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  • Updated 08.17.2022
  • Expires For CME 08.17.2025

Ascomycota mushroom poisoning

Introduction

Overview

At least two distinct neurologic or myologic presentations of mushroom poisoning have been reported for mushrooms of the phylum Ascomycota: morel neurologic syndrome and false morel neurologic syndrome. Of the two, the false morel neurologic syndrome is generally much more serious and often fatal.

Key points

• At least two distinct neurologic or myologic presentations of mushroom poisoning have been reported for mushrooms of the phylum Ascomycota: morel neurologic syndrome and false morel neurologic syndrome. Of the two, the false morel neurologic syndrome is generally much more serious and often fatal.

• Although morel mushrooms are often considered an edible delicacy, they can be toxic when poorly cooked or when eaten in large quantities by susceptible people.

• The toxin responsible for the morel neurologic toxidrome has not been identified.

• The main neurologic signs among cases with the morel neurologic toxidrome were tremor, dizziness or "inebriation," visual disorders, and unsteadiness or ataxia.

• Gyromitrin (acetaldehyde methylformylhydrazone), the toxic substance in false morel mushrooms, is converted to a water-soluble toxin, monomethylhydrazine.

• Monomethylhydrazine can bind to and inhibit pyridoxal phosphokinase.

• Pyridoxine kinase inhibition interferes with production of the active form of pyridoxine, pyridoxal-5'-phosphate, an essential cofactor for glutamic acid decarboxylase, which catalyzes the decarboxylation of glutamate to gamma-amino butyric acid and carbon dioxide.

• GABA deficiency caused by the toxin gyromitrin results in a loss of inhibitory neurotransmission as well as the relative build-up of the excitatory neurotransmitter glutamate; collectively these may produce CNS excitation and seizures that are refractory to standard anticonvulsant therapy.

• Anticonvulsant-refractory seizures and some of the other neurologic manifestations of gyromitrin intoxication may be ameliorated by administering pyridoxine.

• Death from gyromitrin-containing mushrooms is rare in North America, but five people died from ingesting these mushrooms in Minnesota in 1938 (03), and case-fatality rates of 10% to 40% have been reported in other regions of the world.

• Reported complications of gyromitrin or monomethylhydrazine poisoning include aspiration pneumonia, rhabdomyolysis, renal failure (secondary to hemolysis and rhabdomyolysis), liver failure, and anoxic and hepatic encephalopathy.

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