Autoimmune synaptic encephalitis may occur at the same time as other autoimmune diseases, such as myasthenia gravis, according to a new study published in BMC Neurology.
The study reported the case of a 24-year-old male who had seronegative ocular myasthenia gravis and had no acetylcholine receptors in his serum, normally a hallmark of the disease.
He was diagnosed with myasthenia gravis based on single-fiber electrophysiology findings.
Read more about the diagnosis of myasthenia gravis
After 3 months, he developed autoimmune synaptic encephalitis. He was first positive for α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antibodies and then for N-methyl-D-aspartate (NMDA) receptor antibodies, which target excitatory neurotransmission in the brain and lead to autoimmune synaptic encephalitis.
He was treated with aggressive immunosuppression and recovered, being able to return to his normal life 1 year later even though he still had some cognitive problems.
The researchers concluded that myasthenia gravis patients who are seronegative may develop autoimmune synaptic encephalitis with more than one cell-surface antibody, even though these findings may only be expected in myasthenia gravis patients who are seropositive.
Autoimmune synaptic encephalitis is a group of rare autoimmune diseases characterized by brain and spinal cord inflammation. Symptoms of the disease may vary widely from patient to patient and include aphasia, abnormal body movements or seizures, vision loss, limb weakness, and sleep problems. The condition may also cause quickly developing psychiatric problems including mood changes, anxiety, and psychosis.
Myasthenia gravis is also rare, but it is the most common autoimmune disease affecting the neuromuscular junction. Here, autoantibodies attack the receptors in the neuromuscular junction impairing the transfer of electrical signals from the brain to the muscle tissue causing muscular atrophy and degeneration. Ocular myasthenia gravis is a form of the disease in which muscle weakness is limited to the extraocular muscles, the levator palpebrae superioris, and the orbicularis oculi.
Schäfer J, Christensen PB, Jensen K. AMPA and NMDA receptor antibody autoimmune encephalitis preceded by ocular myasthenia gravis: a case report. BMC Neurol. Published online March 10, 2023. doi: 10.1186/s12883-023-03129-2