He is mainly a solo artist, and apart from David Lee Roth I don't think he ever was associated with a mainstream band or artist. Actually he was a promising young metal guitarist (and a friend of Marty Friedman) whose career was suddenly halted in the late 1980s, when he was diagnosed with Lou Gehrig's Disease (he was only in his early 20s then)... Although he has tried to keep composing since then, he now no longer can play the guitar, walk or even communicate in a "normal" way. A sad story, indeed...