intracranial masses rapidly elevate the intracranial pressure because the skull is a closed...

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.

elevation of the head of the patient to 30°;hyperventilation (if the patient is intubated); osmotic diuretics, such as mannitol, given

intravenously,in fractionated daily doses; rapid infusionis important for the generation of an effectiveosmotic gradient; saluretics, too, can transientlylower the intracranial pressure (caution:

excessiveuse of diuretics can lead to dehydration and

impairmentof 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.

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.

epileptic seizures (focal or generalized); mental changes (irritability, fatigability, impairmentof memory and concentration); focal neurological and/or neuropsychological

deficitsdepending on the location and type of the tumor; less commonly, headache (diffuse, at night as well

asin the daytime) and occasionally nausea and vomiting; in some patients, further signs of intracranial

hypertension

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.

Neuroimaging studies are essential 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.

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 form of treatment, or as adjuvant therapy after a complete or incomplete surgical removal.

AstrocytomaGlioblastoma 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.

is a benign tumor usually seen in children and adolescents. On pathological examination, these

tumors are often cystic and partly calcified. Ependymomas usually arise in the

posteriorfossa, most commonly near the fourth

ventricle, and in the conusmedullaris of the spinal cord

focal (often cerebellar) neurological deficits

intracranial hypertension secondary to compression of the CSF

pathwaysand occlusive hydrocephalus

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). gressive clinical manifestations.

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.

arise from the dura mater and are nearlyalways benign, well-demarcated lesions

that displacerather than invade the adjacent neural

tissue as they grow. These mesodermal tumors most often become

clinically evident between the ages of 40 and 50.

Meningioma of the left cerebral convexity as seen by

MRI after the intravenous administration of gadolinium.

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 usually produce extensive peritumoral edema and often cause epileptic seizures; thus, corticosteroids and antiepileptic drugs can be given for palliation. This usually brings a substantial, if only temporary, clinical improvement.

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Neuroanatomy. 1999 5. Headache. Diagnosis and Treatment. 1993 6. Color Atlas of Human Anatomy Sensory organs And Nervous System

(Werner Kahle) – 1986 7. Color Atlas of Neurology (Thieme 2004) http://medic.stup.ac.ru/institute/Anatomy/Lection10.htm http://www.erudition.ru/referat/ref/id.52081_1.html http://www.medicreferat.com.ru/pageid-58-1.html

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