Got another response from the other place i posted-here it is:
Back arching is called Opisthotonus or Opisthotonos. I suffered this in 1997, a couple of years after I had head and spinal injury. I didn't know anything about medical terminology, I thought it was from hard work and getting older, so it took the quick onset of horrific symptoms - cramps, spasms, twitching, tics (these all hurt like crazy) in 2001, before I "accidently" found a name for this condition.
I suffered lock jaw a few times as well as facial grimaces and my legs would move involuntary in a paddling motion. My head rises up and to the right - I had many symptoms, which I later found to be neurological symptoms. One doc thought I might have had Epilepsy - my test was clear.
Doctors apparently think Opistotonus is a rare condition - but research has found it is displayed in many illnesses and conditions. I was by myself when it happened to me, I didn't know what was happening - I read where it can happen to babies soon after birth - I believe it could happen to babies, children and even adults, and no-one would know.
If you put Opisthotonus Opisthotonos (both spellings) in the Search engine, it will bring up sites with symptoms and other info. It may be scary but knowledge is power.
Does the boy's doc know of him having this back arching?
Paula