with middle lesions. About half the patients
with posterolateral lesions were drowsy, but
not comatose, as were about one-half the pa-
tients with the lateral lesions who rarely be-
come comatose. However, massive lesions usu-
ally cause severe impairment of consciousness
including coma. Hemiparesis is common in
posterolateral and massive lesions. Sensory def-
icits are relatively frequent in posterior and
medial lesions. Prognosis is fair to good in pa-
tients with all of the lesions save the massive
ones, where the fatality rate is about 50%. Eye
deviation occurs usually toward the lesion site,
but may be ‘‘wrong way’’ in those with pos-
terolateral and massive lesions.
Thalamic hemorrhages can be categorized
by size (smaller or larger than 2 cm in diame-
ter) and by location (posterolateral, anterolat-
eral, medial, and dorsal; Figure 4–6B). About
one-fifth of patients with thalamic hemorrhages
are stuporous or comatose at presentation.
101
The loss of consciousness is usually accompa-
nied by ocular signs including skew deviation
(the lower eye on the side of the lesion); gaze
preference, which may either be toward or
away (wrong-way eyes) from the side of the
lesion; loss of vertical gaze; and miotic pupils.
‘‘Peering at the tip of the nose’’ is an almost
pathognomonic sign.
102
Sensory and motor
disturbances depend on the site and size of the
lesion. About 25% of patients die,
101
and the
outcome is related to the initial consciousness,
nuchal rigidity, size of the hemorrhage, and
whether the hemorrhage dissects into the lat-
eral ventricle or causes hydrocephalus.
101
Intraventricular hemorrhages may be either
primary or result from extension of an intra-
cerebral hemorrhage. Intraventricular hemor-
rhages were once thought to be uniformly fatal,
but since the advent of CT scanning, have been
shown to run the gamut of symptoms from
simple headache to coma and death.
103
Pri-
mary intraventricular hemorrhages can result
from vascular anomalies within the ventricle,
surgical procedures, or bleeding abnormali-
ties.
104
Clinical findings include sudden onset
of headache and vomiting sometimes followed
by collapse and coma. If the hemorrhage finds
its way into the subarachnoid space, nuchal
rigidity occurs. The clinical findings of second-
ary intraventricular hemorrhage depend on
the initial site of bleeding. Hemorrhage into
the ventricle from a primary intracerebral hem-
orrhage worsens the prognosis.
The treatment of intraventricular hemor-
rhage is aimed at controlling intracranial pres-
sure. Ventricular drainage may help, but the
catheter often becomes occluded by the blood.
Injection of fibrinolytic agents (such as t-PA)
has been recommended by some.
104
The treatment of an intracerebral hemor-
rhage is controversial. Early surgery to evacu-
ate the hematoma has not been associated with
better outcome.
105
However, treatment with
hemostatic drugs, such as recombinant factor
VIIa, which limit hematoma size, are associ-
ated with improved outcomes.
106
Most patients
who have relatively small lesions and do not
die make good recoveries; those with mas-
sive lesions typically either die or are left devas-
tated. Herniation should be treated vigorously
in patients with relatively small hematomas be-
cause of the potential for good recovery.
Despite these similarities, the clinical setting
in which one sees patients with intracerebral
hemorrhage depends on the pathologic process
involved. These include rupture of a deep ce-
rebral endartery, amyloid angiopathy, mycotic
aneurysm, arteriovenous malformation, or hem-
orrhage into a tumor, and each requires a dif-
ferent clinical approach.
Box 4–1 summarizes the major points that
differentiate clinically between acute cerebral
vascular lesions potentially causing stupor or
coma.
Rupture of deep cerebral end arteries usu-
ally occurs in patients with long-term, poorly
treated hypertension; it can also complicate di-
abetes or other forms of atherosclerotic arter-
iopathy. The blood vessels that are most likely
to hemorrhage are the same ones that cause
lacunar strokes (i.e., end arteries that arise at a
right angle from a major cerebral artery): the
striatocapsular arteries, which give rise to cap-
sular and basal ganglionic bleeds; the thalamic
perforating arteries, which give rise to thalamic
hemorrhages; the midline perforating arteries
of the pons, which give rise to pontine hemor-
rhages; and the penetrating branches of the
cerebellar long circumferential arteries, which
cause cerebellar hemorrhages. We will deal
with the first two, which cause supratentorial
masses, in this section, and the latter two in the
section on infratentorial masses.
The focal neurologic findings in each case
are characteristic of the part of the brain that
is injured. Capsular or basal ganglionic hemor-
rhages typically present with the acute onset of
Specific Causes of Structural Coma
137
Box 4–1 Typical Clinical Profiles of Acute Cerebrovascular
Lesions Affecting Consciousness
Acute massive cerebral infarction with or without hypotension
Distribution: Internal carotid-proximal middle cerebral artery or middle cerebral
plus anterior cerebral arteries. Onset during wakefulness or sleep. Massive hemi-
plegia with aphasia, hemisensory defect. Obtundation from the start or within
hours, progressing to stupor in 12 to 24 hours, coma usually in 36 to 96 hours.
Convulsions rare. Pupils small and reactive, or constricted ipsilateral to lesion
(Horner’s), or moderately dilated ipsilateral to lesion (III nerve). Conjugate gaze
paresis to side of motor weakness; contralateral oculovestibulars can be sup-
pressed for 12 hours or so. Contralateral hemiplegia, usually with extensor plantar
response and paratonia ipsilateral to lesion. Cheyne-Stokes breathing 10% to 20%.
Signs of progressive rostral caudal deterioration begin in 12 to 24 hours. Spinal
fluid usually unremarkable or with mildly elevated pressure and cells.
Frontoparietal hemorrhage
Onset during wakefulness. Sudden-onset headache, followed by more or less rap-
idly evolving aphasia, hemiparesis to hemiplegia, conjugate ocular deviation away
from hemiparesis. Convulsions at onset in approximately one-fifth. Pupils small and
reactive, or ipsilateral Horner’s with excessive contralateral sweating, or stupor to
coma and bilateral motor signs within hours of onset. Bloody spinal fluid.
Thalamic hemorrhage
Hypertensive, onset during wakefulness. Clinical picture similar to frontoparietal
hemorrhage but seizures rare, vomiting frequent, eyes characteristically deviated
down and laterally to either side. Pupils small and reactive. Conscious state ranges
from awake to coma. Bloody spinal fluid.
Bilateral thalamic infarction in the paramedian regions
Sudden onset of coma, akinetic mutism, hypersomnolence or altered mental status
may accompany bland infarcts of the paramedian thalamus arising bilaterally as a
result of a ‘‘top of the basilar’’ syndrome or a branch occlusion of a thalamope-
duncular artery (Percheron’s artery) providing vascular supply to both thalami and
often the tegmental mesencephalon.
Pontine hemorrhage
Hypertensive. Sudden onset of coma or speechlessness, pinpoint pupils, ophthal-
moplegia with absent or impaired oculovestibular responses, quadriplegia, irreg-
ular breathing, hyperthermia. Bloody spinal fluid.
Cerebellar hemorrhage
Hypertensive and awake at onset. Acute and rapid onset and worsening within
hours of occipital headache, nausea and vomiting, dizziness or vertigo, unstead-
iness, dysarthria, and drowsiness. Small and reactive pupils, nystagmus or hori-
zontal gaze paralysis toward the side of the lesion. Midline and ipsilateral ataxia,
(continued)
138