Author Response: Asymptomatic Optic Nerve Lesions: An Underestimated Cause of Silent Retinal Atrophy in MS.

Abstract

We thank Dr. Galetta for his comments on our study.1 Three-dimensional double inversion recovery (3D-DIR) is a very helpful MRI sequence for the diagnosis and management of demyelinating diseases affecting the CNS. By combining fat, white matter, and fluid suppression, this 3D MR sequence provides high spatial resolution and high signal-to-noise ratio without blurring effect and gives the opportunity to detect at the same time, cortical, brainstem, cervical spinal cord,2 and optic nerve lesions. Optic nerve DIR/T2 hypersignal is not specific to demyelinating disease,3,4 but, in a context of CNS demyelinating disease or suspicion of, this naturally leads clinicians to suspect a demyelinating process. Furthermore, the presence of asymptomatic optic nerve DIR hypersignals associated with structural retinal changes and visual disability in clinically isolated syndrome and multiple sclerosis (MS) is highly suggestive of optic nerve disease rather than signal change without functional impairment.1,5 This also suggests that asymptomatic optic nerve lesion may potentially lead to asymptomatic retinal neuroaxonal loss. Risk of false positive is decreased by a careful reading in multiple planes on different MRI sequences. In addition, we confirmed that intereye retinal thickness difference measured by optical coherence tomography may be an interesting and alternative tool to MRI for the detection of symptomatic optic nerve lesions. We agree that longitudinal ongoing studies focusing on optic nerve imaging will help clinicians to assess the value of optic nerve as a lesion site in a next revision of MS diagnosis criteria.