Visual pathways evaluation in Kearns Sayre syndrome: a diffusion tensor imaging study
Kearns Sayre syndrome (KSS) is a mitochondrial disorder characterized by development of visual impairment. Electroretinogram (ERG) and visual evoked potentials are not able to provide topographical information of optic damage. The purpose of this study was to explore retrochiasmatic optic pathway alteration in KSS with diffusion tractographic analysis and to compare it with different tracts.
DTI from 8 KSS subjects (14.7 years) and 10 healthy controls (HC) were acquired on a 3T scanner. Optic radiations (OR), optic tracts (OT), inferior frontooccipital fasciculus (IFOF) and corticospinal tract (CST) were reconstructed with probabilistic tractography. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial (RD), and axial diffusivity (AD) were calculated, evaluating group differences. T test on diffusion parameters identified significantly different track portions among cohorts.
All patients had optic pathway alterations at electrophysiological examination. Significant lower FA were found in OT, IFOF, and CST of KSS group. RD was significantly higher in bilateral OR, IFOF, CST, and right OT, while ADC was higher in bilateral OR and CST. RD values were higher in the proximal and distal portion of OR bilaterally and in the distal portion of right OT, while widespread differences were found in IFOF and CST. No significant differences were found for AD. FA profiles analysis demonstrated significant differences between groups in several regions of OT, IFOF, and CST, while ADC assessment revealed spread differences in OR and CST.
DTI evaluation of retrochiasmatic tracks may represent a useful tool to topographically investigate retrochiasmatic visual impairment in KSS.
KeywordsKearns Sayre syndrome Diffusion tensor imaging Mitochondrial disorders Optic pathway Leukodystrophy
Kearns Sayre syndrome
Visual evoked potential
Apparent diffusion coefficient
Pattern reversal visual evoked potential
Inferior frontooccipital fasciculus
Fiber orientation distribution
Progressive external ophthalmoplegia
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
For this type of study, formal consent is not required.
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