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Opioid sedatives linked to brain changes in NICU babies

Exposure to high levels of opioids in anesthesia may have lasting effects on the brains of critically ill infants, a new study found.

Relatively long term or repeated exposure has been linked to abnormalities in their brain developments. 

Researchers from Boston’s Children’s Hospital examined MRI scans of the brains of children who had undergone one or more critical surgeries before their first birthdays.

The study revealed that those underwent surgery had abnormalities in the structures of their brains that could indicate eventual developmental impairments. 

Babies that have to have life-saving surgeries are exposed to higher levels of opioids while under anesthesia. A new study linked infants who had been through these surgeries to brain development issues, including two associated with autism

This research did not attempt to define the cause of these anomalies, but found that greater irregularities in the brains of babies that had been exposed to more anesthesia.

General anesthesia is considered safe for infants, though the FDA has warned previously that prolonged or frequent exposure to its sedative effects may be linked to brain development issues.

The FDA’s warning was based primarily on animal studies. Though this research used scans of human brains, study author Dusica Bajic, a doctoral candidate at Harvard cautions that her study did not analyze other factors that commonly coincide with neonatal surgeries.

‘Other studies should be done to see if antibiotic use, absence of normal environmental stimuli during sedation, absence of normal feeding etc…can play a role instead,’ she says.

The changes the researchers saw to gray and white matter in these babies’ brains, however, could have important effects on development.

Previous research has found that the growth of concentrations of gray and white brain matter in the cerebellum and hippocampus predicts how quickly and well a child’s language skills will develop.

The infants that had had surgeries involving prolonged or repeated sedation tended to have more fluid than other babies on their brains, putting them at greater risk for a variety of cognitive and sensory problems. 

The brain’s system of ventricles and cerebrospinal fluid feed the mind’s neurons critical nutrients, but excess fluid can build up too much pressure in the brain, a condition called hydrocephalus.

Exposure to anesthesia – which commonly uses morphine and midazolam (a kind of benzodiazepine) – was also linked to smaller brain volumes. Taken together with hydrocephalus, smaller brain volume can be predictive of autism, according to the study. 

The researchers said the study’s outcome was a ‘surprise.’

‘The constellation of MRI irregularities suggests prolonged sedation may potentially contribute to delayed brain growth,’ says Bajic. 

The study comes as the US battles an opioid epidemic and struggles to determine how to treat and who to hold accountable for the birth of babies born with neonatal abstinence syndrome (NAS) due to opioid exposure in the womb.  

But the infants studied by Bajic and her team were not born to mothers addicted to drugs. These babies were exposed to opioids by their doctors, in controlled settings necessary to save their lives or treat medical problems they were born with. 

Babies born with NAS, however, are also at greater risk of seizures and neurological issues, lower birth rates and conditions that could land them in the NICU for observation and even surgery. 

The sorts of surgeries that involve the duration of anesthesia studied by Bajic’s team are crucial the the survival of the children involved in the first place.  

‘We do not want to raise unnecessary concern with parents at this early stage of research – specially since these babies undergo life saving surgeries,’ says Bajic.