I am guessing that Kayla was supposed to have had her head shaved, or partially shaved, thus the scarves. She would not be able to wear a hat, except over the scarf.
Some years ago, on GL, a female character had cancer, did chemo, etc. The actress wore scarves, and in real life, insisted on getting a sort of buzz cut, in order to portray accurately the "growing out" phase after the character lost her hair. Talk about being realistic. But it was the actress who insisted on doing that.
In Kayla's case, she had brain surgery, so am just guessing that just a portion of hair was shaved off (the character) so, scarves would be what she would wear. At least until that portion grew back enough. I have seen women in church at times, wearing them. Then they opt for a wig.