Universität zu Köln

Gerlach, Darius A., Marshall-Goebel, Karina ORCID: 0000-0002-5240-7625, Hasan, Khader M., Kramer, Larry A., Alperin, Noam and Rittweger, Joern (2017). MRI-derived diffusion parameters in the human optic nerve and its surrounding sheath during head-down tilt. NPJ Microgravity, 3. LONDON: SPRINGERNATURE. ISSN 2373-8065

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Abstract

More than half of astronauts present with significant neuro-ophthalmic findings during 6-month missions onboard the International Space Station. Although the underlying cause of this Microgravity Ocular Syndrome is currently unknown, alterations in cerebrospinal fluid dynamics within the optic nerve sheath may play a role. In the presented study, diffusion tensor imaging was used to assess changes in diffusivity of the optic nerve and its surrounding sheath during head-down tilt, a ground-based model of microgravity. Nine healthy male subjects (mean age +/- SD: 25 +/- 2.4 years; mean body mass index +/- SD: 24.1 +/- 2.4 kg/m(2)) underwent 5 head-down tilt conditions: -6 degrees,-12 degrees, -18 degrees,-12 degrees and 1% CO2, and -12 degrees and lower body negative pressure. Mean diffusivity, fractional anisotropy, axial diffusivity, radial diffusivity were quantified in the left and right optic nerves and surrounding sheaths at supine baseline and after 4.5 h head-down tilt for each condition. In the optic nerve sheath, mean diffusivity was increased with all head-down tilt conditions by (Best Linear Unbiased Predictors) 0.147 (SE: 0.04) x 10(-3)mm(2)/s (P < 0.001), axial diffusivity by 0.188 (SE: 0.064) x 10(-3)mm(2)/s (P < 0.001), and radial diffusivity by 0.126 (SE: 0.04)x 10 -3mm(2)/s (P = 0.0019). Within the optic nerve itself, fractional anisotropy was increased by 0.133 (SE: 0.047) (P = 0.0051) and axial diffusivity increased by 0.135 (SE: 0.08) x 10-3mm(2)/s (P = 0.014) during head-down tilt, whilst mean diffusivity and radial diffusivity were unaffected (P > 0.3). These findings could be due to increased perioptic cerebral spinal fluid hydrodynamics during head-down tilt, as well as increased cerebral spinal fluid volume and movement within the optic nerve sheath.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Gerlach, Darius A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Marshall-Goebel, Karina UNSPECIFIED orcid.org/0000-0002-5240-7625 UNSPECIFIED Hasan, Khader M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kramer, Larry A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Alperin, Noam UNSPECIFIED UNSPECIFIED UNSPECIFIED Rittweger, Joern UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-227494
DOI:	10.1038/s41526-017-0023-y
Journal or Publication Title:	NPJ Microgravity
Volume:	3
Date:	2017
Publisher:	SPRINGERNATURE
Place of Publication:	LONDON
ISSN:	2373-8065
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CEREBROSPINAL-FLUID ABSORPTION; SPINAL-CORD; PRESSURE; DISTORTION; PERFUSION; SPACE Multiple languages Multidisciplinary Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/22749