Two-year-olds Ahmad and Muhammad Ibrahim are in separate rooms, but visit each other daily.

"Muhammad's legs are getting stronger and he is now sucking occasionally on lollipops," Dr James Thomas, chief of critical care services at Children's Medical Centre Dallas, said in a news release Friday.

"Ahmad's favourite activity is blowing kisses to anyone who comes to greet him."

The twins were separated from the tops of their heads in a 34-hour surgery on 12 October.

They will receive repeat head CT scans on Monday to assess the accumulation of spinal fluid in and around their brains. They do not, however, show any clinical signs of a fluid build-up.

The boys will begin to receive formula once every four hours instead of the continuous feeds to establish a regular eating schedule.