Abstract Details

Title Anatomical Explanation of a Dilated Optic Nerve Sheath Supports Clinical Research Focused on the Use of Ultrasound to Diagnose Mild Traumatic Brain Injury

Topic Neuro Trauma, Critical Care, and Sports Neurology

Presentation(s) S2 - Neurocritical Care (2:06 PM-2:17 PM)

Poster/Presentation
Number 007

Background

Our lab has previously demonstrated that a patient history of mTBI is associated with ONSD dilation, post Valsalva, that can be visualized on ultrasonography. We investigated the anatomical etiology for ONSD dilation and discovered a statistically significant thinning of fibers connecting the optic nerve and optic nerve sheath immediately after injury. The long-term anatomical effects of these fibers have not been previously studied and may hold important implications about post-traumatic recovery mechanisms.

Objective The purpose of this study was to investigate the long-term anatomical effects of mild traumatic brain injury (mTBI) and increased intracranial pressure (ICP) on optic nerve sheath diameter (ONSD) dilation by analyzing optic nerve sheath fibers 30 days after increasing ICP in a swine model.

Design/Methods Increased ICP was induced in two swine models by inflating a fluid-filled catheter in the epidural space. ICP was monitored continuously. The pigs were euthanized 30 days post insult. After enucleation, extracted cross-sections of optic nerve sheath with intact nerve were imaged using a scanning electron microscope. The images were segmented and analyzed using DiameterJ to determine percent porosity of fibers. Percent porosity values for the pigs euthanized 30-days post-insult were compared to the values for two pigs immediately euthanized post-insult and three control pigs.

Results The experimental group euthanized 30 days post-insult demonstrated a statistically significant (p = 0.0092) increase in percent porosity (57.14%) as compared to the control group (43.36%). There was no significant difference (p = 0.9485) in porosity of the experimental group euthanized 30 days post-insult as compared to experimental models euthanized immediately post-insult (57.49%).

Conclusions This study demonstrates that injury associated with increased ICP results in an immediate and sustained statistically significant increase in fiber porosity after 30 days. This suggests that the support structure neither heals nor degenerates over time, resulting in the dilated ONSD seen on ultrasound.

Authors/Disclosures
Zulqar Islam (Please Select) PRESENTER	No disclosure on file
	No disclosure on file
	No disclosure on file
Maegan Newell, MD	Dr. Newell has nothing to disclose.
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Matt Lyon, MD	No disclosure on file

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