Fig. 1

MRI findings and genetic analysis. a Brain MRI images of patients 1 and 2 (Pt. 1 and 2). The T2-weighted images were acquired at the age of 69 (Pt. 1) and 50 years (Pt. 2). Hyperintensity in the intraorbital optic nerves (Pt. 1 and 2, red arrowheads) and preserved extraocular muscles (Pt. 1 and 2, red arrows) are evident. Coronal and sagittal T1-weighted images of Pt. 1 show atrophy of b the intracranial optic nerves (red arrowheads) and c lateral geniculate body (red arrowhead). Note the presence of disproportionately enlarged subarachnoid space hydrocephalus (DESH), a hallmark of idiopathic normal pressure hydrocephalus with enlarged lateral ventricles. Hyperintensities in d the subcortical white matter (Pt. 1, red arrows) and e extending from the middle cerebellar peduncles (Pt. 1, red arrowheads) to the lateral side of the cerebellar white matter. f Sanger sequencing of the mutation in MFN2. Red arrow indicates the mutation. FLAIR, fluid attenuated inversion recovery; Pt, patient; L: Left side of the brain