Photos of Seini in hospital have also been shown to the court. One shows the swollen face of the 2-year-old with tubes in her mouth. Bruising around her eyes is also visible.
Without surgery, Seini would have died in minutes. Dr Law said a portion of Seini's skull was removed in order to drain the blood from under her skull and relieve the pressure on her brain.
But despite the surgery, Seini was unwell. Part of her brain was swelling and had "projected like a mushroom" out the side of her skull.
Dr Law described the damage as "enormous". He said doctors later decided to withdraw all therapy and stop artificial respiration. They made Seini as comfortable as possible.
Dr Law said scans of the injury to the "personality" part of her brain showed it was extremely unlikely she would have any quality of life. But Seini fought back, and when the doctor saw her she appeared brighter and aware of surroundings.
"She was awake, she moved her right arm, right leg and reached up for a toy I had brought into her room ... And she laughed."
Doctors decided to treat Seini again. They gave her antibiotics and cleaned the wound in her head.
However, Seini's awareness deteriorated and her brain began to develop abscesses.
More than eight months after the incident, Seini died in the Starship from pneumonia.
Dr Law said her death was caused by a chest infection that was a result of her injured brain not being able to protect her airway.
In his opening address on Wednesday, Crown prosecutor Phil Hamlin said Ikamanu changed his story when speaking to authorities in the days after Seini's admission to hospital.
Mr Hamlin said Ikamanu told one police officer that Seini and her brother had been playing outside when Seini fell down the steps. "And - to use my words - out of the blue, Seini began to have seizures."
Ikamanu later told another officer a different story.
"He told the police officer that he threw the child against a wall in the lounge room of the house."
A short time later he told the officer that he had been holding the girl's hand and they had both let go and she had fallen against the wall.
Ikamanu's lawyer, Simon Lance, said much of Mr Hamlin's opening address was "Crown theory" and not evidence. He said an example was evidence about bruising on Seini's chest.
"What we know is that Mr Ikamanu attempted CPR. Doctors will say the bruising on the chest is consistent with someone attempting CPR."
He said Ikamanu was there on the night - not Mr Hamlin. "Not all deaths are a murder, and this is one of the cases where it is not."
APNZ
