If a plaintiff has fibromyalgia, what is the impact of the respondent’s negligence on her condition?

If the appellant had pre-existing fibromyalgia or would have developed fibromyalgia in any event, the trial judge should have then considered whether the respondent’s negligence made her condition worse. The trial judge, however, erred in failing to undertake this analysis because he appeared to apply a limited concept of causation. He stated at para. 137: If I conclude that the 1996 accident caused or contributed to the fibromyalgia, then the issue of whether that condition existed pre‑1996 or was likely to develop in any event (the thin v. crumbling skull type questions) must be addressed. However, absent proof of causation those matters are not relevant.