NMO-IgG in idiopathic inflammatory demyelinatingdisorders among Hong Kong Chinese

Abstract

Background and aims: Neuromyelitis optica (NMO) is character-ized by acute transverse myelitis (ATM) and optic neuritis (ON).NMO-IgG facilitates diagnosis of NMO, distinguished from clas-sical multiple sclerosis (CMS). We studied NMO-IgG seropositiv-ity rate among local patients with idiopathic inflammatorydemyelinating disorders.Methods: 94 patients (30 CMS, 30 ATM without ON, 19 ON with-out ATM, 10 ATM with ON not fulfilling diagnostic criteria ofCMS (revised McDonald criteria), 5 ADEM) were studied. Patientsand controls (10 healthy subjects, 27 other neurological disorders)sera were tested for NMO-IgG by indirect immunofluorescenceusing monkey cerebellum slides.Results: 6 of 10 (60%) patients with ATM and ON not fulfillingdiagnostic criteria for CMS were NMO-IgG positive. All 6 hadextensive ATM (>3 vertebral segments), 5 of 6 had severe visualimpairment. 2 of 6 had brainstem dysfunction clinically with MRIbrainstem abnormalities; MRI brain was otherwise normal for all6 who were CSF oligoclonal bands negative. 2 of 4 NMO-IgG neg-ative patients had extensive ATM and one severe visual impair-ment. Among 10 recurrent ATM without ON patients, 6 (60%)were NMO-IgG positive; all 6 had extensive ATM. None of 20 sin-gle ATM attack patients was NMO-IgG positive. 2 of 8 recurrentON without ATM patients were NMO-IgG positive; one of 11 sin-gle ON attack patients was NMO-IgG positive, she had bilateralON. One of 30 CMS patients was NMO-IgG positive. No controlwas NMO-IgG positive.Conclusion: 60% of local patients with NMO or recurrent exten-sive ATM without ON were NMO-IgG seropositive.