Seeking both proper and ongoing treatment for injuries in personal injury cases is extremely important for a multitude of reasons. Not only will proper treatment help you recover from your injuries, but it will significantly improve the strength of your case.
In this recent Supreme Court of Canada case, the judge commented multiple times on the plaintiff's lack of ongoing medical treatment:
http://www.courts.gov.bc.ca/jdb-txt/sc/18/06/2018BCSC0635.htm
At paragraph 21:
[21] It was pointed out to the plaintiff on cross-examination that, since the end of 2013, the only treatment she has received for what she described during her evidence-in chief as “significant” and “constant” pain was six massage therapy sessions between January 8, 2015 and September 3, 2015. The plaintiff insisted that she was “using other forms of treatment” for her other symptoms such as the exercise regime she had learned from some kinesiology sessions she attended in 2013.
[22] It was also pointed out to the plaintiff during her cross-examination that her doctor had recommended she seek counselling for her driving anxiety. She agreed that it was unreasonable for her not to have done so.
The plaintiff had also attended only 4 treatments with their family doctor for treatment related to their motor vehicle collision injuries. The plaintiff had seen their family doctor more regularly, but had not mentioned her injuries from the collision during these visits. In his discussion, the judge further stated:
[89] On cross-examination, the plaintiff became less than steadfast about her pain symptoms and had difficulty explaining why most of the clinical records made no mention of many of them. The best she could do was to say “I don’t remember” or “I was focused on other things”. Moreover, it became clear from the evidence of both Ms. Kilmer and Ms. Lahti, which I accept, that the plaintiff had exaggerated her ongoing pain symptoms and inability to work at Gulfstream.
[90] As this Court has previously noted, the absence of reference to a symptom in a doctor’s notes of a particular visit cannot be the sole basis for any inference about the existence or non-existence of that symptom. However, where, as here, a plaintiff’s description of her symptoms is clearly inconsistent with her failure to seek medical attention and is consistent with improvement in her condition, the court is entitled to draw an adverse inference as to her credibility: Edmondson v. Payer, 2011 BCSC 118, at paras. 36–37.
As stated, while the absence of medical treatment cannot be the "sole" basis for an inference about the existence or non-existence of a symptom, the court can consider these absences when drawing inferences about credibility. In English, a judge can use the presence or absence of medical treatment as a factor when deciding whether or not they believe you.