Is there a link between myasthenia gravis and the risk of autoimmune encephalitis?
Myasthenia gravis (MG) and autoimmune encephalitis (AE) are both autoimmune disorders where the immune system attacks the body's own tissues. In MG, the attack is on the neuromuscular junction, causing muscle weakness. In AE, the attack is on the brain, causing confusion, seizures, and other neurological symptoms. Research shows that these two conditions can occur together more often than expected by chance, suggesting a link. A narrative review of the medical literature found that people with MG have an increased risk of developing AE 5. This overlap may be due to shared immune system problems, such as the production of multiple types of autoantibodies.
What the research says
A narrative review that combined the words 'myasthenia gravis' and 'autoimmune encephalitis' found epidemiological data and multiple case reports showing an increased risk for AE in people with MG 5. The review notes that both MG and AE are antibody-mediated disorders and can co-exist, which presents diagnostic and therapeutic challenges 5. The target antigens for the antibodies vary among patients, and the clinical manifestations, choice of therapy, and prognosis depend on the antibody pattern 5.
Case reports also illustrate this link. For example, a case report described a patient with thymoma (a tumor of the thymus gland) who had both MG and stiff person syndrome, another autoimmune neurological disorder 2. Thymoma is frequently associated with MG and can also be linked to other autoimmune conditions 2. Another study found that patients with MG may produce autoantibodies that neutralize type I interferons, which are associated with severe COVID-19 pneumonia; this risk was higher in patients with thymoma 8. These findings suggest that thymoma may be a common factor that increases the risk of multiple autoimmune conditions, including AE.
Additionally, a study on sequential treatment with efgartigimod and rituximab in three patients with refractory AE showed that these treatments, which are also used in MG, can be effective for AE 4. This suggests overlapping treatment pathways and possibly shared disease mechanisms. The narrative review also states that MG and AE have overlapping pathogenesis and similar preferred drug therapies, including corticosteroids, intravenous immunoglobulin, plasma exchange, and rituximab 5.
What to ask your doctor
- Given my MG diagnosis, what is my personal risk of developing autoimmune encephalitis?
- Should I be monitored for symptoms of autoimmune encephalitis, such as confusion, memory problems, or seizures?
- If I have a thymoma, does that increase my risk for other autoimmune conditions like encephalitis?
- What treatment options are available if I develop both MG and autoimmune encephalitis?
- Are there any specific antibody tests I should have to check for encephalitis risk?
This question is drawn from common patient questions about Rheumatology and answered using cited medical research. We do not provide individualized advice.