Hi Jane:

I don’t know that much about it because after the Neurologist said he had a mild form that he would probably outgrow, we stopped investigating and moved on until we got the CAH diagnosis.

I did learn a little though and I have a co-worker whose spouse has it.  My general understanding is that the cerebullum has tonsils.  In Chiari, the tonsils are elongated and actually go down through the foramen (hole that connects your brain stem to your spinal cord).  The severity of the Chiari depends on how long the tonsils are elongated.  In essence, the tonsils are strangling the spinal cord and can cause many probelms, such as severe headaches, back aches and problems with balance.  The only option is surgery where they remove the first vertebrae and scrape the tonsils.  Kenny was considered to have a mild form because his tonsils were only elongated about 4 mm.

Hope that helps.

Kristin