Hi Richard, I personally believe heavy metals have disrupted the brains ability to cool the body when exposed to sun rays. This causes swelling/oedema. Heavy metals have caused much neurological damage for many of us most sick so this makes sense. Sun rays (UVA) also cause oxidative damage which contributes to inflammation. Heavy metals are resposible for free radical damage in the brain area so adding the free radical load from the sun ray exposure is kind of a double whammy.
"Heat stroke: This medical condition is life-threatening. The person's cooling system, which is controlled by the brain, has stopped working, and the internal temperature has risen to the point where brain damage or damage to other internal organs may result (temperature may reach 105+°F)."
Here is an interesting link explaining the inflammation feeling caused by mercury poisoning:
http://www.mercurypoisoned.com/burning.htmlThere is actually a name for brain swelling, see below. These patients are adviced to stay away from sun rays, heat and exercise (which raises body temp.).
"Description
Encephalitis is an inflammation of the brain. The inflammation is a reaction of the body's immune system to infection or invasion. During the inflammation, the brain's tissues become swollen. The combination of the infection and the immune reaction to it can cause headache and a fever, as well as more severe symptoms in some cases.
In secondary encephalitis, symptoms usually begin five to 10 days after the onset of the disease itself and are related to the breakdown of the myelin sheath that covers nerve fibers.
Symptoms
The symptoms of encephalitis range from very mild to very severe and may include:
headache
fever
lethargy (sleepiness, decreased alertness, and fatigue)
malaise
nausea and vomiting
visual disturbances
tremor
decreased consciousness (drowsiness, confusion, delirium, and unconsciousness)
stiff neck
seizures"
"Another way to expand our knowledge on heatrelated illnesses is to develop a suitable animal model of heat stress simulating clinical conditions. We developed a new mode of heat stress to induce clinical situation in rats that simulates clinical symptoms of alteration in behavioural and cognitive functions and is associated with profound brain dysfunction9,10. Using this model, our laboratory was the first to show that experimental or environmental heat stress without heat stroke is able to cause BBB disruption to protein tracers, viz., Evans blue and radioactive iodine11. Obviously, breakdown of the BBB results in extravasation of serum proteins and other unwanted substances in to the brain extracellular fluid compartment causing vasogenic oedema and cell injury12.
A detailed knowledge of molecular mechanisms of heat induced CNS/PNS injury will provide new insight to develop potential therapeutic measures to minimise nervous system damage in the victims of heat stress and to alleviate their sufferings."
Taken from:
http://findarticles.com/p/articles/mi_qa3867/is_200505/ai_n13643567 
