Background
Hypertrophic pachymeningitis has been recognized in neuromyelitis optica spectrum disorder (NMOSD). However, cranial nerve involvement as a result of pachymeningitis in NMOSD is not well known.
Case presentation
A 49‐year‐old woman, during an 8‐year period, suffered from recurrent, multiple cranial nerve palsies; that is, palsy of the right third (4 times) and right sixth (twice) cranial nerves, due most probably to a right cavernous sinus lesion from NMOSD. Sarcoidosis, Sjögren's syndrome or other collagen diseases were negative. Magnetic resonance imaging was negative for the first to fifth episode. Aquaporin‐4 immunoglobulin G was negative at the first episode; and not measured for the subsequent second to fifth episodes. Therefore, first to fifth episodes could be irrelevant to pachymeningitis or NMOSD. In contrast, at the sixth episode, gadolinium‐enhanced T1‐weighted coronal magnetic resonance imaging showed a pachymeningeal lesion adjacent to the right cavernous sinus. Parallel with this, aquaporin‐4 immunoglobulin G became positive. The patient was finally diagnosed with probable NMOSD and started on steroid pulse therapy, and her symptoms soon disappeared completely. After this, 5 mg/day oral prednisolone was started. In the subsequent 2 years, she has had no recurrence of diplopia.
Conclusions
This case report will help physicians suspect probable NMOSD in patients having recurrent, multiple cranial neuropathies, and provide them appropriate management and care.