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Chapter
4
Specific Causes of Structural Coma
INTRODUCTION
SUPRATENTORIAL COMPRESSIVE
LESIONS
EPIDURAL, DURAL, AND SUBDURAL
MASSES
Epidural Hematoma
Subdural Hematoma
Epidural Abscess/Empyema
Dural and Subdural Tumors
SUBARACHNOID LESIONS
Subarachnoid Hemorrhage
Subarachnoid Tumors
Subarachnoid Infection
INTRACEREBRAL MASSES
Intracerebral Hemorrhage
Intracerebral Tumors
Brain Abscess and Granuloma
INFRATENTORIAL COMPRESSIVE
LESIONS
EPIDURAL AND DURAL MASSES
Epidural Hematoma
Epidural Abscess
Dural and Epidural Tumors
SUBDURAL POSTERIOR FOSSA
COMPRESSIVE LESIONS
Subdural Empyema
Subdural Tumors
SUBARACHNOID POSTERIOR
FOSSA LESIONS
INTRAPARENCHYMAL POSTERIOR
FOSSA MASS LESIONS
Cerebellar Hemorrhage
Cerebellar Infarction
Cerebellar Abscess
Cerebellar Tumor
Pontine Hemorrhage
SUPRATENTORIAL DESTRUCTIVE
LESIONS CAUSING COMA
VASCULAR CAUSES OF SUPRATENTORIAL
DESTRUCTIVE LESIONS
Carotid Ischemic Lesions
Distal Basilar Occlusion
Venous Sinus Thrombosis
Vasculitis
INFECTIONS AND INFLAMMATORY
CAUSES OF SUPRATENTORIAL
DESTRUCTIVE LESIONS
Viral Encephalitis
Acute Disseminated Encephalomyelitis
CONCUSSION AND OTHER TRAUMATIC
BRAIN INJURIES
Mechanism of Brain Injury During Closed
Head Trauma
Mechanism of Loss of Consciousness
in Concussion
Delayed Encephalopathy After
Head Injury
INFRATENTORIAL DESTRUCTIVE
LESIONS
119
BRAINSTEM VASCULAR DESTRUCTIVE
DISORDERS
Brainstem Hemorrhage
Basilar Migraine
Posterior Reversible Leukoencephalopathy
Syndrome
INFRATENTORIAL INFLAMMATORY
DISORDERS
INFRATENTORIAL TUMORS
CENTRAL PONTINE MYELINOLYSIS
INTRODUCTION
The previous chapter divided structural lesions
causing coma into compressive and destruc-
tive lesions. It further indicated that lesions
could be supratentorial, compressing or destroy-
ing the diencephalon and upper midbrain, or
infratentorial, directly affecting the pons and
cerebellum. A physician attempting to deter-
mine the cause of coma resulting from a struc-
tural lesion must establish first the site of the
lesion, determining whether the lesion is supra-
tentorial or infratentorial, and second whether
the lesion is causing its symptoms by compres-
sion or destruction or both. Those considera-
tions were the focus of Chapter 3. This chapter
discusses, in turn, the specific causes of supra-
tentorial and infratentorial compressive and de-
structive lesions that cause coma.
Although these designations are useful for
rapid bedside diagnosis, it is of course possible
for a lesion such as an intracerebral hemor-
rhage both to destroy and to compress normal
tissues. Extracerebral mass lesions can also
cause sufficient compression to lead to infarc-
tion (i.e., tissue destruction). Thus, in some
instances, the division is arbitrary. However,
the types of conditions that cause the com-
pression versus destruction of neural tissue
tend to be distinct, and often they have distinct
clinical presentations as well. The guide pro-
vided in this chapter, while not exhaustive, is
meant to cover the most commonly encoun-
tered causes and ones where understanding
their pathophysiology can influence diagnosis
and treatment (Table 4–1).
When any structural process impairs con-
sciousness, the physician must find a way to
halt the progression promptly or the patient
will run the risk of irreversible brain damage or
death. Beyond that generality, different struc-
tural lesions have distinct clinical properties
that govern the rate of progression, hint at the
diagnosis, and may dictate the treatment.
Structural causes of unconsciousness often
cause focal signs that help localize the lesion,
particularly when the lesion develops acutely.
However, if the lesion has developed slowly,
over a period of many weeks or even months,
it may attain a remarkably large size without
causing focal neurologic signs. In those cases,
the first evidence of a space-occupying lesion
may be signs of increased intracranial pressure
(e.g., headache, nausea) or even herniation
itself (see Patient 3–2).
SUPRATENTORIAL
COMPRESSIVE LESIONS
The supratentorial compartments are domi-
nated by the cerebral hemispheres. However,
many of the most dangerous and difficult le-
sions to diagnose involve the overlying me-
ninges. Within the hemisphere, a compressive
lesion may originate in the gray matter or the
white matter of the hemisphere, and it may di-
rectly compress the diencephalon from above
or laterally (central herniation) or compress the
midbrain by herniation of the temporal lobe
through the tentorial notch (uncal herniation).
In addition, there are a number of compressive
lesions that affect mainly the diencephalon.
EPIDURAL, DURAL, AND
SUBDURAL MASSES
Tumors, infections, and hematomas can oc-
cupy the epidural, dural, and subdural spaces
to eventually cause herniation. Most epidural
tumors result from extensions of skull lesions
that grow into the epidural space. Their growth
is relatively slow; they mostly occur in patients
with known cancer and are usually discovered
long before they affect consciousness. Dural tu-
mors, by contrast, are usually primary tumors
of the meninges, or occasionally metastases.
120
Plum and Posner’s Diagnosis of Stupor and Coma