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methanol intoxication

Etiology: - ingestion of methanol Epidemiology: - windshield washing fluid - commercial solvents - paints - some antifreezes - 2 teens die of Ingestion of a racing fuel* and carbonated soft drink mixture * racing fuel is ~100% methanol Pathology: 1) when ingested, methanol is rapidly metabolized to formaldehyde & to formic acid 2) formic acid is slowly metabolized & causes the pathology 3) major damage occurs at the retrolaminar optic nerve with intra-axonal swelling & organelle destruction 4) little to no change is seen in the retina 5) affects the basal ganglia; with severe intoxication, hemorrhagic & nonhemorrhagic damage of the putamen Clinical manifestations: 1) metabolic acidosis 2) central nervous system dysfunction - encephalopathy - nausea/vomiting 3) optic disc congestion, papilledema 4) mydriasis - afferent pupillary defect - pupillary response to light is compromised &, subsequently, is lost 5) complete blindness is common 6) hypotension [1] 7) abdominal pain, pancreatitis 8) inebriation less prominent than with ethylene glycol Laboratory: 1) anion gap metabolic acidosis a) arterial blood gas b) Chem7 or basic metabolic panel (calculate anion gap) 1] serum Na+ 2] serum K+ (not used in calculation of anion gap) 2] serum bicarbonate (< 10 meq/L) 3] serum chloride 2) serum osmolality, osmolal gap (> 10 mOsm/kg H2O) 3) serum ketones are negative 4) measurement of methanol in serum 5) labs with Loincs - methanol in specimen - methanol in air - methanol in exhaled gas - methanol in tissue - methanol in gastric fluid - methanol in meconium - methanol in blood - methanol in serum/plasma - methanol in urine Differential diagnosis: - isopropanol intoxication does not show anion gap [1] - ethylene glycol toxicity (renal manifestations) Complications: - mortality may be as high as 80-90% - permanent blindness may occur [1] Management: 1) fomepizole (Antizol) agent of choice [1] 2) ethanol 10% solution a) loading dose: 10 mL/kg b) maintenance dose: 1.5 mL/kg c) titrate to blood alcohol level of 22 mmol/L (100 mg/dL) 3) hemodialysis 4) blindness sometimes responds to therapy [2] 5) sodium bicarbonate 6) folic acid

Related

ethanol intoxication methanol; methyl alcohol (racing fuel)

General

alcohol toxicity

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 16, 17, 18. American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2012, 2018.
  2. eMedicine: Medicine http://www.emedicine.com/NEURO/topic217.htm
  3. Kruse JA Methanol and ethylene glycol intoxication. Crit Care Clin. 2012 Oct;28(4):661-711 PMID: 2299899
  4. Fill MA, Seger DL, Dunn JR, Schaffner W, Jones TF. Notes from the Field: Intoxication and Deaths Associated with Ingestion of a Racing Fuel and Carbonated Soft Drink Mixture - Tennessee, January 2016. MMWR Morb Mortal Wkly Rep 2016;65:585-586 http://www.cdc.gov/mmwr/volumes/65/wr/mm6522a4.htm
  5. Kruse JA. Methanol and ethylene glycol intoxication. Crit Care Clin. 2012 Oct;28(4):661-711. Review. PMID: 22998995