Cerebrospinal fluid levels of brain specific proteins in optic neuritis

This study evaluates levels of cerebrospinal fluid (CSF) brain-specific proteins (BSP) in subjects with optic neuritis (ON) who are at high risk of progression to multiple sclerosis (MS). Forty-one subjects had acute ON and 17 subjects with other neurological diseases (OND) served as controls. Twenty-one subjects with ON had white matter lesions on magnetic resonance imaging (MRI) and intrathecal synthesis of oligoclonal IgG bands (OB) consistent with being at high risk of progression to MS; eight of whom later were diagnosed with clinically definite MS (CDMS). Levels of S100B, ferritin and two neurofilament heavy chain phosphoforms (NfH(SM134) and NfH(SM135)) were analysed using ELISA technique. A putative index of 'axonal health' was expressed as a ratio of NfH(SM134) to NfH(S135). NfH(SM134) and the NfH(SM134:SM135) were significantly elevated in subjects with ON compared to controls. No significant differences in levels of CSF BSP were seen between ON subjects with CDMS plus those at high risk of progression to MS and ON subjects with normal MRI and negative CSF analysis. In conclusion, there is evidence of axonal damage in subjects who present with ON, which is independent of the diagnosis of CDMS.