Hello all
I felt very privileged after speaking to the neuro- surgeon (no, not the neurologist, family doctor, or radiologist) about what my MRI showed in regards to Chiari. He talked about the sagittal view which showed that I did have descending tonsils. This is the view that is typically posted on this site that shows the skull cut in half with the nose pointing forward. It is from this view that doctors measure the length of the tonsillar hernia.
The second view that he looked at and explained was the horizontal view. This is when you look down onto your head from above. He was interested in the level of the foramen magnum and lower where the tonsils bulge downward into the spinal canal. He said that this is the more important view as it shows how much crowding there is at the spinal cord level. A person can have any length of hernia and it can be thicker or thinner resulting in more or less compression of the spinal cord structures. Compared to a horizontal view of a normal MRI, that spinal cord was sure squished!
I do not even know how much my hernia descended as he never told me. I had Chiari symptoms and a hernia and crowding. Good to go for surgery!
There are lots of different structures in the spinal cord. The cerebral spinal fluid vessels are only one of those structures and my understanding is that CFS blockage or no blockage should not be used as the defining factor on a Chiari diagnosis. I live in an area with a teaching University and the medical parts do a lot of research into what testing is appropriate for what conditions when making a diagnosis. Basically, they want to save money on unnecessary tests and decrease wait times for appropriate treatment.
They found that examining an MRI and taking a subjective history provided sufficient information to diagnosis Chiari. Of course major conditions were also ruled out with blood work and all the other basic tests that Chiari folk have done on their journey. Checking the CSF flow was extra and did not provide any additional information - also expensive with a long wait time and doctors dislike ordering the test. Just what I was told! I also saw this information on an interview with a couple of neurosurgeons being interviewed about their practices with Chiari diagnosis and surgery.
I guess what I am saying is that it might be worthwhile to ask the neurosurgeon to discuss the horizontal view with you and explain what the impact can be when the other structures in the spinal cord are compressed. Of course, sometimes we just have to move on to another health care professional who knows more and who is not putting us in to the "crazy category". Also, in the Chiari diagnosis, size does not matter. A little hernia or a big hernia can both have a strong compressive force on the spinal cord. We just need to have a look from above to determine that. The length is immaterial.
So speak up and ask questions!