0:00

Okay, so let's start with the basic principles.

0:03

So from an epidemiological standpoint, uh,

0:06

in the United States and developed countries, about 10% of,

0:10

um, babies are born preterm.

0:12

Now they're varying levels of prematurity, uh,

0:15

but approximately one in 10, uh, babies.

0:18

And then one in three out

0:20

of every thousand live births suffers from

0:22

hypoxic ischemic injury.

0:23

So this could be difficult delivery,

0:25

placental abruption, uh, and so forth.

0:28

And, uh, in undeveloped countries, the incidence is,

0:31

is higher, it's around 11% preterm and up to 30, uh,

0:35

or more per thousand live births.

0:39

So these conditions have a high morbidity in

0:42

mortality, uh, for a couple reasons.

0:43

Uh, the primary insult essentially hits

0:47

what we call the selectively vulnerable structure.

0:49

So essentially in these early, uh, phases

0:52

of neonatal development,

0:54

there are certain immature structures

0:56

or maturing structures that are developing.

0:58

And so if you have a hypoxic and

1:01

or ischemic insult, those will be selectively hit, right?

1:04

So you'll see these imaging patterns that are unique

1:07

to the neonate and not seen in older children or adults.

1:11

Um, and maybe even more importantly for prognosis,

1:14

there are, uh, secondary

1:16

and tertiary delayed injuries, um,

1:19

that essentially are metabolic,

1:20

inflammatory cascades induced by the primary insult.

1:23

And the tertiary effects on neurodevelopment can actually

1:26

persist for months or even years at school age or adulthood.

1:30

We can see, for example, impact of, um, extreme

1:33

or very preterm birth.

1:36

So the outcomes, there's this term called cerebral palsy

1:39

or cp, it's kind of a bucket, you know,

1:41

waste bucket, uh, diagnosis.

1:43

And so, uh, it can mean many different things, right?

1:46

And it's not always, uh,

1:48

although it's clinically diagnosed, it on imaging,

1:50

it can actually reflect many different things.

1:52

So in terms of the clinical definition,

1:55

they are disturbances of movement and or posture.

1:58

Uh, there are different subtypes.

1:59

The spastic, uh, which is stiffer, uh, usually associated

2:03

with, um, more white matter injury.

2:05

The diskinetic is, uh, abnormal uncontrolled motions,

2:08

and those that are typically more gray matter injury.

2:11

And then ataxic, uh, imbalance,

2:13

which is often cerebellar injury.

2:14

And obviously you can have mixed subtypes,

2:17

but when you look at imaging, there's all sorts

2:19

of preterm term birth injury.

2:20

Genetic diagnoses actually is now up to a quarter

2:23

of them unsuspected, genetic malformation.

2:25

So again, it's a, it's a very loose term

2:28

that's used clinically

2:29

and really can lead to a lot

2:31

of different imaging manifestations.

2:34

And then importantly,

2:35

and we still don't understand this completely,

2:36

but you know, how do we intervene and,

2:38

and optimize these outcomes, right?

2:40

So obviously modifying risk, any risk for preterm birth,

2:43

any risks in terms of the extended or difficult delivery.

2:46

And then neuroprotection, can we modify, um,

2:50

and decrease the burden of delayed injury, right?

2:53

The secondary and tertiary, um, injuries on top

2:56

of the primary insult.

2:59

So, you know, as a radiologist, like,

3:02

it's actually very important and even more so in this, uh,

3:05

perinatal neonatal period to, to know the clinical history

3:07

because there are many, uh, different factors that can lead

3:10

to kind of a final common pathway for injury.

3:13

So you want to look in the note, um,

3:15

and if you really need to actually contact the clinician

3:18

and ask, uh,

3:19

get whatever information you can about prenatal history,

3:22

you know, uh, what was the fetal course?

3:24

Did they have regular checkups, right?

3:26

Was anything detected? Uh, maternal things, you know,

3:28

gestational diabetes, preeclampsia, you know, all

3:31

of these things that might affect the health of the fetus.

3:33

Uh, what was the gestational age at birth?

3:35

Were they premature? Were they term?

3:38

Um, and then postnatally, what was the delivery course?

3:41

Was there an assisted delivery?

3:43

Uh, was it a, you know, normal delivery?

3:45

Was the, uh, baby requiring res resuscitation

3:49

or support, you know, what were their AP course scores?

3:52

Uh, were they looking a little blue?

3:54

And then, um, afterwards, what, uh, what testing was done?

3:57

If they're in the nicu, you know, what are their labs?

4:00

Uh, what, what might that entail in terms of, you know,

4:02

metabolic disruptions and whatnot.

4:06

So let's talk a little bit about gestational age.

4:08

Um, preterm by definition,

4:10

preterm birth is anything less than, uh, 37 weeks, uh, uh,

4:15

since the last menstrual period, uh, at the time of birth.

4:18

And we round down to the last completed week.

4:20

So even 36 weeks,

4:22

six days would be considered a late preterm,

4:23

obviously very mild, right?

4:26

But now that is technically preterm.

4:27

And so the more preterm you are,

4:29

the more immature these these structures are,

4:31

and the more likely you are to have, uh, brain injury, uh,

4:34

multi-organ injury and long-term complications.

4:37

Um, term is anything, you know, between like 37 to 41,

4:41

but full term technically is the, you know,

4:43

around the 40 week period, you could be, you know,

4:46

early term or late term.

4:48

Uh, there's also post-term, so 42 weeks or higher.

4:52

And, uh, this is also associated with complications,

4:54

you know, oligohydramnios

4:55

and placental, um, you know, degradation and so forth and,

5:00

and, uh, macro somia.

5:01

So typically they will induce, um, a pregnant lady if,

5:04

if she goes beyond, uh, 42 weeks to, to avoid that, okay?

5:09

So the term neonate, uh, officially means, uh, up to 28 days

5:13

after birth, uh, no matter gestational age.

5:16

Uh, in colloquially they also call this the newborn

5:20

period, although that's a looser term.

5:22

Um, infant is up to 12 months, right?

5:25

The term baby is, uh, is also used generically,

5:28

but some people will use that, uh,

5:29

for a wider sprint up till they're walking.

5:31

And now let's talk about corrected age.

5:33

So if you're preterm, right,

5:35

then you're actually gonna be behind on your milestones.

5:37

So you can't use the normal pediatric milestones like

5:39

walking, rolling, right?

5:41

Because you're actually behind.

5:42

So let's say you were born at 34 weeks, right?

5:44

So you're actually six weeks behind from a full term baby.

5:47

So you need to actually correct for

5:49

that prematurity when you look at the milestones.

5:51

So until at, you know, at birth,

5:53

they're actually negative six weeks, right?

5:56

And so not until they reach, uh, six weeks chronological age

5:59

after birth will they actually catch up

6:01

with the full-term baby in terms of milestones.

6:03

So that's the idea of corrected age for prematurity.