Data from: Longitudinal optic neuritis-unrelated visual evoked potential changes in NMO spectrum disorders

Objective: To investigate, if neuromyelitis optica spectrum disorder
(NMOSD) patients develop subclinical visual pathway impairment independent
of acute attacks. Methods: 548 longitudinally assessed full-field visual
evoked potentials (VEP) of 167 NMOSD patients from 16 centers were
retrospectively evaluated for changes of P100-latencies and
P100-N140-amplitudes. Rates of change in latencies (RCL) and amplitudes
(RCA) over time were analyzed for each individual eye using linear
regression and compared using generalized estimating equation models.
Results: The rates of change in the absence of optic neuritis (ON) for
minimal VEP intervals of ≥3 months between baseline and last follow-up
were +1.951ms/year (N=101 eyes; SD=6.274; p=0.012) for the P100-latencies
and -2.149µV/year (N=64 eyes; SD=5.013; p=0.005) for the
P100-N140-amplitudes. For minimal VEP intervals of ≥12 months the RCL was
+1.768ms/year (N=59 eyes; SD=4.558; p=0.024) and the RCA was -0.527µV/year
(N=44 eyes; SD=2.123; p=0.111). The history of a previous ON >6
months before baseline VEP had no influence on RCL and RCA. ONs during the
observational period led to mean RCL and RCA of +11.689ms/year (N=16 eyes;
SD=17.593; p=0.003) and -1.238µV/year (N=11 eyes; SD=3.708; p=0.308),
respectively. Conclusions: This first longitudinal VEP study of NMOSD
patients provides evidence of progressive VEP latency delay occurring
independently of acute ON. Prospective longitudinal studies are needed to
corroborate these findings and help to interpret the clinical relevance.