conservatively with antibiotics and drainage of
the sinus rather than the epidural mass.
42
Dural and Subdural Tumors
A number of tumors and other mass lesions may
invade the dura and compress the brain. These
lesions include dural metastases,
43
primary tu-
mors such as hemangiopericytoma,
44
hema-
topoietic neoplasms (plasmacytoma, leukemia,
lymphoma), and inflammatory diseases such as
sarcoidosis.
44
These are often mistaken for the
most common dural tumor, meningioma.
45
Meningiomas can occur anywhere along the
dural lining of the anterior and middle cranial
fossas. The most common locations are over
the convexities, along the falx, or along the base
of the skull at the sphenoid wing or olfactory
tubercle. The tumors typically present by com-
pression of local structures. In some cases, this
produces seizures, but over the convexity there
may be hemiparesis. Falcine meningiomas may
present with hemiparesis and upper motor neu-
ron signs in the contralateral lower extremity;
the ‘‘textbook presentation’’ of paraparesis is
quite rare. If the tumor occurs near the frontal
pole, it may compress the medial prefrontal
cortex, causing lapses in judgment, inconsis-
tent behavior, and, in some cases, an apathetic,
abulic state. Meningioma underlying the orbi-
tofrontal cortex may similarly compress both
frontal lobes and present with behavioral and
cognitive dysfunction. When the tumor arises
from the olfactory tubercle, ipsilateral loss of
smell is a clue to the nature of the problem.
Meningiomas of the sphenoid wing may invade
the cavernous sinus and cause impairment of
the oculomotor (III), trochlear (IV), and abdu-
cens nerves (VI) as well as the first division of
the trigeminal nerve (V
1
).
On rare occasions, a meningioma may first
present symptoms of increased intracranial
pressure or even impaired level of conscious-
ness. Acute presentation with impairment of
consciousness may also occur with hemorrhage
into a meningioma. Fortunately, this condition
is rare, involving only 1% to 2% of meningio-
mas, and may suggest a more malignant phe-
notype.
46
In such cases, the tumor typically has
reached sufficient size to cause diencephalic
compression or herniation. There is often con-
siderable edema of the adjacent brain, which
may be due in part to the leakage of blood ves-
sels in the tumor or to production by the tumor
of angiogenic factors.
47
Treatment with corti-
costeroids reduces the edema and may be life-
saving while awaiting a definitive surgical pro-
cedure.
On CT scanning, meningiomas are typically
isodense with brain, although they may have
areas of calcification. On MRI scan, a typical
meningioma is hypointense or isointense on
T1-weighted MRI and usually hypointense on
T2. In either imaging mode, the tumor uni-
formly and intensely enhances with contrast
unless it is heavily calcified, a situation where
the CT scan may give more accurate informa-
tion. The CT scan may also help in identifying
bone erosion or hyperostosis, the latter rather
characteristic of meningiomas. Meningiomas
typically have an enhancing dural tail that
spreads from the body of the tumor along the
dura, a finding less common in other dural tu-
mors. The dural tail is not tumor, but a hyper-
vascular response of the dura to the tumor.
48
Dural malignant metastases and hematopoi-
etic tumors grow more rapidly than meningio-
mas and cause more underlying brain edema.
Thus, they are more likely to cause alterations of
consciousness and, if not detected and treated
early enough, cerebral herniation. Breast and
prostate cancer and M4-type acute myelomo-
nocytic leukemia have a particular predilection
for the dura, and that may be the only site of
metastasis in an otherwise successfully treated
patient. CT and MRI scans may be similar to
those of meningioma, the diagnosis being esta-
blished only by surgery.
PITUITARY TUMORS
Tumors of the pituitary fossa are outside the
brain and its coverings, separated from the sub-
arachnoid space by the diaphragma sellae, a
portion of the dura that covers the pituitary fossa
but that contains an opening for the pituitary
stalk. Pituitary tumors may cause alterations of
consciousness, either by causing endocrine fail-
ure (see Chapter 5) or by hemorrhage into the
pituitary tumor, so-called pituitary apoplexy.
49
Pituitary adenomas typically cause symptoms
by growing out of the pituitary fossa. Because
the optic chiasm overlies the pituitary fossa,
the most common finding is bitemporal hemi-
anopsia. If the tumor extends laterally through
the wall of the sella turcica into the cavern-
ous sinus, there may be impairment of cranial
Specific Causes of Structural Coma
127
nerves III, IV, VI, or V1. In some cases, pituitary
tumors may achieve a very large size by supra-
sellar extension. These tumors compress the
overlying hypothalamus and basal forebrain and
may extend up between the frontal lobes or
backward down the clivus. Such tumors may
present primarily with prefrontal signs, or signs
of increased ICP, but they occasionally present
with impairment of consciousness.
The most common endocrine presentation in
women is amenorrhea and in some galactorrhea
due to high prolactin secretion. Prolactin is the
only pituitary hormone under inhibitory con-
trol; if a pituitary tumor damages the pituitary
stalk, other pituitary hormones fall to basal lev-
els, but prolactin levels rise. Most pituitary ad-
enomas are nonsecreting tumors, but some
pituitary tumors may secrete anterior pituitary
hormones, resulting in Cushing’s syndrome (if
the tumor secretes adrenocorticotropic hor-
mone [ACTH]), hyperthyroidism (if it secretes
thyroid-stimulating hormone [TSH]), galactor-
rhea/amenorrhea (if it secretes prolactin), or
acromegaly (if it secretes growth hormone).
Pituitary adenomas may outgrow their blood
supply and undergo spontaneous infarction or
hemorrhage. Pituitary apoplexy
49
presents with
the sudden onset of severe headache, signs of
local compression of the optic chiasm, and some-
times the nerves of the cavernous sinus.
50,51
There may be subarachnoid blood and there
often is impairment of consciousness. It is not
clear if the depressed level of consciousness is
due to the compression of the overlying hypo-
thalamus, the release of subarachnoid blood (see
below), or the increase in intracranial pressure.
If there are cranial nerve signs, pituitary apo-
plexy is often sufficiently characteristic to be
diagnosed clinically, but if the main symptoms
are due to subarachnoid hemorrhage, it may be
confused with meningitis or meningoencepha-
litis
52
; the correct diagnosis is easily confirmed
by MRI or CT scan (Figure 4–3). If the tumor
is large, it typically requires surgical interven-
tion. However, subarachnoid hemorrhage can
be treated conservatively. The hemorrhage may
destroy the tumor; careful follow-up will deter-
mine whether there is remaining tumor that
continues to endanger the patient.
Craniopharyngiomas are epithelial neo-
plasms that are thought to arise from a remnant
of Rathke’s pouch, the embryologic origin of
the anterior pituitary gland.
53
The typical pre-
sentation is similar to that of a pituitary tumor,
but craniopharyngiomas are often cystic and
may rupture, releasing thick fluid into the sub-
arachnoid space that may cause a chemical
meningitis (see below). Craniopharyngiomas
are more common in childhood, but there is a
second peak in the seventh decade of life.
54
Figure 4–3. Images from a patient with pituitary apoplexy. This 63-year-old man had a severe headache with sudden onset
of left III and IV nerve palsies. In A, the examiner is holding the left eye open because of ptosis, and the patient is trying to
look to his right. An MRI scan, B, shows a hemorrhage (bright white on T1 imaging) into a large pituitary tumor that is
invading the left cavernous sinus (arrow). The tumor abuts the optic chiasm. In pituitary apoplexy, there may be sudden
visual loss in either or both eyes if the optic nerves are compressed, or in a bitemporal pattern if the chiasm is compressed,
as well as impairment of some combination of cranial nerves III, IV, VI, and V
1
.
128
Plum and Posner’s Diagnosis of Stupor and Coma