Ozzy commented in an interview about this. He was told that after having his hair colored blonde numerous times his hair was unhealthy. A hair stylist recommended shaving his head so he would regrow hair that was healthy.
According to eyewitnesses right after he did this he came onstage with a wig, and took it off during the show to shock the crowd.
You can see Ozzy in the background with his hair just starting to grow back after he had shaved his head completely bald that year. Brad Gillis during his time with Ozzy in 1982 in the front.
