Timothy Steel, a senior brain and spine surgeon at St Vincent's Hospital, was accused of kicking and punching Emma Steel during a scuffle over her mobile phone in their home in December 2019.

Each alleged the other had launched an attack first.

Magistrate Vivien Swain said elements of Ms Steel's evidence were at odds with what she'd told the triple-zero operator and the evidence of other witnesses.

"Often in the stress of making a triple-zero call, such inconsistencies would not be significant," Ms Swain said on Thursday.

"However, with other inconsistencies, it takes on significance in these proceedings."

During the three-day hearing in Downing Centre Local Court, one witness admitted under cross-examination they'd discussed the alleged incident with Ms Steel before giving evidence.

But Ms Steel denied doing so, Ms Swain said.

The location of the alleged assault - in the Steels' bedroom or another room of their Bellevue Hill home - also differed between prosecution witnesses.

Conversely, the surgeon gave a consistent account to police at the scene, in a recorded police interview and in this week's hearing, the magistrate said.

Dr Steel, 56, had pleaded not guilty to common assault, assault occasioning actual bodily harm and destroying Ms Steel's phone.

Ms Swain was satisfied Dr Steel believed his conduct was necessary to defend himself and there was a reasonable possibility he had a lawful excuse.

She took the neurosurgeon's character into account - including a witness's opinion that it was unlikely he had a tendency towards violence.

But she said his job was irrelevant and she gave no regard to it.

"I've applied the law to the facts as presented in the prosecution and defence case," Ms Swain said.

Ms Steel also alleged she suffered financial abuse by having part of her $20,000 monthly allowance withheld, but the magistrate she wasn't satisfied on balance that was so.

Both Steels cast themselves as the victim of previous domestic violence assaults committed by the other.

"It seems there were but as to who was the perpetrator and who was the victim, it is unclear and I cannot make that determination," Ms Swain said.

Dr Steel described himself as one of Sydney's leading neurosurgeon and spine surgeons with more than 21 years of experience.

He's performed more than 2000 brain surgery procedures, 8000 minimally invasive spine procedures and more than 2000 complex spine procedures such as disc replacement and fusion surgeries, his website states.

Australian Associated Press