This variability is important. And along with a list of possible behaviors that might suggest pain, alternative pain scales are all, in some way, individualized. Because these pain scales treat cerebral palsy and autism under the same umbrella, Voepel-Lewis says, they rely heavily on parents and caregivers to tell doctors which behaviors to look for in their child. “We could create a little list of behaviors that may relate to pain or may typically relate to pain,” she said. “But when you start looking at a kid with cerebral palsy or autism, they may have behaviors that are so unique to them that we would not know that, as a caregiver that just interacts with them maybe only once.”

Rosa, for example, knows what to look for in Leo. “We've learned that it's better to pay attention to his behavior, because if he is in pain, his behavior will change,” she said. “If he's really in pain, he will cry. This is far from perfect, but until we get a communication system in place (and not that that's a guarantee anyhow), it's what we've got.”

Knowing how a particular child reacts to pain is key to the success of all of these alternative pain scales. “If we’re going to assess pain, we need input from those who know these children,” Voepel-Lewis said. But how does a nurse pick which scale to use?

Crosta is one of many researchers who has tried to compare the effectiveness of the pain measures out there. She published a review study that looked at four different choices. But even these review comparisons don’t agree. Crosta and Voepel-Lewis conducted independent comparisons. They both came to the conclusion that the revised Face, Leg, Activity, Cry, and Consolability (rFLACC) scale was the best. This version has nurses run through a checklist of the five categories listed in the scale's name, looking for things like how consolable the patient is, how much they're kicking their legs, and how much they're crying.

But another review paper, by Giovanna Ferrara, looked at a similar set of scales and picked the Non-Communicating Child's Pain Checklist-Postoperative Version, one that has more categories and questions. "In my opinion the NCCPC-PV allows us to capture the slightest change in the state of the patient and therefore a better rating of pain, as it contains more items," Ferrara said. She worried that the rFLACC scale might miss something in its simplicity.

No matter what scale you pick, lumping together all patients who have trouble picking a number from one to 10 to express pain means simplifying the needs of each patient. There are more basic problems too. Doctors are trained to think about pain on a 0-10 scale, for better or worse. Several of these alternate pain scales work on a totally different numerical system. One is out of 81, another is out of 54.

And some scales require more input than others. The Pediatric Pain Profile (PPP), for example, is predominantly made up of an extensive, parent-generated history, in which caregivers describe what the child is like “at their best” and “at their worst.” This works really well if the parents continually update the document, and put the work in. But if a child is coming into the emergency room, if the parent isn’t present, or the caregiver simply doesn’t yet know what behaviors to look for, it might not be the best choice. Crosta says that the PPP might be a great document for parents with autism to start working on before any kind of medical need arises (the form is free and available online), but it might not be the one nurses turn to at the hospital.