Xenon combined with therapeutic hypothermia is not neuroprotective after severe hypoxia-ischemia in neonatal rats

Therapeutic hypothermia (TH) is standard treatment following perinatal asphyxia in newborn infants. Experimentally, TH is neuroprotective after moderate hypoxia-ischemia (HI) in seven-day-old (P7) rats. However, TH is not neuroprotective after severe HI. After a moderate HI insult in newborn brain injury models, the anesthetic gas xenon (Xe) doubles TH neuroprotection. The aim of this study was to examine whether combining Xe and TH is neuroprotective as applied in a P7 rat model of severe HI.120 P7 rat pups underwent a severe HI insult; unilateral carotid artery ligation followed by hypoxia (8% O2 for 150min at experimental normothermia (NT-37: Trectal 37°C). Surviving pups were randomised to immediate NT-37 for 5h (n = 36), immediate TH-32: Trectal 32°C for 5h (n = 25) or immediate TH-32 plus 50% inhaled Xe for 5h (n = 24). Pups were sacrificed after one week of survival. Relative area loss of the ligated hemisphere was measured, and neurons in the subventricular zone of this injured hemisphere were counted, to quantify brain damage.Following the HI insult, median (interquartile range, IQR) hemispheric brain area loss was similar in all groups: 63.5% (55.5-75.0) for NT-37 group, 65.0% (57.0-65.0) for TH-32 group, and 66.5% (59.0-72.0) for TH-32+Xe50% group (not significant). Correspondingly, there was no difference in neuronal cell count (NeuN marker) in the subventricular zone across the three treatment groups.Immediate therapeutic hypothermia with or without additional 50% inhaled Xe, does not provide neuroprotection one week after severe HI brain injury in the P7 neonatal rat. This model aims to mimic the clinical situation in severely asphyxiated neonates and treatment these newborns remains an ongoing challenge

DIJAGNOSTIČKE MOGUĆNOSTI VIDEO-ELEKTROENCEFALOGRAFIJE I AMPLITUDNO-INTEGRIRANE ELEKTROENCEFALOGRAFIJE U RANOJ DJEČJOJ DOBI

The main aim in managing sick newborns is to prevent or at least to minimize brain injury and to establish optimal neuro-developmental outcome. Electroencephalography (EEG) which reflects brain electrical activity, is regarded as the most reliable tool in recognition of possible central nervous system dysfunction (e. g. seizures) and in predicting outcome. The best surveillance of a neonate and young infant can be achieved by continuous functional monitoring, but long term EEG has limited availability in many centres and requires interpretation by a skilled paediatric electroencepahlographist. Therefore, amplitude-integrated EEG (aEEG) is a technique for simplified EEG monitoring which has an increasing clinical potential in neonatal intensive care. The article presents literature data as well as our own experience with diagnostic possibilities of both, standard (digitalized and video-assisted) EEG as well as aEEG and stresses the importance of using new generation machines that incorporate, along with aEEG signal, also a display of raw EEG for better seizure detection.Glavni ciljevi tijekom nadzora bolesne novorođenčadi su sprječavanje ili bar umanjivanje oštećenje mozga te postizanje optimalnog neurorazvojnog ishoda. Elektroencefalografiju, kao odraz električne aktivnosti mozga, smatramo najpouzdanijom metodom u prepoznavanju moguće disfunkcije središnjeg živčanog sustava (tj. konvulzija) kao i u predviđanju ishoda. Najbolje praćenje novorođenčadi i male djece možemo postići služeći se kontinuiranim funkcionalnim monitoringom, ali dugotrajni EEG ima ograničenu dostupnost u mnogim centrima i zahtijeva interpretaciju iskusnog pedijatra-elekroencefalografista. Tako je amplitudno integrirana EEG (aEEG) tehnika za pojednostavljeni EEG monitoring s rastućim kliničkim potencijalom u neonatalnoj intenzivnoj njezi. Ovaj rad prikazuje literaturne navode i podatke iz našeg osobnog iskustva s dijagnostičkim mogućnostima obje metode, standardnim (digitalnim, uz video) EEG-om, kao i aEEG-om te upućuje na važnost upotrebe aparata nove generacije koje na ekranu, uz aEEG signal, prikazuju i standardni EEG za uspješnije otkrivanje konvulzija

Prognostic Value of Various Diagnostic Methods for Long-Term Outcome of Newborns After Hypoxic-Ischemic Encephalopathy Treated With Hypothermia

IntroductionPrediction of outcome in newborns with hypoxic-ischemic encephalopathy (HIE) has been modulated by hypothermia treatment (HT). We assessed the predictive value of diagnostic methods commonly used in neonates with HIE for short-term neurodevelopmental outcome and long-term neurological outcome.Materials and MethodsThis longitudinal cohort study followed up 50 term newborns who underwent HT after HIE between July 2006 and August 2015, until preschool age. We estimated sensitivity and specificity for short-term neurodevelopmental outcome at 18 months and long-term neurological outcome at five years based on Amiel-Tison Neurological Assessment (ATNA), electroencephalography (EEG), and magnetic resonance imaging (MRI) performed in the neonatal period.ResultsThe accuracy of all neonatal methods tested was higher for long-term neurological outcome compared to the predictive accuracy for short-term neurodevelopmental outcome at 18–24 months. Sensitivity and specificity in predicting unfavorable long-term neurological outcome were: MRI (sensitivity 1.0 [95%CI 0.96–1.0]; specificity 0.91 [95%CI 0.86–1.0]), EEG (sensitivity 0.94 [95%CI 0.71–1.0]; specificity 1.0 [95% CI 0.89–1.0]), and ATNA (sensitivity 0.94 [95%CI 0.71–1.0]; specificity 0.91 [95%CI 0.76–0.98]).ConclusionMRI is a powerful predictor of long-term neurological outcome when performed in the first week after HIE in HT treated infants, as are EEG and ATNA performed in the second or third week postnatally

Monitoring of cerebral blood flow during hypoxia-ischemia and resuscitation in the neonatal rat using laser speckle imaging

Neonatal hypoxic‐ischemic encephalopathy (HIE) is associated with alterations in cerebral blood flow (CBF) as a result of perinatal asphyxia. The extent to which CBF changes contribute to injury, and whether treatments that ameliorate these changes might be neuroprotective, is still unknown. Higher throughput techniques to monitor CBF changes in rodent models of HIE can help elucidate the underlying pathophysiology. We developed a laser speckle imaging (LSI) technique to continuously monitor CBF in six postnatal‐day 10 (P10) rats simultaneously before, during, and after unilateral hypoxia‐ischemia (HI, ligation of the left carotid artery followed by hypoxia in 8% oxygen). After ligation, CBF to the ligated side fell by 30% compared to the unligated side (P < 0.0001). Hypoxia induced a bilateral 55% reduction in CBF, which was partially restored by resuscitation. Compared to resuscitation in air, resuscitation in 100% oxygen increased CBF to the ligated side by 45% (P = 0.033). Individual variability in CBF response to hypoxia between animals accounted for up to 24% of the variability in hemispheric area loss to the ligated side. In both P10 and P7 models of unilateral HI, resuscitation in 100% oxygen did not affect hemispheric area loss, or hippocampal CA1 pyramidal neuron counts, after 1‐week survival. Continuous CBF monitoring using LSI in multiple rodents simultaneously can screen potential treatment modalities that affect CBF, and provide insight into the pathophysiology of HI

Treatment temperature and insult severity influence the neuroprotective effects of therapeutic hypothermia

Therapeutic hypothermia (HT) is standard care for moderate and severe neonatal hypoxic-ischaemic encephalopathy (HIE), the leading cause of permanent brain injury in term newborns. However, the optimal temperature for HT is still unknown, and few preclinical studies have compared multiple HT treatment temperatures. Additionally, HT may not benefit infants with severe encephalopathy. In a neonatal rat model of unilateral hypoxia-ischaemia (HI), the effect of five different HT temperatures was investigated after either moderate or severe injury. At postnatal-day seven, rat pups underwent moderate or severe HI followed by 5 h at normothermia (37 °C), or one of five HT temperatures: 33.5 °C, 32 °C, 30 °C, 26 °C, and 18 °C. One week after treatment, neuropathological analysis of hemispheric and hippocampal area loss, and CA1 hippocampal pyramidal neuron count, was performed. After moderate injury, a significant reduction in hemispheric and hippocampal loss on the injured side, and preservation of CA1 pyramidal neurons, was seen in the 33.5 °C, 32 °C, and 30 °C groups. Cooling below 33.5 °C did not provide additional neuroprotection. Regardless of treatment temperature, HT was not neuroprotective in the severe HI model. Based on these findings, and previous experience translating preclinical studies into clinical application, we propose that milder cooling should be considered for future clinical trials

Variability and sex-dependence of hypothermic neuroprotection in a rat model of neonatal hypoxic-ischaemic brain injury:a single laboratory meta-analysis

Therapeutic hypothermia (HT) is standard care for term infants with hypoxic–ischaemic (HI) encephalopathy. However, the efficacy of HT in preclinical models, such as the Vannucci model of unilateral HI in the newborn rat, is often greater than that reported from clinical trials. Here, we report a meta-analysis of data from every experiment in a single laboratory, including pilot data, examining the effect of HT in the Vannucci model. Across 21 experiments using 106 litters, median (95% CI) hemispheric area loss was 50.1% (46.0–51.9%; n = 305) in the normothermia group, and 41.3% (35.1–44.9%; n = 317) in the HT group, with a bimodal injury distribution. Median neuroprotection by HT was 17.6% (6.8–28.3%), including in severe injury, but was highly-variable across experiments. Neuroprotection was significant in females (p < 0.001), with a non-significant benefit in males (p = 0.07). Animals representing the median injury in each group within each litter (n = 277, 44.5%) were also analysed using formal neuropathology, which showed neuroprotection by HT throughout the brain, particularly in females. Our results suggest an inherent variability and sex-dependence of the neuroprotective response to HT, with the majority of studies in the Vannucci model vastly underpowered to detect true treatment effects due to the distribution of injury

Neonatal systemic inflammation induces inflammatory reactions and brain apoptosis in a pathogen-specific manner

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; After neonatal asphyxia, therapeutic hypothermia (HT) is the only proven treatment option. Although established as a neuroprotective therapy, benefit from HT has been questioned when infection is a comorbidity to hypoxic-ischaemic (HI) brain injury. Gram-negative and gram-positive species activate the immune system through different pathogen recognition receptors and subsequent immunological systems. In rodent models, gram-negative (lipopolysaccharide [LPS]) and gram-positive (PAM&lt;sub&gt;3&lt;/sub&gt;CSK&lt;sub&gt;4&lt;/sub&gt; [PAM]) inflammation similarly increase neuronal vulnerability to HI. Interestingly, while LPS pre-sensitisation negates the neuroprotective effect of HT, HT is highly beneficial after PAM-sensitised HI brain injury. &lt;b&gt;&lt;i&gt;Objective:&lt;/i&gt;&lt;/b&gt; We aimed to examine whether systemic gram-positive or gram-negative inflammatory sensitisation affects juvenile rat pups per se, without an HI insult. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; Neonatal 7-day-old rats (&lt;i&gt;n&lt;/i&gt; = 215) received intraperitoneal injections of vehicle (0.9% NaCl), LPS (0.1 mg/kg), or PAM (1 mg/kg). Core temperature and weight gain were monitored. Brain cytokine expression (IL-6, IL-1β, TNF-α, and IL-10, via PCR), apoptosis (cleaved caspase 3, via Western blots), and microglial activation (Iba1, via immunohistochemistry) were examined. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; LPS induced an immediate drop in core temperature followed by poor weight gain, none of which were seen after PAM. Furthermore, LPS induced brain apoptosis, while PAM did not. The magnitude and temporal profile of brain cytokine expression differed between LPS- and PAM-injected animals. &lt;b&gt;&lt;i&gt;Conclusion:&lt;/i&gt;&lt;/b&gt; These findings reveal sepsis-like conditions and neuroinflammation specific to the inflammatory stimulus (gram-positive vs. gram-negative) in the neonatal rat. They emphasise the importance of pre-clinical models being pathogen dependent, and should always be carefully tailored to their clinical scenario.</jats:p