Atrophy of optic nerve detected by transorbital sonography in patients with demyelinating diseases of the central nervous system

Abstract

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.

Quantification of Optic Nerve and Sheath Diameter by Transorbital Sonography: A Systematic Review and Metanalysis

“…Furthermore, differences due to ethnic/racial variability and genetic differences have often been discussed in the literature as an influence on OND and ONSD. 7,8 In the subgroup analysis, sorted by geographic continent, we did not find any significant association between geographic area and ONSD in our evaluation (cf. Figure 5).…”

“…Orbital sonography can also be a helpful method for the diagnosis and follow‐up of optic neuritis . Recently, it was shown that even optic nerve atrophy can be detected reliably by means of TOS in patients with chronic demyelinating diseases of the central nerve system, as TOS findings correlated significantly to findings of optic coherence tomography …”

“…With regard to ONSD measurement, in the vast majority of published studies, ONSD is defined as the distance between the external borders of the hyperechogenic area surrounding the optic nerve, which represents the subarachnoidal space including the arachnoid mater. 1,5,7 In some studies, however, the ONSD includes also the outer hypoechogenic rim, which represents the dura mater, resulting to a large heterogeneity of reported reference values. 8 Several studies have further investigated the relationship between age, gender, and body-mass-index (BMI) and ONSD, but with inconsistent results.…”

“…8 Several studies have further investigated the relationship between age, gender, and body-mass-index (BMI) and ONSD, but with inconsistent results. 5,[7][8][9] In addition, the influence of ethnic/racial variability and genetic differences on the normal values has not been sufficiently investigated up to date. 7,8 In this systematic review and metanalysis, we aimed to provide the reference values, based on a metanalytical model, for OND and ONSD and their variance in an adult healthy population, give an overview of the published literature, and discuss the used measurement methods.…”

“…In some studies, however, the ONSD includes also the outer hypoechogenic rim, which represents the dura mater, resulting to a large heterogeneity of reported reference values . Several studies have further investigated the relationship between age, gender, and body‐mass‐index (BMI) and ONSD, but with inconsistent results . In addition, the influence of ethnic/racial variability and genetic differences on the normal values has not been sufficiently investigated up to date …”