Reversible sub-acute motor neuron syndrome after mushroom intoxication masquerading as amyotrophic lateral sclerosis

Abstract

A 56-year-old man presented with rapidly evolving/sub-acute upper and lower motor neuron syndrome in 2015 with significant weakness in the four limbs and the bulbar region. Amyotrophic lateral sclerosis functional rating scale-revised (ALSFRS-r) was rated 34/48. On electromyography, there was a diffuse and active denervation in the four limbs and the tongue. A diagnosis of definite ALS according to international criteria was made. Six months later the patient stopped worsening. In the following years he progressively recovered. ALSFRS-r score improved to reach 48/48 in 2021. His neurological examination is normal and electromyography shows no denervation. Inquiry revealed that he presented a few months and, again a few days before onset, a mushroom poisoning. He was used to eating false morels either crude or undercooked and developed muscles cramps, nausea and vertigo. The relationships between this reversible sub-acute motor neuron syndrome and mushroom intoxication are discussed in the light of the recently described cluster in the Alps with a high incidence of ALS cases. Epidemiological investigations showed that all patients, but not their spouses, used to eat crude or undercooked false morels. Such a mushroom contains hydrazines, a known neurotoxic agent. We are not aware of another case of ALS reversal in that cluster area. We propose that a potential mushroom poisoning be thoroughly searched for when facing with a patient with sub-acute or rapidly worsening ALS syndrome.

Keywords:

• ALS
• hydrazine
• ALS reversal
• mushroom
• poisoning

Ethical approval

This work was approved by the Institutional Review Board of the CHU of Montpellier, number: IRB-MTP_2021_00923. Patient consent obtained.

Author contributions

Clinical data: EL, NP, WC. Writing of the manuscript: ED, EL, JPV, WC. Critical revision of the manuscript: all authors.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Data availability statement

Data are available on request to the corresponding author.