Cerebral edema early stroke or hypoxia, cardiac arrest, and pseudotumor cerebri. During an ischemic stroke, a lack of oxygen and glucose leads to a breakdown of the sodium-calcium pumps on brain cell membranes, which in turn results in a massive buildup of sodium and calcium intracellularly. This causes a rapid uptake of water and subsequent swelling of the cells. It is this swelling of the individual cells of the brain that is seen as the main distinguishing characteristic of cytotoxic edema, as opposed to vasogenic edema, wherein the influx of fluid is typically seen in the interstitial space rather than within the
Macular edema layer secondary to abnormal perifoveal retinal capillary permeability. The edema is termed "cystoid" as it appears cystic; however, lacking an epithelial coating, it is not truly cystic. The cause for CME can be remembered with the mnemonic "DEPRIVEN" (diabetes, epinepherine, pars planitis, retinitis pigmentosa, Irvine-Gass syndrome, venous occlusion, E2-prostaglandin analogues, nicotinic acid/niacin). Diabetic macular edema (DME) is similarly caused by leaking macular capillaries. DME is the most common cause of visual loss in both proliferative, and non-proliferative diabetic retinopathy. Macular edema sometimes occurs for a few days or weeks after cataract surgery, but most such cases can be successfully treated