Researchers have developed a new, more accurate way to identify when infants are in pain – welcome news to parents whose pre-verbal children must undergo surgery and other invasive procedures.

“As babies cannot talk it is difficult to know whether pain relief is working,” said Caroline Hartley, PhD, of Oxford University’s Department of Paediatrics, Medical Science Division, and lead author of the study published in the journal Science Translational Medicine. “Also, as babies are still developing, we cannot assume that drugs will work in the same way that they do in adults.”

Until now, doctors have had to take cues from cries and facial expressions, like grimaces, to diagnose pain in infants, and to infer that if medicinal pain relief eases these signs, it must also ease the underlying pain. Instead, the research team used brain scan technology called an EEG (or, electroencephalogram) to compare babies’ brain activity at rest, in response to a mildly painful heel-prick blood test, and in response to painless stimuli (a touch, flashing light, or sound). By comparing the results, the team was able to paint a picture of what a baby’s brain does when it’s in pain. They then compared this template to EEGs of infants who received an anaesthetic cream before the heel-prick; sure enough, their brain activity was different, suggesting the anaesthetic had been effective in preventing or reducing the babies’ pain.

Hartley says it’s unlikely parents will walk into a doctor’s office with their crying baby for an pain-reading brain scan any time soon (although she calls that possibility a “useful extension” of her team’s research). But that doesn’t mean individual babies won’t benefit at all.

“Overall, we hope that this measure of pain-related brain activity will be used by other research groups, as well as ourselves, to better understand the development of pain in infancy, and to test pain-relieving drugs so that better treatment options can be provided in the future for infants in hospital,” she said.