Abstract Details

Title The Effect of Demyelinative Damage on Neighboring White Matter Integrity: An Optic Neuritis Study

Topic Neuro-ophthalmology/Neuro-otology

Presentation(s) IN4 - (-)

Poster/Presentation
Number 003

Objective

Background Diffusion Tensor Imaging (DTI) has been increasingly used to evaluate white matter's micro-structure. Studies of axon and myelin pathology in animal models suggested that reduced longitudinal diffusivity [?||] associates with axonal pathology. Changes in radial diffusivity [?[perp]] may derive from variety of factors, including demyelination. The combination of these values provides the fractional anisotropy (FA), thought to reflect fiber integrity. ON, a relatively demarcated demyelinative disease, makes fine model to study fiber integrity changes.

Design/Methods We collected anatomical and diffusion-weighed images using 3T MRI in 13 chronic ON patients and 10 normally-sighted subjects. We used probabilistic tractography algorithm to identify the optic tracts and radiations.

Results The optic tracts of ON patients demonstrated reduced ?|| (patients: 1.23±0.1, controls: 1.33±0.08, p=0.02). The optic radiations in ON demonstrated reduced FA, derived mainly by increased ?[perp] (patients: 0.48±0.02, controls: 0.52±0.02, p=0.002). Separating the optic radiations of the patients into 2 groups- with and without lesions, suggested that reduced FA derived from the presence of lesions along the optic radiation (lesion group: 0.47±0.02, p=0.0008 compared with controls. No-lesions group: 0.5±0.02, p>0.05). Lesions in the optic radiations did not affect white matter integrity in the optic tracts. No correlations were found between diffusivity measurements in the patients' optic tracts and radiations.

Conclusions Our results indicate long term anterograde degeneration in the optic tract following optic nerve demyelination. No effect on post-synaptic fibers was evident. In the optic radiations, impaired diffusivity was derived from demyelinative lesions in the fiber bundles themselves and was not affected by anterior visual damage. Lesions in the optic radiations did not affect anterior visual pathways integrity, opposing retrograde degeneration. Thus, demyelinative lesions may have a local but no trans-synaptic effect on white matter integrity.

Authors/Disclosures
PRESENTER	No disclosure on file
	No disclosure on file
Tamir S. Ben-Hur, MD, PhD (Hadassah Hebrew University Medical Center)	The institution of Dr. Ben-Hur has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for MAPI Pharma. The institution of Dr. Ben-Hur has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Kadimastem. The institution of Dr. Ben-Hur has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sipnose. The institution of Dr. Ben-Hur has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Regenera Pharma. The institution of Dr. Ben-Hur has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Medasense. Dr. Ben-Hur has received stock or an ownership interest from Sipnose. Dr. Ben-Hur has received stock or an ownership interest from Kadimastem. Dr. Ben-Hur has received stock or an ownership interest from MAPI Pharma. Dr. Ben-Hur has received intellectual property interests from a discovery or technology relating to health care.
Netta Levin, MD, PhD (Hadassah Hebrew University Hospital)	Dr. Levin has nothing to disclose.
Richard Watson, MD (Revalesio Corporation)	No disclosure on file

��ɫ��

��ɫ��