If you don't have the major headache any more, but still have simular ones with certain activities described by Chiari Specialist, the proceedure could have made the problem worse at the time, but it corrected itself to the degree it could over time. If you had Chiari herniation before the test, I would suspect that degree of herniation would not have got better since it was caused by something else and possibly long standing and the correction would have only been to that point. I hope this makes sense. Just remember, I'm not a doctor, just a suffering patient that has been driven by doctors and medical suffering to learn. Dee