An inquest was told that doctors thought Zoe Adams, 28, had a 'relatively minor' infection but it was in fact an abscess that was virtually undetectable.
However, the coroner said doctors could not have done any more to save the mother-of-three.
Surgeon Andrew Camilleri, who carried out an investigation for the hospital into Zoe's death, said there was a one-in-4,000 chance of an ear infection leading to a brain abscess.
The court heard from two doctors who saw Zoe in the weeks before her death and two nurses who had taken calls from her.
They said her symptoms were consistent with nothing more than an ear infection.
But Zoe had developed a middle ear infection which had led to a 4cm abscess developing on the left side of her brain.
Even after Zoe, from Rusholme, Manchester, was admitted to Wythenshawe hospital on March 20 last year, she did not display signs of illness that could have prompted doctors to order a brain scan.
Dr Praful Patel, Zoe's GP, said that on February 12 last year, he diagnosed an outer ear infection, and prescribed pain-killers and antibiotics.
Coroner Nigel Meadows said this diagnosis of a 'relatively minor' infection was 'completely appropriate'.
Concluding that Zoe had died from natural causes, Mr Meadows said that she had died from a cerebral abscess caused by a middle ear infection.
He said: "Zoe has just been extremely unlucky to contract this infection and to have a robust constitution [that meant doctors could not tell she had an abscess]."
Speaking after the inquest in Manchester, Zoe's mum, Michelle Holt, said she accepted the verdict, adding: "It's been a very, very hard time. My daughter was like me and had a very strong pain threshold."