AQP4 and myelitis: One of these patients had symptoms of diplopia and an isolated brain lesion involving the AQP4-rich periaqueductal area [24], and the other had recurrent mild symptoms and signs of myelitis (e.g. hypesthesia, pain in lower extremities, voiding difficulty, hyper-reflexive deep tendon reflex) but no definite lesion that could be seen on repeated spinal MRI.