medwireNews: Predicting adverse motor and cognitive outcomes in preterm neonates with white matter injury (WMI) requires the mapping of both lesion volume and location, suggests a magnetic resonance imaging (MRI) study.
While greater WMI volume predicted poor motor outcomes, only frontal WMI volume predicted adverse cognitive development, Steven Miller (The Hospital for Sick Children Research Institute, Toronto, Ontario, Canada) and colleagues note.
“Outcome-based maps and [odds ratio] maps indicate that lesion location in the frontal lobes is key to predicting adverse cognitive and motor outcomes,” they write in Neurology.
“These findings should assist in counseling of families, including providing reassurance after the diagnosis of posteriorly located WMI, and will improve our ability to identify neonates for early developmental interventions or emerging strategies to promote brain repair.”
The team used MRI to quantify and locate WMI volume at an average of 32 weeks after gestation in 58 babies whose motor and cognitive abilities were assessed at 18 months’ corrected age. They then developed probability maps to ascertain the likelihood of a lesion predicting outcome at this age.
The researchers found that WMI occurred in a characteristic pattern. Most lesions were located in the periventricular central region, followed by posterior and frontal regions.
WMI volume, irrespective of location, was significantly greater in neonates who developed adverse motor outcomes, defined as a Bayley outcome score below 85 points, after taking into account gestational age, gender, age at scan, and total brain volume. But this distinction was not evident between infants who did and did not develop cognitive problems.
Adverse cognitive outcomes were associated with greater WMI volume in frontal lobes only, which the team points out was not the brain region with the highest WMI occurrence rate.
“WMI may have affected the underlying connectivity of the striatum and frontal lobes, perhaps underlying the delays in cognitive and motor functions that are primarily subserved by these regions,” they suggest.
The importance of lesion location was borne out on voxelwise odds ratio maps, showing that frontal lobe WMI predicted adverse motor and cognitive development with maximum odds ratios of 63.8 and 78.9, respectively.
In a related editorial, Gregory Lodygensky (University of Montréal, Quebec, Canada) and Deanne Thompson (University of Melbourne, Victoria, Australia) highlight the “noteworthy finding” that focal WMI is best seen on early MRIs, as confirmed in this study.
“Indeed, the loss of substance with ventricular dilation or tissue reorganization during the last trimester may obscure the identification of these focal injuries on term-equivalent MRI,” they explain.
The editors say that the study “is an important, highly relevant, and innovative first step toward providing tangible quantitative evidence for the probability of a patient with WMI developing later dysfunction so that they can be streamlined into early intervention.”
And add: “This is important as we move toward targeted neuroprotective therapy in preterm infants at risk of poor long-term outcome.”
By Lucy Piper
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