Neonatal Encephalopathy – Interventions Likely To Come In the Future

Arun Nair MD FRCPCH FRACP

Neonatologist & Sr. Cl. LecturerWaikato Hospital, Hamilton & College of

Medicine University of AucklandNEW ZEALAND

Neonatal Encephalopathy

• 50 -80% of all encephalopathies in newbornpopulation are HIE that follows asphyxia

• Other Entities to be considered– Genetic Syndromes & Isolated Gene Conditions– Neuro-Metabolic Disorders– Acquired Conditions like Cong. Infections, Menigitis,

Haemorhage, stroke etc.– Neonatal Epilepsy Syndromes– Accidental & Non Accidental Injuries– ‘Double trouble’ pathologies: Primary disorders like

neuromuscular, cardiac, infection etc worsening HIE

Perinatal Asphyxia

• Global -130 million annual births, 4 million asphyxiated ( 30/1000)– India – 20-160/1000 ( 28 – 56/1000 in Large

Hospital based studies)– Developed World – 3 - 4 /1000 & Mod. to

Severe HIE in 0.5 -1/1000• (NZ 1.24/1000 term births ≥ 37/40)

• High mortality and morbidityUp to a million deaths worldwide (22% of all neonatal deaths)

About a million develop C P

In India – Fatality Rate 38.5 – 74% (8.7% in large Hospital based studies)

Life long personal, healthcare and societal burdens

Causes of Asphyxia

• Diverse antecedents/causes

– Acute

• Sentinel events (cord prolapse, uterine rupture, abruption, complications of malpresentation)

– Sub Acute

• Intermittent cord events

• Chronic – placental dysfunction

– Unidentified Causes

Neuro-physiological events post Asphyxia:

0 8 12 72

Time in Hrs

Even

tsCarotid occlusion

Latent Phase

(Secondary Energy Failure Phase)

Late Phase

N

CBF

EEG

C Imp.

(Primary EnergyFailure Phase)

Modified from Gunn et al: Pediatrics 1998: 102(5) 1098 - 1106

Effects of Hypoxia & Ischemia on Energy Metabolism

• Brain Glucose

• Glucose influx into nerve cells

• Glycolysis

• Lactic Acid production & Acidosis

• ATP

Primary Energy Failure

Glucose

PyruvateLactate + H+

NADH NAD

Acetyl – Co A

Isocitrate

Succinate

Fumarate Citric Acid cycle

Electron Transport System

2 ATP

36 ATP

An

aerob

ic Ph

aseA

erob

ic Ph

aseGlycolysis

ATP

KA/AMPA

NMDA

Axon Glu

Astrocyte

DentriteGluGlnNH3

Gln GluNH3

Na+

K+

Ca++, Na+K+

Ca++

Na+

Calcium & Glutamate Metabolism

Modified from Siesjo,B K : European Neurology 1990: 30 3 -9

Neuronal Cell Injury Cycle

Hypoxia- Ischemia

Primary Energy Failure

Membrane Depolarisation

Glutamate Release

Intracellular Calcium

Enzyme Induction

Free Radicals & NO

DNA breakage

DNA repair

NAD & NADHDepletion

Impaired glycolysis

Inflammation

ApoptosisFocal Infarction Cell NecrosisFocal Infarction

Interferenceof

Electron transport

Secondary EnergyFailure

Failure Na+/K+ pump

Activation of Caspases

KA / AMPA Receptors

NMDA Receptors

Jayasree Nair & VHS Kumar. Current and emerging therapies in the management of HIE in neonates. Children 2018 ,5, 99

Potential For Intervention

Reperfusion/ Reoxygenation Damage

Established Post Resuscitation Management

Effective Cardio – Respiratory support~ Maintain BP and ABg WNL

Fluid Management ~ Restrict to 2/3rd Maintenance

Blood sugar and calcium level etc.(No role for hypertonic saline, Hyperventilation,

mannitol, steroids or diuretics)

Organ Specific interventions~ Myocardial support, Renal & other

visceral perfusion, PPHN therapy etc.Brain – Seizure Control

(No role for prophylaxis)Therapeutic Hypothermia since 2005

Effectiveness of Hypothermia• TH improves prognosis in those with moderate to severe HIE – But

the benefit is modest at best– Statistically significant reductions in mortality [NNT 11 (95% CI 6, 50)] – Statistically significant reductions in neurodevelopmental disability in

survivors [NNT 8 (95% CI 4, 33)].– Statistically significant and clinically important reduction in the combined

outcome of mortality or major neurodevelopmental disability to 18 months of age [NNT 7 (95% CI 4, 14)].

• > 40% of infants from the trials who received TH either died or suffered mod - severe disabilities including CP, Intellectual impairment and epilepsies

• Not Tested for Mild HIE – Mild HIE is also known to impair ND

Sankaran et al. N Eng J Med 2012;366(22) 2085-92

Jacobs. S et al. Cochrane Database Sys Rev 2013;(1):CD003311

Further Optimisation of Therapeutic Hypothermia

• 3 hrs vs 6 hrs: Significantly higher median psychomotor development index at 18 months (Thoresen et al., 2013)

• Extending cooling to 120 hours: Small but significant reduction in cortical and dentate gyral neuronal survival but worse histological outcomes after 1 year (Davidson et al., 2015 & 2016)

• Deeper cooling to 32 Degrees: Less than 2% benefit (Shankaranet al., 2014, 2017), – animal studies have shown harm (Alonso-Alconada et al., 2015)

• Cooling after missing the Window for TH : Hypothermia initiated at 6 to 24 hours after birth may have benefit but there is uncertainty in its

effectiveness. (Abbot R. Laptook, et al JAMA. 2017)

• Cooling for Mild HIE: Being Explored

Other Potential Areas & Agents for Intervention

1. Energy depletion : Barbiturates, Topiramate, Magnesium

2. Glutamate Release: Ca++ channel blockers, Magnesium

3. Glutamate Uptake: Magnesium, Kynurenic Acid, MK-801

4. Free Radicals & NO: Allopurinol, Mg, Melatonin, Erythropoietin

5. Cytokines, Prostaglandins : Pentoxyphylline, Indomethacin,

Erythropoietin, Azithromycin & Monosialoganglioside

6. Apoptosis: Melatonin, Xenon, Argon, Erythropoietin

7. Cell Regeneration & Recovery: Stem Cells, Erythropoietin

Current Status of Trials

Erythropoietin

• EPO receptors expressed by most cells in developing CNS

•

• Following asphyxia there is increased expression of these receptors (neurons, astrocytes, microglia)

•

• Over 68 preclinical animal studies show convincing histologic and functional evidence of benefit

•

• Many effects distinct from those of hypothermia

• Commercially available, easy to administer and good safety profile

PAEANPreventing Adverse Outcomes of Neonatal HIE with Erythropoietin:

A Phase III Multicentre RCT

• General aim:To determine whether Epo given in conjunction with hypothermia to infants with mod to severe HIE will improve neurodevelopmental out comes at 2 years of age without significant adverse effects, when compared to hypothermia alone

• Primary objective: To compare composite of death or mod/severe disability in infants treated with either Epo or control group (placebo) at 2 years of age

Secondary objectives:- death- cerebral palsy- Cognitive deficit (Bayley III)- Need for supplementary respiratory or nutritional support- Cortical visual impairment- Hearing impairment- Autistic spectrum disorder (M-CHAT score)- Epilepsy- costs of healthcare and service utilisation

Summary• Birth asphyxia is only an event, but the damages to the brain are on

going.

• No matter how severe the asphyxia, if no HIE is detected, the outcome is good- normal outcome and function in line with their peers academically can be expected

• There is a therapeutic window available for prevention or limitation of secondary damage.

• Hypothermia is established but its effect is modest, there is a need for additional strategies.

• Epo may be the first such additional strategy to find clinical use

• Many other interventions are still in the pipeline

Thank You

Additional Strategies

Jayasree Nair & VHS Kumar. Current and emerging therapies in the management of HIE in neonates. Children 2018 ,5, 99

Role of Glutamate

Glutamate

MetabotropicReceptors

NMDAReceptors

KA / AMPAReceptors

Intracellular Ca++ Membrane Depolarisation

Free Radicals

Cell Disintegration

Insert CT picture of asphyxiated brain

EPO plus TH: Clinical Studies

NEATO (Neonatal Epo and Therapeutic Hypothermia Outcomes)

PAEAN (Preventing Adverse Outcomes of Neonatal Hypoxic Ischaemic Encephalopathy with Erythropoietin: A Phase III Randomised Controlled Multicentre Clinical Trial)

HEAL ( High –Dose Erythropoietin for Asphyxia & Encephalopathy- RCT)

References

Some Newer Concepts

TRPM2 channel: A novel target for alleviating ischaemia‐reperfusion, chronic cerebral hypo‐perfusion and neonatal hypoxic‐ischaemic brain damage

Chendi Mai et al. Journal of Cellular and Molecular Medicine, September 2019; 00: 1-9

Remote Ischemic Post Conditioning - RIPostC

Status of other agents• Melatonin: In a randomized controlled pilot trial in term infants , the melatonin/hypothermia group also had fewer seizures,

less evidence of white matter injury on MRI, and a lower rate of mortality without developmental or neurological abnormalities (Aly, H et al. J. Perinatol. 2015)

• Allopurinol: Only a few small trials in human neonates have been published so far and a Cochrane review in 2012 did not reveal any statistically significant difference in the risk of death or a composite of death or severe neurodevelopmental disability. However a follow-up of two earlier performed randomized controlled trials at 4–8 years suggested a neuroprotective effect of neonatal allopurinol treatment in the subset of moderately asphyxiated infants (Kaandorp, J.J et al Arch. Dis. Child. Fetal Neonatal. Ed. 2012)

• Stem Cells: Stem cells are predominantly derived from two sources—bone marrow derived mesenchymal stem cells (BM-MSC) and umbilical cord blood derived mesenchymal stem cells (UCB-MSC). Five newborns (four with moderate and one with severe HIE) have undergone autologous UCBCs therapy without any significant adverse effects of treatment with survival up to one year (Nabetani, M et al Pediatr. Res. 2018)

• Magnesium: Magnesium sulfate is an NMDA receptor antagonist believed to reduce excitotoxic damage after a hypoxic ischemic insult. A meta-analysis of five small randomized controlled trials evaluating MgSO4 in HIE concluded that there was improvement in short-term outcomes without significant increase in side effects (Tagin, M.et al J. Perinatol. 2013)

• RIPC: In a piglet model of neonatal asphyxia, RIPC demonstrated a beneficial effect, mediated by modulation of nitrosativestress, despite glial activation (Rocha-Ferreira et al Oxid. Med. Cell. Longev. 2016)

• Endo Cannabinoids: Cannabinoid (CBD) receptor 1 and 2 (CBR1 and CBR2) agonist WIN 55212-2. In asphyxiated newborn piglets, intravenous administration of CBD improved brain oxygenation and induced a partial EEG recovery after HI (Alvarez, F.J.et al Pediatr. Res. 2008)

• Monosialoganglioside: In a meta-analysis of all published clinical studies, involving 10 trials consisting of 787 neonates, it was shown that adjuvant treatment with onosialoganglioside potentially offers additional benefits in terms of improving short-term clinical effects and reducing long-term neurodevelopmental disabilities (Sheng et al PLoS ONE 2017. )

• Topiramate : In newborns, it has been extensively studied in the management of HIE in combination with hypothermia.. Although administration of topiramate in newborns with HIE is safe, it did not reduce the combined frequency of mortality and severe neurological disability (Filippi, L. et al J. Matern. Fetal Neonatal. Med. 2018)

• Azithromycin : Recent abstracts have investigated the possibility of using azithromycin in neonatal HIE alone and as an adjunct to hypothermia (Barks, J.L.Y et al PAS: Toronto, ON, Canada, 2018.)

Further Optimisation of therapeutic hypothermia

• Although there is little systematic clinical evidence, some clinical studies support the importance of initiating hypothermia as early as possible. For example, in a cohort study of 80 term infants with moderate to severe HIE treated with hypothermia, infants in whom hypothermia was started less than three hours after birth had significantly higher median psychomotor development index at 18months than infants in whom hypothermia was started between three to six hours after birth (Thoresen et al., 2013). Taken together, these studies suggest that hypothermia needs to be started within 6 hours of birth but that the earlier treatment can be started, the more likely it is to achieve improved outcomes.

• Extending the duration of hypothermia to 120 hours started 3 hours after global ischemia was associated with a small but significant reduction in cortical and dentate gyral neuronal survival, and no greater microglial suppression compared to 72 hours of hypothermia (Davidson et al., 2015).

• In a follow-up study, partial protection of oligodendrocytes and myelin basic protein expression was seen after 120 hours of hypothermia, but this protocol was not associated with significant microglial suppression in the white matter (Davidson et al., 2016). Taken together, these data suggest that prolonging the duration of hypothermia is not beneficial and may be deleterious. The apparently worse histological outcomes may be related to over-suppression of neuronal activity and delayed restoration of the central nervous system microenvironment with longer cooling (Wassink et al., 2018).

• Clinical trial investigating longer duration of cooling also investigated deeper cooling of HIE infants to 32°C (Shankaran et al., 2014). In this trial, the probability of detecting a statistically significant benefit for longer or deeper cooling, or both, was less than 2% (Shankaranet al., 2014, 2017). Collectively, hypothermia started within six hours of birth, continued for 72 hours to a depth of 33.5°C appears to provide optimal neuroprotection.

• Reducing core temperature by 8.5°C was associated with impaired neuroprotection in thalamic and striatal regions, and has been associated with adverse systemic effects such as alterations to blood pH, glucose handling and cardiac arrest in neonatal piglets after HI (Kerenyi et al., 2012; Alonso-Alconada et al., 2015).

• There is now compelling evidence that therapeutic hypothermia for moderate to severe HIE started within 6 hours after birth, for a period of 72 hours to a target brain temperature of 33.5 ± 0.5°C significantly reduces neonatal mortality and major morbidity. Deviation from this evidence-based protocol compromises neurological recovery and worsens outcomes in large animal models of HIE

• Benefit of TH after missing the therapuetic window, if any.

• Cooling for mild HIE:

Anthony Davies et al . Neural Regen Res. 2019 Oct; 14(10): 1678–1683

Global Suppression of cerebral Metabolism

Targeted suppression of specific Pathophysiological mechanisms

Newer & Emerging Neuroprotective Strategies:

Earlier Evidence from Clinical Trials

1. Barbiturate: Not enough data available for routine use ~ Evans & Levene. Cochrane 2001

2. Magnesium: No long term data but short term data shows survival at 14 days without EEG or CT abnormalities.

~ Ichiba, Tamai,Negishi et al.Ped. International 2002

3. Ca++ channel Blockers: Problems with hypotension & cerebral Hypoperfusion.

~Boylan,Young,Panerai et al . Pediatr research 2000

4. Allopurinol: No neurological outcome data yet but promising report.~ Van Bel,Shadid, Moison et al. Pediatrics 1998

https://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/tileshop_pmc_inline.html?title=Click on image to zoom&p=PMC3&id=4680177_fetalneonatal-2014-306284f01.jpg

Effects of Energy Failure

ATP

Failure Na+/K+ pump Failure of Ca+ pump

Membrane Depolarisation&

Cellular Edema

Intracellular Ca++

Activation of Enzymes

Xanthine Oxidase

Lipase Protease NucleaseNO Synthetase

Release of Free Radicals

Cytoskeletal Disruption

Cell Disintegration

Interference ofElectron transport

Release of Free Radicals

Cytoskeletal Disruption

Secondary Energy Failure

Pathophysiological mechanism of brain injury

A. Neuronal Cell Edema & Death by Necrosis • Failure Na/K pump – Cerebral Edema

• Intracelluar accumulation of Calcium

• Interference with glutamate pathway

Activates enzymes & release of O2 free radicals & NO

• Damage DNA and protein containing sulfhydril groups

• NO reacts with oxygen free radicals to form peroxynitrate

• NO also causes inhibition of glycolytic enzymes

• Initiate Apoptosis & induces apoptosis

B. Infarction & Cell Death – by inflammatory mediators

(Lessons from the laboratory)

Conflict/Disclosures

I have no conflicts of interest or financial disclosures to make

World Map

Map of NZ

Some interesting facts about NZ

Polpulation- Sheep to men ratio

Kiwi Bird/ Moa

All Blacks - Haka

America Cup

Middle Earth- Film Industry

Everest Conquest

No Snakes

Father of Nuclear Physics

Pioneers of Perinatal Medicine from NZ

Sir Albert William Liley(1926-1983) Liley Curve

Pioneers of Perinatal Medicine from NZ

Sir Graham “Mont” Liggins(1926-2010) Cochrane Logo

Picture of Waikato Hospital

Hypothermia

Head cooling with mild systemic hypothermia is feasible and potentially safe ~ Gunn et all. Pediatrics 1998

Possible mechanisms : Modification of apoptosis ~ Edwards 1995Reduction of energy expenditureAttenuation of Glutamate releaseDecreased production of Free Radicals & NODecreased production of inflammatory mediators

Requirement : Modest reduction of rectal temp. to 33 -35 C within the first six hrs after insult and continue for 72 hrs.

Modality: Selective Head Cooling, Head + Body Cooling, Body coolingusing Cooling Caps and / or Cooling mattresses

Potential side effects: Infection, DIC, Ventricular fibrillation, Hypoglycemia, hypotension etc.

Evidence So Far– Eight randomised controlled trials - 638 term infants

– Moderate/ severe encephalopathy and evidence of intrapartum asphyxia.

– Therapeutic hypothermia resulted in ~

• Statistically significant reductions in mortality [typical RR 0.74 (95% CI 0.58, 0.94), typical RD -0.09 (95% CI -0.16, -0.02), NNT 11 (95% CI 6, 50)]

• Statistically significant reductions in neurodevelopmental disability in survivors [typical RR 0.68 (95% CI 0.51, 0.92), typical RD -0.13 (95% CI -0.23, -0.03), NNT 8 (95% CI 4, 33)].

• Statistically significant and clinically important reduction in the combined outcome of mortality or major neurodevelopmental disability to 18 months of age [typical RR 0.76 (95% CI 0.65, 0.89), typical RD -0.15 (95% CI -0.24, -0.07), NNT 7 (95% CI 4, 14)].

• Some adverse effects of hypothermia included an increase in the need for inotrope support of borderline significance and a significant increase in thrombocytopaenia.

Cooling for newborns with hypoxic ischaemic encephalopathy~Jacobs S, Hunt R, Tarnow-Mordi W, Inder T, Davis P

The Cochrane Library, Issue 4, 2007

Long term Follow Up

• Therapeutic hypothermia resulted in a statistically significant and clinically important reduction in the combined outcome of mortality or major neurodevelopmental disability to 18 months of age (typical RR 0.75 (95% CI 0.68 to 0.83); typical RD -0.15, 95% CI -0.20 to -0.10) Cochrane 2013((NNTB) 7 (95% CI 5 to 10) (8 studies, 1344 infants)

• At 6-7 years age, a total of 75 of 145 children (52%) in the hypothermia group versus 52 of 132 (39%) in the control group survived with an IQ score of 85 or more (relative risk, 1.31; P=0.04 (Toby Trial)

• More children in the hypothermia group than in the control group survived without neurologic abnormalities (65 of 145 [45%] vs. 37 of 132 [28%]; relative risk, 1.60; 95% confidence interval, 1.15 to 2.22)

• Among survivors, children in the hypothermia group, as compared with those in the control group, had significant reductions in the risk of cerebral palsy (21% vs. 36%, P=0.03) and the risk of moderate or severe disability (22% vs. 37%, P=0.03); they also had significantly better motor-function scores

PAEANPreventing Adverse Outcomes of Neonatal Hypoxic Ischaemic Encephalopathy with Erythropoietin: A Phase III Randomised

Controlled Multicentre Clinical Trial

Novel methods of Prevention

• Pomegranate

Neuroprotective Strategies in Developing Countries

Free Radicals & Role of NO

Free radicals: Highly reactive compounds with an uneven electronsin their outermost orbit.

They are byproducts of mitochondrial electron transport under normal circumstances.

They react with lipids of the cell membrane causing damage.

Damage DNA and protein containing sulfhydril groups & Initiate Apoptosis

NO produced by neurons and microglia in response to ischemia

NO reacts with oxygen free radicals to form peroxynitrate

NO also causes inhibition of glycolytic enzymes & induces apoptosis

Mechanism of Apoptosis

Intrinsic Pathway

Mitochondrial Damage

Extrinsic Pathway

DNA Fragmentation

Cytochrome C & AIF

Activated Caspase

Cell Surface Death Receptors

Fas & Tumor Necrosis factor

Role of Inflammatory Mediators

Cytokines are known to be increased in CSF following HI

Blood specimens collected for neonatal screening showed increased cytokines levels in infants who developed CP

Cytokines may influence CNS injury by inciting inflammatory response and by causing focal cerebral infarction through vascular injury

Focal Vascular injury can also result from production of prostaglandins, leukotrienes and PAF