Hayden Panettiere was struggling with “pain” before her death, according to her mother Lesley Vogel.

The Heroes star — who died on August 16 aged just 36 — was estranged from Vogel but they are said to have spent some time together in Los Angeles last year.

Vogel claims her daughter was battling a mysterious condition that left her in agony.

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“She was in pain. She was afraid. She couldn’t physically function properly,” Vogel told the The New York Times.

Vogel said Panettiere had “pins in needles” in her lower extremities that made it difficult for her to walk and she went to a number of doctors and tried massage and acupuncture treatments in a bid to ease her suffering.

She also claimed the actor wondered whether the mysterious condition was linked to injuries she suffered while working in Hollywood as a child.

Hayden Panettiere ‘couldn't physically function properly’ before her death, her mother Lesley Vogel says. Credit: AAP

The Nashville actor — who was mother to 11-year-old daughter Kaya with former partner Wladimir Klitschko — died at an apartment in South Carolina.

Her cause of death has yet to be confirmed and an investigation remains ongoing.

A statement from Greenville County Coroner’s Office read: “An autopsy was completed today. At autopsy no signs of trauma were discovered that would have contributed to the death.

“The cause and manner of death remain pending further investigation and the completion of additional studies. This investigation remains active and ongoing.

“No further details are available for release at this time.”