Neonatal Cranial Ultrasound

Dr Mohit GoelJR 1

The acoustic windows :

Anterior FontanelThe Standard view window Posterior

FontanelSupplementary view window

Mastoid FontanelSupplementary view window

TemporalSupplementary view window

Coronal Views

(at least 6 standard planes)

The orbital ridge forms the inferior boundary of this image.First coronal plane (C1) at the level of the frontal lobes

Second coronal plane (C2) at the level of the frontal horns of the lateral ventricles

Third coronal plane (C3) at the level of the third ventricle

Fourth coronal plane (C4) at the level of the bodies of the lateral ventricles.1. Interhemispheric fissure8. Temporal lobe9. Sylvian fissure14. Body of lateral ventricle15. Choroid plexus16. Thalamus17. Hippocampal fissure18. Aqueduct of Sylvius19. Brain stem20. Parietal lobe

Brain stem

Fifth coronal plane (C5) at the level of the trigone of the lateral ventricles

Sixth coronal plane (C6) through the parieto-occipital lobes

Sagittal Views (at least 5 standard planes)

Standard Views(Anterior Fontanel)

Midsagittal plane (S3) through the third and fourth ventricles

Cingulate sulcus

Thalamus

Cisterna quadrigemin

PonsMedulla oblongata

Second and fourth parasagittal planes (S2, S4) through the right and left lateral ventricles

Arrow indicates internal capsule

Choroid plexus

First and fifth parasagittal planes (S1, S5) through the insulae (right and left)

Insula Sylvian fissure

Supplemental Acoustic Windows

Coronal view, using the posterior fontanel as an acoustic window

Falx

Calcarine fissure

Occipital horn

of lateral ventricleStraight sinus

Tentorium

Cerebellum (a: hemispheres; b: vermis)

Parasagittal view, using the posterior fontanel as an acoustic window

Temporal lobe

Thalamus

Trigoneof lateral ventricle

Parietallobe

Upper Transverse view using the left temporal window

Mesencephalon

Interpeduncular fossa

Temporal lobe

Arrow indicates mesencephalic aqueduct

Lower transverse view using the left temporal window

Pons

Prepontine cistern

Cerebellum(a: hemispheres;b: vermis

Coronal view using the mastoid fontanel as an acoustic window

Cisterna magna

Fourth ventricle

Pons

Transverse view using the mastoid fontanel as an acoustic window

Occipital lobe

Temporal lobe

Arrow indicates fourth ventricle

(also known as periventricular hemorrhage or preterm caudothalamic hemorrhage)

These germinal matrix hemorrhages occur in the highly vascular but also stress sensitive germinal matrix, which is located in the caudothalamic groove. This is the subependymal region between the caudate nucleus and thalamus.

The germinal matrix is matured by 34 weeks gestation, such that hemorrhage becomes very unlikely after this age.

Most GMHs occur in the first week of life

These hemorrhages start in the caudothalamic groove and may extend into the lateral ventricle and periventricular brain parenchyma.

Germinal matrix hemorrhage (GMH)

Grade 1 and 2 bleeds generally have a good prognosis.

Grade 3 and 4 bleeds have variable long-term deficits

An intracranial hemorrhage confined to the caudothalamic groove.It is staged as grade 1 hemorrhage.

In the acute phase these bleedings are hyperechoic, changing to iso- and hypo-echoic with time.

Coronal and Sagittal US of a grade 2 hemorrhage

On the coronal image only the cavum septi pellucidi is seen.Both lateral ventricles are filled with blood, but there is no ventricular dilatation.

Intraventricular hemorrhage and hydrocephalus (Grade 3 GMH),Coronal sonograms, and sagittal sonogram, show progressive hydrocephalus. The ventricular walls have become very echogenic, caused by a chemical ventriculitis from blood. The lateral and third ventricles are enlarged, and there is a clot in the back of the third ventricle causing aqueductal obstruction.

Intraparenchymal hemorrhage (grade IV hemorrhage).Parietal cortex hemorrhage may involve the motor area, causing contralateral hemiparesis.

Grade 4 intracranial hemorrhageOriginally these grade 4 hemorrhages were thought to result from subependymal bleeding into the adjacent brain.

Today however most regard these grade 4 hemorrhages to be venous hemorrhagic infartions, which are the result of compression of the outflow of the veins by the subependymal hemorrhage. These venous infarctions resolve with cyst formation. These cysts can merge with the lateral ventricle, finally resulting into a porencephalic cyst.

grade 4 hemorrhage at a later stage with extensive cyst formation.

Peri Ventricular Leukomalacia (PVL)

PVL is also known as Hypoxic-Ischemic Encephalopathy (HIE) of the preterm.

It is a white matter disease that affects the periventricular zones.

In prematures this white matter zone is a watershed zone between deep and superficial vessels.

PVL presents as areas of increased periventricular echogenicity.

PVL occurs most commonly in premature infants born at less than 33 weeks gestation (38% PVL) and less than 1500 g birth weight (45% PVL).

Detection of PVL is important because a significant percentage of surviving premature infants with PVL develop cerebral palsy, intellectual impairment or visual disturbances.

Grading PVL

The pathogenesis of PVL has been found to relate to three major factors:

(1)the immature vasculature in the periventricular watershed;

(2)the absence of vascular autoregulation in premature infants, particularly in the cerebral white matter; and

(3)the maturation-dependent vulnerability of the oligodendroglial precursor cell

damaged in PVL. These cells are extremely vulnerable to attack by free radicals generated in the ischemia-reperfusion sequence.

PVL grade 1

PVL is diagnosed as grade 1 if there are areas of increased periventricular echogenicity without any cyst formation persisting for more than 7 days.

Increased periventricular echogenicity is however a nonspecific finding that must be differentiated from the normal periventricular halo or normal hyperechoic 'blush' posterosuperior to the ventricular trigones.

Suspect PVL if the echogenicity is asymmetric, coarse, globular or more hyperechoic than the choroid plexus.

The abnormal periventricular echotexture of PVL usually disappears at 2-3 weeks.

PVL can be differentiated from hemorrhages because PVL lacks mass effect.

PVL grade 2

The images demonstrate a PVL grade 2 with small periventricular cysts.The echogenicity has resolved at the time of cyst formation.

2% of the preterm neonates born before 32 weeks develop cystic PVL.

Cystic PVL has been identified on cranial ultrasounds on the first day of life, indicating that the adverse event was at least 2 weeks prenatal rather than perinatal or postnatal.

PVL grade 3

Sagittal image demonstarting extensive PVL grade 3

PVL is diagnosed as grade 3 if there are areas of increased periventricular echogenicity, that develop into extensive periventricular cysts in the occipital and fronto-parietal region.

PVL grade 4

PVL is diagnosed as grade 4 if there are areas of increased periventricular echogenicity in the deep white matter developing into extensive subcortical cysts.

PVL grade 4 is seen mostly in fullterm neonates as opposed to PVL grade 1-3, which is a disease of the preterm neonate.

Flaring

The term flaring is used to describe the slightly echogenic periventricular zones, that are seen in many premature infants in the first week of life.During this first week it is not sure if this is a normal variant or a sign of PVL grade 1.

Flaring persisting beyond the first week of life is by definition PVL grade 1. Follow up is needed to differentiate flaring from PVL grade I.

HYDROCEPHALUS

Anechoic cerebrospinal fluid is seen above thalamus (T)

Hydrocephalus results from an imbalance between CSF production and its drainage by the arachnoid villi.

Ventricular measurement

Coronal section through the lateral ventricles slightly posterior to the foramen of Monro is taken.3 echogenic dots representing the choroid plexus in the lateral ventricles and in the roof of the third ventricle are seen.Furthermore symmetrical image of the Sylvian fissure on both sides and the hippocampus (green and orange arrows) should be seen.

Levene index

Up to 40 weeks of gestational age the Levene-index should be used and after 40 weeks the ventricular index.The Levene index is the absolute distance between the falx and the lateral wall of the anterior horn in the coronal plane at the level of the third ventricle.

These measurements can be compared to the reference curve and are quite usefull for further follow-up.

Ventricular index

Ventricular indexAfter 40 weeks the ventricular index or frontal horn ratio should be used, i.e. the ratio of the distance between the lateral sides of the ventricles and the biparietal diameter.

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