Deep nuclei injury distribution in isolated “basal ganglia–thalamus” (BGT) versus combined “BGT and watershed” patterns of hypoxic–ischaemic injury (HII) in children with cerebral palsy

Developmental anatomy of the thalamus, perinatal lesions, and neurological development

The thalamic nuclei develop before a viable preterm age. GABAergic neuronal migration is especially active in the third trimester. Thalamic axons meet cortical axons during subplate activation and create the definitive cortical plate in the second and third trimesters. Default higher-order cortical driver connections to the thalamus are then replaced by the maturing sensory networks, in a process that is driven by first-order thalamic neurons. Surface electroencephalographic activity, generated first in the subplate and later in the cortical plate, gradually show oscillations based on the interaction of the cortex with thalamus, which is controlled by the thalamic reticular nucleus. In viable newborn infants, in addition to sensorimotor networks, the thalamus already contributes to visual, auditory, and pain processing, and to arousal and sleep. Isolated thalamic lesions may present as clinical seizures. In addition to asphyxia and stroke, infection and network injury are also common. Cranial ultrasound can be used to classify neonatal thalamic injuries based on functional parcelling of the mature thalamus. We provide ample illustration and a detailed description of the impact of neonatal focal thalamic injury on neurological development, and discuss the potential for neuroprotection based on thalamocortical plasticity.

Distinguishing multicystic from focal encephalomalacia on delayed MRI in children with term hypoxic ischemic injury

BACKGROUND AND PURPOSE

To define cystic patterns resulting from term hypoxic ischemic injury (HII) on delayed Magnetic Resonance Imaging (MRI) and determine associated HII patterns and lesions that reflect the severity of injury, from a database of African children with cerebral palsy.

METHODS

Retrospective review of 1175 children with cerebral palsy due to term HII diagnosed on late MRI, identifying those with cystic changes. These were classified as multicystic or (multi-) focal-cystic, and were evaluated for associated injuries-thalami, basal ganglia, hippocampi, cerebellum, and presence of ulegyria.

RESULTS

Three hundred and eighty-eight of 1175 (33%) children had cystic encephalomalacia. Two hundred and seven of 388 (53.3%) had focal-cystic and 181/388 (46.6%) had multicystic injury. The focal-cystic group comprised 87.9% (182/207) with thalamic injury, 25.6% (53/207) with basal ganglia injury, and 15% (31/207) with cerebellar involvement. Basal-ganglia-thalamus (BGT) pattern was present in 43.9% (91/207) and ulegyria in 69.6% (144/207). In the multicystic group, 88.9% (161/181) had thalamic injury, 30.9% (56/181) had basal ganglia injury, and 21% (38/181) had cerebellar involvement. BGT pattern was observed in 29.8% (54/181) and ulegyria in 28.7%. (52/181). Significant associations (p<.05) were found between multicystic injury and caudate/globus pallidus involvement, and between focal-cystic pattern of injury and ulegyria.

CONCLUSIONS

Cystic encephalomalacia was seen in almost one-third of patients with term HII imaged with delayed MRI, with a similar prevalence of focal-cystic and multicystic injury. Multicystic injury was associated with caudate and globus pallidi involvement, typical of the BGT pattern of HII, whereas the focal-cystic pattern was associated with ulegyria, typical of watershed injury.

Frequency of Cerebellar Abnormalities Associated With the Differing Magnetic Resonance Imaging Patterns of Term Hypoxic-Ischemic Injury in Children

BACKGROUND

We aimed to determine the frequency of cerebellar injury using delayed magnetic resonance imaging (MRI) in children with cerebral palsy, diagnosed with term hypoxic-ischemic injury (HII), and to characterize this for the different MRI patterns of HII.

METHODS

We retrospectively reviewed delayed MRI scans in children with cerebral palsy, of whom 1175 had term HII. The pattern of HII was classified into basal ganglia-thalamus (BGT) pattern, watershed (WS) pattern, combined BGT/WS, and multicystic HII. Cerebellar location (hemisphere versus vermis) and the MRI characteristics were documented overall and for each of the different patterns of HII, as well as the association with thalamic injury.

RESULTS

Cerebellar injury was found in 252 of 1175 (21.4%) (median age 6 years [interquartile range: 3 to 9 years]). Of these, 49% (124 of 252) were associated with a BGT pattern, 13% (32 of 252) with a WS pattern, 28% (72 of 252) with a combined BGT/WS pattern, and 10% (24 of 252) with a multicystic pattern. The vermis was abnormal in 83% (209 of 252), and the hemispheres were abnormal in 34% (86 of 252) (with 17% [43 of 252] showing both vermis and hemispheric abnormality).

CONCLUSIONS

Over a fifth of patients with cerebral palsy due to HII had a cerebellar abnormality on delayed MRI, most commonly involving the vermis (83%), and as part of a BGT pattern of injury in just under half of these likely reflecting the association of cerebellar vermis injury with profound insults.

Neuroquantification enhances the radiological evaluation of term neonatal hypoxic-ischaemic cerebral injuries

Background

Injury patterns in hypoxic-ischaemic brain injury (HIBI) are well recognised but there are few studies evaluating cerebral injury using neuroquantification models.

Objectives

Quantification of brain volumes in a group of patients with clinically determined cerebral palsy.

Method

In this retrospective study, 297 children with cerebral palsy were imaged for suspected HIBI with analysis of various cerebral substrates. Of these, 96 children over the age of 3 years with a clinical diagnosis of cerebral palsy and abnormal MRI findings underwent volumetric analyses using the NeuroQuant® software solution. The spectrum of volumetric changes and the differences between the various subtypes (and individual subgroups) of HIBI were compared.

Results

Compared with the available normative NeuroQuant® database, the average intracranial volume was reduced to the 1st percentile in all patient groups (p < 0.001). Statistically significant differences were observed among the types and subgroups of HIBI. Further substrate volume reductions were identified and described involving the thalami, brainstem, hippocampi, putamina and amygdala. The combined volumes of five regions of interest (frontal pole, putamen, hippocampus, brainstem and paracentral lobule) were consistently reduced in the Rolandic basal ganglia-thalamus (RBGT) subtype.

Conclusion

This study determined a quantifiable reduction of intracranial volume in all subtypes of HIBI and predictable selective cerebral substrate volume reduction in subtypes and subgroups. In the RBGT subtype, a key combination of five substrate injuries was consistently noted, and thalamic, occipital lobe and brainstem volume reduction was also significant when compared to the watershed subtype.

Contribution

This study demonstrates the value of integrating an artificial intelligence programme into the radiologists' armamentarium serving to quantify brain injuries more accurately in HIBI. Going forward this will be an inevitable evolution of daily radiology practice in many fields of medicine, and it would be beneficial for radiologists to embrace these technological innovations.

Unequal Cerebral Magnetic Resonance Imaging Changes in Perinatal Hypoxic Ischemic Injury of Term Neonates

BACKGROUND

Perinatal hypoxic ischemic injury (HII) has a higher prevalence in the developing world. One of the primary concepts for suggesting that an imaging pattern reflects a global insult to the brain is when the injury is noted to be bilateral and symmetric in distribution. In the context of HII in term neonates, this is either bilateral symmetric ( a ) peripheral/watershed (WS) injury or ( b ) bilateral symmetric basal-ganglia-thalamus (BGT) pattern, often with the peri-Rolandic and hippocampal injury. Unilateral, asymmetric, or unequal distribution of injury may therefore be misdiagnosed as perinatal arterial ischemic stroke.

OBJECTIVES

We aimed to determine the prevalence of unequal cerebral injury in HII, identify patterns, and determine their relationship with existing classification of HII.

MATERIALS AND METHODS

Review of brain magnetic resonance imaging from a database of children with HII. Reports with any unequal pattern of injury were included and further classified as a unilateral, bilateral asymmetric, or symmetric but unequal degree pattern of HII.

RESULTS

A total of 1213 MRI scans in patients with a diagnosis of HII revealed 156 (13%) with unequal involvement of the hemispheres: unilateral in 2 of 1213 (0.2%) (involvement only in the WS), asymmetric in 48 of 1213 (4%) (WS in 6 [0.5%], BGT in 4 [0.3%], and combined BGT and WS in 38 [3.1%]), and bilateral symmetric but unequal degree in 106 of 1213 (8.7%) (WS in 20 [1.6%], BGT in 17 [1.4%], and combined BGT and WS in 69 [5.7%]).

CONCLUSIONS

The majority of children with cerebral palsy due to HII demonstrate a characteristic bilateral symmetric pattern of injury. In our study, 13% demonstrated an unequal pattern. Differentiation from perinatal arterial ischemic stroke, which is mostly unilateral and distributed typically in the middle cerebral artery territory, should be possible and recognition of the typical BGT or WS magnetic resonance imaging patterns should add confidence to the diagnosis, in such scenarios.

Distribution of IntraThalamic Injury According to Nuclei and Vascular Territories in Children With Term Hypoxic-Ischemic Injury

BACKGROUND

Term hypoxic-ischemic injury (HII) on magnetic resonance imaging (MRI) is described as the basal ganglia thalamus [BGT], watershed [WS], or combined [BGT/WS] groups. We aimed to determine differences between HII groups in intrathalamic distribution.

METHODS

Delayed MRIs of children with HII and thalamic injury were reviewed. Custom tools were placed over T2-weighted and/or fluid-attenuated inversion recovery axial images to determine distribution of intrathalamic injury: (1) six subjective (whole/near-whole, central, anterior, posterior, lateral, medial); (2) four nuclear (anterior [AN], ventrolateral [VLN], medial [MN], and pulvinar [PN]); and (3) three arterial (thalamoperforating arteries [TPA], thalamogeniculate arteries [TGA], and posterior choroidal arteries [PCA]) locations. We compared the frequency of injury of the aforementioned intrathalamic locations between HII groups.

RESULTS

The 128 children (mean age at MRI 7.35 ± 3.6 years) comprised 41% (n = 53) BGT, 26% (n = 33) WS, and 33% (n = 42) BGT/WS. The VLN was the most frequent injured nuclear region (66%, n = 85), and the TGA (93%, n = 128) was the most frequent arterial region involved. VLN injury occurred more frequently in the BGT group (P < 0.001), PN in the WS group (P < 0.001), and AN (P < 0.001), MN (P < 0.001), PN (P = 0.001), and all nuclei together (P < 0.001) in the BGT/WS group. The combination of all vascular territories was significantly associated with BGT/WS (P < 0.001).

CONCLUSIONS

There are significant differences in intrathalamic nuclear and arterial injuries between the different types of HII.