Lateral geniculate nucleus volume changes after optic neuritis in neuromyelitis optica: A longitudinal study

Objectives: Lateral geniculate nucleus (LGN) volume is reduced after optic neuritis (ON) in neuromyelitis optica spectrum disorders (NMOSD). We aimed at a longitudinal assessment of LGN volume in NMOSD. Methods: Twenty-nine patients with aquaporin 4-IgG seropositive NMOSD (age: 47.8 +/- 14.6 years (y), female: n = 27, history of ON (NMO-ON): n = 17, median time since ON: 3[1.2-12.1]y) and 18 healthy controls (HC; age: 39.3 +/- 15.8y; female: n = 13) were included. Median follow-up was 4.1[1.1-4.7]y for patients and 1.7[0.9-3.2]y for HC. LGN volume was measured using a multi-atlas-based approach of automated segmentation on 3 Tesla magnetic resonance images. Retinal optical coherence tomography and probabilistic tractography of the optic radiations (OR) were also performed. Results: At baseline, NMO-ON patients had lower LGN volumes (395.4 +/- 48.9 mm(3)) than patients without ON (NMO-NON: 450.7 +/- 55.6 mm(3); p = 0.049) and HC (444.5 +/- 61.5 mm(3), p = 0.025). LGN volume was associated with retinal neuroaxonal loss and microstructural OR damage. Longitudinally, there was no change in LGN volumes in the absence of ON, neither in all patients (B =-0.6, SE = 1.4, p = 0.670), nor in NMO-ON (B =-0.8, SE = 1.6, p = 0.617) and NMO-NON (B = 1.7, SE = 3.5, p = 0.650). However, in four patients with new ON during follow-up, LGN volume was reduced at last visit (median time since ON: 2.6 [1.8-3.9] y) compared to the measurement before ON (352 +/- 52.7 vs. 371.1 +/- 55.9 mm(3); t =-3.6, p = 0.036). Conclusion: Although LGN volume is reduced after ON in NMOSD, this volume loss is not progressive over longer follow-up or independent of ON. Thus, our findings-at least in this relatively small cohort-do not support occult neurodegeneration of the afferent visual pathway in NMOSD.

Automated summary

In patients with NMOSD, LGN volume is reduced after ON but does not change longitudinally in the absence of ON, suggesting no occult neurodegeneration of the afferent visual pathway in NMOSD.