# Lady With the Blue Hair: An Atypical Cause of Myasthenic Crisis

## TL;DR

A woman with myasthenia gravis experienced two myasthenic crises linked to hair dye containing methylisothiazolinone, highlighting a new potential trigger.

## Contribution

Identifies methylisothiazolinone in hair dye as a possible precipitating factor for myasthenic crises.

## Key findings

- The patient's myasthenic crises were temporally linked to hair dyeing with products containing methylisothiazolinone.
- Methylisothiazolinone is suspected to exacerbate myasthenia gravis, suggesting a novel precipitating factor.
- Physicians should consider non-traditional triggers like beauty products when evaluating myasthenic crises.

## Abstract

A myasthenic crisis denotes a severe exacerbation of myasthenia gravis, leading a patient to enter a life-threatening state due to progressing muscle weakness that ultimately results in respiratory failure. A crisis can require intubation, mechanical ventilation, and additional critical care to prevent further decompensation and potentially death. Numerous well-documented precipitating factors exist, such as infections, surgery, stress, and various medications. We present the case of a 43-year-old woman recently diagnosed with myasthenia gravis who has experienced two myasthenic crises since diagnosis without evident triggers such as surgery, changes in medication, or infection. Following an unremarkable initial diagnostic test and continued treatment for the crisis, we sought additional information from the patient’s family member at the bedside. We were informed that two weeks prior to both times of crisis with intubation, the patient had dyed her hair blue. The common chemical component in the two different hair dyes used was methylisothiazolinone, which is suspected to have contributed to the exacerbation of the patient's myasthenia gravis. As more evidence for new precipitating factors of myasthenic crises develops, it is crucial for physicians to quickly identify signs and symptoms of a crisis so appropriate intervention can occur in a time-sensitive manner. In addition, myasthenia gravis patients should be made aware to be cautious of precipitating factors of a crisis, including but not limited to new beauty products.