My 33 year old daughter has Arnold Chiari I malformations and her father is a US Navy Vietnam war veteran, served 1970-1973. I precisely remember a letter he wrote to me (and I still have all those letters) where he said that they were performing unreps (loading and unloading stores on and off the ship) and a barrel of Agent Orange had burst the seal in the 100+ degree heat and leaked all over him. He then said he and a couple of others were then hosed down by others on the ship.
When she was diagnosed at age 19 it was my very first thought that this birth defect was caused by that exposure of Agent Orange on her father. My daughter was also a fraternal twin and her twin died in utero (appx 20-24 weeks - no exact way of knowing, there were no ultrasounds in 1974). I've always instinctively known that what killed her twin caused her birth defect. I had one miscarriage before becoming pregnant with my daughter and her twin.
Reading your post is the first confirmation I've ever had that my instincts were on target.
My daughter had very, very minor effects from AC until she was 19 and had an immediate and extreme brain swelling. Prior to that, she did not have anything present that was life altering. She did have seizures (non-febrile) while eating in her high chair when she was 11 months old. A full neuro workup then showed nothing.
As a child, and even into adulthood, she had trouble swallowing pills which we now realize is a common AC symptom. She could not pick up small objects on the floor easily such as coins. Also been noted as an AC symptom.
Her severe presentation was almost fatal. Her brain swelled and she began passing out if she did simple things such as combing her hair (reaching over her shoulders) or reaching for a box on a shelf. She believes this abrupt presentation was related to her being at an amusement park the day before with her younger brother and riding a high-speed roller coaster.
She survived that event without surgery, but by changing a few things in her life. Since that event she sleeps propped at an angle. She has even slept sitting up in a chair on bad days to aid drainage of cebrospinal fluids. She did take a prescription diuretic, but the side effects were so bad that she switched to a natural diuretic that she's taken for over 12 years.
My daughter has one natural child. Her pregnancy was a good one, but her delivery (by scheduled C-section) was difficult. She was considered an extremely high risk pregnancy. She has not elected to have another child, in her words, "to not push her luck".
Hope that some of this information helps. I wonder how many other children of Vietnam vets have similar birth defects. The greatest power of the internet is the ability to share and learn from others. It's also the greatest freedom we have.