Brain abnormalities seen in late pre-term infants

A study looked into MRI scans of late pre-term infant and found that they have brain abnormalities.

Babies born 32 to 36 weeks into gestation may have smaller brains and other brain abnormalities that could lead to long-term developmental problems, according to a new study published online in the journal Radiology.

Much of the existing knowledge on preterm birth and brain development has been drawn from studies of individuals born very preterm, or less than 32 weeks into gestation at birth.

For the new study, researchers in Australia focused on moderate and late preterm (MLPT) babies -- those born between 32 weeks, zero days, and 36 weeks, six days, into gestation. MLPT babies account for approximately 80 percent of all preterm births and are responsible for much of the rise in the rates of preterm birth over the last 20 years. Despite this, to date there have been no large-scale studies published on brain alterations associated with MLPT birth that may provide insight into brain-behavior relationships in this group of children.

"In those very preterm babies, brain injury from bleeding into the brain or a lack of blood flow, oxygen or nutrition to the brain may explain some of the abnormal brain development that occurs," said the study's lead author, Jennifer M. Walsh,M.B.B.Ch., B.A.O., M.R.C.P.I., from the Royal Women's Hospital in Melbourne, Australia. "However, in some preterm babies, there may be no obvious explanation for why their brain development appears slow compared with babies born on time."

To learn more, the researchers performed magnetic resonance imaging (MRI) exams on 199 MLPT and 50 term-born infants (greater than 37 weeks gestation) between 38 to 44 weeks of gestation. They looked for signs of brain injury and compared the size and maturation of multiple brain structures in the two groups.

While injury rates were similar between the two groups, MLPT birth was associated with smaller brain size at term-equivalent age. In addition, MLPT infants had less developed myelination in one part of the brain and more immature gyral folding compared with term-born controls. Myelination -- the formation of a fatty insulating sheath around some nerve fibers -- and gyral folding -- the folding of the cerebral cortex to increase the brain's surface area -- are important processes in early brain development.

The findings suggest that MLPT birth may disrupt the expected trajectory of brain growth that would normally occur in the last two or so months in utero, according to Dr. Walsh.

"Given that brain growth is very rapid in the last one-third of pregnancy, it is perhaps not surprising that being born during this potentially vulnerable period may disrupt brain development," she said. "Brain growth is very complex, involving not only the neurons with which we think and do things, but also the other brain cells that support the neurons and are vital for normal brain function."

The researchers are hoping to learn in greater depth the impact that moderate to late preterm birth has on the brain, so that they can then begin to try different treatments designed to improve brain function and long-term outcome in these infants.

"Medications, along with early intervention to help parents understand their baby's needs, have been effective in helping very preterm babies catch up to their term-born peers," Dr. Walsh said. "However, whether any of the existing treatments will help babies born between 32 and 36 weeks is unknown, as they have not been studied very much at all."

The researchers plan to follow the infants in the study group through childhood to learn more about the relationship between brain abnormalities and later outcomes. They also are assessing additional MRI information about brain structure and function in these children.

"Understanding what problems they have and what might be causing them is the first step in trying to improve their long-term outcome," Dr. Walsh said.

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Study: Brain Abnormalities in Migraine Patients

Brain abnormalities are present in people who have migraines. Some are present at birth while others progress over time.

A new study suggests that migraines are related to brain abnormalities present at birth and others that develop over time.

The research is published online in the journal Radiology.

Migraines are intense, throbbing headaches, sometimes accompanied by nausea, vomiting and sensitivity to light. Some patients experience auras, a change in visual or sensory function that precedes or occurs during the migraine. More than 300 million people suffer from migraines worldwide, according to the World Health Organization.

Previous research on migraine patients has shown atrophy of cortical regions in the brain related to pain processing, possibly due to chronic stimulation of those areas. Cortical refers to the cortex, or outer layer of the brain.

Much of that research has relied on voxel-based morphometry, which provides estimates of the brain's cortical volume. In the new study, Italian researchers used a different approach: a surface-based MRI method to measure cortical thickness.

"For the first time, we assessed cortical thickness and surface area abnormalities in patients with migraine, which are two components of cortical volume that provide different and complementary pieces of information," said Massimo Filippi, M.D., director of the Neuroimaging Research Unit at the University Ospedale San Raffaele and professor of neurology at the University Vita-Salute's San Raffaele Scientific Institute in Milan. "Indeed, cortical surface area increases dramatically during late fetal development as a consequence of cortical folding, while cortical thickness changes dynamically throughout the entire life span as a consequence of development and disease."

Dr. Filippi and colleagues used magnetic resonance imaging (MRI) to acquire T2-weighted and 3-D T1-weighted brain images from 63 migraine patients and 18 healthy controls. Using special software and statistical analysis, they estimated cortical thickness and surface area and correlated it with the patients' clinical and radiologic characteristics.

Compared to controls, migraine patients showed reduced cortical thickness and surface area in regions related to pain processing. There was only minimal anatomical overlap of cortical thickness and cortical surface area abnormalities, with cortical surface area abnormalities being more pronounced and distributed than cortical thickness abnormalities. The presence of aura and white matter hyperintensities -- areas of high intensity on MRI that appear to be more common in people with migraine -- was related to the regional distribution of cortical thickness and surface area abnormalities, but not to disease duration and attack frequency.

"The most important finding of our study was that cortical abnormalities that occur in patients with migraine are a result of the balance between an intrinsic predisposition, as suggested by cortical surface area modification, and disease-related processes, as indicated by cortical thickness abnormalities," Dr. Filippi said. "Accurate measurements of cortical abnormalities could help characterize migraine patients better and improve understanding of the pathophysiological processes underlying the condition."

Additional research is needed to fully understand the meaning of cortical abnormalities in the pain processing areas of migraine patients, according to Dr. Filippi.

"Whether the abnormalities are a consequence of the repetition of migraine attacks or represent an anatomical signature that predisposes to the development of the disease is still debated," he said. "In my opinion, they might contribute to make migraine patients more susceptible to pain and to an abnormal processing of painful conditions and stimuli."

The researchers are conducting a longitudinal study of the patient group to see if their cortical abnormalities are stable or tend to worsen over the course of the disease. They are also studying the effects of treatments on the observed modifications of cortical folding and looking at pediatric patients with migraine to assess whether the abnormalities represent a biomarker of the disease.

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