We are having a hard time figuring out how to word the manner and means for an abusive head trauma case. There is no blunt force, so it would be just the rapid acceleration/deceleration that caused bleeding on the brain.

Any suggestions are much appreciated!

Do you have an admission or a witness who saw what the defendant did? if so then allege that act, i.e. "by shaking baby" or "by swinging baby against X." If, as is likely, you don't know the act--only that D caused the injury--then maybe "by causing a brain bleed to X by a manner and means unknown to the grand jury." You may not need to include the injury into the unknown manner and means allegation, but it will insulate you somewhat from a notice attack.

Have you talked with your pathologist/attending physician? You need to encompass the entire possibility of manner and means.

Here is an example of one of ours (it is trauma, so it will be a little different) :
did then and there commit or attempt to commit an act clearly dangerous to human life, to-wit: by striking XXXXXXX with or against a hard or soft object or surface, that caused the death of XXXXX, and the defendant was then and there in the course of and in the furtherance of the commission or attempted commission of a felony, to-wit: injury to a child.

And it is further presented that the defendant used or exhibited a deadly weapon, to-wit: the defendant's hands, that in the manner of their use or intended use were capable of causing death or serious bodily injury.

And it is further presented that the defendant used or exhibited a deadly weapon, to-wit: a hard or soft surface or object, that in the manner of its use or intended use were capable of causing death or serious bodily injury.