Lethal hypothermia – a sometimes elusive diagnosis
Lethal hypothermia - a sometimes elusive diagnosis
Roger W. Byard 0 1
Fiona M. Bright 0 1
0 School of Medicine, The University of Adelaide , Frome Road, Level 3 Medical School North Building, Adelaide 5005 , Australia
1 Roger W. Byard
Significant hypothermia occurs when the body core
temperature falls from its usual 37 °C to below 35 °C. The findings at
autopsy can be quite subtle and there is a lack of accord on the
necessary features required to make the diagnosis [
]. It is
even less clear to what degree hypothermia may contribute to
lethal outcomes in the presence of significant underlying
organic illnesses. For example, the relationship between
hypothermia and the metabolic derangements that occur in elderly
individuals with frailty syndrome has only recently been
explored . The following discussion looks at the complexities
of this diagnosis and points out the gaps in our knowledge
which could result in under diagnosis.
Diagnostic issues with hypothermia were summarized
quite succinctly and presciently by Casper in the nineteenth
century. Over a century and a half ago he commented that
“even in regard to the appearances found on dissection, there
is not one which can with any certainty justify the assumption
of death from cold” [
]. Hypothermia still carries a significant
risk of death with >70% mortality with core temperature of
30 °C, increasing to 90% at 26 °C [
Environmental factors clearly play a significant role in
deaths attributed to hypothermia with a common scenario
being individuals who have been lost in areas with sub-zero
temperatures. The finding of a non-traumatized body with
no significant underlying disease and a high alcohol level in
a snow bank is strong supportive evidence for death from
hypothermia. Cases become more complex, however, where
there has been an elderly individual found at their home
address having collapsed from a cardiovascular, orthopedic,
neurological or endocrine event [
]. Exacerbating factors
include cold flooring, damp conditions, wet or inadequate
clothing, low muscle mass, immobility, certain drugs, and some
psychiatric conditions [
]. Poor home insulation and
heating are recently recognized factors that have produced
the counter-intuitive finding of higher death rates from
hypothermia in South Australia with its Mediterranean climate than
in Sweden [
]. This has also been reported in other
temperate areas [
Individuals die of hypothermia because of failure of
hypothalamic counter-regulatory mechanisms that initiate and
maintain chemical thermogenesis and vasoconstriction [
]. Death likely results from a combination of events such
as ventricular fibrillation or asystole, initiated or exacerbated
by hypoxia, myocardial ischemia, increased circulating
catecholamines and electrolyte derangements [
1, 9, 15
The major problems for forensic pathologists are firstly
how to accurately identify cases, and then how to make a
credible diagnosis. As with cases of hyperthermia, the core
temperature of a decedent at the time of death is not usually
available, and so evaluation of potential cases at autopsy
requires a clear understanding of the circumstances of the death
(ideally with a recording of the ambient temperature) and the
exclusion of other possibilities [
3, 8, 16
]. Issues occur with
differences in diagnostic practices arising from the
nonspecific and subtle nature of findings at autopsy, and the
possibility of inflicted injury due to the sometimes bizarre
nature of behavior that may occur before death [
Biochemical markers are not currently routinely assessed
in these cases [
The peri-mortem behavior of individuals who have
succumbed to hypothermia that may create concerns of a
suspicious death include so-called paradoxical undressing where,
most typically, an individual has sequentially removed clothes
as he or she has staggered through snow. This has been called
“hypothermic confusion” and results from terminal failure of
thermoregulatory control [
]. Socially isolated individuals
may also exhibit features of the “hide and die” syndrome or
“terminal burrowing” where they may be found hidden under
a pile of newspapers or rubbish [
]. This is most likely in
hoarding disorders as a manifestation of Diogenes, Havisham,
or so-called senile squalor, syndrome [
At autopsy in those exposed to the cold there are may be a
series of characteristic but not diagnostic findings that occur
with variable frequency. Externally these features include pink
discoloration of the skin over the extensor surfaces of large
joints. On internal examination there may be superficial
gastric erosions, or Wischnewski spots, vacuolization of renal
tubular cells, acute pancreatic inflammation with fat necrosis,
fatty change in cells of the heart, liver and kidneys, and
skeletal muscle hemorrhage [
Wischnewski spots in the gastric mucosa are considered the
most reliable marker of hypothermia at post mortem [
]. There is, however, considerable variation in their
reported incidence which may be related to the length of
exposure to low temperatures, or to idiosyncratic general and
gastric mucosal responses to cold stress [
Spots may occur because of disturbances in
microcirculation with ischemic-reperfusion injury and hemoglobin
3, 24, 27, 30
]. The role of stress in their etiology has
been debated, with a recent low-stress animal model failing to
generate Wischnewski spots in anesthetized rats exposed to
low temperatures .
Hypothermia is also related to a wide variety of disparate
organic conditions that include diabetes mellitus, stroke,
sepsis, hypothyroidism and cardiac, renal, and hepatic failure [
]. These conditions may alter thermoregulatory
responses leading to abnormal temperature control and
regulation . Determining the exact cause of death in cases with
multiple medical conditions may be difficult as the potential
role of hypothermia in the deaths may be obscured [
addition, a number of psychiatric and neurodegenerative
conditions such as bipolar disease, schizophrenia, Alzheimer’s
disease, and dementia increase the risk for lethal hypothermia
In conclusion, it appears that although the phenomenon of
lethal hypothermia is well recognized in forensic pathology,
the diagnostic criteria and evaluation of cases remain
problematic. The percentage of cases with Wischnewski spots
exemplifies this situation with the frequency of these lesions
varying from 40 to 91% of cases in different series [
]. While this may be a reflection of the pathogenesis and
time course of these spots, it may also be a marker of
diagnostic practices, with hypothermia being a more likely
diagnosis in some centers only if the spots are present.
The conclusion that hypothermia is the cause of death often
relies not only on the quality of the death scene examination
by police investigators, but also on the documentation of key
features such as the ambient temperature, and the adequacy of
insulation and heating for indoor deaths. In addition, the
detection and correct interpretation of subtle autopsy markers is
sometimes not easy. Finally, the role of hypothermia in
triggering natural deaths from organic illness is yet another area in
forensic practice to be explored.
Thus, it would appear not unreasonable to suggest that
some cases of hypothermia might not be being recognized in
contemporary forensic facilities. This would, of course come
as no surprise to Professor Casper, who also commented in
1862 in Berlin, that “physiology has not yet determined, and
probably never will determine, how it happens…” [
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