Elsevier

Pediatric Neurology

Volume 44, Issue 4, April 2011, Pages 254-258
Pediatric Neurology

Original Article
The Role of Hypoxia-Ischemia in Term Newborns with Arterial Stroke

https://doi.org/10.1016/j.pediatrneurol.2010.10.013Get rights and content

The role of generalized hypoxia-ischemia in the genesis of perinatal focal arterial stroke remains puzzling. Animal studies have demonstrated that hypoxia-ischemia may alter blood flow through the ductus venosus, thereby increasing the risk for placental emboli entering the cerebral circulation. A retrospective review was performed of clinical records of all term newborns admitted to a tertiary perinatal center between January 1995 and May 2007 with acute arterial stroke on neuroimaging during the first week of life. Newborns were classified into 2 groups on the basis of neuroimaging abnormalities: stroke alone, or stroke and nonfocal hypoxic-ischemic brain injury. A total of 62 newborns had focal or multifocal stroke, 36 with stroke alone and 26 with stroke with nonfocal hypoxia-ischemia. Multiple risk factors for hypoxia-ischemia occurred in most newborns in both groups. These data indicate that hypoxia-ischemia may play a role in the genesis of stroke in the term newborn with or without evidence of nonfocal hypoxic-ischemic brain injury on neuroimaging.

Introduction

Focal cerebral infarction in the distribution of a single (or multiple) major artery, also termed arterial stroke, is a distinctive pattern of perinatal brain injury of heterogeneous etiology that occurs predominately in term infants [1]. Although doubtlessly underrecognized during the newborn period, perinatal arterial stroke has been estimated to occur in approximately 1:2,500 to 1:5,000 term newborns [2] and accounts for 50-70% of hemiplegic cerebral palsy in this population [3]. The topography of perinatal arterial stroke identified by neuroimaging has demonstrated that 75% of lesions are unilateral, most commonly involving the distribution of the left middle cerebral artery [1].

Despite its frequent occurrence, the pathogenesis of perinatal arterial ischemic stroke remains poorly understood. Recognized causes include vascular maldevelopment, trauma, thrombosis from infection, coagulopathies, and emboli arising from cardiac sources, involuting placental and fetal vessels or traumatic catheter placement [1]. In a series of 250 newborns reported in the 1980s and 1990s, an underlying etiology could not be identified in 50%, and a specific underlying cause was identified in only approximately 15%. In the same series, 35% of strokes occurred in the context of perinatal asphyxia [1]. With more rigorous neuroimaging, focal/multifocal cerebral injury, especially focal arterial infarction (stroke), is increasingly recognized in term newborns with hypoxic-ischemic encephalopathy. In a prospective cohort study of 124 term newborns with neonatal encephalopathy related to hypoxia-ischemia, 6 had acute focal arterial stroke identified on neuroimaging [4]. The occurrence of stroke in this cohort was more frequent than in population-based data, which suggests that acute events during the intrapartum period are important in the pathogenesis of perinatal stroke and deserve to be examined more closely.

The objectives of this study were to compare the clinical risk factors or markers for hypoxic-ischemic insult in term newborns who had stroke alone or who had a combination of stroke and hypoxic-ischemic brain injury. Our hypothesis is that clinical risk factors for hypoxia-ischemia differ between term newborns with stroke alone compared to those who have a combination of stroke and additional nonfocal hypoxic-ischemic injury on neuroimaging.

Section snippets

Study Population

The study population comprised all term newborns (gestational age ≥36 weeks) admitted to a tertiary-level perinatal referral center between January 1995 and May 2007 in whom acute cerebral infarction in an arterial distribution was identified on neuroimaging (computed tomography [CT] and/or magnetic resonance imaging [MRI]) during the first week of life.

Review of neuroimaging was performed by a pediatric neuroradiologist (KP) who was blinded to the newborn’s medical history. Newborns were

Results

From January 1995 to May 2007, a total of 62 term newborns (36 boys) had acute focal or multifocal cerebral infarction in an arterial distribution on neuroimaging. Thirty-six (58%) had infarction alone (stroke group), and 26 (42%) had infarction as well as evidence of nonfocal hypoxic–ischemic brain injury on neuroimaging (stroke + hypoxia-ischemia group). The demographic data of these groups is compared in Table 1. There was no significant difference in the severity of neonatal encephalopathy

Discussion

Perinatal arterial stroke is not uncommon and often leads to significant long-term neurologic morbidity. We identified 62 term newborns with acute focal or multifocal arterial stroke during a 12-year study period. The location of infarction in our series is similar to previous reports, which demonstrated that most neonatal ischemic infarcts involve the anterior circulation with a predominance of unilateral left hemispheric lesions [1], which supports a thromboembolic etiology. Other possible

Conclusion

Few differences exist between term newborns who have stroke alone and those who have a combination of focal stroke and more extensive nonfocal hypoxic-ischemic injury in terms of clinical features and shared clinical risk factors or markers for hypoxia-ischemia. Thus hypoxic-ischemic insult may play a role in the genesis of arterial stroke in the term newborn even when it is not of sufficient magnitude to result in typical hypoxic-ischemic abnormalities on neuroimaging.

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