Alan Hill

Current concepts of hypoxic-ischemic cerebral injury in the term newborn

Acute perinatal hypoxic-ischemic cerebral injury in the term newborn is a major cause of long-term neurologic abnormalities in childhood. Earlier diagnosis and more precise localization of hypoxic-ischemic cerebral injury has been made possible by optimal timing and the use of new imaging modalities (e.g., magnetic resonance imaging, spectroscopy, computed tomography, cerebral perfusion techniques). Recent concepts on pathogenesis of such injury involves metabolic factors, regional distribution of excitatory (glutamate) synapses, and factors related to active myelination in specific areas at the time of insult. Consideration of these aspects of pathogenesis permit a rational approach to the management of this major neurologic problem in the newborn.

White Matter Injury in Term Newborns With Neonatal Encephalopathy

White matter injury (WMI) is the characteristic pattern of brain injury detected on magnetic resonance imaging in the premature newborn. Focal noncystic WMI is increasingly recognized in populations of term newborns. The aim of this study was to describe the occurrence of focal noncystic WMI in a cohort of 48 term newborns with encephalopathy studied with magnetic resonance imaging at 72 ± 12 h of life, and to identify clinical risk factors for this pattern of injury. Eleven newborns (23%; 95% CI 11–35) were found to have WMI (four minimal, three moderate, and four severe). In 10 of the 11 newborns, the WMI was associated with restricted diffusion on apparent diffusion coefficient maps. An increasing severity of WMI was associated with lower gestational age at birth (p = 0.05), but not lower birth weight. Newborns with WMI had milder encephalopathy and fewer clinical seizures relative to other newborns in the cohort. Other brain injuries were seen in three of the 11 newborns: basal nuclei predominant pattern of injury in one and cortical strokes in two. These findings suggest that WMI in the term newborn is acquired near birth and that the state of brain maturation is an important determinant of this pattern of brain injury.

Cortical visual impairment following birth asphyxia

Visual defects are often poorly recognized in children with multiple neurologic problems due to perinatal hypoxic-ischemic encephalopathy. We report the clinical, radiologic, and electrodiagnostic characteristics of 20 children with cortical visual impairment secondary to birth asphyxia. Clinical diagnosis often was delayed. Ten patients recovered vision during the first two years of life. Four infants had coexisting damage to the pregeniculate visual pathway. Useful investigations included cranial computed tomography and visual evoked potential mapping. Electroencephalographic abnormalities were nonspecific. The classical definition of cortical blindness must be modified for children.

Measurement of intracranial pressure using the Ladd intracranial pressure monitor

an intraperitoneal air-fluid level on a true horizontal beam roentgenogram; if present, laparotomy is indicated. If a neonate has both a posterior pneumomedias t inum and a large pneumoperi toneum, or a peak inspiratory pressure of at least 30 cm H~O with evidence of extraalveolar air a n d a large pneumoperi toneum, the infant can be safely observed. If a ventilated neonate with a pneumoperi toneum has no extra-alveolar air dissection and a peak inspiratory pressure o f less than 28 cm H20, laparotomy should be undertaken. Although each of our 12 cases could be retrospectively differentiated, some may occur in which a clear differentiation cannot be made because of inconsistency of the above findings. In such a situation, additional information is needed. Paracentesis with an intravascular catheter is advocated as the next diagnostic maneuver to allow a prompt decision regarding operation. Looking for a leak on serial decubitus films performed with water, soluble contrast using Portable equipment in the nurserY , or waiting for the development of an intraperitoneal airfluid level on serial decubitus films wastes time for an infant who may have peritonitis; these findings are helpful only if they are positive. Paracentesis allows prompt assessment of a continuous air leak, measurement of the oxygen concentration in the peritoneal gas, and the sampling of any intra-abdominal fluid present. Bubbling from the drainage tubing with ventilator cycling confirms the respiratory origin of the pneumoperi toneum. 6 A high oxygen concentration in the peritoneal gas favors a respiratory origin of the pneumoperi toneum. 7 Obtaining more than one-half a cubic centimeter of green or turbid brown fluid on aspiration favors a diagnosis of intestinal perforationY

Germinal matrix–intraventricular hemorrhage in the premature newborn: management and outcome

Germinal matrix-intraventricular hemorrhage (GMH-IVH) in the premature newborn results from rupture of fragile capillaries in the germinal matrix. Its pathogenesis is multifactorial and relates principally to a pressure-passive cerebral circulation, fluctuations in cerebral blood flow, and derangements of coagulation and fragility of the germinal matrix microvasculature. Several interventions have beneficial effects for prevention of GMH-IVH. Outcome after GMH-IVH relates largely to the severity of hemorrhage, the extent of hemorrhagic and ischemic parenchymal involvement, and complications (e.g., posthemorrhagic hydrocephalus). Even in the absence of neuroimaging abnormalities, VLBW infants have a high incidence of academic and behavioral problems which persist into adolescence and early adulthood.

Intraventricular hemorrhage and posthemorrhagic hydrocephalus. Current and potential future interventions.

Enhanced survival of very premature infants may be regarded as the most striking demonstration of the major improvements in perinatal medicine during the last two decades. This article discusses recent perinatal interventions in the context of the pathogenesis and know risk factors for intraventricular hemorrhage (IVH). In addition, controversies related to the evolution and management of posthemorrhagic hyrdocephalus (PHH) are examined, and current concepts concerning potential brain injury to PHH are reviewed.

Brain Injury Patterns in Hypoglycemia in Neonatal Encephalopathy

In this study, prospective imaging was obtained in 179 term newborns with available glucose data. In these subjects, hypoxic-ischemic encephalopathy resulted in watershed, basal ganglia, total brain, and multifocal injury patterns. In 34 babies with hypoglycemia, selective involvement of posterior white matter and pulvinar edema were found. Conclusion: In term infants with hypoglycemia, specific imaging features for both hypoglycemia and hypoxia-ischemia can be identified. BACKGROUND AND PURPOSE: Low glucose values are often seen in term infants with NE, including HIE, yet the contribution of hypoglycemia to the pattern of neurologic injury remains unclear. We hypothesized that MR features of neonatal hypoglycemia could be detected, superimposed on the predominant HIE injury pattern. MATERIALS AND METHODS: Term neonates (n = 179) with NE were prospectively imaged with day-3 MR studies and had glucose data available for review. The predominant imaging pattern of HIE was recorded as watershed, basal ganglia, total, focal-multifocal, or no injury. Radiologic hypoglycemia was diagnosed on the basis of selective edema in the posterior white matter, pulvinar, and anterior medial thalamic nuclei. Clinical charts were reviewed for evidence of NE, HIE, and hypoglycemia (<46 mg/dL). RESULTS: The predominant pattern of HIE injury imaged included 17 watershed, 25 basal ganglia, 10 total, 42 focal-multifocal, and 85 cases of no injury. A radiologic diagnosis of hypoglycemia was made in 34 cases. Compared with laboratory-confirmed hypoglycemia, MR findings had a positive predictive value of 82% and negative predictive value of 78%. Sixty (34%) neonates had clinical hypoglycemia before MR imaging. Adjusting for 5-minute Apgar scores and umbilical artery pH with logistic regression, clinical hypoglycemia was associated with a 17.6-fold higher odds of MR imaging identification (P < .001). Selective posterior white matter and pulvinar edema were most predictive of clinical hypoglycemia, and no injury (36%) or a watershed (32%) pattern of injury was seen more often in severe hypoglycemia. CONCLUSIONS: In term infants with NE and hypoglycemia, specific imaging features for both hypoglycemia and hypoxia-ischemia can be identified.

Newborn radial nerve palsy: report of four cases and review of published reports

Four newborns presented with isolated radial nerve palsy during the first 2 days of life. In three, there was a history of failure of progression of labor, which may have resulted in prolonged radial nerve compression. Furthermore, three infants had fat necrosis of the upper arm above the elbow, suggestive of compression of the radial nerve in the region of the spiral groove. Significant recovery of function was evident within 1 month in all four infants. The authors review published reports about the rare condition of isolated radial nerve palsy in the newborn.

Evolution of pattern of injury and quantitative MRI on days 1 and 3 in term newborns with hypoxic-ischemic encephalopathy

Background:Brain injury in term neonatal hypoxic–ischemic encephalopathy (HIE) emerges on magnetic resonance imaging (MRI) by day 3. This study aimed to address the relationship of MRI, diffusion tensor imaging (DTI), and MR spectroscopic imaging (MRSI) findings on days 1 and 3 in a prospective cohort of term newborns with HIE.Methods:A total of 24 term newborns with HIE were prospectively studied with MRI on days 1 and 3; 19 were imaged with DTI and MRSI on days 1 and 3. MRI was assessed using validated scores. The relationship between MRI, DTI, and MRSI values on days 1 and 3 was determined using linear regression for repeated measures.Results:Conventional MRI showed a complex variation of findings from day 1 to 3. In gray matter, mean diffusivity (Dav) and metabolite ratios measured on day 1 were predictive of values on day 3 (all P ≤ 0.04). In white matter, Dav, fractional anisotropy (FA), and N-acetylaspartate (NAA)/choline on days 1 and 3 were strongly related (all P ≤ 0.003). Hypothermia appeared to attenuate the severity and progression of brain injury in the six treated newborns.Conclusion:In term newborns with HIE, quantitative MR values on days 1 and 3 are strongly associated, providing an objective measure of injury before qualitative images.

MAGNETIC RESONANCE IMAGING IN PSEUDOTUMOR CEREBRI

The pathophysiology of pseudotumor cerebri is unclear, but may relate to an abnormality in water transport in the brain. The authors performed MR imaging in seven children with pseudotumor cerebri; the signal intensity in the white matter was normal in all patients. These data suggest that periventricular brain water content is not increased markedly in children with pseudotumor cerebri. The authors speculate that this may relate to the establishment of an equilibrium between increased resistance to cerebrospinal fluid outflow and increased brain stiffness, occurring as a consequence of increased cerebral blood‐volume and/or interstitial pressure.