Level of Consciousness
Alert
15 (0)
Drowsy
21 (3)
Stuporous
4 (3)
Coma
40 (32)
Respiratory Disturbance
Yes
37 (29)
Brachycardia
Yes
34 (23)
Hyperthermia
Yes
32 (30)
Pupils
Normal
29 (1)
Anisocoria
29 (11)
Pinpoint
23 (17)
Mydriasis
9 (9)
Motor Disturbance
Hemiplegia
34 (4)
Tetraplegia
22 (17)
Decerebrate posture*
16 (14)
*Number that died in parentheses.
Modified from Murata.
250
Specific Causes of Structural Coma
167
Patient 4–7
A 54-year-old man with poorly treated hyperten-
sion was playing tennis when he suddenly col-
lapsed on the court. The blood pressure was 170/
90 mm Hg; the pulse was 84 per minute; respi-
rations were Cheyne-Stokes in character and 16
per minute. The pupils were pinpoint but reacted
equally to light; eyes were slightly dysconjugate
with no spontaneous movement, and vestibulo-
ocular responses were absent. The patient was flac-
cid with symmetric stretch reflexes of normal am-
plitude and bilateral flexor withdrawal responses
in the lower extremities to plantar stimulation. CT
scan showed a hemorrhage into the pontine teg-
mentum. The next morning he was still in deep
coma, but now was diffusely flaccid except for
flexor responses to noxious stimuli in the legs.
He had slow, shallow, eupneic respiration; small,
equally reactive pupils; and eyes in the neutral
position. Shortly thereafter, breathing became ir-
regular and he died. A 3-cm primary hemorrhage
destroying the central pons and its tegmentum was
found at autopsy.
The clinical features in Patient 4–7, includ-
ing coma in the absence of motor responses,
corneal reflexes, and oculocephalic responses,
predicted the poor outcome.
258
In addition, if
CT scanning shows a hematoma greater than
4 mL, hemorrhage in a ventral location,
259
evidence of extension into the midbrain and
thalamus, or hydrocephalus on admission, the
prognosis is poor.
258
Primary hemorrhage into the medulla is
rare.
251
Patients present with ataxia, dyspha-
gia, nystagmus, and tongue paralysis. Respira-
tory and cardiovascular area may occur, leav-
ing the patient paralyzed and unable to breathe,
but not unconscious.
Basilar Migraine
Altered states of consciousness are an uncom-
mon but distinct aspect of what Bickerstaff
called basilar artery migraine,
260
associated with
prodromal symptoms that suggest brainstem
dysfunction. The alteration in consciousness
can take any of four major forms: confusional
states, brief syncope, stupor, and unarousable
coma. Although not technically a destructive
lesion, and with a pathophysiology that is not
understood, basilar migraine clearly causes pa-
renchymal dysfunction of the brainstem that
is often mistaken for a brainstem ischemic at-
tack.
Alterations in consciousness often last longer
than the usual sensorimotor auras seen with mi-
graine. Encephalopathy and coma in migraine
occur in patients with familial hemiplegic mi-
graine associated with mutations in a calcium
channel
261
and in patients with the disorder
known as cerebral autosomal dominant arter-
iopathy with subcortical infarcts and leukoen-
cephalopathy (CADASIL)
262
(see page 276,
Chapter 5). The former often have fixed cer-
ebellar signs and the latter multiple hyperin-
tensities of the white matter on MR scanning.
Blood flow studies concurrent with migraine
aura have demonstrated both diffuse and focal
cerebral vasoconstriction, but this is an insuf-
ficient explanation for the striking focal symp-
toms in basilar migraine; however, some clini-
cal lesions suggestive of infarction can be found
in patients with migraine significantly more of-
ten than in controls.
263
Selby and Lance
264
observed that among 500
consecutive patients with migraine, 6.8% had
prodromal episodes of confusion, automatic be-
havior, or transient amnesia, while 4.6% actually
fainted. The confusional and stuporous attacks
can last from minutes to as long as 24 hours or,
rarely, more. They range in content from quiet
disorientation through agitated delirium to un-
responsiveness in which the patient is barely
arousable. Transient vertigo, ataxia, diplopia,
hemianopsia, hemisensory changes, or hemipa-
resis changes may immediately precede the
mental changes. During attacks, most observers
have found few somatic neurologic abnormali-
ties, although occasional patients are reported
as having oculomotor palsies, pupillary dilation,
or an extensor plantar response. A few patients,
at least briefly, have appeared to be in unarous-
able coma.
Posterior Reversible
Leukoencephalopathy Syndrome
Once believed to be associated only with ma-
lignant hypertension (hypertensive encepha-
lopathy),
265
posterior reversible leukoenceph-
alopathy syndrome (PRES) is known to be
caused by several illnesses that affect endothe-
168
Plum and Posner’s Diagnosis of Stupor and Coma
lial cells, particularly in the posterior cerebral
circulation.
266
Among the illnesses other than
hypertension, pre-eclampsia and immunosup-
pressive and cytotoxic agents (e.g., cyclosporin,
cisplatin) are probably the most common cau-
ses. Vasculitis, porphyria, and thrombotic
thrombocytopenic purpura are also reported
causes, as is occasionally migraine. Posterior
leukoencephalopathy is characterized by vaso-
genic edema of white matter of the posterior
circulation, particularly the occipital lobes, but
sometimes including the brainstem. Clinically,
patients acutely develop headache, confusion,
seizures, and cortical blindness; coma is rare.
The MRI reveals vasogenic edema primarily
affecting the occipital and posterior parietal
lobes. Brainstem and cerebellum may also be af-
fected. With appropriate treatment (controlling
hypertension or discontinuing drugs), symp-
toms resolve. In patients with pre-eclampsia
who are pregnant, intravenous infusion of mag-
nesium sulfate followed by delivery of the fe-
tus has a similar effect. If PRES due to pre-
eclampsia occurs in the postpartum period, im-
mediate administration of magnesium sulfate
followed by treatment for several weeks with
verapamil is often effective, in our experience.
The differential diagnosis includes posterior
circulation infarction, venous thrombosis, and
metabolic coma (Table 4–19 and Patient 5–8).
INFRATENTORIAL
INFLAMMATORY DISORDERS
The same infective agents that affect the ce-
rebral hemispheres can also affect the brain-
stem and cerebellum. Encephalitis, meningi-
tis, and abscess formation may either be part
of a more generalized infective process or be
Table 4–19 Common Differential Diagnoses of Posterior Leukoencephalopathy
Syndrome
Posterior
Leukoencephalopathy
Central Venous
Thrombosis
Top of Basilar
Syndrome
Predisposing
factors
Eclampsia, renal failure,
cytotoxic and
immunosuppressive
agents, hypertension
Pregnancy, puerperium,
dehydration
Risk factors for
stroke, cardiac
disorders
Onset and
progression
Acute, evolves in days
Acute, evolves in days
Sudden, evolves
in hours
Clinical features
Seizures precede all other
manifestations, visual
aura, cortical blindness,
confusion, headache,
rarely focal deficit
Headaches, seizures,
stupor or coma, focal
neurologic deficits
(monoparesis or
hemiparesis), papilledema,
evidence of venous
thrombosis elsewhere,
infrequently hypertensive
Cortical blindness,
hemianopia,
confusional state,
brainstem signs,
cerebral signs,
rarely seizures
Imaging features
Predominantly white
matter edema in
bilateral occipital and
posterior parietal regions,
usually spares paramedian
brain parenchyma
Hemorrhage and ischemic
infarcts, small ventricles,
‘‘cord sign’’ caused by
hyperdense thrombosed
vein, evidence of major
venous sinus thrombosis
on MRI
Infarcts of bilateral
paracalcarine
cortex, thalamus,
inferior medial
temporal lobe,
and brainstem
Prognosis
Completely resolves after
rapid control of BP and
removal of offending drug
Intensive management is
needed; mortality
high in severe cases
No recovery
or only partial
eventual recovery
BP, blood pressure; MRI, magnetic resonance imaging.
From Garg,
266
with permission.
Specific Causes of Structural Coma
169
restricted to the brainstem.
267
Organisms that
have a particular predilection for the brain-
stem include L. monocytogenes, which often
causes brainstem abscesses
268
(Figure 4–13).
Occasionally herpes zoster or simplex infection
that begins in one of the sensory cranial nerves
may cause a segmental brainstem encephali-
tis.
269
Behc¸et’s disease may also cause brain-
stem inflammatory lesions.
270
These disorders
usually cause headache with or without nuchal
rigidity, fever, and lethargy, but rarely coma. In
a minority of instances, the CT scan may show
brainstem swelling. The MR scan is usually
more sensitive. CSF usually contains an in-
creased number of cells. In bacterial infections
cultures are usually positive; in viral infections
PCR may establish the diagnosis. Stereotactic
drainage of a brain abscess often identifies the
organisms; appropriate antimicrobial therapy
is usually successful.
271
A brainstem disorder often confused with
infection is Bickerstaff’s brainstem encephali-
tis.
272
Patients with this disorder have often
had a preceding systemic viral infection, then
acutely develop ataxia, ophthalmoplegia, long-
tract signs, and alterations of consciousness in-
cluding coma. In some patients, MRI reveals
brainstem swelling and increased T2 signal
273
;
in others, the scan is normal. The CSF protein
may be elevated, but there are no cells. The dis-
ease is believed to be autoimmune in origin
related to postinfectious polyneuropathy (the
Guillain-Barre´ syndrome) and the related
Miller Fisher syndrome.
272
The diagnosis can
be established by the identification of anti-
GQ1b ganglioside antibodies in serum.
272
Pa-
tients recover spontaneously.
INFRATENTORIAL TUMORS
Tumors within the brainstem cause their symp-
toms by a combination of compression and
destruction. Although relatively common in
children, primary tumors of the brainstem
(brainstem glioma) are rare in adults. Meta-
static tumors are more common, but with both
primary and metastatic tumors, slowly or sub-
acutely evolving brainstem signs typically es-
tablish the diagnosis long before impairment
of consciousness occurs. An exception is the
rare instance of an acute hemorrhage into the
tumor, causing the abrupt onset of paralysis
and sometimes coma, in which case the signs
and treatment are similar to other brainstem
hemorrhages.
Figure 4–13. A pair of magnetic resonance images demonstrating a multiloculated pontine abscess in a 73-year-old
woman (Patient 2–2) who had been taking chronic prednisone for ulcerative colitis. She developed a fever, nausea and
vomiting, left facial numbness, left gaze paresis, left lower motor neuron facial weakness, and left-sided ataxia. Lumbar
puncture showed 47 white blood cells/mm
3
, but culture was negative. She was treated for suspected Listeria mono-
cytogenes and recovered slowly, but had residual facial and oropharyngeal weakness requiring chronic tracheostomy.
170
Plum and Posner’s Diagnosis of Stupor and Coma
CENTRAL PONTINE
MYELINOLYSIS
This is an uncommon disorder in which the
myelin sheaths in the central basal pons are
destroyed in a single confluent and symmetric
lesion. Similar lesions may be found in the
corpus callosum or cerebral hemispheres.
274
Lesions vary from a few millimeters across to
ones that encompass almost the entire base of
the pons, sparing only a rim of peripheral mye-
lin. The typical clinical picture is one of quad-
riparesis, with varying degrees of supranuclear
paresis of lower motor cranial nerves and im-
pairment of oculomotor or pupillary responses.
A majority of patients become ‘‘locked in.’’ Ap-
proximately one-quarter of patients demon-
strate impairment of level of consciousness, re-
flecting extension of the lesion into the more
dorsal and rostral regions of the pons.
It is now recognized that most cases of cen-
tral pontine myelinolysis are due to overly vig-
orous correction of hyponatremia, giving rise
tothe‘‘osmoticdemyelination syndrome.’’Since
the adoption of current regimens that recom-
mend that hyponatremia be reversed at a rate
no greater than 10 mEq/day, the frequency of
this once-feared complication has decreased
dramatically. On the other hand, a similar syn-
drome is seen in patients with liver transplan-
tation, possibly due to the use of cyclospor-
ine.
274
As liver transplant has become more
common, this population is increasing.
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