Atrophy of optic nerve detected by Transorbital Sonography in Patients with Demyelinating Diseases of CNS.

Background and purpose Transorbital sonography (TOS) has emerged as promising imaging method for the diagnosis and follow-up of acute optic neuritis (ON). Available studies report an increase in the optic nerve diameter (OND) and the optic nerve sheath diameter (ONSD) in the case of a first episode of ON in the affected eye compared to either the contralateral unaffected eye or controls. However, the utility of TOS in the case of recurrent episodes of ON has never been assessed. Methods In our prospective cohort study, the diagnostic utility of TOS in patients with demyelinating diseases of the central nervous system was assessed, and the association between TOS, optical coherence tomography (OCT) and visual evoked potentials was examined further. Results Seventy-eight patients with a history of demyelinating disorders of the central nervous system (mean age 38.2 +/- 14.2 years; 24% with acute ON) were included. No differences in the OND (3.2 +/- 0.5 mm vs. 3.2 +/- 0.4 mm) and ONSD (5.1 +/- 0.8 mm vs. 5.1 +/- 0.7 mm) measurements were found between patients with and without acute ON. Papillary swelling was more frequent in patients with acute ON (14.2% vs. 1.5%, P = 0.002). Patients with a history of previous ON were found to have lower OND (P < 0.001) and ONSD (P = 0.007) compared to patients without a history of previous ON. TOS measurements were inversely associated with disease duration and positively correlated with OCT findings. No association with visual evoked potential measurements was found. Conclusion No evidence was found for TOS-sensitive differences in the OND and ONSD of patients with demyelinating diseases, according to the presence of acute ON. The association between TOS and OCT measurements deserves further investigation.