demanding a yes or no answer and opened or
closed her eyes and moved them laterally when
commanded to do so. There was no other voluntary
movement. Four days before she died, she devel-
oped ocular bobbing when commanded to look
laterally, but although she consistently responded
to commands by moving her eyes, it was difficult
to know whether or not her responses were appro-
priate. During the ensuing 3 days, evidence of
wakefulness decreased. She died of gastrointestinal
hemorrhage 26 days after entering the hospital.
The brain at autopsy contained a moderate
amount of dark, old blood overlying the right lat-
eral medulla adjacent to the fourth ventricle. A
raspberry-appearing arteriovenous malformation,
1.4 cm in greatest diameter, protruded from the
right lateral medulla, beginning with its lower
border 2.5 cm caudal to the obex. On section, the
vascular malformation was seen to originate in the
central medulla and to extend rostrally to approx-
imately 2 mm above the obex. From this point, a
large hemorrhage extended forward to destroy the
central medulla all the way to the pontine junction
(Figure 1–9B). Microscopic study demonstrated
that, at its most cranial end, the hemorrhage de-
stroyed the caudal part of the right vestibular nuclei
and most of the adjacent lower pontine tegmen-
tum on the right. Caudal to this, the hemorrhage
widened and destroyed the entire dorsal center of
the medulla from approximately the plane of the
nucleus of the glossopharyngeal nerve down to just
below the plane of the nucleus ambiguus. From
this latter point caudally, the hemorrhage was
more restricted to the reticular formation of the
medulla. The margins of this lesion contained an
organizing clot with phagocytosis and reticulum
formation indicating a process at least 2 weeks
old. The center of the hemorrhage contained a de-
generating clot estimated to be at least 72 hours
old; at several places along the lateral margin of
the lesion were small fresh hemorrhages estimated
to have occurred within a few hours of death. It was
considered unlikely that the lesion had changed
substantially in size or extent of destruction in the
few days before death.
Patient 1–3
A 65-year-old woman was admitted to the neuro-
logy service for ‘‘coma’’ after an anesthetic proce-
dure. She had rheumatoid arthritis with subluxa-
tion of C1 on C2, and compression of the C2 root
causing occipital neuralgia. An anesthesiologist at-
tempted to inject the root with ethanol to elimi-
nate the pain. Almost immediately after the injec-
tion, the patient became flaccid and experienced a
respiratory arrest. On arrival in the neurology in-
tensive care unit she was hypotensive and apneic.
Mechanical ventilation was instituted and blood
pressure was supported with pressors.
On examination she had spontaneous eye move-
ments in the vertical direction only and her eyelids
fluttered open and closed. There was complete flac-
cid paralysis of the hypoglossal, vagal, and acces-
sory nerves, as well as all spinal motor function.
Twitches of facial and jaw movement persisted.
There was no response to pinprick over the face or
body. CT scan showed hypodensity of the medulla
and lower pons.
The patient responded to commands to open and
close her eyes and learned to communicate in this
way. She lived another 12 weeks in this setting, with-
out regaining function, and rarely was observed to
sleep. No postmortem examination was permitted.
However, the injection of ethanol had apparently
entered the C2 root sleeve and fixed the lower
brainstem up through the facial and abducens nu-
clei without clouding the state of consciousness of
the patient.
Comment: Both of these cases demonstrated the
preservation of consciousness in patients with a
locked-in state due to destruction of motor path-
ways below the critical level of the rostral pons.
Chapter 2 will explore the ways in which the neu-
rologic examination of a comatose patient can be
used to differentiate these different causes of loss
of consciousness.
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Pathophysiology of Signs and Symptoms of Coma
35