Anti-aquaporin-4 IgG in Patients Presenting with Unilateral Optic Neuritis: A Cohort Study

Background: optic neuritis (on) can be the first presentationof multiple sclerosis (ms) or neuromyelitis optica (nmo). antiaquaporin-4 igg (aqp4 igg) is a highly specific and moderatelysensitive biomarker for nmo. this study was designed to assessthe rate of seropositivity for aqp4 igg, and the short-termoutcome of patients presenting with single isolated on (sion).methods: a cohort of 41 consecutive patients experiencingsevere ( < 20 / 200) sion (not fulfilling the diagnostic criteria forms or nmo), was prospectively recruited. blood sampling wascarried out immediately after the diagnosis of on, and aqp4 iggwas tested qualitatively, using an indirect immunofluorescence kit.after clinical and paraclinical investigations, all the patients werefollowed up for a short-term period of at least 18 months.results: the seroprevalence among the initial on patients was9.7% (4 / 41). the short-term conversion rate to ms and nmo wasestimated to be about 7.3 and 4.9%, respectively. the conversionrate to nmo in initially seropositive patients was greater than thatfor the whole cohort [2 / 4 (50%) vs. 2 / 41 (4.9%); p = 0.035;odds ratio: 19.5, 95% confidence interval: 1.73 to 219.50].conclusion: aqp4 igg seropositive sion patients were morelikely to develop nmo in comparison to the total sion population.further studies, with a longer follow-up period and larger samplesizes are warranted to assess the clinical and prognostic value ofassessing aqp4 igg in sion.