A man who failed to seek medical help for his mother who lay dying after falling out of bed in their caravan has been jailed.

Wilhelmina Pierce died in March 2011 after spending four days on the floor of the cluttered caravan in the West Australian city of Geraldton.

Her son Corey, 26, was today sentenced to 15 months in prison after being found guilty of manslaughter last month.

During his first trial, the court heard he had tried to lift his mother off the floor but could not move her because of the clutter.

Prosecutors said while he did not intend to kill his mother, his failure to seek proper medical attention hastened her death.

The court heard Mrs Pierce was a stubborn woman who had discharged herself from hospital against medical advice a month before her death.

The jury in the first trial was unable to reach a verdict in the case.

However, Pierce stood trial in the Perth District Court for a second time and was convicted of manslaughter.

Sentencing him, District Court judge Michael Bowden said it was a unique case.

"I accept you both loved your mother and had cared for her for a long time," Judge Bowden said.

"I also accept that your mother held idiosyncratic views of hospitals, views that aren't reflected by the wider community and that your mother's lack of faith in medical services largely influenced your own thoughts."

The judge commented that Pierce was an intelligent and articulate young man.

Socially isolated spending time as carer

A psychological report completed before sentencing found Pierce had become socially isolated after spending most of his time caring for his mother.

Looking through the door of the crowded caravan in Geraldton. ( Supplied: WA Police )

According to the court-appointed psychologist, Pierce had led a sheltered life and his mother was described as a dictator and controller while her son was passive and compliant.

However, the judge said: "It must be said you were aware she needed treatment and you were aware that she would die if she didn't receive it."

While Judge Bowden said there was a low risk of Pierce reoffending, a period of immediate imprisonment was the only appropriate sentence.

"The sanctity of human life must be recognised by the court and the community," he said.

"Your mother was totally dependent on you during the period leading up to her death.

"A clear message must be sent to carers who fail to provide the necessities of life, there will be severe consequences."

Pierce will be eligible for parole after serving half his sentence.