Star neurosurgeon Charlie Teo has admitted making an error during surgery by going "too far" and leaving a patient damaged.

The high-profile doctor is appearing at a medical disciplinary hearing to explain how two of his patients ended up with catastrophic brain injuries after he performed surgery.

Speaking prior to the hearing before the Health Care Complaints Commission (HCCC), he said he hoped the truth would be enough to clear his name of wrongdoing.

"Tell the truth and the truth will set you free," Dr Teo told reporters on Monday.

The hearing resumed after a break of several weeks with a panel of legal and medical experts examining Dr Teo's conduct, including whether he adequately informed his patients of the risks involved.

He was grilled about surgeries he performed on two women who both had terminal brain tumours and had been given only weeks or months to live.

Dr Teo defended his actions in leaving one patient unresponsive, adding there is "no exact science" when it comes to tumour-brain interface.

"It was my hand, my technique, my doing that she didn't wake up. Whatever happened I take full responsibility," Dr Teo said.

The 65-year-old sparred with commission counsel, Kate Richardson SC, denying accusations he deliberately cut across the brain midline, which had heightened risk to the patient.

"Look - we can resolve this. I did something wrong. Clearly I damaged this lady," Dr Teo said.

"The point is I made an error. A surgical error. I went too far and I damaged this lady. No one is disputing that."

In one particularly heated exchange, Judge Jennifer Boland stepped in to maintain order.

"With both of you talking over each other it doesn't help us. I appreciate that it's frustrating," Judge Boland said.

Dr Teo previously gave evidence he doesn't regret the surgeries because he believed at the time they were the best thing for the patients.

The surgeries left both women in vegetative states and they died soon after.

Both of the patients' husbands previously told the inquiry they were given the impression by Dr Teo the women had a good chance of significant improvement in their conditions.

"We never got the discussion that it could go badly," one of the husbands said.

"Charlie Teo had told my wife ... if she didn't have the surgery by Tuesday, she would be dead by Friday.

"That was why my wife made her mind up that she wanted the operation."

Previous hearings have drawn large crowds of supporters for Dr Teo including former Australian cricket captain Steve Waugh, and boxer Anthony Mundine.

Throughout the disciplinary hearing process Dr Teo has continued to operate on patients under additional oversight imposed by the commission.

The inquiry is scheduled to run until Wednesday.