CINCINNATI – Cerebral palsy affects about 3 in every 1,000 children, but there is usually little sign of the condition at birth. Instead, it usually shows clinical manifestation between ages 2 and 5, and a diagnosis can trigger early interventions that can improve long-term outcomes.
Physicians and patients would benefit from a screening method for cerebral palsy at birth, but that has so far eluded researchers.
At the 2022 annual meeting of the Child Neurology Society, researchers presented evidence that , with higher variability associated with increased cerebral palsy risk.
The study results were promising, according to Marc Patterson, MD, who comoderated the session. “It gives us more confidence in predicting the children at risk and making sure that they’re going to be followed closely to get the interventions they need to help them,” said Dr. Patterson, who is a professor of neurology, pediatrics, and medical genetics at Mayo Medical School in Rochester, Minn.
“By the time a child is 5 or 6, the symptoms are usually very obvious, but you really want to intervene as soon as possible before their brain’s plasticity decreases over time, so the earlier you can intervene in general, the better your results are going to be,” said Dr. Patterson.
There are tools available to diagnose cerebral palsy at an earlier age, including the Prechtl General Movements Assessment (GMA), which can be done up to 5 months of corrected age. It has 97% sensitivity and 89% specificity for cerebral palsy. The Hammersmith Infant Neurological Examination (HINE), which can be used in the same age range, and has 72-91% sensitivity and 100% specificity.
Both of the available tools are resource intensive and require trained clinicians, and may be unavailable in many areas. Despite these tools, early diagnosis of cerebral palsy is still underemployed, according to Arohi Saxena, a third-year medical student at Washington University in St. Louis, who presented the study results.
Respiratory rate variability may indicate increased risk
The researchers set out to identify objective metrics that correlated with HINE and GMA scores. They looked at kinematic data from practical assessments carried out by their physical therapists, as well as vital sign instability obtained at NICU discharge, which was based on suggestions that hemodynamic instability may be linked to later risk of cerebral palsy, according to Ms. Saxena.
They analyzed data from 31 infants with a corrected age of 8-25 weeks at a tertiary NICU follow-up clinic. Of these, 18 displayed fidgety movements on their Prechtl assessment, and 13 did not.
They used DeepLabCut software to analyze data from videos of the Prechtl assessment, with a focus on range and variance of hand and foot movements normalized to nose-to-umbilicus distance. They also analyzed pulse and respiratory data from the final 24 hours before NICU discharge.
They found that infants without fidgety movements had decreased hand and foot movement ranges (P = .04). There was no significant difference between the two groups with respect to pulse measurements. However, the respiratory rate range and variance was significantly higher in infants without fidgety movements. “Infants who are at higher risk for developing cerebral palsy had more respiratory instability early on in life,” said Ms. Saxena during her talk.
When they compared values to HINE scores, they found a correlation with less foot movement and a predisposition to develop cerebral palsy, but no correlation with hand movement. A lower HINE sore also correlated to larger respiratory rate range and variance (P < .01 for both).
“Our hypothesis to explain this link is that respiratory rate variability is likely driven by neonatal injury in the brainstem, where the respiratory centers are located. In some infants, this may correlate with more extensive cerebral injury that could predict the development of cerebral palsy,” said Ms. Saxena.
The group plans to increase its sample size as well as to conduct long-term follow-up on the infants to see how many receive formal diagnoses of cerebral palsy.
After her talk, asked by a moderator why motor assessments were not a reliable predictor in their study, Ms. Saxena pointed to the inexperience of assessors at the institution, where Prechtl testing had only recently begun.
“I think a lot of it is to do with the more subjective nature of the motor assessment. We definitely saw kind of a trend where in the earlier data that was collected, right when our institutions started doing these Prechtls, it was even less of a reliable effect. So I think possibly as clinicians continue to get more familiar with this assessment and there’s more like a validated and robust scoring system, maybe we’ll see a stronger correlation,” she said.
Ms. Saxena had no relevant disclosures. Coauthor Boomah Aravamuthan, MD, DPhil, is a consultant for Neurocrine Biosciences and has received royalties from UpToDate and funding from the National Institute of Neurological Disorders and Stroke.