Sudden Infant Death Syndrome

Extensive work has been done in an attempt to determine distinguishing pathological abnormalities that if present at autopsy would definitively identify SIDS as the cause of death. While there are findings that are commonly present at autopsy, no gross anatomical or microscopic abnormalities have been found that are distinct to SIDS. Nevertheless, a thorough postmortem (autopsy) examination demonstrating the absence of a causative abnormality is crucial to the diagnosis of SIDS. Especially important is not missing evidence of child abuse such as signs of (1) suffocation, (2) blunt trauma to the head, ribs, or extremities, and (3) retinal hemorrhages seen in shaken baby syndrome.

Commonly described findings in the central nervous system include: (1) increase in brain weight, presumably due to disordered development of the brain, (2) delayed myelination (maturation) of nerve cells, (3) gliosis (scarring) of brain-stem cells, (4) areas of leukomalacia (degeneration of brain tissue that occurred weeks to months earlier), and (5) abnormal dendritic spine density in selected areas of the brain stem. Evidence of chronic oxygen deprivation—such as persistence of brown fat around the adrenal glands, red blood cell production in the liver, and gliosis of the brain stem—add support to the theory that abnormal respiratory regulation may be the mechanism underlying SIDS.