Ependymal dot-dash sign

Last revised by Rohit Sharma on 21 Feb 2024

The ependymal dot-dash sign has been described as an early MRI imaging feature of multiple sclerosis before other more florid white matter changes (e.g. Dawson's fingers) become evident 1. It has also been suggested as a feature that can be used to distinguish multiple sclerosis from neuromyelitis optica spectrum disorder (NMOSD) which less frequently demonstrate this sign 2


The dot-dash sign represents early perivenular involvement of the ependyma of the lateral ventricles 1

Radiographic features


The sign is best seen on sagittal FLAIR along the inferior surface of the corpus callosum and roof of the lateral ventricle bodies. It is seen as tiny (~1 mm) dots of high signal along the ependymal surface that may coalesce into short dashes 1,2. It presence has been reported as being very sensitive (>95%) and moderately specific (>70%) in younger individuals (<50 years of age) 1. In older patients, who have periventricular high T2 signal due to ischemic change, this sign is less sensitive and specific 1.

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