[The correlation factor analysis for conversion of clinically isolated syndrome to multiple sclerosis and neuromyelitis optica].

OBJECTIVE: To analyze the features of patients who converted from clinically isolated syndrome (CIS) to multiple sclerosis (MS) and neuromyelitis optica (NMO) and explore the correlated factors.

METHODS: A total of 151 patients admitted in our unit as CIS from January 2009 to December 2014 were enrolled in the study. All patients were divided into the following four groups by locations of the initial lesion, which were the spinal cord, the optic nerve, the brain stem and the multifocal lesions. Data were collected at the baseline including demographics, expanded disability status scale (EDSS) score, site of CIS, presence or absence of cerebrospinal fluid (CSF) oligoclonal bands (OB) and serum aquaporin-4 antibody (AQP4-Ab), evoked potential (EP) and MRI lesions. The conversion rates from CIS to clinically definite MS or NMO were calculated and the correlated factors were explored.

RESULTS: With a mean follow-up period of (44.11±17.62)months, 46/151(30.5%) patients converted to MS, 28/151 (18.5%) to definite NMO and 66/151 patients(43.7%)remained as CIS. Other patients were converted to optic neuritis(4/151), one-time transverse myelitis(3/151), acute disseminated encephalomyelitis (1/151) and Balo concentric sclerosis(3/151) . The EDSS score was significantly higher in patients converted to NMO than those converted to MS (P=0.003). The initial manifestation of optic neuritis significantly correlated with the conversion to NMO (P=0.000), while the initial manifestation of CIS with multifocal lesions significantly correlated with the conversion to MS (P=0.000). Neither the isolated BAEP (P=0.703), VEP (P=0.076), SEP (P=0.915) nor the combination of two (P=0.546)or three (P=1.000) of the above parameters could help to distinguish the conversion to MS or NMO. More patients with positive CSF-OB converted to MS (P=0.001), while more patients with positive serum AQP4-Ab converted to NMO (P=0.001). More patients were serum AQP4-Ab positive in those converted to NMO than those converted to MS (P=0.000). Lesions longer than three vertebral segments were dominant in patients converted to NMO (P=0.000). The logistic regression analysis revealed that factors correlated with conversion from CIS to MS were the initial CIS manifestation of multifocal lesions (OR=4.775, P=0.002), positive CSF-OB (OR=7.794, P=0.002) and VEP abnormality (OR=7.251, P=0.001). Factors correlated with conversion from CIS to NMO were female in gender (OR=12.536, P=0.019), positive serum AQP4-Ab (OR=36.410, P=0.002), lesions longer than three vertebral segments (OR=93.602, P=0.001), abnormal VEP and SEP (OR=18.448, P=0.002; OR=12.731, P=0.016).

CONCLUSIONS: Factors correlated with the conversion from CIS to MS are initial CIS manifestation of multifocal lesions, positive CSF-OB and abnormal VEP, while those correlated with the conversion from CIS to NMO are female in gender, positive serum AQP4-Ab, initial CIS manifestation with optic nerve, lesions involved more than three vertebral segments and abnormal VEP and SEP.