ABSTRACT
There are many hypotheses for the cause of death in sudden infant death syn-
drome (SIDS). For many of these hypotheses, little or nothing is known about the
relevant pathophysiological mechanisms. The use of the term sudden unex-
plained death in infants (SUDI) is becoming more common as it now seems
evident that a number of infants formerly diagnosed as SIDS victims should now
be diagnosed with ‘‘accidental suffocation,’’ homicide, cardiac arrhythmias,
inborn errors of metabolism, or other disorders with differing pathophysiological
mechanisms (Table 1). For example, even when death scene findings strongly
support a diagnosis of accidental suffocation as the cause of death, it is believed
by many that such infants may have brain stem defects that predispose them to
suffocation. In such cases it is argued that these deaths are not completely
explained by evidence from the death scene and postmortem examination, and so
the use of the term SIDS still is appropriate. The following overview is divided
into sections where at least some evidence of the pathophysiology has been
documented as well as several more prominent theories for causal mechanism
where evidence is still lacking.
