While "permanency determinations are generally made by juries," a directed verdict on permanency is proper where the evidence of injury and causation is such that no reasonable inference could support a jury verdict for the defendant. Evans v. Montenegro, 728 So. 2d 270, 271 (Fla. 3d DCA 1999). A plaintiff establishes a prima facie case of permanency by presenting expert testimony of permanency. The burden then shifts to the defendant to defeat the directed verdict by presenting countervailing expert testimony, severely impeaching the plaintiff's expert, or presenting other evidence which creates a direct conflict with the plaintiff's evidence. See id. (citing Holmes v. State Farm Mut. Auto. Ins. Co., 624 So. 2d 824 (Fla. 2d DCA 1993), and Jarrell v. Churm, 611 So. 2d 69 (Fla. 4th DCA 1992)).