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Neonatal Echoencephalography

Neonatal Echoencephalography. Tanya Nolan. Embryology. At the end of the 4 th week after conception, the cranial end of the neural tube differentiates into 3 primary brain vesicles Prosencephalon (Forebrain) Diencephalon Thalmus Hypothalmus Posterior Pituitary Telencephalon

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Neonatal Echoencephalography

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  1. Neonatal Echoencephalography Tanya Nolan

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. Anatomy of the Neonatal BrainBrain Stem • Midbrain • Pons • Medulla Oblongata

  10. 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

  11. 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

  12. Anatomy of the Neonatal Skull • Fontanelles (“Soft Spots”) • Spaces between bones of the skull

  13. 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

  14. 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

  15. 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)

  16. Coronal Scan • Transducer placed in anterior fontanelle with scanning plane following coronal suture. • Transducer angled from anterior to posterior • CRITICAL: images must be symmetric!

  17. Coronal Scan • Anterior • Orbits, anterior horns, and lateral ventricles • Anterior • Orbits • Anterior horns of lateral ventricles

  18. 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

  19. Coronal Scan • Posterior • Cisterna magna • Choroids • Glomus of Choroids • Occipital Lobe

  20. 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.

  21. 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

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

  23. 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.

  24. 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.

  25. 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.

  26. 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)

  27. 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)

  28. 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

  29. 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

  30. Parasagittal Scan\ Repeat process on the Left

  31. 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

  32. Pathology

  33. 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

  34. 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

  35. 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

  36. Holoprosencephaly Alobar Holoprosencephaly Semilobar Holoprosencephaly

  37. 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

  38. Dandy-Walker Malformation

  39. 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”

  40. Agenesis of the Corpus Callosum

  41. 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

  42. 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

  43. 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

  44. 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

  45. 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

  46. 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

  47. 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

  48. Hemorrhagic Pathology • Grade I

  49. Hemorrhagic Pathology • Grade II

  50. Hemorrhagic Pathology • Grade III

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