Burgess J.W. Raby & William L. Raby have published Was the Interest Paid "On Account of" the Accident?, also available on the Tax Analysts web page as Doc 2005-4244, 2005 TNT 41-80.  Here is the Introduction:

Section 104(a)(2) excludes from income "the amount of any damages (other than punitive damages) received (whether by suit or agreement and whether as lump sums or as periodic payments) on account of personal physical injuries or physical sickness." (Emphasis added.) Chad Chamberlain, who was severely injured while swimming, recovered $9,253,551.58 from the state of Louisiana, whose negligence caused the injuries. Of that, $3,791,741.53 was prejudgment interest. Was the interest paid to Chad (and his parents) part of the excludable damages? It should be if "on account of" means "as a direct or indirect result of" (as in "They stayed together on account of the children"), which is certainly one "ordinary meaning" of that phrase.