PC Leo Clarke (24) was on his way to an emergency call in Peterborough when he responded to reports from a man saying he was unable to control his adult son who had mental health issues.
He arrived at the incident as the lone officer and found the man and his son outside the house.
The 27-year-old man was in an agitated state and started shouting at the officer before attacking him.
A witness described how PC Clarke suffered several blows to the head before his attacker went back inside.
The assailant was arrested at the scene when other officers arrived and warned him they would use a taser unless he surrendered.
PC Clarke, who had been a police officer for just 18 months at the time of the attack, then left the address and returned to Thorpe Wood Police Station but started to feel unwell.
A welfare check by a supervisor revealed he was squinting and had started to slur his words. He was taken to Peterborough City Hospital where his condition continued to deteriorate and doctors discovered he had a bleed on the brain.
Emergency surgery was performed to stop the bleed and PC Clarke remained in hospital for five days.
The surgery has left him with scarring across his head and his eyesight has yet to fully return to normal. He is still off work and will need a significant recovery time.
His attacker admitted causing grievous bodily harm without intent and was sentenced to one-year and eight months when he appeared at Peterborough Crown Court.
Leo has been put forward for the national Police Bravery Awards by Cambridgeshire Police Federation and will attend the awards ceremony in London on Wednesday (December 8).
Cambridgeshire Police Federation Chair Liz Groom said: “We all wish Leo a speedy and full recovery from his injuries. He showed incredible courage throughout this terrifying incident which highlights how our members put themselves at risk of harm every time they report for duty.”