"Contact was clearly made with Ms Palmer's head on the second attempt and it appeared to be a very violent head-butt."
Carnegie attended the medical centre every day to receive Ritalin to treat his ADHD.
Giving evidence Carnegie said it had been raining on the day and he had requested an umbrella from Palmer.
"He suggested that Ms Palmer said no in a quite loud, aggressive and threatening way and that she put her hands on him, noting that he cannot stand people touching him."
Carnegie told the hearing he asked to go through the glass door and then 'I head-butted Corina'.
He later stated 'I'm not saying I'm not guilty' and 'There may have been a touching of the heads'.
When cross-examined and asked whether he could have head-butted Palmer, Carnegie responded: 'It could be possible, feasible, but there's no proof'.
Judge Carter said there was some conflict between the evidence given by two Corrections officers and Carnegie.
He also noted Carnegie conceded he had assaulted Palmer in some parts of his evidence but denied any head-butt took place.
After hearing all of the evidence Judge Carter reserved his decision in the case and released his findings on Monday. He found Carnegie guilty of assault.
"I found his evidence to be entirely unconvincing and reject it as unworthy of belief.
"Mr Carnegie virtually admitted the assault on several occasions during his evidence and at one point coyly suggested that there is no proof."
Judge Carter said in assessing the credibility and reliability of two Corrections officers he had been influenced in the way they were matter-of-fact and calm.
"Their evidence was not overstated or embellished and their evidence was corroborated by the CCTV and bodycam footage."
As a result of the attack Palmer suffered an "egg" on her forehead, bruising and had a headache all day.
Judge Carter accepted the assault was an isolated incident but said any attack on prison staff required a stern response.
He sentenced Carnegie, who was already serving a lengthy sentence of imprisonment for unrelated offending, to an additional four months jail to be served concurrently.
