5 – The brainstem pattern of damage
Myers (1972) confirmed the findings of Ranck and
Windle (1959).  Damage caused by sudden and total
asphyxia affects brainstem structures [1, 2].  The first
to sustain visible damage are the inferior colliculi.  
"Thereafter, in a monotonously repetitive rank order,
follow other brainstem structures including the
superior olives, the sensory nuclei of the trigeminal
nerve, the gracile and cuneate nuclei, the medial and
spinal vestibular nuclei, and the posterior and lateral
ventral thalamic nuclei.  These structures are injured
by asphyxial episodes lasting for only 10 to 13 min." [1,
p251].

Further, "The rank order of involvement of the various
brainstem structures following total asphyxia remains
constant from animal to animal" [1, p253].

Beyond 16 to 18 minutes of asphyxia the damage
extends widely throughout the brainstem, affecting the
thalamus almost in its entirety.  The lateral brainstem
tegmentum along with brainstem motor nuclei such as
the trigeminal and facial nerves, and the intermediate
and anterior gray columns of the spinal cord also
sustain injury of longer duration.

Microscopic changes were detected within the first half
hour following asphyxia in the most vulnerable
structures such as the inferior colliculus.  Nerve cells
had begun to shrink in size.  Ultrastructural (electron
microscope) examination revealed (a) mitochondrial
shrinkage and (b) loss of membrane integrity.
  1. Myers RE (1972) Two
    patterns of perinatal brain
    damage and their
    conditions of occurrence.  
  2. Ranck JB, Windle WF
    (1959). Brain damage in
    the monkey, Macaca
    mulatta, by asphyxia
    neonatorum.
References