Sudden Infant Death Syndrome (SIDS) is marked by the sudden death of an infant less than 1 year of age that cannot be explained until a thorough investigation (autopsy, examination of the death scene, review of the clinical history) is conducted.
When SIDS occurs, one should obtain the following history :
Apparent life threatening events (ALTE) may include:
When an infant has died from SIDS, the scene of death needs to be examined for any signs of external airway obstruction, entrapment of the neck or presence of any environmental toxin like carbon monoxide. For infants who are found alive and brought to the Emergency room, most will be lethargic and not show any signs of outward distress. In more than half of these infants, the physical exam is normal. In the remaining infants one may find fever or signs of an infection. The work up of a child with suspected SIDS depends on the physical medical judgment and expertise. The history of the child may suggest that the apnea may be obstructive central or mixed.
All the findings from a clinic exam have to be photographed and recorded, it is important to note that if any dead infant arrives to the ED, the physician should call the coroner first without manipulating the body. The autopsy is vital to rule out SIDS and other causes of death. Manipulation of the body can distort signs and lead to false conclusions.
The autopsy of an infant suspected of SIDs should be thorough and usually includes the following:
SIDS versus infanticide
Whenever a death in an infant occurs, infanticide has to be ruled out.
Findings that raise the suspicion of child abuse are as follows:
Features suggestive of SIDS include the following:
However, the absence of any clinical features does not mean that the death was due to natural causes. There are cases where a hand or a pillow has been used to smother the child, called gentle battering. In some cases of SIDS, the infant may have clenched fists at birth signalling terminal motor activity.
It is vital not to jump to conclusions as misinterpretation of post mortem changes that are seen in SIDS related death like anal dilatation or post-mortem lividity.
In most cases, the infant is dead at the scene, but if there is any sign of life, EMS should be called and the infant transported to the nearest ED. In many jurisdictions, an autopsy is usually performed when the cause of death is unknown and sudden. There are national guidelines in many countries on reporting of SIDS to the coroner.
A diagnosis of SIDS is only made by excluding all other possible disorders. Information collected at the scene and the infant’s medical history is vital to make the diagnosis. During an autopsy, images of the organ systems are obtained. In addition, Tissue is obtained for microbiology, biochemistry, toxicological analysis and drugs. Tissues are also analyzed under a microscope to ensure that there are no structural causes that may account for the sudden death. A diagnosis of SIDS is made only when all other organic causes have been excluded .
In all surviving infants, more exhaustive workup is done that includes the following:
To rule out skeletal trauma, whole body X-rays must be obtained. These images should be checked to look for metaphyseal fractures that are often seen in cases of nonaccidental trauma like child abuse. Anytime a fracture is seen in a child less than 12 months of age child abuse should be suspected. Even during CPR, it is almost impossible to fracture the ribs of an infant. Anterioposterior and lateral soft tissue films of the cervical spine should be obtained to look for obstruction of the upper airways or presence of a foreign body. If child abuse is suspected, a CT scan of the skull is recommended.
From autopsy studies done in infants with a possible diagnosis of SIDS, only 6% of infants have been shown to have an organic cause of death. All these infants has a relevant history of an organic cause. In the absence of suggestive clinical history and absence of any gross abnormalities, histological examination of the brain is rarely productive in determining the cause of death. The yield is improved in infant with a clinical history and evidence of gross brain findings.
The diagnosis of SIDS is made by excluding other potential disorders. The biggest difference in an infant who dies suddenly is child abuse, and hence every effort must be made to ensure that the infant death was not due to harm by the parent or the caregiver. Even though SIDs deaths are much rarer than child abuse cases, the onus is on the healthcare provider to rule it out. Thus, it is vital to obtain a thorough history from the caregiver about the infants present and past illnesses. Child abuse maybe suspected if the history is inconsistent with the physical findings. The physical exam must also be thorough to look for evidence of any intentional trauma.
Because the etiology of SIDs is multifactorial, several recommendations have been made to prevent SIDS.
The treatment of SIDs requires providing emotional support for the parents. It is important to note no diagnosis should be offered to the parent until after the autopsy is done. SIDs cases have frequently been followed by litigation by caregivers when a wrong diagnosis is given and child abuse is missed. In cases, where the infant has passed away, a team approach consisting of social workers, healthcare providers, and any relevant religious leader should be present. Telling parents about the death of the infant in an emergency setting is stressful and this is often worsened by feelings of inadequacy or guilt at not having saved the infant.
The prognosis of SIDS has improved over the past 2 decades because of better parental education on how the infant should sleep. The mortality rates have declined but SIDs still continues to occur at a rate of 1 death per every 10,000 births. Because the disorder occurs in apparently healthy infants, it is hard to predict who will develop SIDS.
Many causes of SIDS have been put forward but there is still disagreement as to which is most significant or relevant . Various classifications of risk factors have been developed and the one most widely used is as follows:
The frequency of SIDS has been declining over the past 2 decades, partly because of more awareness of the disorder and better parent education. However, the disorder is still a leading cause of unexpected deaths in infancy accounting for 30-60% of deaths within the post neonatal period. The one key feature that has led to a reduction in SIDs death is the avoidance of PRONE sleeping. The National institute of Child Health and Human Development has issued a statement saying that supine position can lower the risk of SIDS. Since this statement was introduced in 1992, there has been a significant reduction in infants being placed prone for sleep . Awareness of SIDS over the past 2 decades has led to a significant drop in deaths both in the USA and in most western countries. Currently an incidence of 1 death per 10,000 live births is reported in the USA. Sadly while SIDS is decreasing what is now coming to the forefront is that many of infants deaths previously thought to be SIDs may have been due to child abuse, and the number of cases are on the increase.
Worldwide the rate of SIDS have been dropping because of public health campaigns and education of parents emphasizing the use of supine sleeping positions versus prone. Another modifiable risk factor for SIDS that has recently emerged is tobacco smoke exposure. It is well known that there is a 2-4 fold increase in SIDS in infants whose mother smoke. Unfortunately despite public campaigns, maternal smoking rates have not been declining but in fact increasing.
Other modifiable risk factors which have led to a decrease in SIDS include over bundling or covering the infants head before age of 3 months has been shown to increase risk of SIDS. Another controversial factor that has led to a decrease in SIDS is bed sharing. While bed sharing is more convenient for mothers who breast feed as it also enhances maternal bonding, epidemiological data indicate that bed sharing may be hazardous in certain conditions. There are conflicting reports on bed sharing with mothers who do not smoke and occurrence of SIDS. This risk is increased when there are multiple people sharing the bed, and especially if the individual has consumed alcohol. Finally there is some evidence linking SIDS to the duration of sleep with a partner. More recent studies show that room sharing rather than bed sharing is associated with a decreased risk of SIDS.
The use of pacifiers has been associated with a protective effect against SIDS but the mechanism appears unclear. However, introduction of the pacifier in infants is also associated with dental malocclusion, non-nutritive sucking behavior and a slightly higher risk of otitis media. Initially it was suspected that apnea was the cause of SIDS and hence home apnea monitors were widely sold to parents to prevent SIDS. Unfortunately there is no evidence that home monitors are effective in preventing SIDS. However, some experts recommend use of home apnea monitors in a select group of infants who develop apnea and may have evidence of airway obstruction. So far most studies have refuted the association between SIDS and immunizations.
Recent studies indicate that breast fed infants are more arousable from sleep than those who are not breast fed, suggesting that breast feeding may have a possible protective effect. Unfortunately there is little solid evidence to support that breast feeding is protective. While the habit is beneficial one should not rely on it as a method to prevent SIDS. SIDS generally affects infants between 2-4 months of age and the majority are less than 6 months old. Close to two third of SIDS death are in males. In the USA, SIDS rates are highest in Native American Indians and Alaskan natives followed by African Americans. The reason is believed to be in the fact that the infants in these races, who often tend to sleep in the probe position, may have low birth weight, young maternal age and perhaps high parity.
The exact cause of SIDS is not known but there are countless theories. Even though many hypotheses have been used to explain SIDS, none has been proven clinically. The overall theme is that there are several factors which interact, resulting in SIDS. These factors include the following:
In general SIDS rarely occurs in the presence of only one risk factor, but it is more likely to have two or more risk factors present. It is believed that in vulnerable infants, the stressors override the normal defense mechanism and lead to death. Over the years many studies have looked at genes that code for certain neurotransmitters and nerve conduction pathways, but so far no specific gene has been identified .
Theories that have been linked to cause of SIDS include the following:
The recommendation for prevention of SIDS is to place the infant supine while sleeping, avoiding maternal smoking, alcohol and use of illicit drugs. The infant should not sleep in the same bed as the caregiver but may sleep in the same room. Use of a firm mattress, adequate temperature control, avoiding over bundling and sharing the infant's crib with other children are other preventive measures.
Sudden infant death syndrome (SIDS) is the death in infants less than 12 months of age. These deaths often occur unexpectedly, suddenly and in most cases, there is no obvious cause. SIDS is the leading cause of sudden infant death in the United States and the diagnosis is only made after a thorough forensic autopsy. The pathogenesis of SIDS is poorly understood. In summary, SIDS most likely occurs in infants who have delayed the development of nerve networks in the brain that play a role in arousal to life threatening events during sleep. In addition, some infants may also have temporary defects in control of the respiratory or cardiovascular system, and the thermoregulation and chemoreceptor sensitivity. The exact anatomical dysfunction in the brain stem is not known but it is believed that it may be a delay in development of mature neuronal connections to the mid-brain. Regardless of the brainstem dysfunction, it is believed that SIDS occurs because the infant’s response to certain stimuli and stress are not well developed or absent. There are now guidelines established for physicians to report all suspected cases of SIDS to the local medical examiner. It is hoped that collection of data from ED physicians will help provide more information about this condition  .
SIDS is a disorder that leads to unexpected and sudden death of an otherwise healthy infant. The exact cause of SIDS remains unknown but placing the infant on his stomach to sleep is a major risk factor. In most cases, the parent or caregiver reports no problems with the infant and after putting him or her to sleep is later found unresponsive. Numerous hypotheses have been developed and the overall feeling is that the infant has poor development of some reflexes which help fight stress and low oxygen. Other risk factors for SIDS include maternal smoking, drug use, sleeping in the same bed as the infant and over bundling the infant with loose blankets. The risk of SIDS can be decreased by use of a pacifier and placing the child on his or her back during sleep. While the infant should not share the same bed as the parent, the infant can be placed in the same room.