You all have done a lot of research on the subject of stun gun paralysis, etc., and I'm gobbling up what you've posted with relish.
I did some research, too, many moons ago, about petechial hemorrhaging as it relates to asphyxiation. I'm not a doctor, but what follows is some of what I found out: (I will eventually get back to the subject of paralysis)
Petechial hemorrhaging, such as that discovered by the coroner on JonBenet's body, in the lungs, on the heart (loosely speaking), on the conjunctiva, in proximity to and in association with the neck ligature, and on the left shoulder in proximity to the delto-pectoral groove, etc., is suggestive (to put it gently) of asphyxiation by ligature strangulation.
There is one mechanism by which petechial hemorrhaging in assocation with strangulation is caused by applying pressure to the jugulars (which are shallower than the carotids, if memory serves), thereby impeding the flow of blood through them, which, in turn, produces pressure in the capillaries which is higher than normal, indeed high enough to produce leakage. This leakage, results in noticeable skin discoloration in the form of small (if not tiny) red spots--the petechiae. It is not necessary to block the airway to have this result. When this is the mechanism, the victim will lapse into unconsciousness a few minutes before he/she dies. If the pressure on the jugulars (and the carotids) is removed prior to death, the victim may recover, though possibly with some brain damage.
Another way to produce petechiae in association with strangulation, is to block the airway. This can be done by collapsing the trachea, either manually or via ligature, gagging the victim or by covering the mouth to prevent respiration. If the airway, alone, is blocked (not the jugulars or the carotids), as in smothering, the victim will struggle to breath--the diaphragm will be employed in this attempt as there is no other way to breath naturally (without mechanical assist). So the diaphragm, a powerful muscle, will be trying to draw air into the lungs, and push air out of the lungs, to no avail; this will put excessive pressure on the lungs, which will also impede the flow of venous blood into the lungs; hence out of the brain and face, etc., (just as pressure against the jugulars would) and result in the tell-tale petechiae in the conjunctiva, on the face and elsewhere associated with this event. Again, petchiae associated with asphyxiation caused by "smothering".
There is a phenomenon called the Valsalva maneuver, which is sometimes employed by folks when they go to the bathroom, popularly known as straining. This same maneuver is employed by weight lifters when they are strainging to lift a weight. It is not uncommon for petechiae to occur on the face, conjunctiva and elsewhere during, and as a result of, this maneuver. In this example, breathing is suspended VOLUNTARILY, unlike the suspension of breathing in the smothering example, but the result, insofar as the petechiae are concerned, is the SAME.
Petechiae, in association with asphyxiation, can also be produced by deliberately sitting on the chest of the victim, or, involuntarily, by any sufficiently heavy weight which presses against the chest, as in a cave-in construction accident. Physiologically, the mechanism is the same--restricting blood flow through the capillaries by preventing proper venous drainage. Any time, forced flow through a vessel, such as that effected by a pumping heart, is restricted, the flow will diminish and the fluid pressure in the vessel, on the pump side, will increase accordingly. The formation of petechiae requires excessive pressure in the capillaries (vessels), and it doesn't matter how this excessive pressure comes about; excessive pressure is excessive pressure. But, pressure of any magnitude, whether excessive or not, with respect to the human circulatory system (other than pressure due to gravity), requires an operating pressure pump--the heart. Pressure of the sort required to produce petechiae can't develop unless the HEART is BEATING and the flow is restricted.
About pressure in vasculature due to gravity: it is possible to have petechial hemorrhaging in assocation with venous insufficiencies such as those assocated with varicosity. This hemorrhaging has nothing to do with asphyxiation. It is also possible to have petechial hemorrhaging in association with certain diseases and/or poisons which affect the capillaries directly and make them prone to leakage. Again, this has nothing to do with asphyxiation.
So, there would be NO petechial hemorrhaging associated with the paralysis of the diaphragm. A paralyzed diaphragm cannot exert pressure on the lungs, which, in turn, could interfere with proper blood flow through the capillaries. Therefore, JonBenet's petechiae can not be attributed to paralysis of the diaphragm brought about by stunning with an electrical appartus. Further, there was, in JBR's case, petechial hemorrhaging along the ligature groove, further evidence that the ligature was involved in the production of the hemorrhaging.
Therefore, there can be no doubt that JBR was strangled by the cord around her neck that is displayed in the photos. Whether there was any other strangulaton attempt, either with the same or another device, is open to question.