Muscarine Mushroom Toxicity Clinical Presentation

Ask the patient about how many mushrooms were consumed, how they were prepared, and when the mushrooms were eaten. The concentration of active substances is low in any one mushroom. The effects of mushrooms vary greatly, and cooking may not alter toxicity. Typically, the amount consumed at a meal or a single whole mushroom is sufficient to cause symptoms.^[1]

Obtain a history of the exposure that includes the following:

• Quantity of mushrooms ingested
• Preparation of the mushroom (eg, raw, cooked)
• Source of the mushroom (eg, outdoors, the Internet)
• Time of the ingestion
• Symptoms and time of onset after ingestion
• Prehospital treatment including home remedies
• Medications regularly taken and any coingestants
• Past medical history with a focus on arrhythmias, asthma, prostatic hypertrophy, and gastric outlet obstruction

The timing of symptom onset is a crucial element of the history in differentiating life-threatening or severe mushroom poisonings from those that are less serious and typically have an onset of symptoms well within 5 hours of ingestion such as the muscarine-containing mushrooms.^{[6, 7, 3, 4, 5]}

Mushrooms from the cyclopeptide (Amanita phalloides) or orellanine (Cortinarius mushrooms) groups, which can produce hepatic or renal failure, respectively, typically produce symptoms 6-24 hours after ingestion.

Amanita smithiana (allenic norleucine group) found in the Northwestern states can also be nephrotoxic, but it has an onset of gastrointestinal distress within 1-12 hours.^[11] These mushrooms are often confused with edible pine mushrooms.

For mushroom ingestions in the Pacific Northwest region of the United States, patients who have early-onset symptoms (< 3 h after ingestion) and remain symptomatic should be fully evaluated in a hospital until the mushroom identity is confirmed to be nontoxic or the patient’s condition improves.^[5]

Identification of the actual mushroom consumed is important but is typically impossible because the mushroom in question has already been digested. Clitocybe mushrooms are found as single specimens on lawns in the summer and fall. The mushrooms are whitish tan-to-gray and have 15- to 33-mm caps. Their stalks are hairless and are 1- to 5-cm long. Their gills are decurrent (running down the stalk), and the spores are white.

Inocybe mushrooms are typically found in or under hardwoods and conifers in the summer and fall. The mushrooms are small and brown and have conical caps as large as 6 cm in diameter. Stalks are 2-10 cm and have fine, brown-to-white hairs. The gills are notched, and the spores are brown.

Different types of mushrooms can be found in the same location, and a single sample can lead to false identification of the mushroom that was ingested. Consider all possible mushrooms in the immediate vicinity of where the ingestion occurred.

When no specimen is brought in by a patient with a suspected mushroom ingestion, sending an experienced forager to the site to collect any mushrooms growing in the area might be helpful.

When mushrooms are obtained for identification, the entire mushroom should be dug up to preserve the architecture of the bulb, stem, and cap. Place individual mushrooms in a dry, paper bag, not a plastic or cloth bag. Transporting the mushrooms in a careful, dry manner minimizes destruction of the natural architecture of the mushrooms, discoloration of the cap or gills, and premature release of the spores. Do not refrigerate or crush the mushrooms.

Collecting the patient's gastric contents by means of gastric lavage or after emesis might yield identifiable spores.

Remote viewing of the mushroom by digital photography and Internet transmission may aid the identification of unknown mushrooms by mycologists.^[12]

Signs and symptoms related to the ingestion of a muscarine-containing mushroom typically appear after 0.5-2 hours and may last for 6-24 hours. Muscarinic effects, such as sweating, salivation, lacrimation, urination, defecation, abdominal cramps, miosis, emesis, bronchorrhea with shortness of breath, and bradycardia are seen. Profuse sweating and facial flushing are prominent features and should raise the suspicion of a muscarinic poisoning.^{[1, 2]}

The acronyms SLUDGE (salivation, lacrimation, urination, diarrhea, gastric distress, and emesis) and DUMBBELS (diarrhea, urination, miosis, bradycardia, bronchorrhea, emesis, lacrimation, and salivation) may be useful memory aids for the cholinergic syndrome affecting muscarinic receptors.

Muscarine does not directly cause CNS symptoms because it does not cross the blood-brain barrier due to its chemical nature as an ionized quaternary amine. The dizziness and headache occasionally experienced by patients poisoned with muscarine are the consequence of the peripheral cardiovascular and respiratory effects.

If symptoms such as vomiting, diarrhea, and abdominal pain begin 5 hours or more after ingestion, poisoning with the potentially life-threatening or severe mushrooms such as the cyclopeptide (Amanita phalloides) or orellanine (Cortinarius mushrooms) groups, which can produce hepatic or renal failure, respectively, should be considered.^{[6, 7, 3, 4, 5]}Amanita smithiana (allenic norleucine group) found in the Northwestern US can also be nephrotoxic but has an onset of gastrointestinal distress within 1-12 hours after ingestion.^[11] For mushroom ingestions in the Pacific Northwest region of the United States, patients who have early-onset symptoms (< 3 hr after ingestion) and remain symptomatic should be fully evaluated in a hospital until the mushroom identity is confirmed or the patient’s condition improves.^[5]

• Vital signs
• Pulse - Bradycardia or reflex tachycardia

  • Respiration - Unaffected to labored with shortness of breath
  • Blood pressure - Hypotension in severe cases
  • Temperature - No changes expected
• Integumentary findings

  • Facial flushing
  • Sweating
• Head, ears, eyes, nose, and throat findings

  • Pupillary constriction
  • Blurred vision
  • Excessive salivation
  • Watery eyes
• Cardiovascular symptoms

  • Bradycardia (more common)
  • Reflex tachycardia
• Respiratory signs

  • Copious bronchial secretions
  • Wheezing
  • Shortness of breath
• GI symptoms

  • Cramps
  • Vomiting
  • Increased bowel activity
  • Diarrhea
• Urinary tract symptoms

  • Increased urination
  • Bladder spasms
• Neurologic signs

  • Dizziness and headache from hypotension

• Incorrect mushroom identification by a naive forager, such as an immigrant who mistakes one of the local poisonous varieties for an edible mushroom native to his or her homeland or a novice mushroom harvester
• Intentional ingestion by a suicidal person or person attempting substance abuse
• Unintentional ingestion by a child who found mushrooms growing in yards or outdoor play areas
• Foul play in which an individual is poisoned by someone else
• Inadvertent poisoning from dried mushrooms purchased on the Internet or from other sources where the composition of the mushroom is unreliable or where the mushroom might contaminated with unknown toxic compounds