A teenager who heard voices telling her to harm others inflicted horrific knife attacks on two strangers within six months, a court has heard, including one where a man on a date was left with part of a blade lodged in his skull.

But Anne-Marie Hart is still not getting the psychiatric treatment needed to keep the community safe from her, the County Court heard on Wednesday.

The crime scene in North Melbourne in December 2016 after a woman was the victim of a random stabbing. Credit:Seven News

Hart was 17 when she used a serrated fishing knife to slash a cyclist's face after grabbing the woman in a headlock in an early-morning attack in North Melbourne on December 21, 2016.

Then on May 4 last year, Hart and two teenage girls stabbed a 26-year-old man they were in a stationary car with, after one of the girls met him on the dating app Tinder and asked that he drive the trio to Sunshine North.