Not everyone will have a headache or even all the same sx. Perhaps just look at this as another thing to consider when your doctor next looks at your MRI. You can mention CM and/or ask him if there's anything abnormal about how the tonsils are situated and if your brainstem looks normal. I don't know about other conditions like CM but I wouldn't be surprised if there are other structural things that can cause neurological problems. Maybe just the question will get a doctor thinking! There could be something RIGHT there in an MRI that someone doesn't notice. This was the case for both of these women.