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Neurofilament results for the phase II neuroprotection study of phenytoin in optic neuritis
Author(s) -
Raftopoulos R.,
Kuhle J.,
Grant D.,
Hickman S. J.,
Altmann D. R.,
Leppert D.,
Blennow K.,
Zetterberg H.,
Kapoor R.,
Giovani G.,
Gnanapavan S.
Publication year - 2021
Publication title -
european journal of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 124
eISSN - 1468-1331
pISSN - 1351-5101
DOI - 10.1111/ene.14591
Subject(s) - phenytoin , medicine , placebo , neuroprotection , optic neuritis , neuromyelitis optica , gastroenterology , nerve fiber layer , ophthalmology , neurofilament , anesthesia , multiple sclerosis , optic nerve , epilepsy , pathology , immunology , alternative medicine , psychiatry , immunohistochemistry
Background A randomized trial of phenytoin in acute optic neuritis (ON) demonstrated a 30% reduction in retinal nerve fiber layer (RNFL) loss with phenytoin versus placebo. Here we present the corresponding serum neurofilament analyses. Methods Eighty‐six acute ON cases were randomized to receive phenytoin (4–6 mg/kg/day) or placebo for 3 months, and followed up for 6 months. Serum was collected at baseline, 3 and 6 months for analysis of neurofilament heavy chain (NfH) and neurofilament light chain (NfL). Results Sixty‐four patients had blood sampling. Of these, 58 and 56 were available at 3 months, and 55 and 54 were available at 6 months for NfH and NfL, respectively. There was no significant correlation between serum NfH and NfL at the time points tested. For NfH, the difference in mean placebo – phenytoin was −44 pg/ml at 3 months ( P = 0.019) and −27 pg/ml at 6 months ( P = 0.234). For NfL, the difference was 1.4 pg/ml at 3 months ( P = 0.726) and −1.6 pg/ml at 6 months ( P = 0.766). Conclusions At 3 months, there was a reduction in NfH, but not NFL, in the phenytoin versus placebo group, while differences at 6 months were not statistically significant. This suggests a potential neuroprotective role for phenytoin in acute ON, with the lower NfH at 3 months, when levels secondary to degeneration of the anterior visual pathway are still elevated, but not at 6 months, when levels have normalized.