HEAD AND NECK INJURIES - Medicine for Mountaineering and Other Wilderness Activities - page 99

that compresses the brain, which often results in death unless treated by surgical decom-
pression in a timely fashion.
Bleeding develops either outside the dura (epidural hematoma), due to tearing of arter-
ies, or inside the dura (subdural hematoma), due to tearing of bridging veins ( Fig. 8-1 ).
Traumatic hemorrhage may occur within the brain, either as bleeding with a contusion or
as a so-called subarachnoid hemorrhage. Epidural and subdural hematomas are associated
with the worst prognosis of all bleeding patterns associated with head injury. Individuals
at risk for developing a significant hemorrhage after head trauma must be identified and
evacuated at the earliest opportunity.
Assessment
One of the greatest pitfalls in assessing an individual who has sustained a head injury is
underestimating the severity of injury. In fact, initial trauma may represent just the begin-
ningofthedamage, andsecondary deterioration mayoccurovertime. Theclassic example
is the individual who may be fully awake, alert, and talking shortly after sustaining a brain
injurybutdeterioratesanddieswithinafewhoursasaresultofaggravatingcircumstances,
such as delayed bleeding inside the skull. A high level of suspicion, in conjunction with a
complete assessment and estimation of potential risk, should mandate early evacuation of
these individuals.
Figure 8-1. Subdural hematoma
Theassessment oftrauma mustinclude estimating theforceoftheimpact, including the
fallingheightandthepresenceofashort-termlossofconsciousnessaftertheaccident.The
critical falling height for sustaining a significant head injury is considered 20 feet (6 m)
or more, although falls from lower heights may also result in severe brain injuries, partic-
ularly in the presence of individual risk factors. Amnesia or a history of a brief period of
unconsciousness after trauma is an important indicator of a significant brain injury.