BACKGROUND AND PURPOSE: Widespread brain structural changes are seen following extended spaceflight missions. The purpose of this study was to investigate whether these structural changes are associated with alterations in motor or cognitive function. MATERIALS AND METHODS:Brain MR imaging scans of National Aeronautics and Space Administration astronauts were retrospectively analyzed to quantify pre-to postflight changes in brain structure. Local structural changes were assessed using the Jacobian determinant. Structural changes were compared with clinical findings and cognitive and motor function. RESULTS:Long-duration spaceflights aboard the International Space Station, but not short-duration Space Shuttle flights, resulted in a significant increase in total ventricular volume (10.7% versus 0%, P , .001, n = 12 versus n = 7). Total ventricular volume change was significantly associated with mission duration (r = 0.72, P = .001, n = 19) but negatively associated with age (r = À0.48, P = .048, n = 19). Long-duration spaceflights resulted in significant crowding of brain parenchyma at the vertex. Pre-to postflight structural changes of the left caudate correlated significantly with poor postural control; and the right primary motor area/midcingulate correlated significantly with a complex motor task completion time. Change in volume of 3 white matter regions significantly correlated with altered reaction times on a cognitive performance task (bilateral optic radiations, splenium of the corpus callosum). In a post hoc finding, astronauts who developed spaceflight-associated neuro-ocular syndrome demonstrated smaller changes in total ventricular volume than those who did not (12.8% versus 6.5%, n = 8 versus n = 4). CONCLUSIONS:While cautious interpretation is appropriate given the small sample size and number of comparisons, these findings suggest that brain structural changes are associated with changes in cognitive and motor test scores and with the development of spaceflight-associated neuro-optic syndrome.

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Background Complications after microvascular surgery, such as partial flap loss, and arterial/venous compromise cannot only increase morbidity for the patient but also tax the healthcare system. Thrombocytosis, both essential and reactive, can predispose patients to thrombosis and hemorrhage and thus should intuitively have an effect on the outcome of microvascular free tissue transfers. We sought to evaluate the effect of preoperative thrombocytosis on outcomes after microvascular free flap surgery. Methods A retrospective review of the 2013–2016 American Collges of Surgeons, National Surgical Quality Improvement Program (ACS NSQIP) database identified 4,299 patients who had microsurgical flaps. Of these 3,744 had preoperative platelet levels recorded. Fifty‐four patients had preoperative thrombocytosis, defined as a platelet count >450 K/CUMM, while 3,690 did not. The groups were compared; demographics, comorbidities, and smoking status were recorded. We then examined outcomes between groups including average operative time, length of hospital stay, need for transfusion, deep vein thrombosis (DVT) postoperatively, and need for reoperation. Results When comparing the two cohorts, there was no statistical difference in comorbidities. We found a significant difference between the thrombocytosis and control cohort in need for transfusion (29.6 vs. 12.8%, p = .0002), average days till discharge (8.36 vs. 5.75, p = .009), and need for reoperation (27.8 vs. 13.8%, p = .003). There was no difference in DVT occurrence (0 vs. 0.1%, p = .46) or average operation time (535 m vs. 482 min, p = .088). Conclusion Patients with thrombocytosis undergoing microvascular free flaps are at increased risk for complications, including the need for a blood transfusion, prolonged hospital stays, and reoperation.