Does the "crumbling skull" principle affect the quantum of damages awarded in a motor vehicle accident case?

In my view, it would not be appropriate to reduce this award on the basis of the "crumbling skull" principle. The fundamental principle in assessing tort damages is that the quantum should be that which is required to place the plaintiff in her original position; that is, the position she would have been in absent the defendant's negligence: Athey v. Leonati, 1996 CanLII 183 (SCC), [1996] 3 S.C.R. 458 at paras. 32–35. If there is a measurable risk that a pre-existing condition or an intervening event would have resulted in the same loss even without the defendant's negligence, that risk must be taken into account in reducing the damages award. Measurable risks, or in other words contingencies, need not be proved on a balance of probabilities. Rather, as with any hypothetical event, they are given weight in the assessment of damages according to their relative likelihood: Athey, para. 27.