I have Chiari malformation and have never been told it caused my fibro. I do have terrible headaches and suffer from migraines.

I worked with Dr. John Sampson at Duke Hospital in NC.

I have had surgery for Chiari In 2002 with included removing skull bone (decompression). I had to have additional surgery in 2007 to remove part of the malformation. I was later diagnosed with Fibromyalgia after additional tests for spinal fluid pressure showed that the Chiari wasnt the cause of my pain, stinging, etc. (2010)

My husband has a cousin who has both Chiari malformation and fibro. I think she was diagnosed with Chiari first.

While some symptoms overlap there seem to be no correlation between chiari malformation and FM so far according to studies.
A male family member was diagnosed with chiari malformation, he had no FM symptoms in his mid 30s. Hope this helps a little.