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Methyl iodide rhombencephalopathy: clinico-radiological features of a preventable, potentially fatal industrial accident
  1. Ivan Iniesta1,
  2. Mark Radon2,
  3. Colin Pinder1
  1. 1Department of Neurology, The Walton Centre Foundation Trust, Liverpool, Merseyside, UK
  2. 2Department of Neuroradiology, The Walton Centre Foundation Trust, Liverpool, Merseyside, UK
  1. Correspondence to Dr Ivan Iniesta, Department of Neurology, The Walton Centre Foundation Trust, Lower Lane, Fazakerley, Liverpool, Merseyside CH64 9RS, UK; iniesta.ivan{at}

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Methyl iodide or ‘Mel’ is a dense, colourless, volatile monohalomethane, which is rapidly metabolised in man (Ofigures 1 and 2); the organically bound iodine is converted to inorganic iodide and excreted in this form in the urine.1 It is used as a pesticide in the USA and in a variety of organic chemical reactions and for dye-works and detergents in the UK. Although methyl iodide is a rare intoxicant, its manifestations are similar to those of poisoning with the other more common monohalomethane agents. Indeed, methyl iodide intoxication resembles that of methyl bromide and methyl chloride. Characteristics of the poisoning include a delay between exposure and onset of symptoms with early systemic toxicity, including congestive changes in the lungs and oliguria; metabolic acidosis; prominent cerebellar and extrapyramidal neurological features; and in severe cases, seizures and coma. Psychiatric disturbances may persist for years.

Figure 1

Molecular structure of methyl iodide (CH3I).

Figure 2

Ball and stick model of methyl iodide.


A previously healthy 40-year-old man employed in a chemical factory manufacturing methyl iodide for detergents was admitted to the intensive care unit in status epilepticus. The previous day he had inhaled an unspecified amount of methyl iodide. On returning home his wife described him as ‘out of character’, incoherent at times and with visual hallucinations …

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