In Oliveira v. Warren (1938) 24 Cal.App.2d 712, Oliveira, the plaintiff was involved in a car accident and suffered injuries to her knee, forehead, and coccyx, as well as headaches and dizziness. (Oliveira, supra, at pp. 713, 714-715.) The appellate court held that because the plaintiff introduced expert testimony stating that the car accident probably caused plaintiff's injuries, there was sufficient evidence to support the jury's finding of causation. Such evidence was required because the plaintiff's injuries were wholly subjective. (Id. at pp. 716-717.)