CRANIAL ULTRASONOGRAPHY IN NEWBORN

USG IN NEONATES

1. Cranial Ultrasonography in the Newborn Dr. Murtaza Kamal MBBS, MD, DNB Division of Neonatology Department of Pediatrics Safdarjung Hospital & VMMC, New Delhi DOP- 23.11.2011

2. Introduction Neonatal Care in India is advancing at an impressive phase at the level of the community as well as in tertiary care unit. The concept of survival of the new born has predictably given way to the importance of “ INTACT SURVIVAL ” of the high risk infant ,prompting initiation of strategies to identify neurological subnormality at the earliest. Advances in imaging techniques have contributed significantly to early detection of abnormalities of the brain.

3. Ultrasonography ,now ubiquitously available,is an ideal tool for primary screening of neonatal brain. Despite the wide availability of USG machine in the hospitals,the penetration of CUS in Indian NICUs is still very little. In this guideline,an attempt will bemade to answer the following issues related to the use of CUS in the new borns :

4. Role of CUS in the newborn Characteristics of USG equipment Technical aspects of performing the USG examination Indications of doing CUS in preterm and term neonates Objective grading of lesions and prognostic significance

5. Need of Imaging in Neonatal Units Demonstration of cerebral pathologies in premature and sick newborn babies  hemorrhage,ischemia and ventricular dilaatation . Knowledge of cerebral pathology  predicting neurological outcome according to the grade of injury. To assess the timing of brain injury ( eg : in neonatal encephalopathy,early CUS  determining as to whether the injury was antenatal or postnatal) 1 .

6. Why CUS as a tool? Safe and radiation free. Safety well established in fetuses and infants except  transcranial doppler  local rise of temperature and cavitation if performed for long duration 1 . Bedside. Portable USG machine  in the NICU  point of care testing (POCT).

7. Reliable for commonly occuring neonatal conditions  hemorrhages,cystic lesions,major malformations and fluid collections. Can be initiated even immediately after birth  suitable for screening. Can be repeated as often as possible without any adverse effects  proper follow up of babies with neurological problems.

8. Significantly cheaper modality of neuroimaging compared with other techniques 1 .

9. Requirements for a CUS Machine Easily transportable to the bed side in the NICU. Settings and knobs should be easy to operate. Should have colour doppler in it,to measure the vascular resistance and cerebral blood flow. Special software and presets for neonatal CUS,making procedure easier and consistent.

10. Should have the ability to store images for later reproducibility. A facility to print images and generate reports. Detailed technical specifications on:www.nfequipment.org

11. Transducer requisites 5 Sector or curved linear probe. Ideal frequency 5-8 MHz ,usually as a multifrequency probe.Higher frequencies  better near-view resolution but loose penetration. Transducer head  appropriately sized to fit AF. Transducer gel  good contact between the probe and skin.

12. Who should do? A caregiver having good knowledge of the brain anatomy,maturational changes and common pathologies at various gestational ages. A pediatric radiologist with experience of CUS in newborn. A neonatologist with special training and experience in neonatal CUS. I mages should  stored for records,review and confirmation.

13. During the procedure these vulnerable babies  handled gently,avoid procedure related hypothermia and follow standard asepsis protocols.

14. Windows in the skull useful for CUS examination Several windows in the unfused skull  look into various parts of the brain with a reasonable degree of accuracy and detail 5 : Standard or Conventional views  obtained through AF. Coronal planes :Probe swept from orbits to occiput , 6 views ,marker on the right.

15. Saggital planes :Probe swept from midline to either side till sylvian fissures and insulae.A midline and 2 views on either side are recorded.Posterior part of probe angled a little laterally to get a complete view of the lateral ventricles.Be careful to mark as to which side is being scanned. Supplemental windows ( Posterior,Mastoid and Temporal fontanelle ):Help visualise structures closer to the windows in a better way  the probes of higher frequencies.

16. Additional windows  skill and expertise  cannot be used initially during the learning process. These views useful in suspected cerebellar hemorrhage/posterior fossa abnormalities (baby with respiratory instability,stridor,neck retraction or suspicion on a standard CUS),in IVH to r/o occipital or cerebellar extension or in ventricular dilatation of unknown origin.

17. Approach in doing CUS 5 The following points need to be considered when doing CUS: Are the anatomical structures distinguishable ,do they appear normal?Is it essential to identify the following structures-ventricular system,interhemispheric fissures,corpus callosum,sylvian fissure,thalamus and basal ganglia. Does the maturation of the brain appear appropriate for the gestation?Degree of cortical folding on the cortical surfaces and along the interhemispheric fissure is to be looked at.

18. Are the basal ganglia and thalami prominently echogenic ? Is the normal echogenicity and homogenicity of periventricular and subcortical white matter ? Does the size,lining and the echogenicity of ventricular system appear normal? In case of ventricular enlargement,the ventricles should be measured and compared with normograms .

19. Are there any extra axial collections such as subarachnoid hemorrhage or subdural effusion? Is there a midline shift? The findings should be recorded in a structured performa .

20. Indications Screening CUS in a premature baby. Clinical suspicion of intracranial hemorrhage. Neonatal seizures. Evaluation of large or rapidly enlarging head. Serial follow up of post hemorrhagic hydrocephalus. Hypoxic Ischemic encephalopathy.

21. Lesions accurately detected by CUS Recommendation :CUS is useful in detecting IVH,cystic PVL and ventriculomegaly besides important congenital malformations such as hydrocephalus,corpus callosum agenesis and others. Evidence :In 4 studies 13-16 reporting results of a total of 87 autopsies on PT infants,USG was 76% to 100% accurate in detecting grade 1 lesions of >5mm and grade 3 and grade 4 hemorrhages. Detection of grade 2 hemorrhage was much less accurate.

22. Correlation of USG findings of cystic PVL with neuropathological data was evaluated in 3 studies 16-18 .Each study found 100% correlation b/w USG finding and neuropathologic data. Also particularly useful in detecting some important congenital malformations such as cystic lesions( hydrocephalus,porencephalic cysts,Dandy Walker cysts complex,holoprosencephaly,choroid plexus cysts and arachnoid cysts),corpus callosum agenesis and aneurysm of vein of Galen ( colour doppler ).

23. Screening CUS in a premature baby Screening CUS in premature infants detect IVH,cystic PVL and ventriculomegaly.Detection of agenesis of corpus callosum,cystic lesions,and vein of Galen malformation  chance findings. Recommendations :Routine screening CUS should be performed on all infants with birth weight <1250 grams or gestation <30 weeks, irrespective of signs and symptoms.

24. Timing of screening CUS USG evidence of injury to the developing brain varies with time. Grade 3 and 4 IVH,which may alter medical management,may be detected as late as 3 rd wol . Cystic PVL and ventriculomegaly,which may alter prognosis and treatment programs,may be first seen by USG at term. These lesions may be detected in many infants after previously normal USG finding.

25. Levene’s Index used in premature babies  measure ventriculomegaly ,measured as a distance b/w falx (or inter hemispheric fissure) to the lateral tip of lateral ventricle in the plane of 3 rd ventricle. Screening USG  done to identify lesions which help in acute management or in prognostication. Ideal time of screening  varies from day 1 ol to discharge from hospital or at term corrected age.

26. Recommendation:Screening CUS should be performed on all infants with GA of <30 weeks at 7 to 14 dol and should be optimally repeated at 36 to 40 weeks’ postmenstrual age.This is to detect clinically unsuspected IVH and also PVL/ventriculomegaly 8 . In babies <28 weeks a CUS may be done on d1ol to r/o severe IVH and anterior brain injury.This may facilitate decision making for aggressive management of such infants.

27. Apart from screening USG,CUS in PT infants is required in the following clinical situations: Neonatal seizures (major malformations,intra cranial hemorrhage). Clinical suspicion of intracranial hemorrhage. Unexplained CCF (Vein of Galen and AV malformations).

28. Ability of CUS to predict long term neurodevelopmental outcome in VLBW infants One of the aims of screening neonatal CUS is to identify neonates at risk of long term neurodevelopmental outcome such as: Cerebral palsy Lower IQs Sensory impairments or motor handicaps.

29. Recommendations:For VLBW infants,CUS can be used to predict long term neurodevelopmental outcome. The findings of grade 3 and 4 IVH , periventricular cystic lesions,and moderate to severe ventriculomegaly are all associated with adverse outcomes.

30. Usefulness in term babies with encephalopathy Following pathologies may be detected by careful USG examination in a term baby with encephalopathy: Basal ganglia injury  echodense (hemorrhagic necrosis) , echolucent lesions (non hemorrhagic necrosis). Focal ischemic lesion  echodensity in an area of vascular distribution associated with loss of pulsations in the affected vessel.

31. Periventricular injury ,like in a premature baby  periventricular flare,cyst formationand progressive ventricular dilatation. Can’t detect other forms of injury seen in HIE such as selective neuronal necrosis(cortical and brain stem) and parasaggital injury. Detect indirect evidence of cerebral edema in the form of chinked ventricles.Easily detect various forms of ICB such as cerebellar,parenchyma and IVH associated with asphyxia.

32. Recommendations:At present evidence does not support the role of routine grey scale CUS in the diagnosis and management of term neonate with encephalopathy. However in cases of encephalopathy,a screening USG may occasionally detect structural malformations,ischemic insults such as porencephalic cysts and hemorrhagic manifestations such as ICH.

33. Role of Doppler in CUS Doppler assesssment  measurement of cerebral blood flow velocity (cerebral hemodynamics ). Main indication  to measure the CBF in babies with HIE. CBF velocities initially increase due to hyperperfusion and later decrease in those who develop HIE.

34. Asymmetry in the MCA Doppler  infants with u/l MCA infarction. Arterial,venous or AV malformations/thrombosis can also be detected. Recommendations:RI <.5 or >.9 in the CBVs is associated with immediate and long term poor outcome,but the current evidence is inadequate to suggest routiene doppler screening of HIE infants. Resistive index(RI):Measures the cerebral blood flow velocity.

35. Limitations of CUS Evaluation of superficial structures just beneath the probe  difficult.Use a high frequency probe or view by a different window. Visualization and precise deliniation of posterior fossa structures not possible unless one gets perfection to use supplemental windows. Extracerebral hemorrhages not well deliniated (SAH,SDH,EDH).

36. Damage to basal ganglia is not precisely detected. Ischemia difficult to detect compared to the hemorrhages.

37. Next best imaging techniques if CUS information is inadequate CUS,CT and MRI complementary in modern neonatology. Main drawback of CT and MRI  these require the babies to be shifted to another place. More expensive. CT carries risk of radiation Monitoring of babies during CT/MRI  difficult.

38. CT Brain Extremely sensitive to detect all forms of ICH including SD and SAH. Cerebral calcifications and cystic malformations  easily detected. R-> apidly performed.No sedation. For encephalopathic term neonates -2 studies suggested that low attenuation in the basal ganglia and/or thalami indicates severe injury consistent with HIE.

39. MRI Brain Very sensitive in early detection of HIE. Diffuse and non cystic lesions better detected. Precisely delineates cortical dysplasia 9 . Time consuming. Cannot be repeated frequently.

40. Recommendations:Currently,data available for class 2 studies do not provide sufficient evidence that routiene MRI should be performed on all VLBW infants for whom results of screening CUS are abnormal.

41. Intracranial Hemorrhage Grades Grade 1 Subependymal hemorrhage only Grade 2 SEH +Blood in non dilated ventricles Grade 3 SHE +Blood in dilated ventricles Grade 4 SHE +Blood in dilated ventricles + Intraparenchymal blood.

42. PVL Grades Grade 1 Transient echodensities persisting for >7 days Grade 2 The above evolving into small localised frontoparietal cyst Grade 3 Extensive cystic lesions Grade 4 Extending into deep white matter.

43. Ventriculomegaly Mild .5-1cm Moderate 1-1.5cm Severe >1.5cm

44. Lateral Ventricals measurement Levene’s Index: Mostly used in premature babies  measured as a distance b/w falx to the lateral tip of lateral ventricle in the plane of 3 rd ventricle. Ventricular Head Ratio (VHR): In full term babies the ventricular size  measured as a ratio b/w combined coronal ventricular width to combined hemispheric width.

45. Doppler Vascular Measurement The DVM can be made on all cerebral vessels. Vessels that are earliest to access are ACA,best seen through the AF in the sagittal plane and the MCA best seen through the temporal window in the axial plane. Resistive index calculation:PS -ED/PS Where PS=Peak systolic velocity and ED=End diastolic velocity.The normal range fo the RI IS ABOUT .65-.90.Values <.5 or>.9 are abnormal.

46. Take home message CUS is the best point of care neuroimaging methord available for preterm and sick babies. The USG mechine should be portable,should have presets for neonatal CUS and there should be facility to print and store the images.The transducer should be of 5-8 Mhz multifrequency sector probe and its head be small enough to fit the windows. The sonographer should have knowledge about the brain anatomy,maturation,common neurological morbidities and the art of handling such fragile patients.

47. A systemic structured approach should be followed to detect cerebral pathology and the same should be documented methodically. PVH,cystic PVL ad VD can be accurately detected and followed by CUS. Routiene screening CUS should be performed on all infants with bw <1250 grams or gestation <30 weeks.

48. Screening CUS should be performed at 7 to 14 days of age and repeted at 36 to 40 weeks postmenstrual age. Role of grey-scale CUS in term asphyxiated babies is not proven.However measurement of CBF by Doppler helps in predicting the neurodevelopmental outcome in HIE.

49. Thank you