White matter hyperintensities and hypobaric exposure.

OBJECTIVE: Demonstrate that occupational exposure to nonhypoxic hypobaria is associated with subcortical white matter hyperintensities (WMHs) on fluid-attenuated inversion recovery magnetic resonance imaging (MRI). METHODS: Eighty-three altitude chamber personnel (PHY), 105 U-2 pilots (U2P), and 148 age- controlled and health-matched doctorate degree controls (DOC) underwent high-resolution MRI. Subcortical WMH burden was quantified as count and volume of subcortical WMH lesions after transformation of images to the Talairach atlas-based stereotactic frame. RESULTS: Subcortical WMHs were more prevalent in PHY (volume p = 0.011/count p = 0.019) and U2P (volume p < 0.001/count p < 0.001) when compared to DOC, whereas PHY were not significantly different than U2P. INTERPRETATION: This study provides strong evidence that nonhypoxic hypobaric exposure may induce subcortical WMHs in a young, healthy population lacking other risk factors for WMHs and adds this occupational exposure to other environmentally related potential causes of WMHs. Ann Neurol 2014;76:719-726.

Aeromedical decision making and seizure risk after traumatic brain injury: longitudinal outcome.

INTRODUCTION: Traumatic brain injury (TBI) is common in young adults and therefore of significant concern to an aircrew population. This paper reports the occurrences of seizures in U.S. Air Force (USAF) aircrew following receipt of an aeromedical waiver for TBI. METHODS: Using both an aeromedical waiver tracking system database and medical records, we identified surrogate seizure markers such as all episodes of subsequent TBI, seizure, loss of consciousness, or prescription of anticonvulsant medications from the time of initial TBI until the last medical visit or entry recorded in either the database or medical records for our study population. RESULTS: The seizure rate for aircrew who met USAF waiver criteria was 24.53/100,000 person-years. One pilot experienced a major motor seizure 14.9 yr following a severe TBI for an incidence of 308.64/100,000 person-years. DISCUSSION: The USAF waiver process following TBI was sufficiently effective in removing aircrew with elevated risk for seizure following TBI. While our rates of post-traumatic seizure appear to be lower than previously published civilian population rates, direct comparison cannot be made secondary to differences in study design and selection criteria. Further areas of study could involve a more detailed analysis of aircrew neurocognitive status following TBI for subtle changes, crosschecking USAF Safety Center data for changes in accident rates among post-TBI aircrew, and analysis of lost aircrew flying time as a result of TBI and the degree of burden that loss places on the flying mission. CONCLUSION: Application of these stringent criteria is sufficient to fulfill aeromedical safety standards, but costs remain undetermined.

Hyperintense white matter lesions in 50 high-altitude pilots with neurologic decompression sickness.

INTRODUCTION: Neurologic decompression sickness (NDCS) can affect high-altitude pilots, causing variable central nervous system symptoms. Five recent severe episodes prompted further investigation. METHODS: We report the hyperintense white matter (HWM) lesion imaging findings in 50 U-2 pilot volunteers, and compare 12 U-2 pilots who experienced clinical NDCS to 38 U-2 pilots who did not. The imaging data were collected using a 3T magnetic resonance imaging scanner and high-resolution (1-mm isotropic) three-dimensional fluid-attenuated inversion recovery sequence. Whole-brain and regional lesion volume and number were compared between groups. RESULTS: The NDCS group had significantly increased whole brain and insular volumes of HWM lesions. The intergroup difference in lesion numbers was not significant. CONCLUSION: A clinical episode of NDCS was associated with a significant increase in HWM lesion volume, especially in the insula. We postulate this to be due to hypobaric exposure rather than hypoxia since all pilots were maintained on 100% oxygen throughout the flight. Further studies will be necessary to better understand the pathophysiology underlying these lesions.

OnabotulinumtoxinA successfully used as migraine prophylaxis during pregnancy: a case report.

Botulinum toxin (btx) received U.S. Food and Drug Administration approval for migraine treatment in 2010 with a pregnancy category C. There are minimal reports of its usage in pregnancy with no adverse effects; however, there are no reported cases of usage in a known pregnancy for the successful treatment of migraines. We present a patient with a history of 4 to 5 migraines per week refractory to treatment who was subsequently controlled with btx. She initially stopped injections, however, her migraines increased to 5 to 6 per week while using standard medications for migraine treatment in pregnancy. She requested btx while 18 weeks pregnant after which she had full resolution of her migraines. She gave birth to a healthy full-term girl with no neuromuscular or developmental concerns spanning the first 6.5 years of her life, the longest reported follow-up of an infant whose mother received btx while pregnant. This is the first reported case in the literature of a patient requesting btx injections for migraine treatment while knowingly pregnant. The foundation of a btx pregnancy registry, similar to those used for antiepileptics, would be greatly beneficial to gather more safety data in regard to its further usage during pregnancy.