Does a plaintiff have a thin skull and crumbling skull?

It is during the damages assessment that the doctrines of thin skull and crumbling skull apply. If the damages are unexpectedly severe owing to a pre-existing condition that was latent and symptomatic and would not have affected the plaintiff in the future, then the thin skull would entitle the plaintiff to the full amount of his or her damages (Athey v. Leonati, 1996 CanLII 183 (SCC), [1996] 3 S.C.R. 458).

Conversely, if the pre-existing condition was manifest and disabling, or would have become so in any event in the future, then the crumbling skull rule entitles the plaintiff only to additional damages suffered by the plaintiff as a result of the accident (Smyth v. Gill, 2001 BCCA 650).

The measurable risk of debilitating effect in the future of the plaintiff’s pre-existing condition must be reflected in both the non-pecuniary damages and loss of income award (McKelvie v. Ng, 2001 BCCA 384). There should be a similar reduction of damages to reflect unrelated intervening events that would have affected the plaintiff’s original position adversely in any event (TWNA v. Clarke, 2003 BCCA 670).