I have been raising this point with my my consultant and MS nurse, and have been ignored ,saying no link to MS. In the end I went to my local GP and got referred to my local Hospital . They did all the tests my pulse was good and blood pressure was good but my feet were purple. Then i found this link on web explaining temperature changes make the blood vessels contract caused my MS see link https://ms-uk.org/blog/ms-and-raynauds-syndrome-whats-the-link/