BOOK
Intracranial Pressure And Its Effect On Vision In Space And On Earth: Vision Impairment In Space
Hargens Alan R | Liu John H K | Otto Christian A
(2017)
Additional Information
Book Details
Abstract
Fluid distribution during spaceflight and impact on brain and vision health is an emerging field of high-priority research in the NASA human space program. International Space Station astronauts have developed ocular refraction changes during prolonged spaceflight. Within this book, experts review current data related to fluid shifts during microgravity exposure and the impact of fluid shifts on astronaut health.This work also compares current astronaut health problems with Earth-based health conditions such as elevated intracranial pressure and glaucoma. Chapters include discussion of altered fluid distribution, including intracellular and extracellular fluid shifts, eye morphology and vision disturbances, and intraocular pressure. In addition, chapters will include a discussion of advanced non-invasive technologies to investigate the abovementioned fluid volume and pressure variables.As such, the book aims to bridge health professionals, researchers, and science professionals by a presentation of ophthalmology topics critical to future human space exploration, thus providing new perspectives to solve emerging brain and eye disease on Earth and in Space.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Contents | v | ||
| Chapter 1 Introduction to Visual Impairment and Intracranial Pressure | 1 | ||
| References | 3 | ||
| Chapter 2 Early Evidence of Vision Impairment after Long-Duration Spaceflight | 5 | ||
| 1. Introduction | 5 | ||
| 2. Anatomic Changes during Long-Duration Spaceflight | 6 | ||
| 2.1. Disc edema | 6 | ||
| 2.2. Globe flattening | 10 | ||
| 2.3. Choroidal expansion | 13 | ||
| 3. Other Possible Causes of Visual Changes | 15 | ||
| 3.1. Corneal refractive changes | 15 | ||
| 3.2. Crystalline lens changes | 16 | ||
| 3.3. Other ramifications of a dynamic choroid | 16 | ||
| References | 18 | ||
| Chapter 3 Eye, Orbit, and Pituitary MRI: Relevance to Space Medicine | 23 | ||
| 1. Introduction | 23 | ||
| 2. MRI Technique | 24 | ||
| 3. Normal Anatomy of the Orbit and Pituitary Gland | 26 | ||
| 4. Anatomic Alteration of the Globe, Optic Nerve Sheath, Optic Nerve in Astronauts Exposed to Microgravity | 28 | ||
| 5. Anatomic Alteration of the Pituitary Gland in Astronauts Exposed to Microgravity | 33 | ||
| 6. Dose Response Effect of Microgravity Exposure | 34 | ||
| 7. Conclusion | 35 | ||
| References | 36 | ||
| Chapter 4 Fluid Shifts and Cardiovascular-Related Factors That May Contribute to the VIIP Syndrome in Astronauts | 39 | ||
| 1. Introduction | 39 | ||
| 2. Background | 40 | ||
| 3. Cephalad Fluid Shift | 41 | ||
| 4. Intravascular Shift | 43 | ||
| 5. Extravascular Shift | 44 | ||
| 6. Compartmentalization | 46 | ||
| 7. Central Venous Pressure | 47 | ||
| 8. Cranial Venous Drainage | 48 | ||
| 9. Intracranial Pressure and Cerebral Autoregulation | 49 | ||
| 10. Vascular Compliance and Remodeling | 51 | ||
| 11. Carbon Dioxide | 54 | ||
| 12. Exercise | 56 | ||
| 13. Intraocular Pressure | 56 | ||
| 14. Ocular Blood Flow | 59 | ||
| 15. Conclusion | 60 | ||
| References | 60 | ||
| Chapter 5 Intracranial Pressure Physiology and VIIP | 69 | ||
| 1. Introduction | 69 | ||
| 2. Intracranial Pressure and Craniospinal Compliance | 69 | ||
| 2.1. The CSF system and circulation | 70 | ||
| 2.2. Determinants of craniospinal compliance and ICP | 72 | ||
| 3. Known Gravitational Effects on ICP | 75 | ||
| 4. Arguments for and Against ICP Elevation in Spaceflight | 79 | ||
| 4.1. Cephalad fluid shift directly causes ICP elevation | 79 | ||
| 4.2. ICP, SSSP, and CVP are insufficiently low in microgravity | 80 | ||
| 4.3. Increased abdominopelvic venous volume and pressu rereduces spinal canal volume and craniospinal compliance | 81 | ||
| 4.4. Increased cerebral capillary filtration increases cerebral interstitial fluid volume and ICP | 81 | ||
| 4.5. Lower blood pressure causes cerebral arteriolar vasodilation and ICP elevation | 82 | ||
| 4.6. Increased CO2 concentration causes cerebral arteriolar vasodilation and ICP elevation | 82 | ||
| 4.7. Impaired autoregulation causes cerebral arteriolar vasodilation and ICP elevation | 83 | ||
| 5. Conclusion | 83 | ||
| References | 84 | ||
| Chapter 6 High-Altitude Illness and Intracranial Pressure | 91 | ||
| 1. Introduction | 91 | ||
| 1.1. Changes in the atmosphere with altitude | 92 | ||
| 1.2. Historical accounts of high-altitude hypoxia | 92 | ||
| 1.3. The spectrum of HAI | 93 | ||
| 2. Pathophysiological Theories of HAI | 94 | ||
| 2.1. Evidence for the role of ICP | 95 | ||
| 2.2. Direct invasive ICP measurement | 95 | ||
| 2.3. Indirect invasive ICP measurement | 96 | ||
| 2.3.1. Lumbar CSF pressure | 96 | ||
| 2.4. Noninvasive ICP measurements | 96 | ||
| 2.4.1. Tympanic membrane displacement | 96 | ||
| 2.4.2. Pulsatility index | 97 | ||
| 2.4.3. Optic nerve sheath diameter | 97 | ||
| 2.4.4. Retinal imaging | 97 | ||
| 2.4.5. Cerebral imaging | 98 | ||
| 2.4.6. MRI-ICP measurement | 99 | ||
| 2.4.7. Potential importance of the venous system in hypoxia and microgravity | 100 | ||
| 3. Conclusion | 101 | ||
| References | 102 | ||
| Chapter 7 Noninvasive Measurement of Intracranial Pressure with the Vittamed Absolute Value Meter | 107 | ||
| 1. Introduction | 107 | ||
| 2. Normal ICP Physiology | 108 | ||
| 3. Noninvasive ICP Monitoring | 108 | ||
| 4. TCD Principles | 109 | ||
| 5. OA Characteristics | 111 | ||
| 6. Vittamed Two-Depth TCD Based NonInvasive ICP Meter | 111 | ||
| 7. Contraindications to Two-Depth TCD Measurement | 115 | ||
| 7.1. Previous and ongoing clinical studies | 115 | ||
| 8. Baylor College of Medicine and National Space Biomedical Research Institute Study | 116 | ||
| 8.1. Potential limitations | 116 | ||
| 8.2. Safety measures | 117 | ||
| 9. Future Aims | 117 | ||
| Acknowledgments | 118 | ||
| References | 118 | ||
| Chapter 8 NASA’s Research Approach to the Visual Impairment Intracranial Pressure Risk | 123 | ||
| 1. Introduction to the Problem | 123 | ||
| 2. VIIP Etiology | 126 | ||
| 3. Cardiovascular | 127 | ||
| 4. Central Nervous System | 128 | ||
| 4.1. Venous sinus evaluation | 129 | ||
| 4.2. CSF production and outflow | 129 | ||
| 4.3. CSF dynamics pre and post-flight | 130 | ||
| 4.4. Cerebral vascular autoregulation | 131 | ||
| 4.5. White matter microstructure | 132 | ||
| 4.6. Biomarker analysis and LP | 133 | ||
| 4.7. Direct ambulatory intracranial pressure measurement: invasive ICP | 134 | ||
| 5. Ocular | 135 | ||
| 6. Genetic | 137 | ||
| 7. Combined System Studies | 138 | ||
| 7.1. Analog | 138 | ||
| 7.2. In-flight | 139 | ||
| 7.3. Modeling | 142 | ||
| 7.4. Animal studies | 147 | ||
| 8. Environmental Impacts | 150 | ||
| 8.1. CO2 | 150 | ||
| 8.2. Radiation | 152 | ||
| 8.3. Exercise | 153 | ||
| 9. Diagnostic tools | 155 | ||
| 9.1. Diagnostic tools under development | 158 | ||
| 10. VIIP Mechanical Countermeasures | 160 | ||
| 10.1. Lower body negative pressure | 161 | ||
| 10.2. Alter the translaminar pressure gradient by increasing IOP | 162 | ||
| 11. VIIP Drug Countermeasures | 162 | ||
| 12. Summary | 164 | ||
| References | 164 | ||
| Chapter 9 Advanced Imaging of the Intracranial Physiology of Spaceflight | 173 | ||
| 1. Introduction | 173 | ||
| 2. Intracranial Physiology Associated with the Supine Posture | 174 | ||
| 2.1. Magnetic resonance intracranial pressure (MR-ICP) | 178 | ||
| 3. The Dural Venous System and ICP | 180 | ||
| 3.1. Dural venous sinus anatomy | 180 | ||
| 3.2. Venous insufficiency due to dural venous sinus obstruction and idiopathic intracranial hypertension | 182 | ||
| 3.3. Imaging of intracranial venous outflow | 183 | ||
| 4. Imaging of CSF Flow | 186 | ||
| 4.1. Nuclear medicine CSF flow study | 186 | ||
| 4.2. MRI-based CSF flow studies: phase contrast and MR time-spatial labeling inversion pulse | 188 | ||
| 5. Imaging of Microscopic Tissue Water | 190 | ||
| 6. Structural Brain Changes Following Long-Term Bed Rest | 192 | ||
| 7. Cerebral Perfusion and Spaceflight | 195 | ||
| 7.1. The regulation of cerebral blood flow | 196 | ||
| 7.1.1. Cerebrovascular autoregulation | 196 | ||
| 7.1.2. Partial pressure of CO2 | 196 | ||
| 7.1.3. Functional hyperemia | 198 | ||
| 7.1.4. Neurovascular innervation | 199 | ||
| 7.2. Cerebral autoregulatory adaptation to microgravity | 200 | ||
| 7.3. Imaging of cerebral perfusion | 206 | ||
| 8. Carbon dioxide Exposure During Spaceflight and Cerebral Perfusion | 209 | ||
| 8.1. Imaging of CO2 cerebral vascular reactivity | 212 | ||
| 9. Conclusion | 213 | ||
| Acknowledgment | 216 | ||
| References | 216 | ||
| Chapter 10 Sensory and Sensorimotor Changes with Spaceflight: Implications for Functional Performance | 225 | ||
| 1. Introduction | 225 | ||
| 2. Effects of Elevated Intracranial Pressure on Brain Structure and Neurocognitive Function | 226 | ||
| 3. Effects of Spaceflight on Multisensory Integration and Sensorimotor Function | 230 | ||
| 3.1. Multisensory integration and sensory weighting for balance and functional mobility | 230 | ||
| 3.2. Strategic and adaptive motor learning mediating recovery as a function of spaceflight | 232 | ||
| 4. Effects of Spaceflight on Dynamic Visual Acuity (DVA) | 233 | ||
| 4.1. Spaceflight effects on head movement control during locomotion: impacts on vision | 235 | ||
| 4.2. Effects of plastic adaptive modification of the vestibulo-ocular reflex (VOR) on full body gaze control | 238 | ||
| 4.3. Effects of long-duration spaceflight on full body gaze control | 239 | ||
| 4.4. Vestibular-somatosensory convergence in head movement control during locomotion after long-duration spaceflight | 240 | ||
| 5. Looking Forward: Conclusions and Future Directions | 243 | ||
| References | 243 | ||
| Chapter 11 Lower Body Negative Pressure as a VIIP Countermeasure | 253 | ||
| 1. Introduction | 253 | ||
| 2. LBNP Devices | 254 | ||
| 3. Physiological Responses to LBNP | 254 | ||
| 3.1. Nonhypotensive pressures | 256 | ||
| 3.2. Hypotensive pressures | 256 | ||
| 4. LBNP During Spaceflight | 257 | ||
| 5. LBNP, Exercise, and Simulated Spaceflight | 260 | ||
| 6. LBNP and Exercise as Countermeasures for VIIP | 264 | ||
| 7. Conclusions | 265 | ||
| References | 265 | ||
| Chapter 12 A Pressure Theory Links the VIIP Syndrome and Eye Diseases | 273 | ||
| 1. Introduction | 273 | ||
| 2. VIIP Syndrome | 274 | ||
| 3. Idiopathic Intracranial Hypertension | 275 | ||
| 4. Glaucoma | 276 | ||
| 5. Ocular Hypertension | 278 | ||
| 6. Hypotony Maculopathy | 279 | ||
| 7. A Unified Pressure Theory | 280 | ||
| 8. Countermeasures of the VIIP Syndrome | 283 | ||
| References | 285 | ||
| Index | 289 |