sudden unexpected death in infancy

Sudden Unexpected Death in Infancy by

Dr. Varughese George

Objectives

• Introduction to SUDI, SIDS, Ascertained/ Not Ascertained Deaths

• Epidemiology• Classification of SIDU• Current theories on causation of SIDS• Forensic Aspects• Summary

Introduction to Sudden Unexpected Death in Infancy (SUDI)

• Sudden unexpected death of an infant < 1 year of age who– was healthy.– not thought to have any life-threatening disease prior to death.

• The definite cause of death is not identified.

• Majority of deaths of young infants occurs between 1 week and 6 months of age.

• SUDI should be investigated by a multidisciplinary team following a standard protocol.

• Team should include– Police/ Social Services.– Specialist Pediatrician.– Pathologist/ forensic pathologist.

Sudden Death Infant Syndrome (SIDS)

• Sudden unexpected death of an infant < 1 year of age which remained unexplained even after a thorough case investigation which includes –– Complete Autopsy.– Examination of a death scene.– Review of clinical history.

• SUDI is often confused for SIDS.

• Infant usually dies while asleep, mostly in the prone or side position (pseudonyms of crib death or cot death).

• Some pathologists consider infants co-sleeping with a parent as a exclusion criteria, whereas others don’t.

Ascertained/ Not Ascertained Deaths

• Cause of death when death is not explained after full investigation with consideration of the following factors : – Child is older/younger than age acceptable for SIDS.– Atypical clinical features in the history.– Atypical/Unexplained pathological features.

• Some authors suggest that these could be classified as SUDI.

Objectives



Epidemiology

• The rate of SIDS/ascertained deaths is about 0.5 per 1000 live births.

• Rates of SUDI are also broadly similar across the world.

• It has been observed 600 infants per year still die suddenly and unexpectedly in UK of causes unexplained.

Objectives


• Epidemiology• Classification• Current theories on causation of SIDS• Forensic Aspects• Summary

Classification of Natural Infant Deaths

• According to Presentation Expected Unexpected

Observed Unobserved

Well Unwell Well Unwell

Classification of Natural Infant Deaths

• According to Cause

Commonest causes areInfections.Cardiac Diseases.Respiratory Tract Diseases.Metabolic Diseases.Miscellaneous.

Infections• Bacterial infections causing pneumonia, septicaemia and

meningitis is a common cause of death in infancy.

• Bacterial pneumonia preceded by minor respiratory symptoms causes unobserved death in apparently well babies.

• The inflammation may not be histologically prominent in early stages

Infections• Epiglottis due to Hemophilus Influenza is a fairly

common illness – rare these days due to advent of Hib immunization

programme.

• Babies with meningitis shows some vague and non-specific symptoms.

• Babies with acute encephalitis may lead to sudden collapse through invovement of vital structures in the brain stem.

• Peritonitis may also cause sudden death in infants with vague symptoms. Pathology includes volvulus , Hirschsprung’s disease , meconium ileus, intussusception,congenital bands etc.

Primary peritonitis typically due to pneumococcus

• Gastroenteritis could cause death as a result of dehydration which may not be assessed by the family.

Infections• Viral infections are prevalent and fatal, but are less

frequently identified as a cause.

• Viral myocarditis caused by Type B Coxsackie virus could be fatal.

– Baby may appear non-specifically unwell prior to collapse in the first few weeks of life.

• Viral encephalitis is usually symptomatic, babies die before reaching the hospital, having being non-specifically unwell.– Enterovirus predominate in first 3 months of life

followed by Herpes simplex after 6 months of life.– Others - adenoviruses,measles,mumps,rubella

• Viral pneumonitis caused by RSV is generally symptomatic.

– can lead to apnea in very young/premature infants.

Infections

• Babies with asplenia are particular prone to infections especially pneumococcus.

• A congenital/acquired immune deficit in cases of overwhelming infection should be considered as investigation after death, beyond histopathology could be problematic.

Cardiac Diseases

• Undiagnosed congenital heart malformations remain a common cause of death in 1st week of life.

• Affected babies are poor feeders which may be observed by their parents.

• Common cardiac disorders which cause sudden collapse are – Aortic stenosis/atresia– Hypoplastic left ventricle– Transposition of the great arteries.– Anomalous origin of coronary arteries.

Cardiac diseases• Infantile Cardiomyopathy causes SUDI, usually an observed

collapse.– At autopsy, heart is severely hypertrophic than dilated.– Possibility of a metabolic /mitochondrial disease should be considered

with appropriate samples taken.

• Endocardial fibro-elastosis typically presents as fetal hydrops, but occasionally leads to SUDI.– Possibilty of a metabolic disease should be considered.– There is an association with maternal autoimmune diorders

(Anti-Ro/Anti-La antibodies)

Cardiac diseases• Cardiac tumors

– may lead to arrhythmias and severe cardiac enlargement.

– Multiple rhabdomyomas alert the possibility of tuberous sclerosis

• Disorders of the cardiac conducting system may lead to SUDI– Long QT Syndrome should be

considered if there’s positive family history of sudden death.

– Family members should be offered ECG screening and storage of DNA for genetic analysis.

Respiratory Tract Diseases • Infections of the respiratory tract play a major role in causing SUDI.• Structural malformations of the upper airways may be associated with respiratory obstructions

– Choanal Atresia– Laryngomalacia– Tracheomalacia

Noisy breathing/stridor may be apparent Condition may be exacerbated by concurrent respiratory infection.

Respiratory failure due to neuromuscular disorders – Congenital myopathies– Polymyositis– Viral myositis– Anterior horn cell disease.

A careful examination of the respiratory tract is essential.

Metabolic Diseases• Babies are at a risk of sudden cardiac collapse and seizures.• An unwell infant usually collapses suddenly rather than ‘cot death’. • Onset is usually in early neonatal period.• Follows an infectious disease, most often gatroenteritis.• The baby’ condition deteriorates drowsy collapses

• Typically seen in MCAD deficiency, other fatty acid oxidation defect and mitochondrial disease.

• Fat stains of liver, kidney,muscle & hear should be routine to SUDI workup.• Ideal biochemical screening of blood and bile by tandem mass

spectrometry should be carried out.

Miscellaneous• Epileptic seizures in infants with known epilepsy may result in sudden

unobserved death.– Typical features may not be apparent at post-mortem examination.– Death is more likely in infants with underlying neurological disease than with idiopathic

epilepsy. – Samples to be taken for anticonvulsant levels.

• Pulmonary vascular disease is difficult to diagnose in early in infancy due to ongoing vascular remodelling.– Typically associated with other syndromes– Smith Lemli Opitz Syndrome.– Williams Syndrome (Supraclavicular aortic stenosis & abnormal peripheral pulmonary

vessels)

Objectives


• Epidemiology• Classification of SIDU• Current theories on causation of SIDS• Forensic Aspects

Current Theories on Causation of SIDS

Current favoured theories are : -

• Respiratory Arousal/Brainstem Development.

• Inflammatory mediators/Bacterial toxins.

• Cardiac Arrythmias.

Respiratory Arousal/Brainstem Development

Recent studies have shown evidence of SIDS being a result of

• Failure of normal respiratory arousal in response to adverse sleeping environment.

• Failure of normal respiratory arousal in response to hypoxia in the first 6 months of life.

• Subtle abnormalities in development of brainstem could affect cardiorespiratory centres – present in at least 50% of SIDS.

Inflammatory mediators/Bacterial toxins


• Immune activation– Increase of inflammatory cells in the lungs.– Thymic enlargement.– Raised levels of cytokines

• Abnormal Cytokine response to minor infection– Excess of high activator alleles of IL-10.– Polymorphisms in VEGF & IL-6.

• Bacterial infections– Bacterial toxins trigger SIDS by inappropriate cytokine response as a result of genetic

polymorphisms.

Cardiac Arrythmias


• Mutations in genes coding for membrane ion channels.– LQTS predisposing to cardiac arrythmias sudden death– LQTS attributes to 5% of cases classified as SIDS.– Gene SCN5A could lead to sudden death in sleep.– Polymorphisms in LQTS genes could result in SIDS.– Genetic testing of child or ECG screening of close family members is

necessary if there is positive family h/o sudden unexplained/cardiac death.

Objectives



Forensic Aspects

Suffocation• Study by carpenter et al identified 87% in their series as natural • Pathological appearances of suffocation are commonly identical

to those in a true SIDS – Negative biopsy.• May be accidental – suffocating with pillow, cushion, hands• May be inflicted upon as in abuse – a forensic + paediatric

pathologic should take the lead in investigation.• Rarities include obstruction of airway by a foreign object.• Careful history & detailed external examination of infants are

essential.

Forensic AspectsSuffocationExternal findings

• Facial and conjuctival petechiae - non-specific for upper airway obstruction.

• Facial bruising, pressure marks & abrasions - require an explanation.

• Frank bleeding from upper airways is unusual in the context of SIDS - h/o resuscitation needs to be excluded.

• Frenulum injury may require careful assessment if intubation has been carried out.

• Natural causes (infection/vascular lesions) should also be excluded.

• H/o co-sleeping with parent should also be considered.

Forensic AspectsSuffocationInternal Findings

• Severe alveolar hemorrhages – May be an indicator of airway obstruction

(suffocation) or resuscitation.– Feature of co-sleeping deaths – mechanism

unclear.

• Haemosiderin- laden macrophages- Suggested as a marker of previous upper

airway obstruction though there is no literature to substantiate this fact.

- Natural causes like pulmonary hemosiderosis, bleeding disorders & cardiac disease needs to be excluded.

Forensic AspectsSuffocationInternal Findings

• The presence or absence of petechiae – whether thymic , cardiac or pleural – has no diagnostic significance .

• Epidural hemorrhage around the spinal cord– May be a postmortem artefact.– Caused by congestion of epidural fat

network.

Forensic Aspects

Co-sleeping Deaths

• This group has increased incidence with parental co-sleeping & smoking.

• Legal issues arise if the carer was under the influence of alcohol/drugs

• Some infants are vulnerable to transient airways obstruction.

Forensic AspectsMunchasen Syndrome by Proxy

• The carer (commonly the mother) causes harm to the infant to bring it to the attention of the medical authorities.

• Identification of such cases are extremely difficult.

• Infants may present with apparent life-threatening events – poisonings.

• History of apnoeic episodes in infants before sudden death.

• Attention should be given to any injuries identified, external airway occlusion being the commonest pathology.

• Toxicological analysis is essential – should be done as routine.

Summary• Investigation of SUDI requires a multidisciplinary team.

• Case review by the team can be helpful in refining the diagnosis.

• A full postmortem should be undertaken to an agreed protocol including ancillary tests.

• Tissue should be stored in case DNA is required for genetic tests.

• A diagnosis of long QT Syndrome (LQTS) should be considered if there s a family h/o sudden death.

• Current theories highlight possible role of poor respiratory arousal, inflammatory response/infection/LTQS for causes of SIDS.

• Suffocation (accidental/deliberate) is difficult to diagnose in this young age group.

• The significance of fresh alveolar hemorrhage & haemosiderin macrophages need to be judged in the light of all findings & circumstances of death.

• Fresh spinal epidural hemorrhage may be a postmortem artefact.

• Toxicological testing should be routine part of the postmortem examination in SIDS.

sudden unexpected death in infancy

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