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Neonatal Echoencephalography
Tanya Nolan
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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
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Anatomy of the Neonatal Brain Cerebrum
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.
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Anatomy of the Neonatal Brain Cerebrum
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
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Cerebrum Basal Ganglia Caudate Nucleus & Lentiform Nucleus Thalmus
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
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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.
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Ventricular System Cisterns Cisterna Magna
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.
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Anatomy of the Neonatal Brain
Choroid Plexus Cavum Septum Pellucidum 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
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Anatomy of the Neonatal Brain Brain Stem
Midbrain Pons Medulla Oblongata
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Anatomy of the Neonatal Brain Cerebellum
Posterior cranial fossa 2 Hemispheres connected by Vermis 3 Pairs of Nerve Tracts Superior Cerebellar Peduncles Middle Cerebellar Peduncles Inferior Cerebellar Peduncles
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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
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Anatomy of the Neonatal Skull
Fontanelles (“Soft Spots”) Spaces between bones of the skull
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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
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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
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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 Coronal (mastoid fontanelle and occipitotemporal area) Modified Coronal Sagittal Parasagittal (with increased focal depth & decreased frequency)
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Coronal Scan Transducer placed in anterior fontanelle with scanning plane following coronal suture. Transducer angled from anterior to posterior CRITICAL: images must be symmetric!
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Coronal Scan Anterior Anterior Orbits
Orbits, anterior horns, and lateral ventricles Anterior Orbits Anterior horns of lateral ventricles
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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
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Coronal Scan Posterior Cisterna magna Choroids Glomus of Choroids
Occipital Lobe
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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.
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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
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Coronal Scan (Posterior)
Coronal studies through the Posterior Fontanelle provides an alternate window to visualize the choroid plexus and lateral ventricles.
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Modified Coronal Scan 3rd Ventricle
Transducer positioned over anterior fontanelle with an angle of approximately 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.
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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.
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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.
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Sagittal Scan (Midline)
Supratentorial Structures Choroid plexus (CP) Corpus callosum (CC) Septum pellucidum(SP) Third ventricle (3V) Infratentorial Structures Brain stem (BS) Cerebellar vermis (V) Cisterna magna (CM) Fourth ventricle (4V)
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Parasagittal Scan (Right)
Close to Midline Caudo-thalmic groove important because subependymal hemorrhages begin in the germinal matrix at the level of these ganglia Slightly more lateral anechoic frontal horns and bodies of lateral ventricles echogenic choroid plexus (2-3 mm height)
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Parasagittal Scan (Right)
External to Lateral Ventricles White Matter Important in studying intraparenchymal hemorrhages, porencephaly, and periventricular leukomalacia Most Lateral Aspect Sylvian Fissure Middle Cerebral Artery Insula
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Parasagittal Scan (Right)
Close to Midline Caudo-thalmic groove important because subependymal hemorrhages begin in the germinal matrix at the level of these ganglia Slightly more lateral anechoic frontal horns and bodies of lateral ventricles echogenic choroid plexus (2-3 mm height) External to Lateral Ventricles White Matter Important in studying intraparenchymal hemorrhages, porencephaly, and periventricular leukomalacia Most Lateral Aspect Sylvian Fissure Middle Cerebral Artery Insula C T
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Parasagittal Scan\ Repeat process on the Left
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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
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Pathology
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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
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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
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Holoprosencephaly Alobar Holoprosencephaly (Most Severe)
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
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Holoprosencephaly Alobar Holoprosencephaly Semilobar Holoprosencephaly
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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
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Dandy-Walker Malformation
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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”
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Agenesis of the Corpus Callosum
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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
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Hydrocephalus Aqueductal Stenosis
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 Widening of lateral and 3rd ventricles Normal 4th ventricle
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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
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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
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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
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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
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Hemorrhagic Pathology
Grades Based on the extension of the hemorrhage Ventricular measurement Mild dilation: 3-10 mm Moderate dilation: 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
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Hemorrhagic Pathology
Grade I
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Hemorrhagic Pathology
Grade II
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Hemorrhagic Pathology
Grade III
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Hemorrhagic Pathology
Grade IV
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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
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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
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Epidural Hemorrhages and Subdural Collections
Best diagnosed with CT because the lesions are located peripherally along the surface of the brain.
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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
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Ischemic-Hypoxic Lesions Periventricular 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)
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PVL or WMN 2 1 4 3
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ECMO Extracorporeal 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
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Brain Infections Common infections referred to by TORCH Consequences
T: Toxoplasma Gondii O: Other (Syphilis) R: Rubella Virus C: Cytomegalovirus H: Herpes Simplex Type 2 Consequences Mortality Mental Retardation Developmental Delay
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Ependymitis and Ventriculitis
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.
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