A disciplinary hearing into the conduct of Charlie Teo has probed whether two patients of the star neurosurgeon adequately consented to surgeries from which they never recovered.
The Health Care Complaints Commission inquiry taking place in Sydney this week stems from complaints related to two surgeries to remove brain tumours that left the patients with catastrophic brain injuries.
Dr Teo, who is famous for performing neurosurgery on cancer patients with tumours other doctors have deemed inoperable, has been accused of charging exorbitant fees and offering some patients false hope.
In one of the cases, Dr Teo told the patient if she didn't have surgery by the following Tuesday she would be "f***ing dead by Friday", her husband told the hearing.
During the early 2019 surgery, the woman received a frontal lobectomy in which a significant portion of her brain was removed - something her husband told the committee was not disclosed before the operation.
Medical consent experts Paul Komesaroff and Chris Ryan told the hearing on Thursday that risk needed to be conveyed to patients to allow them to make informed consent.
Professor Ryan said consent could be derived from one session but patients needed to be given sufficient time to weigh matters to their own satisfaction.
Counsel for the HCCC Kate Richardson SC asked the experts whether it should be disclosed if the risk of neurological deficit or death from a procedure was between 30 and 50 per cent.
They agreed it should.
"For many people, the risk of profound neurological deficit would be even more concerning than death," Professor Komesaroff said.
"One might even raise the question (of) whether you should go ahead with a procedure like that."
On Wednesday, neurology experts Andrew Morokoff, Bryant Stokes and Paul D'Urso told the inquiry it was common during the course of operations to remove healthy brain tissue without first informing the patient.
"I think every brain surgeon in the country would be guilty of not declaring they take out normal brain tissue when they remove a brain tumour," Professor D'Urso said.
"You'd have nothing else to do other than have neurosurgeons in your commission if that was the line you took."
Dr Teo was restrained by the NSW Medical Council in August 2021 from operating without the approval of another doctor after an investigation by the state's health care complaints commission.
He has repeatedly denied any wrongdoing.
According to a list of factual assumptions produced at the hearing on Wednesday, Dr Teo slapped one of the patients across the face in front of family members in an attempt to rouse her after surgery.
The patient was left essentially in a vegetative state following the operation intended to extend her life expectancy by several months.
Outside the hearing, Dr Teo told media the slap was a "kinder and gentler" alternative to other more common techniques for rousing patients.
He said he didn't regret performing brain surgeries that were the focus of the inquiry because he was acting in the patients' best interests.
"I did it in their best interest, thinking it was going to help them - it didn't," he said.