Neonatal Echoencephalography

Tanya Nolan

Embryology At the end of the 4th week after conception,

the cranial end of the neural tube differentiates into 3 primary brain vesicles

Prosencephalon (Forebrain) Diencephalon

Thalmus Hypothalmus Posterior Pituitary

Telencephalon Cerebral hemispheres Cortex & Medullary Center Corpus Striatum Olfactory System

Mesencephalon (midbrain) Cerebral Aqueduct Superior and inferior colliculi

(quadrigeminal body)

Rhombencephalon (hindbrain) Myelencephalon

Closed part of medulla oblongata Metencephalon

Pons Cerebellum 3rd, 4th, and lateral ventricles Choroid Plexus

Anatomy of the Neonatal BrainCerebrum 2 Hemispheres (Gray and White Matter) Lobes of the Brain

Frontal Parietal Occipital Temporal

Gyrus and Sulcus Gyrus: convulutions of the brain surface causing

infolding of the cortex Sulcus: Groove or depression separating gyri.

Anatomy of the Neonatal BrainCerebrum Fissures

Interhemispheric Area of Falx Cerebri

Sylvian Most lateral aspect of brain Location of middle cerebral artery

Quadrigeminal Posterior and inferior from the cavum

vergae Vein of Galen posterior to fissure

Falx Cerebri Fibrous structure separating the 2

cerebral hemispheres Tentorium Cerebelli

“V” shaped echogenic extension of the falx cerebri separating the cerebrum and the cerebellum

Cerebrum Basal Ganglia

collection of gray matter Caudate Nucleus & Lentiform

Nucleus Largest basal ganglia Relay station between the thalmus

and cerebral cortex Germinal Matrix includes

periventricular tissue and caudate nucleus

Thalmus 2 ovoid brain structures Located on either side of the 3rd

ventricle superior to the brainstem Connects through middle of the 3rd

ventricle through massa intermedia Hypothalmus

“Floor” of 3rd Ventricle Pituitary Gland is connected to the

hypothalmus by the infundibulum

Anatomy of the Neonatal Brain

Meninges Dura Mater Arachnoid Pia Mater

Cerebral Spinal Fluid (CSF) Surrounds and protects brain and spinal cord. 40% formed by ventricles, 60% extracellular

fluid from circulation.

Ventricular System Lateral Ventricles: Largest of

the CSF cavities. Frontal Horn Body Occipital Horn Temporal Horn

Trigone “Atrium” Foramen of Monro

3rd Ventricle Aqueduct of Sylvius

4th Ventricle Foramen of Luschka Foramen of Megendie

Cisterns Cisterna Magna

Spaces at the base of the skull where the arachnoid is widely separated from the pia mater.

Anatomy of the Neonatal Brain

Corpus Callosum Broad band of connective fibers between cerebral hemispheres. The “roof” of the lateral ventricles.

Cavum Septum Pellucidum Thin, triangular space filled with CSF Lies between the anterior horn of the lateral ventricles. “Floor” of the corpus callosum

Choroid Plexus Mass of specialized cells that regulate IV pressure by secretion/absorption of CSF Within atrium of the lateral ventricles

Choroid Plexus

Cavum Septum Pellucidum

Anatomy of the Neonatal BrainBrain Stem

Midbrain

Pons

Medulla Oblongata

Anatomy of the Neonatal BrainCerebellum Posterior cranial

fossa 2 Hemispheres

connected by Vermis 3 Pairs of Nerve

Tracts Superior Cerebellar

Peduncles Middle Cerebellar Peduncles Inferior Cerebellar Peduncles

Cerebrovascular System

Internal Cerebral Arteries

Vertebral Arteries Circle of Willis

Middle Cerebral Artery

Longest branch in Circle of Willis that provides 80% of blood to the cerebral hemispheres

Anatomy of the Neonatal Skull

Fontanelles (“Soft Spots”) Spaces between bones of the skull

Function and Physiology

Cerebellum Controls Skeletal Muscle

Movement Cerebral Hemispheres

Frontal Voluntary muscles,

speech, emotions, personality, morality, and intellect

Parietal Pain, temperature, and

spatial ability Occipital

Vision Temporal

Auditory and Olfactory

Indications for Sonographic Exam

Cranial abnormality found on pre-natal sonogram Increasing head circumference with or without

increasing intracranial pressure Acquired or Congenital inflammatory disease Prematurity Diagnosis of hypoxia, hypertension, hypercapnia,

hypernaturemia, acidosis, pneumothorax, asphyxia, apnea, seizures, coagulation defects, patent ductus arteriosus, or elevated blood pressure

History of birth trauma or surgery Suctioning of infant Genetic syndromes and malformations

Sonographic Technique What anatomy do you scan?

Supratentorial Compartment Both cerebral hemispheres Basal Ganglia Lateral & 3rd Ventricle Interhemispheric fissure Subarachnoid space

Views Coronal Modified Coronal (anterior fontanelle) Sagittal (anterior fontanelle) Parasagittal (anterior fontanelle)

Infratentorial Compartment Cerebellum Brain Stem 4th Ventricle Basal Cisterns

Views Coronal (mastoid fontanelle and occipitotemporal area) Modified Coronal Sagittal Parasagittal (with increased focal depth & decreased frequency)

Coronal Scan

Transducer placed in anterior fontanelle with scanning plane following coronal suture.

Transducer angled from anterior to posterior

CRITICAL: images must be symmetric!

Coronal Scan

Anterior Orbits, anterior horns, and lateral ventricles

Anterior• Orbits• Anterior horns of lateral ventricles

Coronal Scan

Middle

• Lateral Ventricles (Asymmetry in the size of the lateral ventricles can be a common normal variant)

• Choroid Plexus

• Cavum Septum Pellucidum

• 3rd Ventricle

• Corpus Callosum

Coronal Scan

Posterior• Cisterna magna• Choroids• Glomus of Choroids• Occipital Lobe

Coronal Scan (Anterior)

Cavum Septum Pellucidum Midline hypoechoic/cystic structure

separating the bodies and frontal horns of the lateral ventricles.

Anterior to corpus callosum Caudate Nucleus

Inferior and lateral walls of ventricles at the body and frontal horns

Higher echogenicity in premature infants in comparison to brain parenchyma

Frontal Horns Midline Slit-like hypoechoic/cystic

formations Posterior “comma-like” Size increase from 2mm at the frontal

lobe to 3-6 mm at the choroid plexus region.

Coronal Scan (Midline)

Choroid Plexus• Frontal and occipital horns devoid of choroid plexus• Becomes enlarged at the level of the atria & almost fills the cavity• Very echogenic structure inside ventricular cavities surrounding the thalmac nuclei• Becomes smaller with increased gestational age

Coronal Scan (Posterior)

• Coronal studies through the Posterior Fontanelle provides an alternate window to visualize the choroid plexus and lateral ventricles.

Modified Coronal Scan

Transducer positioned over anterior fontanelle with an angle of approximately 30-40 degrees between the scanning plane and the surface of the fontanelle.

Demonstrates body of lateral ventricles, 3rd ventricle, and posterior fossa (infratentorial compartment: 4th ventricle, cerebellar hemispheres, and cisterna magna)

3rd Ventricle Not visualized in normal conditions.

Prominent in premature infants less than 32 wks

Thin and very echogenic formation seen in midline immediately below the septum pellucidum corresponding with the choroid plexus and extending into the 3rd ventricle.

Sagittal and Bilateral Parasagittal Scan

Provides most extensive visualization of the brain. Transducer positioned over anterior fontanelle in

sagittal plane and angled medial and lateral.

Sagittal Scan (Midline)

Cavum Septum Pellucidum Anechoic structure

immediately below corpus callosum

Corpus Callosum 2 thin parallel lines separated

by a thin echogenic space 3rd Ventricle

Anechoic structure inferior to the septum

Cerebellum (Tentorium) Vermis appears echo dense

Cisterna Magna Anechoic space next to

vermis 4th Ventricle

Small “v” oriented posteriorly inside the echogenic vermis.

Sagittal Scan (Midline)

Supratentorial Structures

1. Choroid plexus (CP)

2. Corpus callosum (CC)

3. Septum pellucidum(SP)

4. Third ventricle (3V)

Infratentorial Structures

1. Brain stem (BS)

2. Cerebellar vermis (V)

3. Cisterna magna (CM)

4. Fourth ventricle (4V)

Parasagittal Scan (Right)

1. Close to Midline Caudo-thalmic groove

important because subependymal hemorrhages begin in the germinal matrix at the level of these ganglia

2. Slightly more lateral anechoic frontal horns and bodies of lateral ventricles echogenic choroid plexus (2-3 mm height)

Parasagittal Scan (Right)

1. External to Lateral Ventricles White Matter

Important in studying intraparenchymal hemorrhages, porencephaly, and periventricular leukomalacia

2. Most Lateral Aspect Sylvian Fissure Middle Cerebral Artery Insula

Parasagittal Scan (Right)

CT

1. Close to Midline Caudo-thalmic groove

important because subependymal hemorrhages begin in the germinal matrix at the level of these ganglia

2. Slightly more lateral anechoic frontal horns and bodies of lateral ventricles echogenic choroid plexus (2-3 mm height)

3. External to Lateral Ventricles White Matter

Important in studying intraparenchymal hemorrhages, porencephaly, and periventricular leukomalacia

4. Most Lateral Aspect Sylvian Fissure Middle Cerebral Artery Insula

Parasagittal Scan\ Repeat process on the Left

Doppler

Typical transcranial Doppler with imaging scan and recording from middle cerebral artery (MCA).

Doppler image shows circle of Willis. A = anterior cerebral artery M = middle cerebral artery P = posterior cerebral artery RI = resistive index

Demonstrates Decreased blood

flow/ischemia/infarction Vascular abnormalities Cerebral Edema Hydrocephalus Intracranial Tumors Near-field structures

Pathology

Chiari Malformation

Downward displacement of the cerebellar tonsils and the medulla through the foramen magnum.

Arnold-Chiari malformation shows a small displaced cerebellum, absence of the cisterna magna, malposition of the fourth ventricle, absence of the septum pellucidum, and widening of the third ventricle Commonly related

to meningomyelocele

Chiari Malformation Sonographic Features

Small posterior fossa Small, displaced

Cerebellum Possible

Myelomeningocele Widened 3rd Ventricle Cerebellum herniated

through enlarged foramen magnum

4th ventricle elongated Posterior horns enlarged Cavum Septum

pellucidum absent Interhemispheric Fissure

widened Tentorium low and

hypoplastic

Holoprosencephaly Common large central ventricle because prosencephalon

failed to cleave into separate cerebral hemispheres.

Alobar Holoprosencephaly (Most Severe) Fused thalami anteriorly to a fused choroid plexus Single midline ventricle No falx cerebrum, corpus callosum, interhemispheric

fissure, or 3rd ventricle

Semilobar Holoprosencephaly Single ventricle Presents with portions of the falx and interhemispheric

fissure Thalmi partially separated 3rd Ventricle is rudimentary Mild facial anomalies

Lobar Holoprosencephaly (Least Severe) Near complete separation of hemipsheres; only anterior

horns fused Full development of falx and interhemispheric fissure

Holoprosencephaly

Alobar Holoprosencephaly Semilobar Holoprosencephaly

Dandy-Walker Malformation

Congenital anomaly of the roof of the 4th ventricle with occlusion of the aqueduct of Sylvius and foramina of Magendie and Luschka

A huge 4th ventricle cyst occupies the area where the cerebellum usually lies with secondary dilation of the 3rd ventricle; absent cerebellar vermis

Dandy-Walker Malformation

Agenesis of the Corpus Callosum

Complete or partial absence of the connection tissue between cerebral hemispheres Narrow frontal horns Marked separation of lateral ventricles Widening of occipital horns and 3rd Ventricle

“Vampire Wings”

Agenesis of the Corpus Callosum

Ventriculmegaly Enlargement of the ventricles

without increased head circumference Communicating Non-communicating Resut of cerebral atrophy

Sonographic Findings Ventricles greater than

normal size first noted in the trigone and occipital horn areas

Visualization of the 3rd and possibly 4th ventricles

Choroid plexus appears to “dangle” within the ventricular trium

Thinned brain mantle in case of cerebral atrophy

Hydrocephalus Enlargement of ventricles with increased head

circumference Communicating Non-communicating

Sonographic Findings Blunted lateral angles of enlarged lateral

ventricles Possible intrahemispheric fissure rupture Thinned brain mantle

Aqueductal Stenosis Most common cause of congenital

hydrocephalus Aqueduct of Sylvius is narrowed or is a

small channel with blind ends; occasionally caused by extrinsic lesions posterior to the brain stem

Sonographic Findings Widening of lateral and 3rd ventricles Normal 4th ventricle

Hydrancephaly

Occlusion of internal carotid arteries resulting in necrosis of cerebral hemispheres Absence of both cerebral

hemispheres with presence of the falx, thalmus, cerebellum, brain stem, and postions of the occipital and temporal lobes

Sonographic findings Fluid filled cranial vault Intact cerebellum and

midbrain

Cephalocele

Herniation of a portion of the neural tube through a defect in the skull

Sonographic Findings Sac/pouch containing brain tissue and/or CSF and

meninges Lateral Ventricle Enlargement

Subarachnoid Cysts

Cysts lined with arachnoid tissue and containing CSF Causes

Entrapment during embryogenesis Residual subdural hematoma Fluid extravasation sectondary to meningeal tear or

ventricular rupture

Hemorrhagic Pathology

Subependymal-Intraventricular Hemorrhage (SEH-IVH) Caused by capillary bleeding in the germinal matrix Most frequent location is the thalamic-caudate groove Continued subependymal (SEH) bleeding pushes into the

ventricular cavity (IVH) & continues to follow CSF pathways causing obstruction

Treatment: Ventriculoperitoneal Shunt Since 70% of hemorrhages are asymptomatic, it is necessary

to scan babies routinely Small IVH’s may not be seen from the anterior fontanelle

because blood tends to settle out in the posterior horns

Risk Factors Pre term infants Less than 1500 grams birth weight

Hemorrhagic Pathology

Grades Based on the extension of the hemorrhage Ventricular measurement

Mild dilation: 3-10 mm Moderate dilation: 11-14 mm Large dilation: greater than 14mm

Grade I Without ventricular enlargement

Grade II Minimal ventricular enlargement

Grade III Moderate or large ventricular enlargement

Grade IV Intraparenchymal hemorrhage

Hemorrhagic Pathology

Grade I

Hemorrhagic Pathology Grade II

Hemorrhagic Pathology Grade III

Hemorrhagic Pathology

Grade IV

Intraparenchymal Hemorrhage

Brain parenchyma destroyed

Originally considered an extension of IVH, but may actually be a primary infarction of the periventricular and subcortical white matter with destruction of the lateral wall of the ventricle.

Sonographic Finding Zones of increased

echogenicity in white matter adjacent to lateral ventricles

Intracerebellar Hemorrhage Types

Primary Venous Infarction Traumatic Laceration Extension from IVH

Sonographic Findings Areas of increased

echogenicity within cerebellar parenchyma

Coronal views through mastoid fontanelle may be essential to differentiate from large IVH in the cisterna magna

Epidural Hemorrhages and Subdural Collections Best diagnosed with CT because the lesions

are located peripherally along the surface of the brain.

Ischemic-Hypoxic Lesions

Hypoxia: Lack of adequate oxygen to the brain Ischemia: lack of adequate blood flow to the brain

Types Selective neuronal necrosis Status marmoratus Parasagittal cerebral injury Periventricular leukomalacia (PVL), white matter

necrosis (WMN), or cerebral edema Focal brain lesions (occurs when lesions are distributed

within large arteries)

Sonographic Findings Areas of increased echogenicity in subcortical and deep

white matter in the basal ganglia

Ischemic-Hypoxic LesionsPeriventricular Leukomalacia (PVL) or White Matter Necrosis (WMN) Most important cause of abnormal neurodevelopment

in preterm infants Early chronic stage

Multiple cavities develop in necrotic white matter adjacent to frontal horns

Middle chronic Stage Cavities resolve and leave gliotic scars and diffuse

cerebral atrophy Increased Echogenicity

Late chronic stage Echolucencies develop in the echolucent lesions

corresponding to the cavitary lesions in the white matter (cysts)

PVL or WMN1 2

3

4

ECMOExtracorporeal Membrane Oxygenation Used for pulmonary

and Circulatory Support in many neonates to allow additional time for lung development

Cannula inserted into R internal jugular vein and carotid artery

Hemorrhage and ischemia are common in children on ECMO

Brain Infections

Common infections referred to by TORCH T: Toxoplasma Gondii O: Other (Syphilis) R: Rubella Virus C: Cytomegalovirus H: Herpes Simplex Type 2

Consequences Mortality Mental Retardation Developmental Delay

Ependymitis and Ventriculitis

Ependymitis Irritation from hemorrhage within

the ventricle Occurs earlier than ventriculitis

Sonographic Features Thickened, hypoechoic ependyma

(epithelial lining of the ventricles)

Ventriculitis Common complication of purulent

meningitis Sonographic Findings

Thin septations extending from the walls of the lateral ventricles.