TIAs and Parkinson's-like tremors

My husband has been seeing the VA for several years now. Since he came back from Desert Storm I noticed a decline in his alertness. He first only had vague symptoms in this area as well as loose stools. He began having tremors not noticeable to the eye but increasing over the years. Finally he could barely write in the past 8 or so years. He is also incontinent due to the jittery nerves associated with his bladder and colorectal area.
In Oct. 2000 he suffered his first seizure, followed by a heart attack  in Jan. 2001 and another seizure in the spring of 2001. The seizures were at night and were grand mal. Now his shaking and movement act like Parkinson's even though CT and PET scans only show a history of TIAs. His spacial ability is significantly decreased and his memory and thought processes are also. There is (I forget the word) a lax or is it hypotrophy of the brain. He has been exposed to spent uranium and agent orange. Can you provide information that will help me be able to better understand for my own purposes and for speaking intelligently to those who make decisions concerning my husbands health and disability?