A 12-year-old girl who died after being admitted to a specialist mental health unit with acute psychosis was suffering from a potentially treatable brain disorder, a pathologist has told an inquest. Professor Marta Cohen told Sheffield Coroner's Court newly reviewed blood tests confirmed Mia Lucas had autoimmune encephalitis, an inflammatory condition of the brain known to cause severe psychiatric symptoms and which can be treated.
Mia's mum broke down in tears as the findings were presented. Mia was found unresponsive in her room at the Becton Centre in Sheffield on January 29, 2024. A central focus of the inquest, which began last week, has been whether Mia was suffering from autoimmune encephalitis and whether the condition was recognised during her care.
But Prof Cohen said the new results were conclusive. She said the medical cause of Mia's death remained "compression of the neck" but she had now added that this was caused by "acute psychosis", which was caused by "autoimmune encephalitis".
An expert neurologist who told the inquest earlier on Monday that he could only say it was "possible" Mia had the disorder but not "probable", was recalled to the witness box following the new evidence to say it was now "definitive" that she had autoimmune encephalitis, and this was the cause of her psychosis.
Sheffield Coroner's Court has heard Mia ended up in the Becton Centre, which is part of Sheffield Children's Hospital, after her family took her to the emergency department of Queen's Medical Centre (QMC) in Nottingham, where she lived, on December 31 2023.
She had attempted to get knives from the kitchen and had fought her mum, who had tried to stop her.
A jury has heard how Mia was hearing voices telling her she needed to go to heaven or something would happen to her relatives, and she was hallucinating.
Mia was sectioned under the Mental Health Act at QMC and transferred to the Becton Centre on January 9 after doctors in Nottingham decided there was no underlying physical cause of her psychosis.
Earlier on Monday, consultant paediatric neurologist Mike Taylor, who conducted an independent review of the evidence for the coroner, said it was "possible" Mia had autoimmune encephalitis but could not say it was "probable".
But, after Prof Cohen revealed the new blood test evidence in court, Dr Taylor was recalled to the stand and told the jury it was now "definitive" that she had the brain condition.
Earlier the consultant said he would have wanted to go further than the MRI scan performed in Nottingham before her transfer to the Becton Centre.
He said he would have asked for a fluid test through a lumbar puncture and a brain wave scan, called an EEG.
He said it was "quite concerning" that these were not obtained at QMC but he said he understood the difficulties the doctors were facing, and that, if he asked his team in Leeds, they would be 50:50 about whether this was the right thing to do in the circumstances presented by Mia.
Dr Taylor also said the treatments for autoimmune encephalitis can have severe side effects, up to and including death.
He said that if doctors had begun treating her for autoimmune encephalitis on the basis of the evidence they had at QMC it could have "caused her significant harm".
The consultant said autoimmune encephalitis is a "complex and rare presentation which is very difficult for clinicians to pick up".
But he also said extreme psychosis is also very rare in 12-year-old children.
Dr Taylor said it was "not unreasonable" for the Nottingham team to have a low level of suspicion around autoimmune encephalitis and agreed it was very rare for people suffering from the disorder to have no physical symptoms, such as seizures or tremors.
The jury has heard how Mia's behaviour had got worse and her personality had changed in the months leading up to New Year's Eve and how she had a virus in December, which is a known cause of autoimmune encephalitis, although very rare.
Mia was admitted to the hospital due to the extreme behaviour she was exhibiting and was sectioned under the Mental Health Act on January 4 after an assessment found she was suffering an "acute psychotic episode" and was a risk to herself or others.
Mia's mum, Chloe Hayes, of Arnold, Nottingham, wiped away tears as Prof Cohen presented her new evidence, along with a number of members of her family.
Ms Hayes has described previously how her daughter was interested in singing, drawing, crafts and horse riding, and how she had ambitions to either open her own beauty salon or become a vet.