Ultrasound in the evaluation of hypoxic-ischemic injury and intracranial hemorrhage in neonates: the state of the art

Head Ultrasound and MR imaging in the evaluation of neonatal encephalopathy: competitive or complementary imaging studies?

Magnetic resonance (MR) imaging is superior to ultrasonography (US) for the evaluation and prognostication of neonates with neonatal encephalopathy (NE). Nonetheless, US may provide important information early in the course of NE and can be used to document the evolution of lesions. This article provides an overview of useful findings in the US evaluation of infants with NE. Although many of the findings do not appear as conspicuous or as extensively as they do on MR imaging, recognition and familiarity with subtle head US abnormalities may allow head US to play an important complementary role to MR imaging in the evaluation of infants with NE.

Sonographic diagnosis of intracranial hemorrhage and periventricular leukomalacia in premature African neonates

Transfontanelle ultrasound (US) was done prospectively and analyzed for intra-cranial hemorrhage (ICH) and periventricular leukomalacia (PVL) in 110 premature infants. The babies were divided into two subgroups according to their birth weights (BW): those with BW of 1500 g or less (n = 93) belonged to subgroup A while babies of BW between 1500 and 2500 g (n = 17) were placed in subgroup B. Overall incidence of ICH and PVL was 24.5 and 26.4%, respectively in the 110 cases studied. Under subgroup A, 26/93 (28.0%) cases had ICH while 22/93 (23.7%) cases had PVL. In subgroup B, 2/17 (11.8%) cases had ICH while PVL was noted in 7/17 (41.2%) cases. These results show that premature African children have a lower incidence of ICH but a higher incidence of PVL compared to babies from temperate regions. Genetic and environmental factors are probably responsible for these variations in the occurrence of both diseases in population groups from different geographical locations.

Early diagnosis of perinatal cerebral lesions in apparently normal full-term newborns by ultrasound of the brain

The brains of 1000 consecutive, clinically normal, full-term neonate without signs of perinatal distress were examined by ultrasound 3 days postpartum. We found 35 cases of intracranial haemorrhage (periventricular, choroid plexus and intraventricular); 34 possible sequelae of bleeding (subependymal and choroid plexus pseudocysts; local dilatation of the lateral ventricles) and 21 morphological aberrations. Most of these 90 abnormalities were checked several times. Four children with intracranial haemorrhage developed symptoms (3 hemipareses, 1 infantile spasm) within a year of birth. No child without sonographic abnormalities has so far been recognized as developing a clinical deficit.

Sequential change of heterogeneous cerebral blood blow patterns after diffuse brain ischemia

In order to provide an insight into the basic nature of ischemic brain injury, we sequentially studied cerebral blood flow with [99mTc]hexamethylpropyleneamine oxime single photon emission computed tomography (CBF imaging) in a patient with diffuse brain ischemia due to prolonged cardiac arrest. On the 10th postarrest day, concentrated blood flow over superior-medial portion of the occipital lobe was demonstrated. On the 18th postarrest day, the same region became high density on a CT scan, while the concentrated flow on the CBF imaging had diminished. Thus, an abnormal cerebral blood flow (CBF) pattern preceded the density change on CT scan. On the 23rd postarrest day, remarkably concentrated flow over the brainstem was demonstrated. This might have illustrated the reduced metabolic demand of the damaged tissue over the cerebral and cerebellar hemispheres with relative preservation of brainstem perfusion. In patients with diffuse brain ischemia, a CBF imaging may be a useful tool for clarifying pathological process and prognosis.

The predictive value of head ultrasound in the ECMO candidate

Cranial ultrasound (US) examination is the screening technique of choice for assessing preexisting neurological damage in potential neonatal extracorporeal membrane oxygenation (ECMO) candidates. Currently, US evidence of intracranial hemorrhage greater than grade I in severity is a contraindication to ECMO at this ECMO center. In the current study, radiological findings were reviewed in 129 consecutive neonatal ECMO cases in an attempt to identify which pre-ECMO US findings were associated with the development of subsequent intracranial complications while on ECMO. Pre-ECMO head US, post-ECMO head US, and head computed tomography (CT) scans were reviewed retrospectively by one radiology team. Ventricular, parenchymal, and extraaxial fluid abnormalities were recorded for each case. Pre-ECMO US findings were then correlated with the subsequent development of significant intracranial radiological abnormalities noted on post-ECMO studies as well as with clinical data regarding ECMO course and outcome. Results showed that infants with evidence of severe edema or periventricular leukomalacia on pre-ECMO imaging had a 63% incidence of subsequent major intracranial complications. This represents a significantly higher risk than in candidates with a normal examination or evidence of grade I intracranial hemorrhage, subependymal cysts, or mild edema. These results suggest that infants with sonographic evidence of ischemic or anoxic damage on pre-ECMO US are at high risk for the development of significant intracranial complications if ECMO therapy is instituted.

Echoencephalographic findings in neonates associated with maternal cocaine and methamphetamine use: incidence and clinical correlates

Term neonates (n = 74) exposed antenatally to cocaine, methamphetamine, or cocaine and a narcotic but without any other known perinatal complications were prospectively examined with cranial ultrasonography to detect the presence of central nervous system injury. These studies were compared with those of a drug-free but clinically ill group of infants (n = 87) at risk for hypoxicischemic encephalopathy, and with those of infants who were well. Cranial abnormalities were detected by ultrasonography in 35.1% of the drug-exposed infants, similar to the incidence in the infants at risk for hypoxic-ischemic injury (p = 0.7) but significantly greater than the 5.3% incidence of abnormalities in normal infants (p less than 0.001). The lesions in the drug-exposed infants were intraventricular hemorrhage, echodensities known to be associated with necrosis, and cavitary lesions; they were focused in the basal ganglion, frontal lobes, and posterior fossa. The presence of ultrasonographic abnormalities was not predicted by standard neonatal clinical assessment or by other perinatal risk factors present in the drug-using population. The types of cerebral injury are consistent with those seen in adult cocaine and methamphetamine abusers and are probably related to the vasoconstrictive properties of these drugs. Antenatal exposure to stimulant drugs is associated with significant risk for cerebral injury, even among seemingly normal term neonates.

Effect of timing of cerebral ultrasonography on the prediction of later neurodevelopmental outcome in high-risk preterm infants

To determine the predictive value of cranial ultrasonographic examination in high-risk preterm infants at different postnatal ages, we scanned 110 infants less than or equal to 32 weeks gestational age at 1, 2, 3, and 6 weeks postnatal ages and at 40 weeks postconceptional age (PCA). Cranial abnormalities detected by ultrasonography at each postnatal age of examination were classified as minor (periventricular superolateral echogenicity with or without intraventricular hemorrhage, grades 1 to 3) or major (cystic periventricular leukomalacia with or without intraventricular hemorrhage, grade 4) and correlated with neurodevelopmental outcome determined by 1 year of age. Major abnormalities detected by ultrasonography were present in four infants at 1 week, four at 2 weeks, eight at 3 weeks, and 11 infants at 6 weeks and 40 weeks PCA, respectively. Nineteen infants (17%) had moderate to severe functional handicaps defined as cerebral palsy, cognitive or visual deficit, or deafness. The positive and negative predictive values of ultrasound examinations, with regard to later neurodevelopmental outcome, improved with increasing postnatal age at examination and was best at 40 weeks PCA. Negative results of ultrasound study at 40 weeks PCA most correctly predicted satisfactory outcome. Although only 58% of moderately to severely handicapped infants were correctly identified by ultrasound examination at 40 weeks PCA, all infants with major ultrasonographic abnormalities at 40 weeks PCA had moderate or severe handicap. Our data demonstrate that the timing of cerebral ultrasonography is important in the prediction of later neurodevelopmental outcome in high-risk preterm infants.

Cerebral blood flow velocity pattern in healthy and asphyxiated newborns: a controlled study

In a controlled study serial determinations of cerebral blood flow velocity using Doppler ultrasound and repeated real-time ultrasonographic- or computerized axial tomographic studies of the brain were performed in 17 (nearly) full-term newborns who experienced perinatal asphyxia and in 17 healthy matched controls during the first week of life. A higher cerebral blood flow velocity was found during the first 4 days of life, indicating a lower cerebrovascular resistance in the asphyxiated infants compared to the control infants. These haemodynamic changes coincided with cerebral oedema and neurological abnormalities. It is speculated that the changes in the cerebral circulation in asphyxiated infants are at least partly caused by cerebral oedema-induced increase of intracranial pressure due to severe perinatal asphyxia. Serial Doppler ultrasound investigations of the brain may be a useful non-invasive method for early detection and follow-up of the consequences of severe perinatal asphyxia.

Cerebral infarction in term neonates: diagnosis by cerebral ultrasound

Cranial ultrasound (US) through the newborn's open fontanelle can diagnose not only intracerebral hemorrhages but also diffuse and localized hypoxic-ischemic encephalopathies. Sonographically, it was possible to distinguish between different courses of cerebral ischemia in seven neonates: ischemic infarction, usually in the area of the middle cerebral artery: borderline infarction; transient ischemia. The patients showed lateralized seizures during the first days of life with a corresponding focus in the electroencephalogram (EEG). Computed tomography showed areas of partially reduced density corresponding to the regions of increased echogenicity in ultrasound. The course was various; prognosis was good except in one patient. Etiologically, embolism, thromboses or hypoxemia were responsible for cerebral infarction. In some cases secondary bleeding ensued. The prognostic value of cerebral lesions was dependent on the involved area, gestational age, and any concurrent hypoxic cerebral damage.

Cranial ultrasonography of neonatal periventricular/intraventricular hemorrhage: who, how, why and when?

The sex, age, and cranial ultrasound (US) findings of 742 premature neonates evaluated over a 3-year period were reviewed retrospectively. Examinations were performed with a mechanical-sector real-time unit using a 5 MHz or 7.5 MHz transducer. The caudothalamic groove was carefully imaged with periventricular/intraventricular hemorrhage diagnosed by previously described criteria. Intracranial hemorrhage occurred in 44% of patients with 20% being Grade 1, 10% Grade 2, 7% Grade 3, and 7% Grade 4. All hemorrhages occurred during the first week of life. Computed tomography is superior to US for demonstrating parenchymal changes and extent of hypoxic damage. Based on our 3-year experience and a review of the literature, we propose an algorithm for cranial imaging of the preterm neonate. This ordered, sequential approach to the premature neonate with possible intracranial hemorrhage permits accurate initial diagnosis as well as appropriate follow-up for potential complications of ventricular dilatation, hydrocephalus, porencephaly, and hypoxic encephalomalacia.

Neurosonography in full-term cerebral haemorrhage

Full-term as well as preterm infants are liable to cerebral haemorrhage. Not all paediatricians are aware of this, but the availability of ultrasound in many general hospitals which have paediatric beds is alerting them to this possibility. This account draws on a two-year experience at a paediatric institute to which full-term infants with neurological symptoms were referred from a wide area. During this time 23 cases were diagnosed and cases illustrating the spectrum are presented.