Transorbital Ultrasonography and Doppler Ultrasound to investigate Optic Nerves in Multiple Sclerosis

Introduction: Changes of the optic nerve (ON) reflect the overall pathology in multiple sclerosis (MS). Transorbital ultrasonogra- phy (TOUS) is currently gaining interest as a promising tool for detecting ON changes after exposure to optic neuritis. We aimed to explore both ON morphological and haemodynamic changes in a sample of MS patients. Objectives/Aims: Morphological changes in the optic nerve may potentially reflect different stages of disease in multiple sclerosis (MS) patients. In this study we aimed to explore whether tran- sorbital ultrasonography and doppler ultrasound can detect mor- phological and haemodynamic changes in a sample of MS patients. Methods: 98 subjects (27 men and 71 women, F:M=2.6) with a diagnosis of MS according to McDonald criteria, aged 48.0 (14.0) and 45.0 (12.0) (p=ns) years, were enrolled. EDSS score was 0-2.5 in 63 (64.3%) and >2.5 in 35 (35.7%) subjects. Morphometric (ON diameters) and haemodynamic (from ophthal- mic artery, OA, central retinal artery, CRA, posterior ciliary arter- ies, PCA) features were computed for affected (AE) vs. non affected (nAE) eyes. Results: A history of ON (ON+) was detected in 55 (56.1%) patients, 11 (20.0%) men and 44 (80.0%) women (p=0.058). ON+ was associated with lower EDSS scores (76.1% with EDSS 0-2.5 vs. 23.6% >2.5, p=0.006, p-trend=0.005) and although not significant with younger age (<50 years at study time). For the study population, 192 (98.0%) eyes could be investigated, 67 (34.9%) with (AE) and 125 (65.1%) without past history of docu- mented inflammation (nAE). Overall ON diameter at 3 mm (OND3), and ON sheath diameters at 3 (ONSD3) and 5 (ONSD5) mm from papilla did not differ in patients with or without a history of ON, but tended to be smaller in AE. No difference was observed for the myelination index ratio. A tendency for lower mean flow velocities for OA in AE vs. nAE was detected (p=0.070), but not for CRA and PCA. Conclusion: Transorbital ultrasonography and doppler ultrasound methods can be applied to MS patients potentially indicating loss of optic nerve volume in association to past history of ON. A larger sample size is needed for confirmatory findings.