I knew there would be good discussion on this...
Hey Brian M, The neuro did not get into details on how many he finds with CM that do or do not have a syrinx, just that it was definitely less. I do know quite a few dogs with MRIs that show CM, but no formation of syrinx yet. I am always relieved to know of any Cavaliers that do not have SM as a result of CM.
It is true that some have malformations in CM that result in symptoms, while others do not. Gracie has a pretty severe malformation with scar tissue, so that alone could cause some symptoms as I understand it. But most of her symptoms are classic SM signs.
Zumie... I have no idea about the eyes. I do know that Gracie has always blinked her left but her right eye does not blink as much. It also tears more, probably because she can't blink it as well. Her worst symptoms are on the right due to location of syrinx and malformation. I do not think this would be a coloration of the eyes issue... but who knows??