Imaging of Perinatal Stroke

Neuroimaging of Neonatal Stroke: Venous Focus

Perinatal venous infarcts are underrecognized clinically and at imaging. Neonates may be susceptible to venous infarcts because of hypercoagulable state, compressibility of the dural sinuses and superficial veins due to patent sutures, immature cerebral venous drainage pathways, and drastic physiologic changes of the brain circulation in the perinatal period. About 43% of cases of pediatric cerebral sinovenous thrombosis occur in the neonatal period. Venous infarcts can be recognized by ischemia or hemorrhage that does not respect an arterial territory. Knowledge of venous drainage pathways and territories can help radiologists recognize characteristic venous infarct patterns. Intraventricular hemorrhage in a term neonate with thalamocaudate hemorrhage should raise concern for internal cerebral vein thrombosis. A striato-hippocampal pattern of hemorrhage indicates basal vein of Rosenthal thrombosis. Choroid plexus hemorrhage may be due to obstruction of choroidal veins that drain the internal cerebral vein or basal vein of Rosenthal. Fan-shaped deep medullary venous congestion or thrombosis is due to impaired venous drainage into the subependymal veins, most commonly caused by germinal matrix hemorrhage in the premature infant and impeded flow in the deep venous system in the term infant. Subpial hemorrhage, an underrecognized hemorrhage stroke type, is often observed in the superficial temporal region, and its cause is probably multifactorial. The treatment of cerebral sinovenous thrombosis is anticoagulation, which should be considered even in the presence of intracranial hemorrhage. ©RSNA, 2024 Test Your Knowledge questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Intracranial Hemorrhage in Term and Late-Preterm Neonates: An Institutional Perspective

BACKGROUND AND PURPOSE

Distribution of intracranial hemorrhage in term and late-preterm neonates is relatively unexplored. This descriptive study examines the MR imaging-detectable spectrum of intracranial hemorrhage in this population and potential risk factors.

MATERIALS AND METHODS

Prevalence and distribution of intracranial hemorrhage in consecutive term/late-preterm neonates who underwent brain MR imaging between January 2011 to August 2018 were assessed. MRIs were analyzed to determine intracranial hemorrhage distribution (intraventricular, subarachnoid, subdural, intraparenchymal, and subpial/leptomeningeal), and chart review was performed for potential clinical risk factors.

RESULTS

Of 725 term/late-preterm neonates who underwent brain MR imaging, intracranial hemorrhage occurred in 63 (9%). Fifty-two (83%) had multicompartment intracranial hemorrhage. Intraventricular and subdural were the most common hemorrhage locations, found in 41 (65%) and 39 (62%) neonates, respectively. Intraparenchymal hemorrhage occurred in 33 (52%); subpial, in 19 (30%); subarachnoid, in 12 (19%); and epidural, in 2 (3%) neonates. Twenty infants (32%) were delivered via cesarean delivery, and 5 (8%), via instrumented delivery. Cortical vein thromboses were present in 34 (54%); periventricular or medullary vein thromboses, in 37 (59%); and cerebral venous sinus thrombosis, in 5 (8%). Thirty-seven (59%) had elevated markers of coagulopathy (international normalized ratio > 1.2, fibrinogen level < 234), 9 (14%) had a clinically meaningful elevation in the international normalized ratio (>1.4), and 3 (5%) had a clinically meaningful decrease in the fibrinogen level (<150). Three (5%) neonates had thrombocytopenia (platelet count < 100 × 103/μL).

CONCLUSIONS

While relatively infrequent, there was a wide distribution of intracranial hemorrhage in term and late-preterm infants; intraventricular and subdural hemorrhages were the most common types. We report a high prevalence of venous congestion or thromboses accompanying neonatal intracranial hemorrhage.

Neuroimaging Perspectives of Perinatal Arterial Ischemic Stroke

Perinatal stroke ranks second only to that of adult stroke in the overall stroke incidence. It is a major contributor to long-term neurological morbidity, which includes cognitive dysfunction, cerebral palsy and seizures. Risk factors for stroke in the perinatal period differ from those in children and tend to be multifactorial. Differences in territorial predilection, response to injury, and stroke evolution exist when compared with childhood and adult stroke, and also among differing gestation age groups in the perinatal period (i.e., extreme preterm versus preterm versus term). The role of imaging is to diagnose stroke, exclude stroke mimics, establish the nature of stroke (arterial versus venous), and aid in prognostication. Magnetic resonance imaging is the mainstay of neuroimaging in perinatal stroke. Advanced imaging techniques such as diffusion tensor imaging and perfusion-weighted imaging are emerging as useful supplements to conventional imaging sequences. Here we describe the neuroimaging of perinatal arterial ischemic stroke with emphasis on imaging techniques, imaging phenotypes, stroke evolution, role of advanced imaging, and differences between stroke in preterm and term neonates. We also briefly describe the emerging role of fetal magnetic resonance imaging in the diagnosis of in utero stroke.

Correction to: Venous pathologies in paediatric neuroradiology: from foetal to adolescent life

The original version of this article unfortunately contained a referencing omission. Figure 11 is reused from the original publication of Figure 10 of Gunny and Lin [1].

ACR Appropriateness Criteria® Cerebrovascular Disease-Child

Stroke is an uncommon but an important and under-recognized cause of morbidity and mortality in children. Strokes may be due to either brain ischemia or intracranial hemorrhage. Common symptoms of pediatric acute stroke include headache, vomiting, focal weakness, numbness, visual disturbance, seizures, and altered consciousness. Most children presenting with an acute neurologic deficit do not have an acute stroke, but have symptoms due to stroke mimics which include complicated migraine, seizures with postictal paralysis, and Bell palsy. Because of frequency of stroke mimics, in children and the common lack of specificity in symptoms, the diagnosis of a true stroke may be delayed. There are a relatively large number of potential causes of stroke mimic and true stroke. Consequently, imaging plays a critical role in the assessment of children with possible stroke and especially in children who present with acute onset of stroke symptoms. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

[Hypoxic-ischemic brain damage in premature newborns]

One of the main causes of cerebral dysfunction in premature newborns is hypoxia. High mortality and lifelong morbidity in these children is a frequent result of neonatal hypoxic brain damage. The article presents some data on the prevalence of neurological diseases that have arisen in the perinatal period, and highlights the key etiological factors leading to hypoxia in both the intranatal and early postnatal periods. The pathogenesis of hypoxic-ischemic brain lesions in premature infants is described in detail. At the same time, more careful consideration is given to the glutathione system, which protects against lipid peroxidation, the glutamate-calcium cascade, and the excitotoxicity mediated by it, as well as the processes of necrosis and apoptosis of nerve cells. The advantages and disadvantages of modern methods for diagnosing cerebral lesions are noted, and the principles of treatment of these disorders are analyzed.

Tales from the Night:: Emergency MR Imaging in Pediatric Patients after Hours

Overnight in-house radiology has rapidly become an important part of contemporary practice models, and is increasingly the norm in pediatric radiology. MR imaging is an indispensable first-line and problem-solving tool in the pediatric population. This has led to increasingly complex MR imaging being performed "after hours" on pediatric patients. This article reviews the factors that have led to widespread overnight subspecialty radiology and the associated challenges for overnight radiologists, and provides an overview of up-to-date imaging techniques and imaging findings of the most common indications for emergent MR imaging in the pediatric population.

Usefulness of Cranial Ultrasound for Detecting Neonatal Middle Cerebral Artery Stroke

Magnetic resonance imaging is the gold standard technique in establishing the diagnosis of neonatal arterial ischemic stroke (NAIS). The diagnostic value of cranial ultrasound scanning in this clinical context is controversial. We aimed to assess the current sensitivity of the cranial ultrasound scan (CUS) in detecting NAIS, as this issue has not been well described in the literature. Newborns with NAIS diagnosed by magnetic resonance imaging between 2010 and 2016 were included. All CUSs were blindly analyzed retrospectively by a neonatologist expert in neuroimaging and compared with the findings of non-expert evaluators recorded on medical charts immediately after performing the evaluation. The overall sensitivity of CUS in detecting an imaging finding suggestive of NAIS was 87% (95% confidence interval (CI): 79%-95%) for an expert evaluator, but declined to 72% (61%-83%) when performed by a non-expert evaluator (p 0.002). Sensitivity was 83% and 61% in the first 24 h and 86% and 66% at 24-48 h for expert and non-expert evaluators, respectively (p < 0.05). CUS has higher sensitivity than previously reported in the detection of a NAIS, for both expert and non-expert evaluators. These findings may be explained by the advanced technology of new ultrasound equipment. Expertise in performing CUS is useful, particularly in the first 48 h after clinical debut.

Pathways for Neuroimaging of Neonatal Stroke

PURPOSE

To provide consensus-based, suggested imaging protocols to facilitate the accurate and timely diagnosis of a neonate with symptoms concerning for stroke.

METHODS

The Writing Group, an international collaboration of pediatric neurologists and neuroradiologists with expertise in perinatal and childhood stroke, participated in a series of pediatric stroke neuroimaging symposia. These discussions, in conjunction with extensive literature review, led to a consensus for imaging protocols to guide practitioners in the diagnosis of neonatal stroke subtypes as defined by the National Institute of Neurological Disorders and Stroke Common Data Elements. The epidemiology, clinical presentation, and associated risk factors for arterial ischemic stroke, cerebral sinovenous thrombosis, and hemorrhagic stroke are reviewed, with a focused discussion regarding the role of neuroimaging for each subtype.

RESULTS

In a neonate with suspected stroke, magnetic resonance imaging is the preferred modality, given the lack of X-irradiation, superior anatomic resolution, and sensitivity for acute ischemia. Core recommended sequences include diffusion-weighted imaging and apparent diffusion coefficient mapping to diagnose acute ischemia, gradient-recalled echo or susceptibility-weighted imaging to detect intracranial blood and its breakdown products, and T1- and T2-weighted imaging to assess for myelination, extra-axial blood, and edema. Magnetic resonance angiography of the brain may be useful to detect vascular abnormalities, with venography if venous sinus thrombosis is suspected. The application of more novel sequences, as well as the utility of follow up-imaging, is also discussed.

Prognostication Value of Descending Corticospinal Tract DWI Signal in Neonatal Cerebral Sinovenous Thrombosis

BACKGROUND

Descending corticospinal tract diffusion-weighted magnetic resonance imaging (MRI) signal is predictive of poor motor outcome in neonatal and childhood arterial ischemic stroke. However, descending corticospinal tract diffusion-weighted MRI signal has not been documented in the setting of cerebral sinovenous thrombosis, and its role is not understood.

OBJECTIVE

We describe a neonate with cerebral sinovenous thrombosis, extensive diffusion restriction, and bilateral descending corticospinal tract diffusion-weighted MRI signal on MRI of the brain. We discuss the underlying mechanisms and implications of these findings in venous ischemia.

CONCLUSION

The prognostic value of descending corticospinal tract diffusion-weighted MRI signal differs when observed in cerebral sinovenous thrombosis from when observed in arterial ischemic stroke. Consequently, caution should be exercised in using descending corticospinal tract diffusion-weighted MRI signal to predict outcome in children with cerebral sinovenous thrombosis.