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Objectives To report an uncommon seizure precipitant with associated neuroimaging findings. Case A 79 years old female underwent bronchial artery embolisation for the treatment of haemoptysis associated with a cavitating lung lesion from previous Mycobacterium avium complex infection. Her medical history included colorectal adenocarcinoma without known metastases. Approximately 90 min into the procedure she developed rhythmic right-sided limb twitching followed by right hemiparesis. Urgent CT brain, with residual contrast from the procedure, demonstrated strongly asymmetrical, predominantly left hemisphere, cortical and subarachnoid enhancement and cortical swelling. No thrombus was identified on CT angiography. The impression was focal seizure with post-ictal (Todd’s) paresis. Intravenous thrombolysis was not administered. Two hours later she had further right-sided twitching, evolving to a bilateral tonic–clonic seizure. She was given IV midazolam and levetiracetam 500 mg bd. EEG performed shortly thereafter showed generalised slowing and sharply-contoured delta waves with a left-sided predominance but no epileptiform features. There was no personal or family history of epilepsy, although a similar episode had occurred following the previous attempt at this procedure approximately 9 months prior, with unilateral gyral swelling on CT. She was not known to our service at the time. The hemiparesis and CT changes resolved within 24 hours of onset. Contrast MRI brain on day 6 was normal. She was discharged home on day 12 with no further seizures and no residual neurological deficits. Conclusions Iodinated contrast is a rare precipitant of seizures, with an incidence of 0.19% in one series. 1 The risk was higher in patients with pre-existing epilepsy and/or intracranial pathology. Transient asymmetrical cortical swelling, cortical enhancement and sulcal enhancement on contrast CT have been reported to occur acutely following focal seizures. 2,3 Such changes are thought to reflect seizure-associated regional hyperperfusion and blood–brain barrier breakdown.

Immune system adaptation during spaceflight is a concern in space medicine. Decreased circulating leukocytes observed during and after space flight infer suppressed immune responses and susceptibility to infection. The microgravity aspect of the space environment has been simulated on Earth to study adverse biological effects in astronauts. In this report, the hindlimb unloading (HU) model was employed to investigate the combined effects of solar particle event-like proton radiation and simulated microgravity on immune cell parameters including lymphocyte subtype populations and activity. Lymphocytes are a type of white blood cell critical for adaptive immune responses and T lymphocytes are regulators of cell-mediated immunity, controlling the entire immune response. Mice were suspended prior to and after proton radiation exposure (2 Gy dose) and total leukocyte numbers and splenic lymphocyte functionality were evaluated on days 4 or 21 after combined HU and radiation exposure. Total white blood cell (WBC), lymphocyte, neutrophil, and monocyte counts are reduced by approximately 65%, 70%, 55%, and 70%, respectively, compared to the non-treated control group at 4 days after combined exposure. Splenic lymphocyte subpopulations are altered at both time points investigated. At 21 days post-exposure to combined HU and proton radiation, T cell activation and proliferation were assessed in isolated lymphocytes. Cell surface expression of the Early Activation Marker, CD69, is decreased by 30% in the combined treatment group, compared to the non-treated control group and cell proliferation was suppressed by approximately 50%, compared to the non-treated control group. These findings reveal that the combined stressors (HU and proton radiation exposure) result in decreased leukocyte numbers and function, which could contribute to immune system dysfunction in crew members. This investigation is one of the first to report on combined proton radiation and simulated microgravity effects on hematopoietic, specifically immune cells.

Immune system adaptation during spaceflight is a concern in space medicine. Decreased circulating leukocytes observed during and after space flight infer suppressed immune responses and susceptibility to infection. The microgravity aspect of the space environment has been simulated on Earth to study adverse biological effects in astronauts. In this report, the hindlimb unloading (HU) model was employed to investigate the combined effects of solar particle event-like proton radiation and simulated microgravity on immune cell parameters, including lymphocyte subtype populations and activity. Lymphocytes are a type of white blood cell critical for adaptive immune responses and T lymphocytes are regulators of cell-mediated immunity, controlling the entire immune response. Mice were suspended prior to and after proton radiation exposure (0 or 2 Gy doses) and total leukocyte numbers and splenic lymphocyte functionality were evaluated on days 4 or 21 after combined HU and radiation exposure. Total white blood cell (WBC), lymphocyte, neutrophil and monocyte counts are reduced by ∼65, 70, 55 and 70%, respectively, compared with the non-treated control group 4 days after combined exposure. Splenic lymphocyte subpopulations are altered at both time points investigated. At 21 days post-exposure to combined HU and proton radiation, T-cell activation and proliferation were assessed in isolated lymphocytes. Cell surface expression of the Early Activation Marker, CD69, is decreased by 30% in the combined treatment group, compared with the non-treated control group and cell proliferation was suppressed by ∼50%, compared with the non-treated control group. These findings reveal that the combined stressors (HU and proton radiation exposure) induce decreased leukocyte numbers and function, contributing to immune system dysfunction in crew members. This research was supported by the NIH Training Grant 2T32CAO9677 and the National Space Biomedical Research Institute (NSBRI) Center of Acute Radiation Research (CARR) grant. The NSBRI is funded through the National Aeronautics and Space Administration (NASA) Class Code (NCC) 9-58. The authors declare that this work has been published: Sanzari JK, Romero-Weaver AL, James G, Krigsfeld G, Lin L, Diffenderfer ES, Kennedy AR. Leukocyte activity is altered in a ground based murine model of microgravity and proton radiation exposure. PLoS One. 2013;8(8):e71757. doi:10.1371/journal.pone.0071757.