Hi tshadow, I am going to try to explain this as well as I can but as breifly as I can because it would be impossible to explain all the variations of this condition here. The tonsils I refer to are not the ones in your throat. Each person has 2 cerebral tonsils at the base of the back side of your brain. This is part of your brain. In general I will explain part of the Chiari 1 malformation condition. These tonsils can literally be forced down into or pulled down into your spinal canal. They literaly herniate into a persons spinal canal. That is what one form of Chiari 1 Malformation is. Depending on how the tonsils lie or how tight the space is in your head for your brain, it can cause your Cerebral spinal fluid that also lubicates your brain to not circulate correctly and sometimes even get blocked permanently until urgently corrected or intermittantly. Sometimes people don't even have a problem with the tonsils being down in the spinal canal. Meaning "0" Herniation. But they still have a problem with CFS flow in thier head due to a structural problem like possibly too small of a skull for their brain. This can also be caused by even benign growths in the head. (MRI with CFS flow study can help determine what the CSF flow is in your brain. There are other test as well. But spinal taps are not recomended by many doctors because that proceedure can actually pull the tonsils further down into the spinal canal making the problem worse.) When any of brain/tonsil/CSF flow variations happen, any of them can cause pressure to any number of areas of the brain stem or other organs in the skull. This causes a wide variety of symptoms from patinet to patient just depending on where the pressures are, how bad they are, and what ativity the patient is doing at the time. Sometimes a persons tonsils can herniate 25 mm and even more. This can easily cause pressure and over time damage to the spinal cord. I hope this helped.
PS. I will post links to sites in a few minutes to help everyone interested to gain more information. Dee