Thank you, Maddie, for saving me having to search for what Dr. Wecht said. I have a great deal of respect for Dr. Wecht. He was the first so-called expert to have come out publicly to say that results of the AR indicated JonBenet had been sexually assaulted not only when she died, but previously in the days/weeks/months leading up to her death. He was roundly criticized by many, but he stuck to his guns because he knew he was right and it was obvious. And he did this before the full unredacted AR was released to the public.
Everything Wecht said in the statement you quoted is correct. But what he left out is that there can be other things that restrict the flow of blood to the brain. I dont know but that he might have actually added that when he made the statement, and the person quoting him simply left it out. Ill give him the benefit of the doubt on that, because Im sure he knows it -- its just not included in that quote. A more complete answer is much more complicated than the simple explanation he provided in one paragraph. But if anyone cares to read it, Ill try to give a little better explanation. I know its tough to follow, because we only deal with it when we come here and discuss it. Understand that with what I tell you here, I am not promoting a point of view or trying to get support for my theory of what happened. But if we all understand the mechanics of what happened, we can make more informed opinions on what might have happened. Ill give you what I know on both sides of the issue. I am in no way any kind of expert or authority in this. I have only read enough though to understand how little I know. This is what I do know:
The circulatory system is very complicated, and even more so in the system that supplies the brain with blood and oxygen. You know, Im sure, that the main supply of blood to the brain is the carotid arteries (one on either side of the neck), and that the main way that blood exits is through the jugular veins. But these are not the only arteries and veins that provide circulation to the brain through the neck. If these are restricted, there are also smaller vessels which provide what is called collateral circulation, making up for some of the loss in circulation. Also the carotid arteries and the jugular veins are split at a point in the lower neck into an internal and an external vessel. A restriction on the neck may have enough force to restrict the external vessels but not the internal (so named because of their proximity to the surface of the neck). Since the arteries supply fresh blood (IOW, being pumped from the heart), they have more pressure than the veins, and therefore require more pressure to shut them off. However the arteries are for the most part protected by the musculature of the neck. Estimates vary, but most references list anywhere from 6 to 12 lbs. of pressure being required to restrict flow in the arteries. This compares to as little as 3 lbs. to restrict blood flow in the veins. (On the other hand, for comparison, it takes as much as 33 lbs. to compress the airway in the neck causing someone to stop breathing.)
And in addition to all this, there is another factor which has to be considered: One of the reflexes in our bodies is centered where the common carotids divide (into the internal and external) and is triggered by a group of nerve cells which make up the carotid sinus. These nerve cells have the function of maintaining blood pressure at a steady level. They respond to a decrease in blood pressure (like when you stand up) by constricting arteries and telling the heart to beat harder/faster. Without this, you might pass out every time you stood up suddenly because not enough blood was reaching your brain. (The dizziness many people feel when they stand up suddenly is another way of appreciating how quickly and completely sensitive your brain is to the absence of enough blood). Conversely, the carotid sinus responds to an increase in blood pressure by relaxing the arteries and inhibiting the heart. The problem arises because these pressure-receptor nerves arent smart enough to tell the difference between actual internal blood pressure and externally-applied pressure -- such as from a ligature restriction.
Some victims of strangulation will have a swollen (sometimes even bitten) tongue protruding from a bloated blue-gray face with hideously bulging eyes. Others will look livid, or even pale and placid. Some will have (as JonBenet did) small petechial hemorrhages, caused by capillaries leaking (due to the high blood pressure in the absence of oxygen) on the face, eyelids, and/or scalp. Other victims simply dont have these. So what accounts for all these differences? Mostly, its a matter of how quickly and totally the ligature cuts off blood circulation to and from the head. If strangulation is fast and complete, the blood supply both to and from the head will be cut off simultaneously, so there is no excess blood or blood pressure in the head, and thus a more-or-less normal-colored corpse. Similarly, activation of the carotid sinus pressure receptor would cause a decrease in blood flow to the head, leading to paleness in the cadaver (and less bleeding from any broken blood vessels in the brain). If, on the other hand, the pressure on the neck gradually increased as consciousness was lost, its probable that the jugular veins were shut off before the carotid arteries, since it requires less pressure to do this. Thus, in this case blood would continue flowing into the head while having no way to leave it, causing engorgement and blue/purple color (and more bleeding from any broken blood vessels in the brain). In any case, respiration stops before the heart, which may continue to beat for about 10 to 15 minutes. But again, with restriction around the neck, blood to the brain would continue to be slowed.
All in all, you can see why it is so complicated, and why it is that so many different experts cant agree on exactly what happened, or when it happened. Each expert may consider one factor and fail to take into consideration another. Dr. Wecht believes that because of the small amount of blood, she must have been dead or near-dead when the head blow was struck. Dr. Rorke-Adams believes that because of the amount of edema and necrosis of brain tissue, she was hit over the head a full 45-minutes to 2-hours before she was strangled. Dr. Kerry Brega said it is not uncommon for people with skull fractures to not have any bleeding in the brain. (IMO, this is certainly possible if the concussion is slight enough that it causes no breaking of the blood vessels or capillaries -- but I find it hard to believe that it is not uncommon, and certainly not in a case where the fractures are as extensive as JonBenets.)
So just like the eternal question of the chicken or the egg -- which came first -- the ligature or the head blow? You tell me. (I wont even offer my explanation here.)
