Abstract
Early detection of neuromyelitis optica spectrum disorders (NMOSD), especially after optic neuritis, a presenting manifestation commonly observed also in multiple sclerosis (MS), is crucial for timely treatment and prognosis. Integrated visual pathway assessment with optical coherence tomography (OCT) and visual evoked potentials (VEP) may help in this task, showing in vivo different pathophysiological backgrounds. We evaluated combined VEP and OCT in a cross-sectional, single-centre study assessing 50 consecutive NMOSD patients, 57 MS patients and 52 healthy controls. After optic neuritis, VEP were more frequently absent in NMOSD compared to MS; most NMOSD eyes with recordable VEP showed prolonged latency, but extreme latency delays were less common than in MS. OCT showed predominantly axonal involvement in NMOSD, with 88% eyes (95% CI: 69–97%) displaying retinal nerve fibre layer thickness <60 µm even after first optic neuritis episode. Accuracy of OCT was further enhanced by combination with VEP into a new Z-score derived OCT-VEP index, measuring prevalence of axonal damage or demyelination. Our results suggest that integrated optic nerve assessment may elucidate differences in optic neuritis pathophysiology; conduction slowing with relatively preserved nerve fibre layer suggests MS, while severe neuroaxonal loss after optic neuritis, often hindering VEP response, characterizes NMOSD.
Highlights
Recognizing different patterns of damage between neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS), especially in patients experiencing optic neuritis (ON), is an important challenge, both for researchers and clinicians, as the two diseases share many clinical and paraclinical features, but differ in critical aspects, first of all prognosis and therapy
Optical coherence tomography (OCT) studies in NMOSD published since 2008 have shown thinner retinal nerve fibre layer in NMOSD after ON compared to healthy controls[1,2,3,4] and compared to MS eyes with history of ON1
Among eyes with ON history, the frequency of absent 15′ Visual evoked potentials (VEP) was significantly higher in NMOSD (63.0% [95% CI: 49.6–74.6%]) compared to MS (7.3% [CI: 2.9–17.3%], p < 0.001, Fisher’s exact test)
Summary
Recognizing different patterns of damage between neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS), especially in patients experiencing optic neuritis (ON), is an important challenge, both for researchers and clinicians, as the two diseases share many clinical and paraclinical features, but differ in critical aspects, first of all prognosis and therapy. In NMOSD eyes without history of ON, there are contrasting evidences about OCT involvement, with some studies[5,6] showing subclinical abnormalities, but not other ones[1,3,7,8]. It is known from literature that eyes of MS patients show subclinical RNFL thinning regardless of acute ON events along the course of disease[13,14]. It is not clear whether NMOSD presents with similar subclinical changes. The aim of the present study was to explore the value of optic nerve structural and functional metrics, alone or in combination, in characterizing NMOSD and differentiating it from MS, in eyes with and without history of optic neuritis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
