow field, blurred vision, decreased visual acuity, diplopia, and photophobia. Nausea, vomiting, abdominal pain.[mnpoison.org]
Pupillary Abnormality
  • Pupillary abnormality was observed in all. Edema of the optic disc and nerve fiber layer were common fundus findings. The majority of cases were treated with methylprednisolone intravenously.[ncbi.nlm.nih.gov]
Headache
  • A 31-year-old male alcoholic had headache, impaired consciousness, neck stiffness, roving eyes with dilated unreactive pupils, papilloedema, abdominal pain, vomiting, and severe metabolic acidosis after a binge.[ncbi.nlm.nih.gov]
  • Symptoms of methanol poisoning can include fatigue, headaches and nausea, similar to the effects as excessive drinking but with pronounced vision problems that may include blurred vision, flashes of light, tunnel vision, changes in colour perception,[smartraveller.gov.au]
  • Symptoms of methanol poisoning can include fatigue, headaches and nausea, and are associated with increasing vision problems such as heightened sensitivity to light and blurred or reduced vision.[safetravel.govt.nz]
  • Methanol poisoning can show symptoms quite quickly in someone my size with blurred vision, dizziness, headaches and a sensitivity to light being ones that can show up quite quickly. It is easily mistaken for drunkeness.[tripadvisor.co.nz]
  • They also had pounding headaches - another common symptom of methanol poisoning. 'I thought we needed medical help, but neither of us could get out of bed or even make a phone call,' says Kate.[dailymail.co.uk]
Seizure
  • ECG abnormalities did not correlate with coma or seizure. Even though cardiotoxicity in methanol poisoning is high, none of the ECG abnormalities found in our study predicted mortality.[ncbi.nlm.nih.gov]
  • Methanol poisoning results in neurological complications including visual disturbances, bilateral putaminal hemorrhagic necrosis, parkinsonism, cerebral edema, coma, or seizures.[ncbi.nlm.nih.gov]
  • Since the withdrawal seizures are self-limited, patients generally do not need treatment. However, patients with a prior history of seizures, Head injuries, status epilepticus, need treatment with intravenous Valium, Ativan and Dilantin.[doctorniruprasad.com]
  • Recommended indications for extracorporeal treatment: Severe methanol poisoning including any of the following being attributed to methanol: coma, seizures, new vision deficits, metabolic acidosis with blood pH 7.15, persistent metabolic acidosis despite[ncbi.nlm.nih.gov]
  • If treatment is not started, the symptoms worsen to include blurred vision and blindness; difficulty breathing and respiratory failure; muscle weakness; stomach pain, pancreatitis, nausea, and vomiting; low blood pressure; and confusion, seizures, and[sharecare.com]
Dizziness
  • […] definition Methanol poisoning is a rare poisoning resulting in elevated anion gap metabolic acidosis, due to the alcohol dehydrogenase (ADH)-mediated production of formic acid (which is poisonous to the central nervous system), and characterized by dizziness[orpha.net]
  • He said that he only felt dizziness and nausea, but did not vomit. Head of Dawan subprecinct police, Adj. Comr. Dewa Gede Artha said that the police was still investigating the case by collecting evidence from the victims.[lonelyplanet.com]
  • Methanol poisoning can show symptoms quite quickly in someone my size with blurred vision, dizziness, headaches and a sensitivity to light being ones that can show up quite quickly. It is easily mistaken for drunkeness.[tripadvisor.co.nz]
Confusion
  • In 68 methanol fatalities, confusion developedfollowed by coma, hypotension, respiratory depression, and cerebral edema. Blood methanol levels were above 100mg/dL (70%), metabolic acidoses (62%), and anion gaps 25 (100%).[ncbi.nlm.nih.gov]
  • The affected person suffers from headache , nausea, vomiting , confusion, coma and death. A lethal dose of formic acid is present in about 100 milliliters of pure methanol.[health-tutor.com]
  • If treatment is not started, the symptoms worsen to include blurred vision and blindness; difficulty breathing and respiratory failure; muscle weakness; stomach pain, pancreatitis, nausea, and vomiting; low blood pressure; and confusion, seizures, and[sharecare.com]
  • […] poisoning is a rare poisoning resulting in elevated anion gap metabolic acidosis, due to the alcohol dehydrogenase (ADH)-mediated production of formic acid (which is poisonous to the central nervous system), and characterized by dizziness, nausea, vomiting, confusion[orpha.net]
Agitation
  • These are some of the symptoms of methanol poisoning: • Difficulty breathing • Blurred vision • Agitation • Dizziness • Stomach pain No matter where you are, if you expect you’ve been poisoned, get to a hospital immediately.[battleface.com]
  • Symptoms may include: Airway and lungs: Breathing difficulty No breathing Eyes: Blindness, complete or partial, sometimes described as "snow blindness" Blurred vision Dilation (widening) of the pupils Heart and blood: Low blood pressure Nervous system: Agitated[nlm.nih.gov]
  • Mild withdrawal may present as Agitation or aggression a couple days after being brought into the hospital. Severe withdrawal can include Tremors , Seizures , confusion, and psychosis.[stomponstep1.com]

Workup

Diagnosis of MP is based on anamnestic data, clinical presentation and laboratory analysis of blood samples.

Patients may have a history of alcohol abuse, or report having drunk the night before, but due to the high toxicity of methanol metabolites, MP may result from consuming minor quantities of spirits. Patients have to be queried accordingly, they may not relate alcohol intake and symptoms. Simultaneous admission of several patients with similar symptoms should raise suspicion of MP, particularly if all patients attended the same event.

High anion gap metabolic acidosis and base deficit are characteristic findings in MP patients. Serum bicarbonate concentrations are below reference ranges, concentrations of lactate and ketones are increased.

Evaluation of serum levels of methanol, ethanol and formate may be helpful in assessing the severity of the disease.

Because a major share of MP patients develops pancreatitis, serum amylase concentrations should also be measured.

MP patients should undergo a thorough ophthalmologic examination and possible electroretinography to assess vision, visual fields, and retinal function. Optic disc hyperemia and blunted pupillary reflexes are commonly observed, but retinal lesions can generally not be detected. However, MP does cause loss of retinal sensitivity and results in decreased signal amplitudes as measured by electroretinography.

Because basal ganglia may also be compromised, brain imaging - either by magnetic resonance imaging or by computed tomography - should be carried out. Common findings are hemorrhages and necroses of the putamen, but white matter lesions and cerebral edema have also been observed [10]. Of note, anomalies may not be detectable until several days after symptom onset.

Anion Gap Increased
  • As the methanol is metabolised, the osmolar gap returns toward normal and the anion gap increases. A patient presenting late after a significant ingestion may have a normal osmolar gap and a high anion gap acidosis.[anaesthesiamcq.com]
Central Scotoma
  • However, a right central scotoma persisted, and bilateral optic atrophy was present. No reason for the exceptional delay before recovery and degree of recovery could be deduced, although throughout his convalescence he frequently chewed betel nut.[ncbi.nlm.nih.gov]
  • scotoma, reduced visual acuity, loss of color vision, and blindness [ 7 , 11 ].[omicsonline.org]
  • Ocular findings can be prominent and may include photophobia, central scotoma, visual field defects, fixed pupils and difficulty with light adaptation. Pupillary dysfunction has also been shown to be a strong predictor of mortality.[renalandurologynews.com]

Treatment

MP treatment consists in preventing further increases of toxic metabolite concentrations, preventing damage by circulating metabolites and compensating for already manifest symptoms. The following therapeutic measures may be applied to this end:

  • Application of fomepizole and/or ethanol. Both are substrates of alcohol dehydrogenase, but have a higher affinity than methanol, and are thus competitive antagonists of methanol oxidation by this enzyme. Fomepizole is preferred over ethanol because the latter causes side effects corresponding to ethanol intoxication. However, fomepizole stocks are generally limited, if the drug is available at all. It is also very expensive.
  • Administration of bicarbonate to counteract metabolic acidosis. This measure may also relieve neurological symptoms.
  • Hemodialysis aims at removing methanol and its metabolites from circulation. Hemodialysis is indicated in moderate to severe cases, i.e., if patients don't respond to the aforementioned measures and/or present neurological symptoms.
  • Fluid therapy is indicated in case of dehydration.

Besides drug therapy, patients may suffer from respiratory depression and require mechanical ventilation.

Prognosis

MP is associated with high mortality rates; survivors may suffer from permanent sequelae due to the optic nerve and central nervous system lesions. Although treatment protocols are well established, diagnosis is often delayed because of initial, non-specific symptoms and failure to relate recent alcohol consumption to the patient's condition. Most patients do not know they ingested methanol and may not even report having had a drink the night before.

Severe metabolic acidosis (pH < 6.90, base deficit > 28 mmol/l), respiratory arrest and coma have been identified as unfavorable prognostic parameters [5]. A severity of symptoms and thus, the likelihood of a poor outcome, correlate with the amount of ingested methanol and are inversely related to the quantity of consumed ethanol.

A dose of 6 g methanol per kg body weight is lethal, but fatalities have also been registered after consumption of doses as low as 200 mg/kg.

Etiology

Methanol is a chemical whose formula is CH3OH, i.e., a molecule of methanol consists of a single carbon atom which forms four bonds. Three bonds are saturated with hydrogen atoms, the fourth with a hydroxyl group. At room temperature, methanol is a clear, colorless liquid. Its boiling point is approximately 65 °C.

Thus, methanol shares many properties with ethanol, the second simplest alcohol compound. Its formula is CH3-CH2OH, i.e., one of those hydrogen atoms bound to the single carbon atom in methanol is replaced with a methyl group. At room temperature, ethanol is also clear and colorless. It's less volatile than methanol because its boiling point is at 78 °C. Although methanol tastes sweeter than ethanol, this difference may not be noted in alcoholic beverages that contain other ingredients.

The above-described similarities bear the risk of confusion and have been taken advantage of by unscrupulous people who dilute alcoholic drinks with methanol in order to maximize their profit [1]. Because such non-drinkable mixtures are generally sold to many people, MP generally affects many patients at the same time. Thus, "outbreaks" are reported. Of note, the aforementioned measure of ethanol dilution has also been taken by alcoholics in need of their addictive drug [2].

Epidemiology

MP is mainly reported in developing countries [1]. However, repeated outbreaks in industrialized nations illustrate the necessity of awareness in these geographical regions, too. In recent years, outbreaks have been observed in the Czech Republic, Estonia and Norway [3] [4] [5]. In sum, a total of 326 cases of MP were confirmed during these three outbreaks. 118 patients died either outside the hospital or while being hospitalized; this corresponds to a mortality rate of 36%.

Isolated cases corresponding to intended suicide are rare but have been described [6].

The following patient groups are considered to have an increased risk of MP:

  • People living in or traveling to developing countries. Here, methanol is frequently used as a cheap substitute of ethanol. With regards to the local population, people of low socioeconomic status, frequently living in rural areas, are most likely to consume methanol-containing beverages. Travelers are advised not to drink any home-made spirits; they may, however, not be able to recognize which drinks are prepared with such alcohols. In South-East Asia, a tourist presented MP after consuming a drink at a public bar [7].
  • Alcoholics may choose to consume methanol-containing drinks if they are unable to procure potable alcohol.
  • Children may accidentally ingest household products that contain methanol.
  • Employees of methanol-processing plants or laboratories may be exposed to the alcohol, which is readily absorbed through the skin.
Sex distribution
Age distribution

Pathophysiology

Methanol itself has a low toxicity; detrimental effects seen in MP patients are mediated by its metabolites.

Methanol is almost exclusively ingested per os and is easily absorbed through the mucous membranes lining the gastrointestinal tract; in rare cases, employees of methanol-processing installations may be in direct contact with methanol and absorb the alcohol through the skin. Absorbed methanol is then transported to the liver, where the enzyme alcohol dehydrogenase catalyzes its oxidation to formaldehyde. Subsequent conversion of formaldehyde to formic acid is mediated by formaldehyde dehydrogenase [8].

The time-limiting step in methanol metabolism is the oxidation of methanol and because it takes hours until significant amounts of formaldehyde are generated, symptom onset after methanol intoxication occurs in a delayed manner. Once formaldehyde is available, formic acid is produced rapidly. Both formaldehyde and formic acid are highly toxic, but, as has been explained, the half-life of formaldehyde is much shorter.

Further metabolization of formic acid does occur - it is indeed degraded to carbon dioxide and water by the enzyme 10-formyl tetrahydrofolate synthetase - but this process is slow. Consequently, formic acid accumulates in the body of a patient who ingested methanol, and this compound accounts for symptoms characteristic for MP. There is a direct correlation between formic acid concentrations, morbidity, and mortality of MP.

Formic acid primarily causes high anion gap metabolic acidosis. It is also neurotoxic and provokes optic nerve demyelination and atrophy, which results in visual impairment or even complete blindness. Interference with the mitochondrial electron transport chain and disruption of ATP-dependent processes is assumed to account for nerve lesions [9]. Further damage to the central nervous system, mainly to basal ganglia, occurs in MP patients and may be mediated by similar mechanisms.

Prevention

In many countries, methanol is only sold to factories and laboratories that hold an appropriate license [6]. This way, neither people who'd like to use methanol as an inexpensive substitute of ethanol nor those who are ignorant of the compound's toxicity can easily procure methanol. However, individuals may still steal and resell the alcohol. Thus, it is of utmost importance to educate people about the risks associated with methanol consumption. This applies to teenagers as well as adults, to people of low socioeconomic status, alcoholics and employees of institutions that work with methanol.

Unambiguous labeling of methanol-containing receptacle prevents confusion. Any corresponding industrial and laboratory equipment should be maintained in good condition. This also applies to entrance barriers. Safety measures should be taken when transporting methanol.

Summary

Methanol is a compound that may also be referred to as methyl alcohol or, colloquially, as wood alcohol or wood spirit. Today, it is mainly used in the chemical industry. Here it serves as a base material for the synthesis of formaldehyde, formic acid, and acetic acid. These compounds are utilized in a plethora of production processes carried out in the automotive and construction sector as well as in the wood industry. Methanol itself may be used as a solvent and in this form, it may be encountered in paints, varnishes, thinners and similar products. Because its melting point is much lower than that of water, methanol is also added to deicing and windscreen washing fluids.

The latter may be accidentally ingested and cause methanol poisoning (MP), although ethylene glycol poisoning will dominate the clinical picture in such cases. MP more commonly occurs due to a substitution of potable alcohol with methanol. This may occur in an intent to stretch alcoholic beverages and to maximize profit or to mix a drink that provokes inebriation if ethanol cannot be procured. Accidental ingestion of household products by children and intended suicide have also been related to MP.

Initially, MP patients show symptoms of inebriation, i.e., speech disorders, loss of inhibition and ataxia. Nausea, vomiting, and diarrhea are common. In severe cases, respiratory arrest may lead to death within hours after consumption of methanol-containing beverages, but in most cases, patients pass through a latency period of several hours before manifesting neurological symptoms like visual impairment, seizures, and loss of consciousness. A "blind drunk" is highly suspicious for MP.

Diagnosis is confirmed after interpretation of blood sample analyses. These reveal severe metabolic acidosis, increased concentrations of methanol, ethanol and formate, and possibly elevations of amylase concentrations. Ophthalmologic examination and neuroimaging complete MP workup.

Administration of fomepizole and/or ethanol, hemodialysis, mechanical ventilation and therapy of acid-base and electrolyte imbalances are the mainstays of therapy. Despite well-established protocols, MP is often diagnosed belatedly and mortality rates of more than 30% are commonly observed.

Patient Information

Methanol is an alcohol that shares many properties with ethanol, which is the chemical compound corresponding to potable alcohol. At room temperature, methanol is a clear, colorless and liquid. It tastes somewhat sweeter than ethanol, though. If sufficient quantities are consumed, both compounds provoke inebriation, e.g., the affected individual appears drunk, loses their inhibitions, shows speech and walking difficulties. Nausea, vomiting, and diarrhea are common.

However, ingestion of methanol causes additional, severe symptoms, which is why methanol is in no case suitable for consumption and accidental intake of this compound is referred to as methanol poisoning. The aforementioned, additional manifestations are life-threatening respiratory depression, cardiac failure, visual impairment or blindness and central nervous system damage. Up to a third of all patients diagnosed with methanol poisoning die from this condition.

MP more commonly occurs due to a substitution of potable alcohol with methanol. This may occur in an intent to stretch alcoholic beverages - a custom that is mainly observed in developing countries, but that has been described in industrialized nations, too. Alcoholics may be tempted to consume methanol instead of ethanol if they can't procure their addictive substance. Accidental ingestion of methanol-containing household products by children and intended suicide have also been related to MP.

In order to avoid involuntary ingestion of methanol, travelers are strongly advised not to drink home-made spirits they may be offered abroad.

References

Article

  1. Rostrup M, Edwards JK, Abukalish M, et al. The Methanol Poisoning Outbreaks in Libya 2013 and Kenya 2014. PLoS One. 2016; 11(3):e0152676.
  2. Rakus A, Kroczak M, Ruszkowski P. Methanol poisoning--case report. Przegl Lek. 2005; 62(6):514-516.
  3. Zakharov S, Pelclova D, Urban P, et al. Czech mass methanol outbreak 2012: epidemiology, challenges and clinical features. Clin Toxicol (Phila). 2014; 52(10):1013-1024.
  4. Paasma R, Hovda KE, Tikkerberi A, Jacobsen D. Methanol mass poisoning in Estonia: outbreak in 154 patients. Clin Toxicol (Phila). 2007; 45(2):152-157.
  5. Hovda KE, Hunderi OH, Tafjord AB, Dunlop O, Rudberg N, Jacobsen D. Methanol outbreak in Norway 2002-2004: epidemiology, clinical features and prognostic signs. J Intern Med. 2005; 258(2):181-190.
  6. Kristensen IB, Hansen AC. [Methanol poisoning in alcohol abusers]. Ugeskr Laeger. 1994; 156(15):2250-2251.
  7. Gee P, Martin E. Toxic cocktail: methanol poisoning in a tourist to Indonesia. Emerg Med Australas. 2012; 24(4):451-453.
  8. Barceloux DG, Bond GR, Krenzelok EP, Cooper H, Vale JA. American Academy of Clinical Toxicology practice guidelines on the treatment of methanol poisoning. J Toxicol Clin Toxicol. 2002; 40(4):415-446.
  9. Sharma P, Sharma R. Toxic optic neuropathy. Indian J Ophthalmol. 2011; 59(2):137-141.
  10. Blanco M, Casado R, Vazquez F, Pumar JM. CT and MR imaging findings in methanol intoxication. AJNR Am J Neuroradiol. 2006; 27(2):452-454.

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Last updated: 2018-06-22 06:03