From the Guidelines
Treatment of myasthenic crises should prioritize immediate respiratory support and rapid immunomodulation with either plasma exchange or intravenous immunoglobulin (IVIG), alongside careful management of precipitating factors and consideration of high-dose corticosteroids and immunosuppressants as needed, as indicated by the most recent guidelines 1.
Initial Management
Initial management of myasthenic crisis includes:
- Respiratory support with intubation and mechanical ventilation when necessary, as indicated by decreased vital capacity or negative inspiratory force suggesting compromised respiratory muscles.
- Temporary discontinuation of cholinesterase inhibitors like pyridostigmine to avoid complicating respiratory management, with reintroduction once the patient stabilizes.
Immunomodulation
Rapid immunomodulation can be achieved with:
- Plasma exchange (PLEX), typically over several days.
- Intravenous immunoglobulin (IVIG) at a dose of 2 g/kg divided over 2-5 days, as supported by recent guidelines 1.
Corticosteroids and Immunosuppressants
- High-dose corticosteroids, such as prednisone, may be initiated, though they may temporarily worsen symptoms.
- Immunosuppressants like azathioprine, mycophenolate mofetil, or rituximab may be considered for long-term prevention of recurrent crises, especially in cases refractory to initial treatments, as suggested by 1.
Precipitating Factors
Careful management of precipitating factors, including:
- Infections.
- Surgery.
- Medications known to exacerbate myasthenia gravis, such as aminoglycosides, fluoroquinolones, magnesium, and beta-blockers, is crucial, as highlighted in 1 and 1.
Recent Guidelines
The most recent guidelines from 2021 1 emphasize the importance of prompt intervention, grading of symptoms, and tailored management approaches, including the potential use of rituximab in refractory cases, underscoring the need for a personalized and aggressive treatment strategy to improve outcomes in myasthenic crises.
From the FDA Drug Label
Although failure of patients to show clinical improvement may reflect underdosage, it can also be indicative of overdosage. As is true of all cholinergic drugs, overdosage of pyridostigmine bromide may result in cholinergic crisis, a state characterized by increasing muscle weakness which, through involvement of the muscles of respiration, may lead to death Myasthenic crisis due to an increase in the severity of the disease is also accompanied by extreme muscle weakness, and thus may be difficult to distinguish from cholinergic crisis on a symptomatic basis The treatment of the two conditions obviously differs radically. Whereas the presence of myasthenic crisis suggests the need for more intensive anticholinesterase therapy, the diagnosis of cholinergic crisis, according to Osserman and Genkins1, calls for the prompt withdrawal of all drugs of this type.
The options for treating myasthenic crises include:
- More intensive anticholinesterase therapy 2 It is essential to differentiate between myasthenic crisis and cholinergic crisis, as the treatment approaches are radically different. In cases of myasthenic crisis, increasing the intensity of anticholinesterase therapy may be necessary, while cholinergic crisis requires the prompt withdrawal of anticholinesterase drugs and potential use of atropine.
From the Research
Treatment Options for Myasthenic Crises
- The primary goal of treatment is to address the underlying cause of the crisis and provide respiratory support 3.
- Noninvasive positive-pressure ventilation can be an effective initial treatment for respiratory support, even in patients with bulbar weakness 3.
- If intubation is necessary, it is recommended to avoid paralytics or use a reduced dose of nondepolarizing agents 3.
- Immunomodulatory treatments, such as intravenous immunoglobulin or plasmapheresis, are considered cornerstones of therapy 4, 5.
- Corticosteroids, such as methylprednisolone, can be used to manage myasthenic crises, with high-dose intravenous pulses showing rapid improvement in some patients 6.
- Acetylcholinesterase inhibitors, such as pyridostigmine or neostigmine, can be considered as an alternative to intravenous immunoglobulin or plasmapheresis, but caution is advised due to potential complications 7.
Key Considerations
- Identifying and managing potential precipitating factors, such as infections, is crucial in the treatment of myasthenic crises 3, 5.
- Close monitoring and prompt management of complications are essential to reduce mortality rates, which should be 5% or less 4, 5.
- The choice of treatment should be individualized based on the patient's specific needs and circumstances, taking into account the availability of resources and potential side effects 7, 6.