Causation Link between physical trauma and Primary ITP

I am hoping there is someone who might be able to advise me please. In 2018 I was involved in a car accident. Although at the time I was lucky enough to walk away from the accident without any obvious external injury, a couple of weeks later I kept noticing bruising on my body and face. After many months I was eventually given a blood test which showed platelets at 22 and I was then put on steroids and this increased my platelets, although they have dipped again recently...
My consultant did say that Primary ITP could be caused by environmental factors such as physical trauma caused by a car accident but does anyone have any knowledge or experience of this being a cause? I would be very grateful to know if there is evidence of this or other people have experienced similar.
Thank you

In all my time dealing with ITP - 12 years - I've never seen physical trauma mentioned anywhere as a cause of it. A quick search I just now did turned up nothing, either... one article mentioned severe psychological trauma might sometimes effect platelet count the same as chronic, lower-level stress can.
The patient information section on this wonderful website has information about causes on this page - pdsa.org/what-is-itp.html
Be sure to check the link within that information on "The science behind the causes of ITP", here - pdsa.org/images/ScienceBehindCauses.pdf

It may comfort you to know that few people are ever able to identify the cause of their ITP. I hope your recent relapse isn't severe and can be safely monitored without needing treatment. How's your count now?

Thank you so much for your reply and useful links. Most grateful to you.