Prematurity

Question 1

What is often used as a proxy for gestational age due to the high correlation between the two and the difficulty of precisely determining gestational age.

Answer 1

Birth weight

Question 2

Prematurity and Low Birth Weight definitions

Answer 2

Question 3

Most common neurological complications of preterm birth

Answer 3

Periventricular hemorrhagic infarction (PVHI)
- infarction that is most frequently a complication of a large IVH
- results in asymmetric necrosis of the periventricular white matter

periventricular leukomalacia (PVL) - which can be considered a Hypoxic-ischemic encephalopathy (HIE)
- Focal necrotic lesions occur in the border end zones of MCA, PCA, ACA
- Increases the risk for CP, specifically spastic diplegia (stiff legs). More extensive PVL can include involvement of the upper extremities as well.

Question 4

germinal matrix

Answer 4

a highly vascularized region of the developing brain located underneath the lateral ventricles, and hemorrhage in this area (i.e., germinal matrix hemorrhage, GMH) is a devastating neurological disease in premature infants that results in substantial mortality and morbidity.

it is located in a vascular watershed zone

by 36 weeks gestational age the germinal matrix has largely disappeared reducing risk for hemorrhage in this area

Question 5

Intraventricular Hemorrhage Grade

Answer 5

Question 6

Risk Factors for Premature Birth

Answer 6

• Maternal history of previous preterm birth
• Short spacing between pregnancies
• Multiple birth pregnancy
• Younger (<16) and older (>35) maternal age
• Maternal health problems (high blood pressure, diabetes, obesity)
• Maternal alcohol, drug, or cigarette use
• Low SES

Question 7

What accounts for the vast majority of preterm/low birthweight births.

Answer 7

Multiple births (twin and triplet/+)

Question 8

The current threshold of biological viability is considered to be…?

Answer 8

• 23 weeks gestational age in high-income countries
• 34 weeks in low- and lower middle-income countries.

Question 9

When does IVH occur?

Answer 9

• 50% of all IVH occurring in the first 6 to 8 hours of life
• 95% occurring within the first 4 to 5 days.

Question 10

Complications in preterm infants

Answer 10

• hypoxic/ischemic neurological events
• Bronchopulmonary dysplasia (BPD)/chronic lung disease
• apnea of prematurity
  necrotizing enterocolitis (NEC) - condition inflames intestinal tissue, causing it to die d/t bacterial leakage into the belly or bloodstream (25% mortality rate)
• retinopathy of prematurity,
• septicemia/sepsis
• patent ductus arteriosus (PDA)
• respiratory distress syndrome (seen in infants 28 weeks or earlier, d/t lack of surfactant
• pulmonary hypertension

Question 11

Common neuropsychological sequelae among preterm children

Answer 11

• attention/EF
• processing speed
• visuospatial skills (possibly due to injury proximity to optic radiations and dorsal ventral stream)
• general memory recall
• sensorimotor (VMI, dexterity)
• behavioral concerns (hyperactivity, poor social skills)

Question 12

How is gestational age calculated?

Answer 12

typically calculated from the first day of the last menstrual period.

Question 13

Hypoxic-ischemic encephalopathy (HIE)

Answer 13

term used to describe encephalopathy caused by a reduction in cerebral oxygenation and blood flow.

the specific cause or contribution of each risk factor of preterm baby to HIE is often uncertain.

Question 14

Intrauterine growth restriction (IUGR)

Answer 14

Refers to poor growth of a fetus during pregnancy - when the developing fetus’s weight falls below the 10th %ile compared to other babies of equal gestational age

most commonly it is associated with a fetus not receiving enough oxygen and nutrition from the placenta during pregnancy

IUGR is associated with abnormal development of frontal brain regions

Question 15

Intraventricular hemorrhage (IVH)

Answer 15

Refers to increased vascular pressure and consequent vessel rupture and hemorrhage.

Earlier onset of IVH is associated with more severe grade.

90% of all IVH occur in the first four days of life

Even in infants with the lowest grades of IVH, increased incidence of learning disability is apparent.

Question 16

Imaging used in preterm infants.

Answer 16

early ultrasound is helpful in the detection of IVH and more severe white matter damage, it is limited in its ability to detect more subtle forms of white matter damage.

In contrast, MRI is more sensitive in detecting more subtle forms of white matter damage in preterm infants.

Question 17

Periventricular hemorrhagic infarction (PVHI)

Answer 17

• infarction that is most frequently a complication of a large IVH
• results in asymmetric necrosis of the periventricular white matter

Question 18

periventricular leukomalacia (PVL)

Answer 18

• can be considered a Hypoxic-ischemic encephalopathy (HIE)
• Focal necrotic lesions occur in the border end zones of MCA, PCA, ACA
• Increases the risk for CP d/t abnormal functions of the corticospinal tract

specifically spastic diplegia (stiff legs). More extensive PVL can include involvement of the upper extremities as well.

Question 19

Most common MRI findings of preterm birth:

Answer 19

periventricular hemorrhagic infarction and periventricular leukomalacia

Question 20

Neuropsychological outcomes in preterm vs IUGR

Answer 20

IUGR: lower IQ, executive functioning weaknesses, and academic problems

Preterm: visuospatial deficits and motor deficits

Question 21

What are the risk factors that contribute to functional outcomes for preterm infants?

Answer 21

gestational age, availability of NICU care, birth weight, and presence of neurological/medical complications

Question 22

Expected Neuropsychological Profile

Answer 22

Intelligence:
1. FSIQ is lower than full term peers, falls in the average range.
2. ID is more common
3. Higher rates of LD, especially in math and written task; slower academic progress.

Attention/Concentration:
1. Common including ADHD diagnosis
2. Difficulties with selective and sustained attention, shifting attention, and impulsivity.

Language:
1. crystallized verbal abilities are preserved.
2. Challenges with fluid verbal skills, including comprehension, fluency, and pragmatics.
3. naming difficulties and higher order language problems persist.

Visuospatial:
1. Common
2. dysfunction in the optic radiations and dorsal stream contribute to this.

Memory:
1. slower acquisition and retrieval of verbal and visual information.
2. delayed recall and spatial memory deficits, especially in micro premature infants are common.
3. reduced hippocampal volumes are hypothesized to underlie the memory issues.

EF:
1. deficits in WM, planning, set-shifting, inhibition, vigilance, and organization.
2. linked to abnormalities in the frontal and subcortical systems

Sensorimotor:
1. Motor and sensory deficits are common
2. subtle deficits in fine and gross motor coordination, dexterity, and visuomotor integration

Emotion/Personality
1. prone to internalizing and externalizing behaviors.
2. increased prevalence of ASD, and lower cognitive ability.

PVT/SVT:
1. SVT recommended due to suboptimal effort.

Question 23

Apnea of prematurity (AOP)

Answer 23

Refers to unexplained cessation of breathing and is associated with bradycardia, cyanosis, pallor, and/or hypotonia. AOP tends to be caused by an immature respiratory control system and is associated with decreased arterial oxygen saturation. It typically does not persist beyond 40 weeks postconceptual age. Research on AOP and functional outcome is variable, with some research indicating poorer cognitive and academic outcomes and other research reporting no differences in outcome. Apnea of prematurity is treated both inpatient and outpatient using a variety of techniques including medication, continuous positive airway pressure (CPAP), and mechanical ventilation.

Question 24

Bronchopulmonary dysplasia (BPD)

Answer 24

Also known as chronic lung disease. Refers to long-term respiratory problems. Bronchopulmonary dysplasia is caused by lung damage that occurs as a result of requiring mechanical ventilator support (i.e., breathing machine) or receiving high levels of oxygen for long periods shortly after birth. Although the use of a ventilator or high oxygen levels may be necessary to facilitate breathing and survival in a neonate, these interventions may damage the fragile lung tissue through inflammation and irritation. Treatment of BPD often includes continued use of a mechanical ventilator and supplemental oxygen in which pressure and oxygen levels are decreased over time. Bronchopulmonary dysplasia is most common in premature infants. Given that extra calories are needed due to effortful breathing, infants with BPD are typically fed using nasogastric tubes. Both oxygen treatment and tube feedings may continue for several months and may cause long-term lung damage. Diffuse neurocognitive impairments are associated with severe BPD.

Question 25

Necrotizing enterocolitis

Answer 25

The death of intestinal tissue that occurs when the lining of the intestinal wall dies and tissue falls off. Necrotizing enterocolitis most often occurs in preterm or sick infants, and the cause is currently unknown. Prognosis for infants with necrotizing enterocolitis is poor, with death occurring in approximately 25% of cases.

Question 26

Neonatal respiratory distress syndrome (RDS)

Answer 26

A condition characterized by difficulty breathing that occurs almost exclusively in premature infants whose lungs are not yet fully developed.

Respiratory distress syndrome is primarily caused by the lack of surfactant in the infant’s lungs.

Most cases of RDS are seen in infants born before 28 weeks gestational age.

Mortality rates associated with RDS have decreased considerably since the introduction and use of artificial surfactant and prenatal glucocorticoids that help to speed lung development.

Question 27

Neonatal septicemia

Answer 27

Also known as sepsis.

Refers to a severe infection in the blood that spreads throughout the body.

In premature infants, sepsis is believed to be caused by pregnancy complications that increase the likelihood of infection (e.g., premature rupture of the membranes, difficult delivery, infection in uterus or placenta, fever in mother) but can also be contracted in the NICU due to the neonate’s vulnerability to infection.

Question 28

Patent ductus arteriosus (PDA)

Answer 28

A heart condition in which the ductus arteriosus of the heart does not close, resulting in abnormal blood flow between the aorta and the pulmonary arteries, which are connected to the heart. Patent ductus arteriosus can be associated with other morbidities common to preterm infants (e.g., IVH, BPD, NEC, feeding intolerance,
etc.). Patent ductus arteriosus occurs more commonly in preterm infants (approximately 8/1,000 premature births) and in those infants with RDS.

Question 29

Retinopathy of prematurity (ROP)

Answer 29

Occurs when blood vessels in the retina of the eye develop abnormally. Premature birth can disrupt eye development and may cause the blood vessels to stop growing or to grow abnormally. Also the use of excessive oxygen after birth can result in oxygen toxicity and lead to abnormal growth of the blood vessels. Those babies who are the smallest and most premature are at greatest risk for developing ROP. Most infants who develop ROP have stage 1 or 2 and recover with minimal to no long-term visual problems. Stages 3+ may result in significant vision problems or blindness. In a small number of preterm babies, ROP worsens over time, sometimes very rapidly, and can lead to significant vision problems, including blindness. Early intervention is critical in the treatment of ROP.

Question 30

Surfactant

Answer 30

A naturally occurring substance that helps the lungs to inflate and prevents the alveoli (air sacs) from collapsing. Surfactant is produced by fetuses between 24 and 28 weeks gestational age. By approximately 35 weeks gestational age, there is enough surfactant to prevent the alveoli from collapsing. If there is a high risk that a baby will be born prematurely, the mother is given prenatal corticosteroids (i.e., glucocorticoids) to hasten lung development and surfactant production in the fetus. This helps reduce the need of surfactant replacement therapy in the newborn. If, however, there was not time for a course of prenatal corticosteroids or the infant is born with low blood oxygen levels and respiratory distress, postnatal delivery of artificial surfactant is required. Both treatments attempt to ameliorate or prevent RDS and increase the likelihood of survival.

Question 31

Where is Germinal matrix IVH most common?

Answer 31

it is located in a vascular watershed zone and has largely disappeared by 36 weeks gestation

Germinal matrix IVH is the most common type of neonatal hemorrhage and is vulnerable to hypoxic ischemic injury. However, by 36 weeks gestational age the germinal matrix has largely disappeared reducing risk for hemorrhage in this area.