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Neonatal neurosonography

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by Dr Harshita Saxena.

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Neonatal neurosonography

  1. 1. Neonatal neurosonography
  2. 2.  Cranial sonography (US) is the most widely used neuroimaging procedure in premature infants.  US helps in assessing the neurologic status of the child, since clinical examination and symptoms are often nonspecific
  3. 3. Indications  Premature infants - all <1500g or <32 weeks gestation  Low APGAR score  Neurologic changes  Cranial dysmorphism  Seizures  Follow-up of hemorrhage and periventricular leucomalacia.
  4. 4. Advantages of Cranial Ultrasound  Safe  Bedside  Reliable  Early imaging  Serial imaging: Brain maturation Evolution of lesions  Inexpensive  Suitable for screening
  5. 5. Aims of Neonatal Cranial Ultrasound  Exclude/demonstrate cerebral pathology  Assess timing of injury  Assess neurological prognosis  Help make decisions on continuation of neonatal intensive care  Optimize treatment and support
  6. 6.  High-frequency phased array transducer (5-8 MHz) with a small footprint probe  Transducers : 5–7.5–10 MHz  Appropriately sized  Standard examination: use 7.5–8 MHz  Tiny infant and/or superficial structures: use additional higher frequency (10 MHz)  Large infant, thick hair, and/or deep structures: use additional lower frequency (5 MHz) Cranial USG Technique
  7. 7. Examination is preferably done through the cranial incubator opening. All aseptic precautions. Care should be taken not to move the infant & Pressure over the anterior fontanelle is to be avoided, especially in a critically ill premature neonate.
  8. 8. Mastoid and posterior fontanelle approaches are useful in the demonstration of a subtle intraventricular bleed in the occipital horn and minor bleed in the brain stem and cerebellum.
  9. 9. Standard Views(Anterior Fontanel)  Coronal Views(at least 6 standard planes)
  10. 10. Standard Coronal Planes
  11. 11. The third ventricle is often small and difficult to see, but can vary considerably in size. The brainstem may be seen as a tree-like shape.
  12. 12. The choroid plexus fills the lateral ventricles in this view and is prominent in preterm infants. The white matter around the lateral ventricles may appear quite echodense (bright) in this plane and is sometimes called a "blush" or "flare".
  13. 13. Sagittal Views (at least 5 standard planes)
  14. 14. Mid Sagittal plane
  15. 15. Angled Parasagittal View: The choroid tucks up in the caudothalamic groove in the floor of the lateral ventricle. It does not extend beyond the caudothalamic grooves into the frontal horns .
  16. 16. Tangential Parasagittal View: Further angulation of the transducer laterally results in a section lateral to the lateral ventricles. The Sylvian fissure is the key landmark in this view.
  17. 17. Supplemental Acoustic Window
  18. 18. DOPPLER IMAGING Doppler imaging of the circle of Willis and the region of vein of Galen is an essential part of the assessment.
  19. 19.  Doppler Vascular Measurements:  The vessels that are the easiest to access are  the anterior cerebral artery (ACA), best seen through the anterior fontanelle in the sagittal plane and  the middle cerebral artery (MCA) best seen through the temporal window in the axial plane.  The Resistivity index (RI) : PS – ED SV - DV PS SV  Where PS= peak systolic velocity and ED = end diastolic velocity.  The normal range is about 0.65 - 0.90.  Values below 0.5 or above 0.9 are abnormal.
  20. 20. Normal variants and pitfalls that mimics pathologic abnormalities  Immature sulcation in premature infants  Persistent fetal fluid filled spaces  Mega cisterna magna  Asymmetric ventricular size  Choroid plexus variants  Periventricular cystic lesions  Hyperechoic white matter pseudolesions or periventricular halo  Lenticulostriate vasculopathy
  21. 21.  Immature sulcation  Infants born before the 24th week possess a smooth cerebral cortex exhibiting only the sylvian fissures.  a diagnosis of lissencephaly should not be made in newborn younger than 24 weeks’ gestational age
  22. 22.  Persistent fetal fluid filled spaces  Persistent fetal fluid–filled spaces, a common finding in healthy neonates, include the cavum septi pellucidi (CSP), cavum vergae, and cavum veli interpositi.  The CSP is the most anterior and the most common of the fetal fluid– filled spaces.  Persistent fetal fluid–filled spaces occasionally persist into adulthood and are a normal variant of no significance
  23. 23.  Mega cisterna magna  The typical cisterna magna is less than 8 mm in both the sagittal and axial planes  A mega cisterna magna measures greater than 8 mm and is seen in 1% of postnatally imaged brains  A mega cistern magna is a normal variant distinguished from an arachnoid cyst by its lack of mass effect and from a DandyWalker malformation by the presence of the cerebellar vermis
  24. 24.  Assymetric ventricles  Normal ventricles measure less than 10 mm in transverse diameter, with 60% of full term and 30% of premature infants having ventricles smaller than 2–3 mm  Asymmetry between the sizes of the ventricles has been observed in 20–40% of infants
  25. 25.  Choroid Plexus Variants  It does not extend past the caudothalamic grooves into the frontal horns or past the ventricular atria into the occipital horns.  Echogenic material anterior to the caudothalamic groove or in the dependent portions of the occipital horns suggests germinal matrix and intraventricular hemorrhage  Lobular or bulbous variants of the choroid plexus occur most frequently in the glomus within the ventricular atria and lateral ventricles  Choroid cysts smaller than 1 cm are incidentally noted in 1% of infants at autopsy
  26. 26. At prenatal US these cysts can be predictive of trisomy 18
  27. 27.  Periventricular Cystic Lesions  Connatal (or subfrontal) cysts are seen most often during the early postnatal period and may regress spontaneously  The sonographic appearance includes bilateral symmetric cysts located adjacent to the frontal horns, just anterior to the foramina of Monro. The cysts frequently appear in multiples and take on a classic appearance that has been likened to a string of pearls
  28. 28.  Hyperechoic White Matter Pseudolesion or Periventricular Halo  Hyperechoic white matter pseudolesions, or periventricular halos, may appear as artifacts due to anisotropic effect  Additional images obtained at a 90° angle resolve the finding and prevent misinterpretation  periventricular white matter pseudolesions and halos are normally less echogenic than the adjacent choroid plexus
  29. 29.  Lenticulostriate Vasculopathy /Mineralizing Vasculopathy  nonspecific thickening of the lenticulostriate artery walls secondary to a variety of pathologic conditions and infections  seen on sonography as unilateral or bilateral branching, linear, or punctate increased echogenicity within the thalami.
  30. 30. Germinal Matrix Hemorrhage  Far more common in premature infants  Germinal matrix - highly vascular and vulnerable to hypoxemia and ischemia, only present 24-32nd week gestation  Image 4-7 days after birth  90% of hemorrhages occur in first week of life  Follow with weekly U/S to evaluate for hydrocephalus
  31. 31.  Grade I - Confined to germinal matrix  Grade II - Intraventricular without ventricular dilatation  Grade III - Intraventricular with ventricular dilatation  Grade IV - Periventricular hemorrhagic infarction
  32. 32. Grade 1 hemorrhage is limited to the region of the caudothalamic groove, usually less than a centimetre in size.
  33. 33. Secondary hydrocephalus occuring several days after a grade 2 bleed should not be mislabeled as grade 3 hemorrhage
  34. 34. Intraparenchymal Hemorrhage  Brain parenchyma destroyed  Originally considered an extension of IVH, but may actually be a primary infarction of the periventricular and sub cortical white matter with destruction of the lateral wall of the ventricle.  Sonographic Finding  Zones of increased echogenicity in white matter adjacent to lateral ventricles
  35. 35. Epidural Hemorrhages and Subdural Collections  Best diagnosed with CT because the lesions are located peripherally along the surface of the brain. an echogenic layer of clotted blood (arrow) is seen between the cortex and the skull. five hours after the image the clot has started to lyse, and the layer is now hypoechoic. a parasagittal view demonstrates the fluid around the cortical mantle and the paucity of gyri due to the prematurity.
  36. 36. Periventricular Leukomalacia (PVL) or White Matter Necrosis (WMN)  Affects the periventricular zones.  watershed zone between deep and superficial vessels.  Premature infants born at less than 33 weeks gestation (38% PVL) and less than 1500 g birth weight (45% PVL).  Causes:  Ischemia  Infection  Vasculitis
  37. 37. DeVries classification of PVL grading on ultrasound  Grade I PVL: Prolonged periventricular flare present for 7 days or more.  Grade II PVL: Presence of small-localized fronto-parietal cysts.  Grade III PVL: Extensive periventricular cystic lesion involving occipital and fronto-parietal white matter.  Grade IV PVL: Areas of extensive sub cortical cystic lesions.
  38. 38. PVL or WMN 1 2 Sagittal image of a child with PVL grade 1 Transverse and sagittal image of a child with PVL grade 2. Grade I PVL: Prolonged periventricular flare present for 7 days or more. Grade II PVL: Presence of small-localized fronto-parietal cysts. The echogenicity has resolved at the time of cyst formation.
  39. 39. PVL or WMN Coronal and transverse images demonstrating PVL grade 4 Sagittal image demonstrating extensive PVL grade 3 Grade III PVL: Extensive periventricular cystic lesion involving occipital and fronto-parietal white matter. Grade IV PVL: Areas of extensive sub cortical cystic lesions.
  40. 40. LEFT: Initial examination shows flaring. RIGHT: Follow up one month later shows normal periventricular white matter.
  41. 41. Hydrocephalus  Enlargement of ventricles with increased head circumference  Sonographic Findings  Blunted lateral angles of enlarged lateral ventricles  Possible interhemispheric fissure rupture  Thinned brain mantle  Aqueductal Stenosis  Most common cause of congenital hydrocephalus  Sonographic Findings  Widening of lateral and 3rd ventricles  Normal 4th ventricle Ventriculomegaly Mild 0.5-1.0 cm Moderate 1.0-1.5 cm Severe 1.5 cm
  42. 42. 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.
  43. 43. Vein of Galen Malformation  Fistulous connection - cerebral arteries and midline prosencephalic vein  2 types:  Choroidal - 90%, presents in neonate as CHF and intracranial bruit  Mural - presents in infancy with developmental delay, seizures, and hydrocephalus
  44. 44. Gray-scale and Doppler coronal USG demonstrating a cystic midline structure in the region posterior to third ventricle with mass effect. Typical swirl effect is noted on Doppler
  45. 45. Chiari II Malformation  Batwing configuration of frontal horns  Small posterior fossa with low-lying tentorium  Interdigitating gyri  Large massa intermedia  Absence of corpus callosum  Hydrocephalus  Nearly 100% have myelomeningocele
  46. 46. Dandy Walker Malformation  Posterior fossa cyst which communicates with 4th ventricle (arachnoid cyst and enlarged foramen magnum do not)  Large posterior fossa  Hypoplastic cerebellar vermis and laterally displaced cerebellar hemispheres  Frequently associated with other anomalies
  47. 47. Temporal lobe arachnoid cyst  Most common intracranial congenital cystic lesion  Can have mass effect and bony remodeling  Same appearance as CSF on all imaging modalities
  48. 48. Holoprosencephaly Alobar Holoprosencephaly Semilobar Holoprosencephaly
  49. 49. Semilobar Holoprosencephaly  Hypoplastic falx and interhemispheric fissure  Partially separated thalamus  Intermediate in severity between alobar and lobar holoprosencephaly  Can have associated facial anomaly
  50. 50. Lissencephaly  Lack of gyration and sulcation  Thickened cortex  Colpocephaly  Homogeneous or “pseudoliver” appearance to the brain parenchyma  “Figure eight appearance” due to shallow sylvian fissures  Can result from intrauterine infection
  51. 51. Congenital Absence of the Corpus Callosum  80% have associated anomalies  Parallel lateral ventricles  Elevated 3rd ventricle  Absent cingulate gyrus and sulcus  “Sunburst sign” - radially arranged sulci  Probst bundles impress upon lateral ventricles
  52. 52. References  Bhat V, Bhat V. Neonatal neurosonography: A pictorial essay. Indian J Radiol Imaging. 2014 Oct;24(4):389-400.  Lowe LH, Bailey Z. State-of-the-Art Cranial Sonography: Part 1, Modern Techniques and Image Interpretation. AJR Am J Roentgenol. 2011;196:1028–33.  De Vries LS, Eken P, Dubowitz LM. The spectrum of leukomalacia using cranial ultrasound. Behav Brain Res 1992;49:1-6.

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