A "sadistic" teenager who caused an unconscious father brain damage after kicking his head like a football has been locked up indefinitely.

Jamie Brannon will have to serve a minimum of four years before being considered for release.

A judge told the 19-year-old: "This case shows how sadistic and devastating such an attack can be."

Maidstone Crown Court heard victim Dean Staff was left with "life-threatening and life-changing" injuries as a result of his head being stamped on and kicked.

"He has no memory of that evening," said prosecutor Miss Adaku Oragwu. "His brain function remains significantly impaired."

Mr Staff, 26, came across Brannon, who had been drinking all day, and friends on September 19 last year in Five Bells Lane, Rochester.

The father-of-two had just turned into the road where he lived when an argument developed. Brannon swung a bottle at Mr Staff's head. It hit his elbow and broke.

He punched the victim to the ground and then stamped on his head four or five times.

"The only movement from Mr Staff was his head moving as he was being kicked," said Miss Oragwu.

Brannon stood over Mr Staff, repositioned his head and and ran up and kicked him in the head "perhaps like a goalkeeper taking a goal kick".

Mr Staff was taken to hospital in a critical condition. He will need long-term care.

Brannon, of Skinner Street, Gillingham, admitted causing grievous bodily harm with intent.

Imposing the youth custody sentence, the judge said of the attack: "It was sadistic and brutal."

He added he would have passed an eight-year sentence if it was determinate.