OBJECTIVETo assess the seroprevalence and diagnostic value of aquaporin-4 antibody (AQP4-Ab) in patients with inflammatory central nervous system demyelinating diseases.

METHODSSeventy-two patients with neuromyelitis optica (NMO), 68 with multiple sclerosis (MS), 4 with optic neuritis (ON), and 41 with transverse myelitis (TM) were included in this study. The TM group comprised 19 patients with non-longitudinally extensive transverse myelitis (nLETM), 14 with monophasic longitudinally extensive transverse myelitis (mLETM), and 8 with recurrent longitudinally extensive transverse myelitis (rLETM). The serum levels of AQP4-Ab was detected by indirect immunofluorence assay in these patients.

RESULTSAQP4-Ab was detected in 72.2% (52/72) patients with NMO, 5.9% (4/68) patients with MS, 25.0% (1/4) patients with ON, and 17.1% (7/41) patients with TM, showing a significant difference in the positivity between NMO and MS groups (P<0.01). AQP4-Ab seropositivity rate was 5.3% (1/19) in nLETM patients, 62.5% (5/8) in rLETM patients and 7.1% (1/14) in mLETM patients, significantly higher in rLETM than in nLETM (P<0.01) and mLETM groups (P<0.05), but no statistical difference was found between rLETM and NMO groups.

CONCLUSIONSA high seroprevalence of AQP4-Ab is observed in patients with NMO and rLETM, which support the hypothesis that NMO and rLETM belong to NMO spectrum disorders. AQP4-Ab can serve as a useful index for diagnosing NMO and differential diagnosis from MS. More attention and effective immunosuppressive treatments should be given to patients positive for AQP4-Ab.