Abstract
ObjectivesWe aimed to evaluate optic chiasm (OC) measures as potential imaging marker for anterior optic pathway damage assessment in the context of neuromyelitis optica spectrum disorders (NMOSD).Materials and methodThis cross-sectional study included 39 patients exclusively with aquaporin 4-IgG seropositive NMOSD of which 25 patients had a history of optic neuritis (NMOSD-ON) and 37 age- and sex-matched healthy controls (HC). OC heights, width, and area were measured using standard 3D T1-weighted MRI. Sensitivity of these measures to detect neurodegeneration in the anterior optic pathway was assessed in receiver operating characteristics analyses. Correlation coefficients were used to assess associations with structural measures of the anterior optic pathway (optic nerve dimensions, retinal ganglion cell loss) and clinical measures (visual function and disease duration).ResultsOC heights and area were significantly smaller in NMOSD-ON compared to HC (NMOSD-ON vs. HC p < 0.0001). An OC area smaller than 22.5 mm2 yielded a sensitivity of 0.92 and a specificity of 0.92 in separating chiasms of NMOSD-ON from HC. OC area correlated well with structural and clinical measures in NMOSD-ON: optic nerve diameter (r = 0.4, p = 0.047), peripapillary retinal nerve fiber layer thickness (r = 0.59, p = 0.003), global visual acuity (r = − 0.57, p = 0.013), and diseases duration (r = − 0.5, p = 0.012).ConclusionOur results suggest that OC measures are promising and easily accessible imaging markers for the assessment of anterior optic pathway damage.Key Points• Optic chiasm dimensions were smaller in neuromyelitis optica spectrum disorder patients compared to healthy controls.• Optic chiasm dimensions are associated with retinal measures and visual dysfunction.• The optic chiasm might be used as an easily accessible imaging marker of neurodegeneration in the anterior optic pathway with potential functional relevance.
Highlights
Neuromyelitis optic spectrum disorders (NMOSDs) are inflammatory autoimmune CNS diseases that preferentially target the optic nerves and are frequently associated with serum autoantibodies to aquaporin-4 [1, 2]
We report the Optical coherence tomography (OCT) acquisition settings and scanning protocol according to the APOSTEL recommendations [35]: The peripapillary retinal nerve fiber layer (pRNFL) thickness was measured using 3.4-mm ring scans around the optic nerve head (12°, 1536 A-scans, 9 ≤ ART ≤ 100)
Optic nerve diameters were different in NMOSD-optic neuritis (ON) compared to healthy controls (HC) (p < 0.0001), NMOSD-ON compared to NMOSD-NON (p < 0.01), but not in NMOSD-NON compared to HC (p > 0.05)
Summary
Neuromyelitis optic spectrum disorders (NMOSDs) are inflammatory autoimmune CNS diseases that preferentially target the optic nerves and are frequently associated with serum autoantibodies to aquaporin-4 [1, 2]. Optic pathway dimensions as assessed by MRI have been used as a surrogate marker of inflammatory damage and atrophy of the optic nerve and anatomically connected tracts [3, 4, 15,16,17,18]. OCT measures have been successfully used as surrogate markers of optic nerve atrophy [16, 17, 19, 21,22,23,24,25], being associated to MRI-detected macro- and microstructural optic pathway atrophy and visual function [16, 17, 20, 26,27,28]
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