Immediate examination on the radiology table
showed that breathing was slow and regular and
she was unresponsive except to deep pain, with
localizing movements of the right but not the left
extremities. The right pupil was 8 mm and unre-
active to light, and there was no adduction, ele-
vation, or depression of the right eye on oculoce-
phalic testing. Muscle tone was increased on the
left compared to the right, and the left plantar re-
sponse was extensor.
She was immediately treated with hyperventi-
lation and mannitol and awakened. The radiolo-
gist reported that there were fragments of metal
embedded in the skull over the right frontal lobe.
Figure 3–8. Herniation due to a cerebellar mass lesion. The incisural line (A, B) is defined by a line connecting the dorsum
sellae with the inferior point of the confluence of the inferior sagittal and straight sinuses with the great vein of Galen, in a
midline sagittal magnetic resonance imaging (MRI) scan, shown by a line in each panel. The iter, or anterior tip of the cerebral
aqueduct, should lie along this line; upward herniation of the brainstem is defined by the iter being displaced above the line.
The cerebellar tonsils should be above the foramen magnum line (B), connecting the most inferior tip of the clivus and the
inferior tip of the occiput, in the midline sagittal plane. Panel (C) shows the MRI of a 31-year-old woman with metastatic
thymoma to the cerebellum who developed stupor and loss of upgaze after placement of a ventriculoperitoneal shunt. The
cerebellum is swollen, the fourth ventricle is effaced, and the brainstem is compressed. The iter is displaced 4.8 mm above the
incisural line, and the anterior tip of the base of the pons is displaced upward toward the mammillary body, which also lies
along the incisural line. The cerebellar tonsils have also been forced 11.1 mm below the foramen magnum line (demarcated
by thin, long white arrow). Following treatment, the cerebellum and metastases shrank (C), and the iter returned to its normal
location, although the cerebellar tonsils remained somewhat displaced. (Modified from Reich et al.,
59
with permission.)
104
Plum and Posner’s Diagnosis of Stupor and Coma
The patient confirmed that the boyfriend had ac-
tually tried to shoot her, but that the bullet had
struck her skull with only a glancing blow where
it apparently had fragmented. The right frontal
lobe was contused and swollen and downward
pressure had caused transtentorial herniation of
the uncus. Following right frontal lobectomy to
decompress her brain, she improved and was
discharged.
LATE THIRD NERVE STAGE
As the foregoing case illustrates, the signs of the
late third nerve stage are due to more complete
impairment of the oculomotor nerve as well as
compression of the midbrain. Pupillary dilation
becomes complete and the pupil no longer re-
acts to light. Adduction, elevation, and depres-
sion of the affected eye are lost, and there is
Eupneic
Constricts sluggishly
DOLL’S HEAD MANEUVER
ICE WATER CALORICS
Moderately dilated
pupil, usually ipsilateral
to primary lesion
Present or dysconjugate
Full conjugate slow
ipsilateral eye movement
(impaired nystagmus)
or
Appropriate motor
response to noxious
orbital roof pressure.
Contralateral paratonic
resistance
Contralateral extensor
plantar reflex
Dysconjugate, because
contralateral eye does
not move medially
Respiratory
pattern
a.
Pupillary
size and
reactions
b.
Oculocephalic
and
oculovestibular
responses
c.
Motor
responses
at rest
and to
stimulation
d.
Figure 3–9. Signs of uncal herniation, early third nerve stage.
Structural Causes of Stupor and Coma
105
usually ptosis (if indeed the patient opens the
eyes at all).
The lapse into coma may take place over just
a few minutes, as in the patient above who was
uncooperative with the x-ray technician and
10 minutes later was found by the neurologist
to be deeply comatose. Hemiparesis may be
ipsilateral to the herniation (if the midbrain is
compressed against the opposite tentorial edge)
or may be contralateral (if the paresis is due
to the lesion damaging the descending corti-
cospinal tract or to a herniating temporal lobe
compressing the ipsilateral cerebral peduncle).
Breathing is typically normal, or the patient may
lapse into a Cheyne-Stokes pattern of respira-
tion (Figure 3–10).
MIDBRAIN-UPPER PONTINE STAGE
If treatment is delayed or unsuccessful, signs of
midbrain damage appear and progress caudally,
as in central herniation (see below). Both pupils
or
Regular sustained hyperventilation
Rarely, Cheyne-Stokes
Does not constrict
DOLL’S HEAD MANEUVER
ICE WATER CALORICS
ipsilateral pupil widely
dilated
Decorticate or decerebrate
responses
Ipsilateral eye doesn’t move
medially, but contralateral eye
retains full lateral movement
Respiratory
pattern
a.
Pupillary
size and
reactions
b.
Oculocephalic
and
oculovestibular
responses
c.
Motor
responses
at rest
and to
stimulation
d.
Figure 3–10. Signs of uncal herniation, late third nerve stage.
106
Plum and Posner’s Diagnosis of Stupor and Coma