Since leukaemia can cause facial nerve palsy, a complete blood count (CBC) with differential might be worth the effort in children presenting with acute peripheral facial palsy, Victorian clinicians have suggested.
In the course of recruiting for an RCT of prednisolone in paediatric Bell’s palsy, researchers at the Royal Children’s Hospital, Melbourne identified five children with previously undiagnosed leukaemia from 644 presentations.
Four of the five children, all aged between five and nine years, were diagnosed with ALL and the fifth child with AML, according to the researchers led by Professor Franz Babl is the Group Leader of Emergency Research at the Murdoch Children’s Research Institute.
“We estimate the rate of leukaemia in children with acute-onset facial palsy who present to emergency departments to be 0.6% (95% confidence interval 0.2% to 1.6%),” they wrote in the Annals of Emergency Medicine.
“In accordance with these cases, we suggest consideration of a screening CBC count for acute-onset peripheral facial palsy presentations in children before initiation of corticosteroid treatment.”
The investigators, from the Paediatric Research in Emergency Departments International Collaborative (PREDICT) emergency research network, said they have changed their study protocol to mandate a CBC and differential as part of the screening process.
They noted that the use of corticosteroids in children with occult leukaemia may be problematic.
“It may delay the diagnosis of leukaemia by improving the initial symptoms of peripheral facial palsy, which likely happened in case 3,” they said.
“Acutely, the main concern is the precipitation of tumour lysis syndrome, a condition caused by the breakdown of malignant cells, which can lead to extensive metabolic derangement, potentially resulting in acute renal failure, cardiac arrhythmias, seizures, and death.”
“Presumably, this was the cause of the acute renal failure in case 2 after corticosteroid treatment, but was not appreciated at the time because the corticosteroids had cleared the circulating lymphoblasts.”
The investigators said 161 patients would need to be screened with a CBC count to identify one case of leukaemia – assuming all new leukaemia cases could be detected with a CBC count.
Previous research from the group has shown a CBC is typically only ordered in 16% of paediatric Bell’s palsy presentations. Two thirds (67.5%) of the children were treated with steroids.