Researchers from the US presented the case of a patient with Miller Fisher syndrome who was positive for GQ1b and aquaporin-4 (AQP4) antibodies but negative for myelin oligodendrocyte glycoprotein antibodies. She did not show any features of neuromyelitis optica spectrum disorder (NMOSD).
“This finding may lead to investigations and reports of other pathologies that are associated with the aquaporin-4 antibody,” the researchers wrote in a report that they published in the journal Cureus.
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There are currently no AQP4 antibody-associated disorders other than NMOSD.
“Our case report is an interesting observation of detecting AQP4 antibodies in 1 patient with Miller Fisher syndrome. It is far from demonstrating any association,” the authors wrote.
The case they presented is that of a 27-year-old female who came to the emergency department with a headache, pain when moving the eyes, and progressive double vision in both eyes for 5 to 6 days.
Physical examination revealed an inability to look up or down and stand or walk unassisted. Magnetic resonance imaging showed no myelitis. Blood tests revealed the presence of GQ1b and AQP4 antibodies.
She was treated with a course of 1000 mg intravenous solu-medrol each day and daily intravenous immunoglobulin for 5 days, which led to rapid improvement in her symptoms. She was completely asymptomatic 3 weeks after she first came to the hospital.
“With increasing testing for AQP4 antibodies, more disease entities will likely be found with positive AQP4,” the researchers wrote. “Therefore, consideration of the possibility of an AQP4-associated disorder may be warranted.”
Miller Fisher syndrome is a rare acquired nervous system disorder related to Guillain-Barré syndrome, where there are GQ1b antibodies but no myelitis or optic neuritis. The disease is characterized by eye muscle weakness, impaired limb coordination, and instability. It is not considered a component of NMOSD.
Reference
Aylia F, Johri K, Spencer R, et al. A patient with Miller Fisher syndrome with positive GQ1b and aquaporin-4 antibodies: will there be an aquaporin-4 antibody associated disorder? Cureus. Published online August 13, 2023. doi:10.7759/cureus.43428
