Zell must have a brain tumor

There is no other explanation.  

I used to jokingly say that explained the sudden irrational behavior, the sudden conversion when he became Senator.  But now I think it is a definite diagnostic possibility.  It is almost the talk of a paranoid schizophrenic.  

This is a man who not only can't tell the difference between the lies and the truth; but this is a man who has no control over his verbal impulses.  Logorrhea of the mouth.

But this exchange between Zell Miller and Chris Matthews is the kind of lack of control of is indicative of someone with a brain injury.  

Zell: "I'm not gonna take this!" "I wanna get in your face!" "I think we oughta cancel this interview!" "You're hopeless." "I wish we lived in the day... [Cut off by Tweety]" "Get outta my face!" "I wish we lived in the day where you could challenge a person to a duel!"

MORE (EDIT 1):
Zell: "Are you gonna shut up?!" "I don't know why I even came on this program!"

MORE (EDIT 2):
Tweety: "Well that was an unexpected turn of events."

Before I was being sarcastic, now I wouldn't be surprised if he's had a stroke and the lesion has affected parts of the brain having to doing with impulsivity and rational thought.
  [Update] pratice