Novel finding of optic nerve central T2 hypointensity utilizing 3 Tesla MR imaging.

We sought to report a central T2 hypointensity within the optic nerve on 3 T MRI studies obtained as part of the NASA Flight Medicine Visual Impairment Intracranial Pressure Protocol that had not been described previously. Twenty-one astronauts, who had undergone MRI of both orbits with direct coronal T2 sequences between 2010 and 2012, were retrospectively included. Two of the astronauts did not have previous exposure to microgravity at the time of their scans. A central T2 hypointensity was observed in 100% of both right and left eyes. It was completely visualized throughout the nerve course in 15 right eyes (71.4%) and in 19 left eyes (90.5%).We describe a new finding seen in all study participants: a central T2 hypointensity in the epicenter of the optic nerve. We speculate that this T2 hypointensity may represent flow voids caused by the central retinal vessels.

Lumbar puncture during spaceflight: operational considerations, constraints, concerns, and limitations.

Lumbar puncture (LP) is a commonly performed low-risk procedure terrestrially, used diagnostically for evaluation of cerebrospinal fluid (CSF) pressure as well as for collection of CSF for analysis. NASA is investigating noninvasive means for measurement of intracranial pressure (ICP) to assess the potential contribution of elevated intracranial pressures to recently reported changes in astronauts' visual acuity and eye anatomy, known collectively as the Visual Impairment/Intracranial Pressure risk. However, many of these noninvasive technologies are still under development, have limited clinical validation, are several years away from being ready for in-flight use, or only provide qualitative rather than quantitative ICP values. Therefore, performance of in-flight LPs, as part of crewmember evaluation, has also been considered by NASA. This manuscript summarizes the unique operational considerations, constraints, concerns, and limitations of using traditional LP as an adjunct or as an alternative to noninvasive ICP measurements during spaceflight.

Effects of sex and gender on adaptation to space: cardiovascular alterations.

Sex and gender differences in the cardiovascular adaptation to spaceflight were examined with the goal of optimizing the health and safety of male and female astronauts at the forefront of space exploration. Female astronauts are more susceptible to orthostatic intolerance after space flight; the visual impairment intracranial pressure syndrome predominates slightly in males. Since spaceflight simulates vascular aging, sex-specific effects on vascular endothelium and thrombotic risk warrant examination as predisposing factors to atherosclerosis, important as the current cohort of astronauts ages. Currently, 20% of astronauts are women, and the recently selected astronaut recruits are 50% women. Thus there should be expectation that future research will reflect the composition of the overall population to determine potential benefits or risks. This should apply both to clinical studies and to basic science research.

Calcifying nanoparticles (nanobacteria): an additional potential factor for urolithiasis in space flight crews.

Spaceflight-induced microgravity appears to be a risk factor for the development of urinary calculi, resulting in urolithiasis during and after spaceflight. Calcifying nanoparticles, or nanobacteria, multiply more rapidly in simulated microgravity and create external shells of calcium phosphate. The question arises whether calcifying nanoparticles are nidi for calculi and contribute to the development of clinically significant urolithiasis in those who are predisposed to the development of urinary calculi because of intrinsic or extrinsic factors. This case report describes a calculus recovered after flight from an astronaut that, on morphologic and immunochemical analysis (including specific monoclonal antibody staining), demonstrated characteristics of calcifying nanoparticles.

Medullary sponge kidney and urinary calculi: aeromedical concerns.

Medullary sponge kidney (MSK) is a benign disorder associated with a lifetime risk of renal stones in 60% of patients. Patients frequently have episodic painless hematuria, but are often otherwise asymptomatic unless renal calculi or infections complicate the disease. Nephrolithiasis is a relative, but frequently enforced, contraindication to space or other high-performance flight. Two case reports of asymptomatic NASA flight crew with MSK and three cases of United States Air Force (USAF) military aviators diagnosed with MSK are reviewed. All cases resulted in waiver and return to flight status after treatment and a vigorous followup and prophylaxis protocol. MSK in aviation and spaceflight necessitates case-by-case evaluation and treatment to rule out other potential confounding factors that might also contribute to stone formation and in order to requalify the aviator for flight duties.

Breast cancer and spaceflight: risk and management.

Spaceflight exposes astronauts to a host of environmental factors which could increase their risk for cancer. Epidemiological studies have shown an increased incidence of breast cancer in female commercial flight attendants, with occupational risk factors as one of the proposed mechanisms for the higher incidence in this cohort. Since female astronauts are exposed to similar occupational conditions as flight attendants, they too may be at an increased risk for breast cancer. With the planning of exploration class missions to the Moon and to Mars it is important to assess and minimize the risk for breast malignancy, and to have a well-defined protocol for the diagnosis and treatment of a breast mass discovered during a mission. Risk factors for development of breast cancer in the female astronaut include ionizing radiation, disrupted melatonin homeostasis secondary to circadian shifting, chemical exposure, and changes in immune function. Preflight, in-flight, and postflight screening and management modalities include imaging and fine needle aspiration (FNA). Employing such a strategy may provide a viable management approach in the case of a newly diagnosed breast mass inflight.

Percutaneous bladder catheterization in microgravity.

INTRODUCTION: Urinary obstruction (UO) or failure to void has been observed during several episodes of short-duration spaceflight, necessitating bladder catheterization. It should be considered a possible medical condition in long-duration space missions as well. Antiemetics used early in space flight add to the risk and severity of voiding problems, along with the sensory and psychological peculiarities of voiding without gravity and in the unusual setting of a spacecraft. Urolithiasis due to the above-normal calcium excretion increases the risk of UO in long duration space missions. Finally, the individual risk of UO is higher against the background of preexisting conditions such as benign prostatic hyperplasia (BPH) or urethral stricture. Both acute retention and ureteral obstruction are associated with substantial patient distress, and carry a risk of urosepsis and/or acute renal failure. If UO in orbital flight is unresolved or complicated, it would likely result in crew emergency return from orbit. Exploration missions, however, may require means for definitive treatment of urinary tract obstruction. This study documents successful ultrasound-guided percutaneous catheterization of the urinary bladder in microgravity. A porcine model of urethral occlusion was used. The results demonstrate an additional capability from our previous investigations describing endoscopic catheterization and stenting of the ureters in microgravity conditions. METHODS: In an anesthetized porcine model, a Foley catheter was placed in the bladder and clamped after instillation of 200 ml of colored liquid. The bladder was visualized and then drained under ultrasound guidance through suprapubic puncture, employing a 10.3 F pigtail catheter with introducer. The procedural elements were conducted only during microgravity portions of the parabolic flight. RESULTS: Ultrasound imaging was used to successfully perform image-guided percutaneous puncture through the anterior bladder wall with the catheter, without injury to adjacent organs. The percutaneous catheter was able to successfully drain the bladder in microgravity conditions. CONCLUSIONS: Percutaneous bladder catheterization and drainage can be successfully performed in weightless conditions under ultrasound guidance. Ultrasound provides a low-power, portable means to safely conduct minimally invasive procedures in pertinent organs and tissues. Percutaneous bladder catheterization is a standard procedure when luminal bladder catheterization is not possible; this technique can be successfully modified for use in space medicine applications.