Download 1. An introductions to clinical neurology: path physiology, diagnosis

MINISTRY OF THE HEALTHCARE OF THE
REPUBLIC OF UZBEKISTAN
TASHKENT MEDICAL ACADEMY
DEPARTMENT OF NEUROLOGY
Lecture # 14
Intracranial Pressure and Brain Tumors. Differential
Diagnosis. Etiology, pathogenesis, clinic and treatment.
For students of 5th course medical and physician-pedagogical faculty
It Is Approved: 25.08.2012
Tashkent 2012
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Lecture 14.
Intracranial Pressure and Brain Tumors. Differential Diagnosis. Etiology,
pathogenesis, clinic and treatment.
The Purpose:
1. Informing the students with classification of cerebral tumors.
2. Informing the students with etiology and pathogenesis of cerebral tumors.
3. Informing the students with diagnostics and treatment principals of brain tumors.
The Expected results (the problems).
student must know:
- a categorization (classification) of the myelitis
- Etiopathogenesis of the syringomyelia, syringobulbia
- clinical features of most frequent brain tumors
- to find localization according to neurological symptoms found on neurostatus
- differential diagnosis of most frequent brain tumors.
Contents:
Intracranial Pressure
Intracranial masses rapidly elevate the intracranial pressure because the skull is a closed
compartment. Intracranial hypertension is most commonly caused by tumor,
hemorrhage, extensive stroke, trauma (and the edema accompanying these conditions),
and hydrocephalus. It can also be caused by a variety of other conditions. Intracranial
hypertension impairs cerebral perfusion and CSF circulation and may also result in
compression of intracranial structures (e. g., compression of cranial nerves against the
base of the skull, occlusive compression of the posterior cerebral a.) and to shifting of
large portions of the brain within the skull (e. g., herniation of the medial portion of the
temporal lobe into the tentorial notch, or of the cerebellar tonsils into the foramen
magnum). Intracranial hypertension may arise acutely, i. e., in a few minutes or hours
(especially in brain hemorrhage), or chronically (for example, when caused by a slowly
growing brain tumor). Its clinical manifestations vary accordingly. Its treatment consists
of general measures to lower intracranial pressure as well as specific treatment
of the underlying cause. Intracranial hypertension is diagnosed from its characteristic
clinical manifestations and ancillary test biresults. Lumbar puncture for direct easurement
of the CSF pressure is nearly always contraindicated. A lumbar puncture should, in
general, not be performed if there is clinical evidence of intracranial hypertension. It
may be performed only if the imaging studies and ophthalmoscopic examination have
yielded no evidence of acutely elevated ICP with impending brain herniation.
Treatment of intracranial hypertension includes the following general measures to lower
the intracranialpressure:
_ elevation of the head of the patient to 30°;
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_ hyperventilation (if the patient is intubated);
_ osmotic diuretics, such as mannitol, given intravenously, in fractionated daily doses;
rapid infusion is important for the generation of an effective osmotic gradient; saluretics,
too, can transiently lower the intracranial pressure (caution: excessive
use of diuretics can lead to dehydration and impairment of cerebral perfusion);
_ corticosteroids (e. g., dexamethasone, given intravenously)
are used to counteract cerebral edema, particularly of the vasogenic type; they are mainly
effective against peritumoral and inflammatory brain edema, less so against ischemic and
traumatic brain edema, which are predominantly of the cytotoxic
type.
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Brain Tumors
Fundamentals
The prevalence of brain tumors is roughly one per 10 000 to 20 000 individuals. Brain
tumors are one of the more common causes of intracranial hypertension.
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They are subdivided into primary brain tumors arising from the brain tissue itself
(either the neuroepithelial tissue or the neighboring mesenchymal tissues, e. g., the
meninges) and brain metastases. Brain tumors produce focal brain
signs of different types depending on the location of the tumor, as well as signs of
intracranial hypertension that may be more or less rapidly progressive
depending on the rate of tumor growth. General clinical manifestations of brain tumors
include the following:
_ epileptic seizures (focal or generalized);
_ mental changes (irritability, fatigability, impairment of memory and concentration);
_ focal neurological and/or neuropsychological deficits
depending on the location and type of the tumor;
_ less commonly, headache (diffuse, at night as well as in the daytime) and occasionally
nausea and vomiting;
_ in some patients, further signs of intracranial hypertension.
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The clinical manifestations of a brain
tumor progress more or less rapidly
depending on the type and growth rate
of the tumor. Malignant tumors typically
present
with a “crescendo” course, in which
overt signs and symptoms arise soon
after the onset of the illness, then
progress steadily and rapidly. The
manifestations of
benign tumors, on the other hand, often
progress slowly and insidiously, perhaps
over many years. Indeed, the tumor may
be present for years before it becomes clinically
evident.
Diagnosis.
Neuroimaging studies are essential (contrastenhanced CT or, better, MRI; cf. Table 6.9)
but cannot always unequivocally identify the type of tumor. A definitive determination is
often not possible until the tumor has been at least partly removed and the tumor tissue
can be histopathologically examined. If a brain tumor is inoperable because of its
location, or if primary resection is contraindicated by the patient’s general
condition or other illnesses, then a stereotactic brain biresults opsy can be performed to
obtain tissue for diagnosis. This should, in general, be done before any nonsurgical
treatment is undertaken, such as chemotherapy or radiotherapy, so that the form of
treatment can be chosen for maximum effectiveness. A further reason for doing
so is that a small percentage of suspected “brain tumors” will turn out, on biopsy, to be
brain abscesses. These can often be effectively treated with antibiotics (and, in some
patients, resection).
Treatment. Complete resection of the tumor is indicated whenever it is possible. The
operability of brain tumors, however, depends largely on their size, location, histological
grade, and relation to the surrounding brain tissue (infiltration vs. displacement). Not
every tumor is neurosurgically accessible or fully resectable. Depending on the type of
tumor, radiotherapy and/or chemotherapy may have to be used, either as the primary
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form of treatment, or as adjuvant therapy after a complete or incomplete surgical
removal.
The brain edema that usually accompanies malignant tumors is treated with
corticosteroids (usually dexamethasone).
Individual Types of Brain Tumor
The WHO classification of brain tumors (1993) is summarized in Table 6.9, which also
includes figures concerning the relative frequency of tumor types. The characteristic
locations, clinical manifestations, and course of brain tumors all depend on the type of
tumor. Astrocytoma, the most common category of neuroepithelial tumor, has the
following histological subtypes:
Glioblastoma multiforme is themost malignant grade of astrocytoma (grade IV
astrocytoma). This most common and most malignant tumor of the cerebral hemispheres
usually arises between the ages of 40 and 60. It grows by infiltration into brain tissue and
is thus nearly impossible to resect totally, as nests of tumor cells nearly always remain
beyond the margins of resection even if all macroscopically
evident tumor tissue is removed. Though it generally arises in a single hemisphere, it can
infiltrate across the corpus callosum into the opposite hemisphere, creating a so-called
butterfly tumor.
Relative frequency of primary brain tumors:
pilocytic astrocytoma 1%, low-grade astrocytoma 27%, anaplastic astrocytoma 3%,
glioblastoma 28%, oligodendroglioma 2%, ependymoma 1%, medulloblastoma 2%,
meningioma 22%, neurinoma 4%, primary CNS lymphoma 1%
Ancillary diagnostic tests
Imaging studies:
reveal the site and extent of the tumor before surgery (biopsy or resection)
CT with contrast: often the method by which a mass is first diagnosed, but of limited
diagnostic value:
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_ advantages: good at displaying tumor calcification and the relation of certain types of
tumor (e. g., meningioma) to adjacent bony structures disadvantages: even with contrast,
some tumors such as low-grade astrocytomas are revealed poorly or not at all; poor
distinction between tumor tissue and surrounding brain edema; artifact impairs visibility
at the skull base and in the posterior fossa_ MRI with contrast: the imaging method of
choice for all intracranial tumors:
_ advantages: highly sensitive (reveals clinically “silent” metastases), clear visualization
of the site and borders of the tumor in multiple imaging planes
_ disadvantage: calcification not reliably seen
_ angiography: preoperative visualization of blood vessels is useful for certain types of
tumor (e. g., medial sphenoid wing meningiomas impinging on the internal carotid a.);
reveals possible infiltration or occlusion of the venous sinuses; provides access for
intravascular treatment (“embolization”) of meningiomas; enables diagnosis and precise
anatomical characterization of vascular malformations and Aneurysms tomas grow
rapidly, causing rapidly progressive clinical manifestations; they are, therefore, usually
diagnosed within a few weeks or (at most) months of the onset of symptoms. Focal
neurological and/or neuropsychological deficits arise first, sometimes accompanied by
epileptic seizures, soon followed by general manifestations of intracranial hypertension
(see above). The diagnosis can be made with a fair degree of confidence from the typical
appearance in neuroimaging studies, though this does not obviate the need for
histological examination of tumor tissue. CT characteristically reveals a central
hypodense area, corresponding to necrosis in the interior of the tumor. There may be
hyperdense areas indicating intratumoral hemorrhage. Peritumoral brain edema is often
extensive, causing mass effect and midline shift. Ringlike enhancement is seen after the
administration of contrast medium.
Even with the best currently available treatment, i. e., gross total resection of the tumor
with or without adjuvant radio- or chemotherapy, patients with glioblastoma
survive only a few months, or a few years at most, because of the nearly inevitable
recurrences.
Grade III
astrocytoma is another type of histologically malignant astrocytoma. The prognosis of
patients with this type of tumor, though marginally better than that of
glioblastoma patients, is still poor.
Grade I and II astrocytomas (so-called “benign” astrocytomas) are less malignant than
grades III and IV. Astrocytomas of the cerebral hemisphere(s) generally affect
adults aged 30 to 40. Though these tumors displace and infiltrate the surrounding brain
tissue, they are better demarcated from it than glioblastoma; they often grow
quite slowly, sometimes over many years. Their clinical manifestations include
behavioral and neuropsychological changes, increasingly severe focal neurological
deficits (e. g., hemiparesis), focal or secondarily generalized epileptic seizures, and signs
of intracranial hypertension. If epileptic seizures are the only manifestation, tumor
resectionmaybe useful for seizure control, if the location of the tumor permits. After a
tumor is totally resected, it may not recur until years later. Cerebellar astrocytoma is
considerably more benign than the other varieties, usually affects children aged 5 to
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15, and is well demarcate d from the surrounding brain tissue. It is usually foundin the
cerebellar hemispheres or vermis and may extend into the pons. Its main clinical
manifestations are thus ataxia, disequilibrium, nystagmus, and, often, signs of
intracranial hypertension (esp. papilledema) secondary to occlusive hydrocephalus.
Total resection often results in permanent cure.
Brainstem astrocytoma is usually inoperable, though tumors of this type are sometimes at
least partly respectable in special cases. Ependymoma is a benign tumor usually seen in
children and adolescents. On pathological examination, these tumors are often cystic and
partly calcified. They develop from the neuroepithelium of the walls of the cerebral
ventricles and the central canal of the spinal cord; as they grow, they displace, but do not
invade, the adjacent neural tissue. Ependymomas usually arise in the posterior fossa,
most commonly near the fourth ventricle, and in the conusmedullaris of the spinal cord.
Their main clinical manifestations are focal (often cerebellar) neurological deficits and
signs of intracranial hypertension, secondary to compression of the CSF pathways
and occlusive hydrocephalus. An unusually persistent, continuous headache in children
should arouse suspicion of an ependymoma or other mass in the posterior
fossa. The treatment is by resection, followed by radiotherapy of the entire neuraxis.
Seventy percent of treated patients survive for 10 years or longer. Medulloblastoma also
mainly affects children (in threequarters of cases). This is an undifferentiated, highly
malignant tumor characterized by rapid growth and rapidly progressive clinical
manifestations. Medulloblastomas usually arise from the roof of the fourth ventricle,
sometimes filling the entire ventricle, and grow into the inferior portion of the vermis.
They grow by infiltration and often metastasize via the CSF into the spinal canal
(drop metastases). The signs and symptoms resemble those of cerebellar astrocytoma
(headache, nausea, truncal ataxia—see above), possibly combined with manifestations
referable to the spinal cord and cauda equina. Medulloblastoma is treated by resection
followed by radiotherapy or chemotherapy. The prognosis after radical removal is not
unfavorable, but often no more than an incomplete removal can be achieved, in which
case tumor recurrence is the rule. Oligodendroglioma is usually found in the cerebral
hemispheres, particularly the frontal lobes. It tends to arise between the ages of 40 and 50
and is usually a relatively well-differentiated tumor that grows slowly over the years and
often becomes calcified. It usually presents with epileptic seizures; recurrent seizures
affect 70% of patients with this type of tumor. Oligodendroglioma is mostly
radioresistant and is best treated by radical resection.
If this can be achieved, radiotherapy is usually not given. Nonetheless, apparently radical
resection can be followed by tumor recurrence, which may not take place
until years after surgery. Gliomas of the optic nerve and chiasm are found almost
exclusively in children, often in the setting of neurofibromatosis. Meningiomas arise
from the dura mater and are nearly always benign, well-demarcated lesions that displace
rather than invade the adjacent neural tissue as they grow. These mesodermal tumors
most often become clinically evident between the ages of 40 and 50. They are
diagnosed by MRI or CT scanning, which reveals marked, homogeneous contrast
enhancement. Meningiomas tend to appear in certain classic locations with
corresponding typical neurological manifestations, as listed in Table 6.10. They often
growvery slowly and are not uncommonly discovered as an incidental radiological
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finding. The indications for treatment must then be carefully considered: resection may
be desirable in younger patients, but unnecessary in older ones.
Pituitary tumors usually arise fromthe cells of the anterior pituitary lobe. Depending on
their cells origin, they can produce hormones in excess or cause hormone deficiency.
Thus, they present clinically with endocrine disturbances and/or compressive effects on
the adjacent neural tissue (see below). They most commonly present between the ages of
30 and 50. The rare eosinophil adenomas produce excessive growth hormone, causing
acromegaly, while basophil adenomas produce excessive ACTH, causing Cushing
syndrome(which,whencausedby a pituitary tumor, constitutes Cushing disease).
Prolactinomas produce galactorrhea and secondary amenorrhea inwomen and
impotence in men. Although basophil adenomas and prolactinomas rarely cause mass
effect, eosinophil adenomas and, above all, the hormonally inactive
chromophobe adenomas tend to growquite large, causing compression and dysfunction
of the normal pituitary tissue, clinically evident as hypopituitarism (multiple pituitary
hormone deficiencies, including hypothyroidism and secondary hypogonadism).
Chromophobe adenomas can also compress the optic chiasm, causing a visual field
defect, usually bitemporal upper quadrantanopsia or bitemporal hemianopsia.
Compression of the optic nerves themselves may impair visual acuity. Prompt
neurosurgical removal of the tumor can often reverse these visual difficulties if they are
still incomplete at the time of surgery.
Most pituitary tumors do not present with signs of mass effect (only one in 10 enlarges
the sella turcica visibly on plain films of the skull). Tumors that do cause mass effect
should be neurosurgically removed, preferably by the transsphenoidal route. Hormonally
active microadenomas can sometimes be treated withmedication alone (e. g.,
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prolactinoma can be treated with inhibitors of prolactin secretion, such as bromocriptine
and lisuride).
Malformations and hamartomatous tumors include craniopharyngioma, dermoid and
epidermoid tumors, and cavernoma. Craniopharyngioma arises in or above
the pituitary fossa, often growing upward toward the diencephalon and third ventricle.
This is a cystic tumor derived from epithelial remnants in Rathke’s pouch,
generally containing calcifications as well as cholesterol crystals. It presents with
hypopituitarism (see above), diencephalic manifestations (diabetes insipidus), and
visual disturbances. Like a pituitary tumor, it can cause hemi- or quadrantanopsia and
impair visual acuity; it can also cause occlusive hydrocephalus. Craniopharyngioma
is the most common suprasellar tumor in children and adolescents. It is best treated by
complete resection.
Cavernoma (also called cavernous angioma or cavernous malformation) consists of a
well-demarcated agglomeration of blood vessels. Cavernomas can be multiple
and familial (genetic locus on chromosome 7). They present with epileptic seizures and
hemorrhage. Epidermoid tumors are found at the base of the brain, are often calcified,
and cause focal deficits or epileptic seizures. Their peak incidence is between the ages of
25 and 45.
Neurinomas (schwannomas) are benign neoplasms arising from Schwann cells. The most
common type affects the eighth cranial nerve and is usually (though incorrectly)
designated acoustic neuroma. This tumor of the cerebellopontine angle presents initially
with eighth nerve dysfunction: progressive hearing loss, tinnitus, and
disequilibrium. As it grows, it impinges on the other cranial nerves of the
cerebellopontine angle, causing facial palsy and trigeminal sensory deficits. Further
growth leads to compression of the cerebellum and brainstem, causing cerebellar signs
(esp. ataxia) and possibly pyramidal tract signs. Acoustic neuroma typically markedly
elevates the CSF protein concentrate on. Until recently, the optimal treatment in all
patientswas complete resection of the tumor. Now many smaller acoustic neuromas can
be treated safely and effectively with stereotactic radiosurgery. Brain metastases account
for about 15% of malignant brain tumors. The most common source of a brain
metastasis is bronchial carcinoma in men and carcinoma of the breast in women,
followed in both sexes by melanoma and renal cell carcinoma. Brain metastases
sometimes producesymptomsbefore the primary tumor does; in such cases, multiple
brainmetastases are usually already present, even if only a single one is apparent on
the neuroimaging study. Generally speaking, surgical resection makes sense only for
solitary metastases and the surgical indication should always be carefully considered
in the light of the extent of disease. Only about 20% of patients so treated live more than
five years after the operation and postoperative radiotherapy, if they have
not already died of the effects of their primary tumor. Brain metastases usually produce
extensive peritumoral edema and often cause epileptic seizures; thus, corti costeroids
and antiepileptic drugs can be given for palliation. This usually brings a substantial, if
only temporary, clinical improvement.
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The List of the used literature.
1. An introductions to clinical neurology: path physiology, diagnosis and treatment 1998
2. Parkinsons diseas and Movement Disorders. 1998
3. Neuroscience: Exploring the Brain. 1996
4. Anatomical Science. Gross Anatomy. Embryology. Histology. Neuroanatomy. 1999
5. Headache. Diagnosis and Treatment. 1993
6. Color Atlas of Neurology (Thieme 2004)
7. Fundamentals of Neurology (Thieme 2006). Mark Mumenthaler, Heinrich Mattle with
Ethan Taub
http://allrefs.ru/prosmotr/8997-0.htm
http://www.umi.ru/profy.php4/view/2591
http://www.neuronet.ru/educ/100/ana/an4.html
http://www.iamok.ru/podm/allabout/8/0018.html
http://www.glossary.ru/cgi-bin/gl_sch2.cgi?R1dRyiur!klwlig
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