"Scientific Certainty" Not Necessary to Prove Causation in Disc Injury Claim
Reasons for judgement were released this week by the BC Supreme Court, Kelowna Registry, discussing the issue of causation in a disc injury claim.
In this week’s case (Valuck v. Challandes) the Plaintiff was injured in a 2007 head-on collision. Fault was admitted by the offending motorist. The Plaintiff was ultimately diagnosed with a disc protrusion at the L5-S1 Joint.
ICBC argued the disc protrusion was not caused by the crash or if it was it would have occurred even in the absence of the collision. Mr. Justice Rogers disagreed and found that while it was not scientifically possible to say with certainty that the disc injury was caused by the crash, it certainly was an event that materially contributed to the injury.
Mr. Justice Rogers assessed non-pecuniary damages at $100,000 but then reduced this award by 40% to take into account the fact that the injury may have occurred even without the crash. In discussing causation the Court provided the following reasons:
 There is a conflict in the evidence concerning the cause of the herniation of the plaintiff’s lumbar disc at the L5-S1 joint. According to Dr. Laidlow, the plaintiff’s disc was probably not injured in the collision. He bases his opinion primarily on the fact that the plaintiff’s complaints of low back symptoms did not start until several weeks after the accident. According to Dr. Laidlow, if the disc had been damaged in the accident then the plaintiff would have had symptoms in that area right after the event and that she would not have been able to ignore those symptoms. According to Drs. Shuckett and Craig, the impact likely caused some damage to the plaintiff’s lumbar disc and that damage materially contributed to the herniation that the plaintiff subsequently experienced a year and a half later.
 I found Dr. Laidlow’s evidence to be particularly useful here. Dr. Laidlow said, and I accept, that a spinal disc comprises a containment vessel made up of fifteen to twenty layers of fibrous material and of viscous disc material lying within the containment vessel. The fibrous layers of the wall can, over time, suffer tears. The tears can be spontaneous or, rarely, they can be caused by trauma. The tears may heal over time, or they may not. Tears may occur without causing any symptoms at all. Enough tears may, at some point, be present in the disc wall so that the wall begins to fail. If that happens then the disc might bulge out. The bulging can intrude on pain sensitive tissues and pain may result.
 At some further point, enough tears may be present in the fibrous layers to compromise the wall itself and the wall breaks. In that event, the viscous inner disc material will escape from the disc. The escaped material is termed a protrusion and the condition is known as a herniated disc. The protrusion may impinge on surrounding tissues, causing local pain. The protrusion may also impinge on the nerve roots that exit the spine at the site of the hernia. In that case, symptoms usually include pain radiating along the area enervated by that particular nerve.
 Dr. Laidlow testified that an accident such as the one in which the plaintiff was involved would likely have caused damage of some kind to her spine. Dr. Laidlow was not willing to say for sure such damage included tears in the wall of the plaintiff’s lumbar disc. In his view, such damage was possible, but that he could not say for sure one way or the other. Given the several weeks’ delay between the trauma of the accident and the onset of the plaintiff’s low back pain, and the year and half that passed between the accident and the herniation, Dr. Laidlow felt that the accident could not be said to be a material contributing factor in the herniation.
 Although Drs. Schuckett and Craig did not say so in so many words, the gist of their evidence was that they thought that the accident probably did weaken the disc and thus materially contributed to the herniation that occurred on the Labour Day weekend of 2008.
 Dr. Laidlow cannot be faulted for testifying that there is no way to know if the accident in fact caused one or more tears to the wall of the plaintiff’s lumbar disc – no images exist to show the state of her disc in intimate detail immediately before or immediately after the accident, and no physical examination short of a biopsy could have illuminated that issue for him.
 I have concluded that the evidence in this case does not admit a scientifically certain answer to the herniation question. Scientific certainty is not necessary, however. As the Supreme Court of Canada said in Athey v. Leonati,  3 S.C.R. 458 at paragraph 16:
…Causation need not be determined by scientific precision; as Lord Salmon stated in Alphacell Ltd. v. Woodward,  2 All E.R. 475, at p. 490, and as was quoted by Sopinka J. at p. 328, it is “essentially a practical question of fact which can best be answered by ordinary common sense”. …
 After taking into account all of the medical evidence and the all of evidence of the plaintiff and her witnesses, and after applying a soupcon of common sense to the mix, I have concluded that the accident did cause some damage to the containment wall of the plaintiff’s L5-S1 disc and that that damage was a material contributing factor in the herniation that occurred at the end of August 2008. It follows that I find that the defendant is liable for damages caused by that herniation.