Pathogenesis (development of disease)
The pathogenesis is not yet well understood. Exogenous and endogenous factors are thought to contribute to sudden infant death syndrome (SIDS). A no longer fully compensated passive reduced blood flow to the brain stem is discussed. A disturbed serotonin homeostasis in the brain may be the consequence. Serotonin is an important neurotransmitter in the medulla oblongata, the site of the respiratory center. The trigger for the reduced blood flow can be the prone position when the head is strongly rotated and reclined, i.e. turned to the side and hyperextended backwards. This causes a reduction in flow in the vertebral artery on the opposite side of the head rotation. Possible causes also include disorders of membrane channels (“channalopathy”) in the cells of the striated muscles. The SCN4A gene is suspected. This gene contains the information for “NaV1.4”, a sodium channel on the membrane of the striated muscle cells. Four mutations were found in SIDS victims; none occurred in the control group.Note: This discovery could potentially prevent infant death by treating infants with membrane blockers.
Etiology (Causes)
Biographic Causes
- Genetic burden
- Sudden infant death of a sibling or
- Death of an infant with ALTE (apparently life-threatening event; near-SIDS; symptom complex associated with respiratory arrest, slowed heartbeat, and pallor of the infant).
- Socioeconomic factors – low socioeconomic status.
- Short maternal schooling/no maternal high school diploma.
- Unemployment
- Child wealth
Behavioral causes (= exogenous factors).
- Nutrition
- Exclusive bottle feeding
- Consumption of stimulants
- Drug use
- Sleeping in the prone position is considered the main risk factor – side position cannot be recommended either due to instability (10 times the risk)
- Covering the head / pulling the blanket over the head (22-fold risk).
- Overheating of the child (3.5 times the risk)
- Sleeping with another person (or animal).
- Sleeping on the sofa – 67-fold increased risk for infants to die unexpectedly (due to suffocation or strangulation/less due to sudden infant death syndrome)
- “swaddling” (pucking) infants (swaddling technique: wrapping the infant with blankets, sleeping bags, and other wraps)
- Bedding too softly:
- Suffocation due to soft padding (69% of all suffocations); common in adult bed (49%) and most common in prone position (92%)
- Cause was mainly blankets (34%), too soft mattresses (23%) or pillows (22%)
- Blankets, stuffed animals
Other causes: Suffocation death by another person (19% of all cases), most often by mother or father; most often in adult bed (73%).
Disease-related causes (= endogenous factors).
Certain conditions originating in the perinatal period (P00-P96).
- Prematurity
- Low birth weight
- Perinatal asphyxia (threatened asphyxia in the period between the 24th week of pregnancy and the 7th day after birth).
- Prenatal dystrophy (prenatal failure to thrive due to inadequate care of the unborn in the womb/intrauterine growth retardation).
Infectious and parasitic diseases (A00-B99).
- Viral and bacterial infections, recurrent.
Neoplasms (C00-D48)
- Neoplasia, undetected (0.33% of autopsied children) – hematologic malignancies were most common among cancers as a cause of sudden death
Other causes
- Infants born at altitudes above 8,000 feet (2,438 meters) in the U.S. state of Colorado have a 2.3-fold increased risk of sudden infant death syndrome (SIDS), according to a study; probable cause is oxygen deprivation.
