Intravenous corticosteroids raise risk of sudden symptom spikes in bulbar MG

More than half of myasthenia gravis (MG) patients with bulbar symptoms, or difficulties swallowing, chewing, and/or speaking, experience a disease exacerbation shortly after starting corticosteroid treatment, according to a study in China.

The risk for early exacerbation, or sudden symptom worsening, was found to be significantly higher among patients treated with intravenous (into-the-vein) corticosteroids than those treated with oral corticosteroids.

These findings indicate that “caution should be exercised when using [intravenous corticosteroid] regimen in clinical practice for bulbar MG patients,” particularly in those with respiratory muscle weakness, researchers wrote.

The study, “Factors associated with initial exacerbation after corticosteroids treatment in myasthenia gravis patients with bulbar symptoms,” was published in the Journal of Clinical Science.

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MG is an autoimmune disease usually caused by self-reactive antibodies that target proteins involved in nerve-muscle communication, leading to symptoms such as muscle weakness and fatigue. The disease can affect the muscles of the face, neck, and throat, resulting in speaking, chewing, and swallowing issues, known as bulbar symptoms.

Corticosteroids are anti-inflammatory medications widely used to control MG symptoms.

“However, the initiation of [corticosteroid] therapy may temporarily worsen symptoms and even precipitate myasthenic crisis in some patients,” the researchers wrote. Myasthenic crises are a serious MG complication marked by severe breathing problems that require hospitalization.

Whether initiating a corticosteroid regimen of intravenous or oral routes influences the risk or severity of MG remains largely unclear, especially in “the high–risk subgroup of MG patients with bulbar symptoms,” the researchers wrote. “Identifying regimen-specific risk factors in this population is of critical clinical importance.”

In this study, a team of researchers in China aimed to identify factors associated with initial exacerbation after corticosteroid treatment in MG patients with bulbar symptoms. They retrospectively analyzed data from 119 adults, ages 18 to 81 years, who were diagnosed with MG between 2013 and 2023 at a Chinese hospital, showed bulbar symptoms, and received corticosteroids during hospitalization.

Bulbar symptoms included reduced biting strength or difficulty chewing (83.2%), difficulty swallowing (63%), speech issues (47.1%), coughing when drinking (18.5%), and reduced cough strength (11.8%). More than 70% of the patients had three or more bulbar symptoms.

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More than half of patients developed an initial exacerbation

The team focused on two initial corticosteroid regimens: intravenous methylprednisolone (IVMP) — starting at a high dose for three days, followed by dose reduction and transition to oral prednisone tapering — and oral prednisone or similar for at least two weeks, without IVMP.

Initial exacerbation was defined as new or worsening symptoms within two weeks after starting corticosteroids. An exacerbation was deemed severe when the patient needed assisted ventilation or feeding support, was transferred to the intensive care unit, was treated with intravenous immunoglobulins, had severe breathing problems, or died.

Most participants received oral prednisone as the initial treatment (73.9%), while 26.1% received IVMP. More than half (52.1%) developed an initial exacerbation, and 25.8% of them were severe.

Exacerbations developed at a median of three days after starting corticosteroids and lasted a median of 3.5 days. Severe exacerbations developed slightly earlier, at a median of day 2, and lasted a median of four days.

[This study shows that an intravenous corticosteroid regimen] was independently associated with both initial exacerbation … and severe exacerbation, identifying it as a significant risk factor in bulbar MG patient. These findings suggest that caution should be exercised when using IVMP regimen in this high-risk population.

Participants treated with the intravenous regimen were significantly more likely to experience initial exacerbations (74.2% vs. 44.3%) and severe exacerbations (29% vs. 8%) than those receiving oral corticosteroids. There were no significant differences in the time to onset and duration of exacerbations between the two regimens.

Participants with initial exacerbations showed significantly higher rates of biting or chewing difficulties (93.5% vs. 71.9%), problems with swallowing (72.6% vs. 52.6%), and speech issues (56.6% vs. 36.8%). They were, however, significantly less likely to experience three or more types of bulbar symptoms (48.4% vs. 71.9%).

The initial exacerbation group also had significantly more severe functional impairment, according to the MG Activities of Daily Living score (9.13 vs. 7.84).

Statistical analysis adjusted for potential influencing factors demonstrated that reduced biting strength or difficulty chewing was significantly associated with a seven times higher chance of initial exacerbation, while IVMP regimen was significantly linked to a nearly fivefold higher chance.

Finally, IVMP was significantly associated with a higher likelihood of severe exacerbation (by nearly eight times), as were weak cough (by about 11.5 times) and impaired respiratory muscle strength (by eight times).

This study shows that an intravenous corticosteroid regimen “was independently associated with both initial exacerbation … and severe exacerbation, identifying it as a significant risk factor in bulbar MG patients,” the researchers wrote. “These findings suggest that caution should be exercised when using IVMP regimen in this high-risk population.”