The acoustic neuroma is a benign tumor arising from the vestibular nerve (cranial nerve number 8 out of 12 total). Common symptoms are loss of hearing, ringing (tinnitus) and ataxia. The audiogram may show increased "pure tone average" (PTA), increased "speech reception threshold" (SRT) and decreased "speech discrimination" (SD). The MRI commonly shows a densely "enhancing" (bright) tumor in the internal auditory canal. Treatments include surgery, radiosurgery and sometimes observation. Surgical approaches include the suboccipital, translabyrinthine approach and middle fossa approaches. For radiosurgery, single vs. fractionated (multiple smaller treatments rather than one large treatment) are options. The fractionated stereotactic radiosurgery (FSR) appears to offer very high rates of control with preservation of hearing and preservation of the facial strength.

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Loss of ability to recognize objects, people, sounds, shapes, or smells. Usually classified according to the sense or senses affected (hearing, sight, smell, taste, touch), e.g. auditory agnosia, visual agnosia, gustatory agnosia. Symptom common to tumors of the parietal lobe of the cerebral hemispheres.

Deep parietal lobe tumors can result in acalculia (inability to add, subtract), and agraphia (inability to write). The parietal lobe is a sensory integration center, and tumors in this location affect sensory integration.

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Characteristics of a cell (structure as seen under the microscope) that make it identifiable as a cancer cell. These features can include bizarre shape of the nucleus of the cell, evidence of cell division (mitosis) and irregular shape of the cell and/or the nucleus of the cell. Examples are anaplastic meningioma or anaplastic astrocytoma.

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Growth of new blood vessels from surrounding normal tissue into growing tumor tissue. Anti-angiogeneis drugs are being explored for the treatment of many tumors.

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Absence of the sense of smell. This can be a symptom of tumors of the middle of the "skull base" such as the meningioma. The nerves for smell (olfactory nerves) occupy the olfactory groove, a common location for the meningiomas. Sometimes surgery can result in anosmia if the surgery results in disruption or removal of the olfactory nerves.

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Glial tumor that may less invasive (pilocytic astrocytoma WHO Grade I) or moderately invasive (fibrillary astrocytoma WHO Grade II). For fibrillary astrocytomas common therapies are surgery or biopsy followed by observation or conventional radiotherapy. For pilocytic astroytomas the primary treatment is surgery.

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Imbalance of walking (gait). For patients with tumors, the location is commonly within the "posterior fossa" (back of brain), the location for the cerebellum. The cerebellum allows co-ordination of the arms and legs. The tumors that may press on the cerebellum and cause ataxia include acoustic neuromas, meningiomas, epidermoids and astrocytomas (gliomas).

For midline cerebellar tumors (medulloblastoma, for example) there can be "axial" ataxia (inability to control the trunk or midline structures of the body. For the peripheral cerebellar tumors, the co-ordination of the distal extremities is affected.

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Tumors that have non-malignant appearance under the microscope and that demonstrate a long natural history (grow slowly). These tumors usually have slow rates of growth and have low infiltration into surrounding normal brain. Under the microscope these tumors have relatively normal appearing cellular structures and infrequent signs of division (mitosis).

Examples of benign tumors include acoustic neuromas, meningiomas and pituitary adenomas. The "benign" tumors can still pose serious threats to health. If the location is difficult to reach surgically and if growth occurs, critical structures of the brain can be compressed and affected.

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A protective barrier formed by the blood vessels and glia of the brain. It prevents some substances in the blood from entering brain tissue. The blood brain barrier prevents many chemotherapy agents from entering the brain. Because of the blood brain barrier and the restriction of the entry of chemotherapy, techniques such as radiotherapy and the stereotactic radiosurgery are appealing options for the treatment of many brain tumors.

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Tumors that have spread to the brain from outside the brain. The brain metastases can be single (solitary) or multiple. Commonly, brain metastases arise from lung cancer, breast cancer and colon cancer. Options for treatment include surgery, radiotherapy and radiosurgery. For tumors not accessible by surgery, the radiosurgery offers precise treatment while sparing the surrounding normal brain. Radiosurgery can be given with or without whole brain radiation (regular radiation).

The determinants of the best treatment include the patient's age, the patient's "performance status" (Karnofsky Performance Status) ("KPS"), the control of the primary tumor (tumor outside the brain), and the presence of any metastases other than to the brain.

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A carcinoma is a cancer that starts outside of the brain, and is derived from "epithelial" sites such as lung, breast, colon, prostate, and head and neck. The carcinoma can be "adenocarcinoma" or "squamous cell carcinoma." The carcinoma can spread "metastasize" to the brain. The tumor that has spread to the brain (the "metastasis") can be treated with surgery or radiosurgery. The choice depends on the size, number, location and the rapidity of worsening of the symptoms. The carcinoma can be "staged" A carcinoma that starts outside the brain and spreads to the brain is "Stage 4" (on a 1 to 4 scale).

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The region in the back of the brain that is the junction of the "cerebellum" and the "pons." The pons is near the midline and is the exit point for many important cranial nerves, including the facial (facial strength), the auditory (hearing) and vestibular (balance) nerves. Tumors in this region can cause symptoms including hearing loss, ataxia (imbalance while walking), facial weakness, difficulty with swallowing, speaking and facial numbness.

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The portion of the brain in the back of the head between the cerebrum and the brain stem. The cerebellum controls balance for walking and standing, and other complex motor functions.

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The two halves of the brain. The hemispheres of the brain control muscle functions of the body and also controls speech, emotions, reading, writing, and learning. The right hemisphere controls muscle movement on the left side of the body, and the left hemisphere controls muscle movement on the right side of the body.

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The clear fluid made in the ventricular cavities of the brain that bathes the brain and spinal cord. It circulates through the ventricles and the subarachnoid space. If the flow is obstructed by tumor growth or other process, hydrocephalus may result and a "shunt" may be required. If the cerebrospinal fluid becomes infected, the result is meningitis.

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Benign tumor arising from the choroid plexus of the brain. The choroid plexus resides in the "ventricles" (spinal fluid spaces) of the brain. These tumors enhance brightly on MRI. Surgery is the primary treatment.

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Surgical operation on the brain in which a portion of the skull is drilled away leaving an opening in the skull. This opening may be left or may be covered by synthetic material (as in the "cranioplasty"). A common procedure is the "suboccipital craniectomy" for tumors (e.g. acoustic neuromas or meningiomas) in the rear or back of the brain (cerebellum; cerebellopontine angle).

The suboccipital craniectomy can often result in persistent headaches after surgery.

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Surgical operation on the brain in which a portion of the skull is temporarily removed in order to gain access to the brain. In this procedure holes ("burr holes") are drilled circumferentially around the area to be removed. The "burr holes" are joined using a high speed drill. The "bone flap" (circular piece of skull) is then carefully lifted away, exposing the dura underneath. The portion of the skull that is removed is replaced (distinguish "craniectomy"). After the craniotomy, the bone edges of the portion that was removed heals together with the surrounding normal skull, resulting in a hard "fusion" with resultant preservation of the protective skull.

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Cushings Disease is overproduction of ACTH (adrenocorticoctropin hormone) by a pituitary tumor or pituitary hyperplasia. The overproduction of ACTH results in hypercortisolism or Cushings Syndrome characterized by obesity, new hair growth, purple striae (discoloration of skin), mental symptoms, poor wound healing, severe infections, muscle wasting, acne and amenorrhea. The obesity results from the accumulation of adipose tissue particularly in the facial, truncal and girdle areas. Hypertension and osteoporosis are common. Mental symptoms include emotional lability, irritability or psychosis.

Treatments may include surgery, radiotherapy, radiosurgery or fractionated stereotactic radiosurgery (FSR).

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Double vision. The diplopia is often caused by compression of the "cranial nerves" that subserve eye motion. If one eye moves but the other doesn't, diplopia will result.

•The cranial nerve III (oculomotor) causes medial, superior and inferior motion.
•The cranial nerve IV (trochlear) causes inward and downward motion.
•The cranial nerve VI (abducens) causes lateral movement.
 

Diplopia may be caused, for example, by the meningioma of the cavernous sinus that compresses one or more of these cranial nerves.

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Inability to make speech that is understandable. The patient can form sounds, but not speech. The "expressive" dysphasia can be caused by frontal lobe tumors, usually on the "dominant" side of the brain near the inferior motor strip.

In the "receptive" dysphasia the patient cannot understand his own speech and the speech of others, and can be unaware that there is a speech problem. The receptive dysphasia can be caused by tumors of the superior temporal lobe on the dominant side of the brain (left side for most right handed persons).

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The dura is the tough, fibrous covering of the brain. During the craniotomy or craniectomy (operation) the dura is opened with a knife and folded back to expose the brain underneath. After the operation the dura is usually closed with sutures in a "water tight" fashion to prevent leakage of cerebrospinal fluid.

The meningiomas can arise from the dura. During surgery for meningiomas with dural attachments, resection of the dura with the meningioma is desirable to help prevent recurrence of the meningioma.

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Edema is swelling of the brain secondary to the tumor, surgery or radiotherapy. The edema is the result of increased water or fluid content within the brain. The MRI can show edema as bright (white) signal on the "T2 weighted" images. The "infiltrating" tumors (such as glioblastomas) will commonly produce edema. Meningiomas and metastases can result in edema as well. The edema is commonly treated with "dexamethasone" (Decadron) that can reduce the water content and hence reduce the edema. Other causes of edema include stroke.

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Ependymomas are tumors arising from the cells that line the cavities holding the cerebrospinal fluid (CSF) in the brain and the spinal cord. These tumors are usually treated with surgery. Histologically (under the microscope) these tumors are usually benign but can have atypical or even malignant features. Radiosurgery is an option to boost regular radiation or by itself to treat the ependymoma.

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Although it is considered a pure motor nerve, the facial nerve also innervates a small strip of skin of the posteromedial aspect of the pinna and around the external auditory canal. The nervus intermedius of Wrisberg conducts taste sensation from the anterior two-thirds of the tongue and supplies autonomic fibers to the submaxillary and sphenopalatine ganglia, which innervate the salivary and lacrimal glands.

A lower motor neuron lesion (LMNL) of the nerve, also known as peripheral facial paralysis, results in complete ipsilateral facial paralysis; the face draws to the opposite side as the patient smiles. Eye closure is impaired, and the ipsilateral palpebral fissure is wider.

In an upper motor neuron lesion (UMNL), also known as central facial paralysis, only the lower half of the face is paralyzed. Eye closure is usually preserved.

In peripheral facial paralysis, a different type of clinical presentation is seen with four different levels of nerve lesion.

• A) Lesions of the meatal or canalicular segment. Facial paralysis with hearing loss, and loss of taste in the anterior two-thirds of the tongue, imply lesions in the internal auditory canal from fracture of the temporal bone or at the cerebellopontine angle form compression by tumors.

• B) Lesions of the labyrinthine or fallopian segment. Lesions that spare hearing (with hyperacusis) indicate lesions further down the course of the nerve. Loss of taste in the anterior two-thirds of the tongue and loss of tearing imply lesions that involve the chorda-tympani and the secretomotor fibers to the sphenopalatine ganglion in the labyrinthine segment, proximal to the greater superficial petrosal nerve (GSPN). Distal to GSPN lacrimation is normal, but hyperacusis is still present. Geniculate lesions in this segment cause pain in the face.

• C) Lesions of the horizontal or tympanic segment. The lesion is proximal to the departure of the nerve to stapedius and results in hyperacusis, loss of taste in the anterior two-thirds of the tongue, and facial motor weakness.

• D) Lesions of the mastoid or vertical segment. Hyperacusis is present if the lesion is proximal the nerve to stapedius. It is absent if the lesion is beyond the nerve to stapedius and only loss of taste and facial paralysis occur. If the lesion is beyond the chorda tympani in the vertical segment (as in lesions of the stylomastoid foramen), taste is spared and only facial motor paralysis is seen.

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FSR (Fractionated Stereotactic Radiosurgery) is radiosurgery that is given in smaller, separate, daily treatments (fractions) rather than one large single treatment. The total dose (Gray) to the tumor is higher for the FSR treatment when compared to single "shot" radiosurgery. But because the treatment is given over consecutive days in smaller daily doses, there is much greater sparing (saving the function) of normal neural (brain) tissues. This is because normal tissues cannot tolerate large single doses of radiation. These normal brain tissues can tolerate many smaller doses, however. The tumor cannot tolerate either single large treatments or several smaller treatments. FSR therefore exploits this important difference to kill the tumor and spare normal brain. FSR results in less inhomogeneity of the dose.

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This tumor looks just like ovarian or testicular cancer under the microscope. It is the most common of the germ cell tumors of the brain. It may spread or "seed" through the spinal fluid. About one third of tumors in the pineal region are germinomas; however, this tumor can occur in many locations within the brain. This tumor may cause headaches, visual problems, hormonal disturbances and blockage of spinal fluid (hydrocephalus). It is treated with surgery (often a biopsy for making the diagnosis), radiotherapy and sometimes chemotherapy. The germinoma is very responsive to radiation therapy, but doctors may attempt to avoid the use of radiation in the very young.

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Gray is the unit of radiation absorbed dose for the MKS (metric: meter kilogram second) system. The Gray is equal to 100 rad (rad is both singular and plural). The "centigray" (cGy) is equal to 1/100 of a Gray and is equal to 1 rad.

Examples of common doses for single "shot" radiosurgery are 12 to 14 Gray (1200 to 1400 centigray; 1200 to 1400 rad).

Examples of common doses for Fractionated Stereotactic Radiosurgery are 25 Gray (2500 cGy (rad) in 5 fractions (separate daily doses) or 30 Gray (3000 cGy (rad) in 10 fractions.

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These are usually benign tumors of blood vessels, often found in the lower part of the brain (posterior fossa). They may be associated with cysts. Although usually solitary, multiple hemangioblastomas can occur in Von Hippel-Lindau disease (see below), a hereditary disorder that may also be associated with tumors of the retina, pancreas and/or kidney. This tumor may cause dysfunction of the cerebellum (causing difficulty with walking and/or co-ordination, for instance). It also may block the drainage of spinal fluid, leading to hydrocephalus. Treatment is usually by surgical removal, and can be curative. There are some reports of successful treatment with radiosurgery. Radiation therapy or radiosurgery may also be used if the tumor cannot be removed completely.

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Loss of one half of the visual field. May be "homonymous" (same half of both eyes, i.e. left field of both eyes) or bitemporal (lateral portion of visual field for each eye). The bitemporal hemianopsia may be caused by pituitary tumor, craniopharyngioma or meningioma that presses on the optic chiasm. The homonymous hemianopsia may be caused by tumors that press on the optic pathway on one side of the brain, posterior to the optic chiasm. These tumors can include the "visual cortex" (part of the brain that processes visual information) located in the "occipital lobe" at the back of the brain.

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The abnormal accumulation of cerebrospinal fluid in the ventricles of the brain. Tumors may cause hydrocephalus by compressing or occluding the normal pathways for flow of the cerebrospinal fluid in the brain. To restore flow the operative placement of the shunt may be required.

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Hyperfrationation is the administration of a larger number of smaller radiation treatments (fractions). Hyperfractionation takes advantage of the ability of normal brain to tolerate larger numbers of smaller treatments, while the tumor cannot tolerate the smaller treatments, resulting in killing of the tumor and preservation of the surrounding normal brain.

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Inhomogeneity of radiation dose refers to the "hot spot" in radiation treatment plan. This can result from overlap of two or more "isocenters" (center of rotation of the radiation machine) of treatment. The inhomogeneity can result in toxicity (loss of function of normal tissue) if the normal tissue is within the "hot spot." Inhomogeneity is common with the "gamma knife."

The size (magnitude) of the inhomogeneity can be minimized by the larger collimators that are available using the fractionated stereotactic radiosurgery (FSR) technique via the dedicated linear accelerator. To reduce the effect of the inhomogeneity "fractionation" (FSR) (multiple smaller treatments rather than one large treatment) is used.

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Anticancer drugs infused into the thin space between the lining of the spinal cord and brain to treat or reduce the risk of cancers in the brain and spinal cord. The drugs may be given through a "lumbar puncture or lumbar "tap" or via the "Ommaya reservoir."

The intrathecal chemotherapy bathes the tumor via the spinal fluid. This therapy may be give on a "cyclic" basis (regularly at specific intervals or cycles). This therapy is consideration for tumors that have spread throughout the spinal fluid and that coat the surface of the brain, the lining of the brain, or the spinal cord.

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The isocenter is the center of rotation for the linear accelerator that delivers the radiosurgery. For cobalt source devices (gamma knife) the isocenter is the point at which all of the sources point. It is the "focal point" of the radiation treatment. The isocenter is within the tumor target. The resultant dose conforms to the tumor target and drops rapidly outside of the tumor target. A tumor may have more than one isocenter. Multiple isocenters may be necessary to cover the entire volume of the tumor target.

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The lumbar puncture or "tap" is the insertion of a small needle into the lower back, after local anesthetic, to obtain spinal fluid (cerebrospinal fluid, or CSF). The CSF is then examined to determine the presence of any cells (tumor cells from a brain or spinal tumor, or red cells if a bleed is suspected in the brain). If tumor cells are present, this may mean that the brain tumor is not well localized and that therapy other than surgery or radiosurgery may be necessary. The lumbar tap is only performed when the surgeon is convinced that there is not increased pressure in the brain (increased intracranial pressure).

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Cancerous: a growth with a tendency to invade and destroy nearby tissue and spread to other parts of the body. Under the microscope malignant tumors show high rates of cellular division, bizarre-shaped nuclei, irregular shape, and dense staining of the enlarged nucleus (high nuclear to cytoplasmic ratio). Often specific stains are utilized by the pathologist to further characterize the malignant tumor, including estrogen or progesterone receptors (meningioma), Ki-67 (nuclear proliferation antigen), and others. On examination of the tumor during the operation, the malignant tumor shows irregular blood vessels and infiltration (spread) into the surrounding normal brain. This extension into the surrounding brain may make total removal impossible. Examples include glioblastoma multiforme, anaplastic astrocytomas, and malignant meningiomas.

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The meningioma is a benign tumor of the cells that line the brain (meninges). The meningioma arises between the skull and the brain. The meningiomas have "pushing" borders and can compress but usually not invade the brain (see "malignant meningioma"). These tumors are typically benign and grow slowly, but may, on occasion have a more aggressive course (atypical and malignant meningiomas). The locations include convexity (curved part of skull), the cavernous sinus, sphenoid wing, clivus and parasellar regions. Cerebellar meningiomas also occur. Treatments include surgery, regular radiation and radiosurgery. For the meningiomas that are difficult to safely remove (cavernous sinus, parasellar, clivus) the radiosurgery is a useful option for treatment. The fractionated stereotactic radiosurgery results in greater sparing of the normal surrounding tissues and the cranial nerves when compared to the single "shot" radiosurgery techniques.

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Magnetic resonance imaging. A procedure in which a magnet linked to a computer is used to create detailed pictures of areas inside the brain. The MRI may visualize tumor "enhancement" that results from the accumulation of the "gadolinium" that is injected into the vein prior to the MRI. The gadolinium results in brightness in the MRI picture wherever it accumuulates in the brain.

MRI may be used to quantitate "metabolites" or biochemical compounds in brain and brain tumor to estimate how actively growing the tumor may be. This is MRI spectroscopy.

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Neurofibromatosis II is a common autosomal-dominant genetic disorder (parent has 50% risk that children will have NF II) caused by deletion of chromosome 22 and resulting in bilateral acoustic neuromas, meningiomas and optic nerve sheath meningiomas. Raised skin plaques and opacities in the lenses of the eyes are common.

Multiple Schwann cell tumors on the peripheral nerves, cranial nerves and spinal roots are common in patients with bilateral acoustic neuromas (NF II). For the acoustic neuromas arising from NFII the options for treatment include surgery vs. radiosurgery.

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The oculomotor nucleus of the nerve is located in the midbrain and innervates the pupillary constrictors; the levator palpebrae superioris; the superior, inferior and medial recti; and the inferior oblique muscles. Lesions result in paralysis of the ipsilateral upper eyelid and pupil, the inability to adduct and look up or down. Frequently, the eye is turned out (exotropia). In subtle cases, patients complain only of diplopia or blurred vision.

The exotropia seen in 3rd nerve paralysis can be distinguished from that in internuclear ophthalmoplegia because in the latter, convergence is preserved.

Paralysis of the third nerve is the only ocular motor nerve lesion that results in diplopia in more than one direction, thus distinguishing itself from 4th nerve paralysis (which also can result in exotropia). Pupillary involvement is an additional clue to involvement of the 3rd nerve. Pupil-sparing 3rd nerve paralysis occurs in diabetes mellitus, vasculitides of other etiologies and certain brainstem lesions.

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The olfactory groove is the site of many meningiomas. The olfactory nerve (cranial nerve #1 (of 12) may be affected, resulting in "anosmia" (absence of sense of smell).

The olfactory groove arises in the lamina cribrosa of the ethmoid bone, 1 to 2 centimeters anterior to the tuberculum sellae. This means the front, middle part of the skull, between the eyes. The operative approach may include the "bifrontal" craniotomy. For tumors of the olfactory groove, the bifrontal exposure includes elevation of the frontal lobe(s) of the brain to gain the maximal exposure. Alternative treatments for olfactory groove tumors such as the meningiomas, esthesioneuroblastomas, brain metastases and gliomas may include FSR (fractionated stereotactic radiosurgery).

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The oligodendroglioma is a benign tumor that arises from the oligodendroglial cells. The primary therapy is biopsy or surgery. These tumors are thought to arise from the oligodendrocytes, which are the cells that wrap around nerve cells and act as a form of electrical insulation for conducting the nerve impulses. Recent evidence suggests that they may actually arise from progenitor cells that are immature oligodendrocytes. These tumors also tend to occur in young adults and may contain calcium deposits that appear on brain scans. They tend to be slower growing than low-grade astrocytomas, but have the potential to turn into more aggressive tumors. Treatment is usually surgical and radiation therapy may be recommended. Chemotherapy is considered for progressive tumors, and usually recommended for anaplastic (i.e. more malignant) oligodendrogliomas. (Also see anaplastic oligodendroglioma).

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Optic nerve gliomas occur in about 10% of patients with neurofibromatosis type I (NF I -- see below), usually during childhood. They may involve the optic nerve, optic chiasm and/or optic tract, which are various parts of the visual system. The tumor usually does not spread to other parts of the brain, unless it is a higher grade (more malignant) glioma. In those without NF I, they may occur at any age. These tumors may be treated with radiation and/or chemotherapy; surgery is also sometimes used depending on the patient.

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Pilocytic astrocytoma is the most benign variant of astrocytoma in the new World Health Organization classification. Nearly two thirds of cases occur in the cerebellum, 25% to 30% in the region of the optic nerve/ chiasm and hypothalamus, and the remainder in the cerebral hemisphere. In general the patient can be cured by complete resection of the tumor, which is frequently possible depending on location. If the tumor is deep in the brain, surgery may not result in complete removal or may not be feasible at all. There is usually long-term tumor stabilization without adjuvant radiation therapy after resection, even if removal is incomplete.

Pilocytic astrocytomas in the chiasm and hypothalamus are the most difficult to treat. They usually cause visual loss, endocrinological dysfunction, and/or raised intracranial pressure from obstruction of the foramen of Monro. At least 40% of optic/chiasmatic tumors are associated with NF. Complete resection is rarely possible and management of residual tumor is controversial given the risks associated with radiation and chemotherapy, especially in children. Options include conservative management, stereotactic biopsy with or without radiation, resection with or without radiation, and/or chemotherapy.

Pilocytic astrocytomas of the optic chiasm and hypothalamus typically are histologically benign tumors that present in childhood. The management of these tumors is controversial. Presumed hypothalamic/chiasmatic astrocytomas have traditionally been treated with surgical biopsy followed by conventional radiation therapy. More recently other approaches have been advocated, including radical surgical debulking as primary treatment for exophytic tumors; however, the benefit of this strategy has been difficult to demonstrate. Radical surgery carries the risk of damage to the hypothalamus, visual apparatus, and vascular structures. Furthermore, these tumors often have a long course, and the small groups of patients reported who have been treated with aggressive surgery have had a relatively short follow-up period.

The most important aspect of the pilocytic astrocytoma suitable for radiosurgery is the size. Smaller tumors are treated more effectively by the radiosurgery.

 

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The pineal gland is a small gland located in the cerebrum that produces melatonin. Also called pineal body or pineal organ.

The pineoblastoma is a fast growing type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain. Treatment is biopsy or surgical removal followed by radiotherapy with or without chemotherapy.

The pineocytoma is a slow growing type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain. Treatment is biopsy or surgery followed by observation or radiotherapy.

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Pituitary adenomas are common benign tumors of the pituitary gland. It is said that up to 10 percent of people will have a pituitary adenoma (which might never have caused a problem) by the time of their death. The pituitary gland is considered the "master gland" of the body; it produces hormones that regulate the other glands. Some tumors secrete one or more of these hormones in excess. Such so-called secretory pituitary adenomas are usually found due to hormonal imbalances that affect bodily functions. They may be relatively small when detected.

Pitutary adenomas have specific signs and symptoms that are primarily related to the endocrinopathies produced by hypersecretion.

• The prolactin-secreting pituitary adenomas are the most common, and account for approximately 30% of all pituitary tumors. The clinical findings are galactorrhea and reproductive dysfunction.
  
   

• The endocrinopathy of excess growth hormone results in enlargement of the extremities, face and the soft tissues, producing a characteristic appearance called acromegaly. Acromegaly can be associated with hypertension, diabetes mellitus and cardiovascular disease. Further, acromegaly is associated with decreased life expectancy.
  
   

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The pituitary tumor starts in the pituitary gland. These tumors can produce prolactin (prolactinomas), ACTH (Cushings disease), growth hormone, and can, on occasion, produce no hormone (non-functional adenoma). In addition to the endocrine effects, the pituitary tumors can can cause visual abnormalities (decreased peripheral vision bilaterally) (bitemporal hemianopsia) due to pressure upon the optic nerve(s) or the optic chiasm (juncture of the optic nerves, above the pituitary gland). The pituitary gland tumors may remain within the bony confines of the "sella turcica" or may extend laterally into the "cavernous sinuses." For the cavernous sinus location, the surgical resection may be difficult because of the closeness to the cranial nerves that subserve eye movements and facial sensation. The treatments include surgery, radiation, radiosurgery, medications, and sometimes, observation.

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This is a malignant tumor arising from cells that are believed to remain from fetal brain development. They usually occur in early childhood but may become symptomatic in adult life. In children, they commonly occur in or near a spinal fluid sac known as the fourth ventricle and are called medulloblastomas. Under the microscope, a PNET is seen to consist of densely-packed small cells that are usually blue in color (when common tissue processing is performed). PNETs have a tendency to spread over the brain and spinal cord by way of the spinal fluid. Treatment usually begins with surgery. Radiation therapy is used in adults, along with chemotherapy. Young children are usually treated with chemotherapy alone, since radiation may stunt intellectual development when given at an early age.

PNET staging is an important consideration, since the extent of treatment needed depends on how widely the PNET has spread at the time of diagnosis. This "staging process" requires MRI scans of the brain and spinal column, as well as examination of the spinal fluid under the microscope to look for tumor cells.

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The prolactinoma is a type of pituitary tumor that produces prolactin. The prolactin stimulates milk production from the breast. The prolactinoma may present with visual symptoms due to compression of the optic chiasm if the tumor is large. The prolactin levels in the blood help to make the diagnosis, and these levels can be very high. The levels of prolactin are useful to monitor the success of treatment (lower after treatment).

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Quadrigeminal refers to the posterior midbrain (deep brain) that holds the superior and inferior colliculi (for processing of vision and hearing). Tumors in the region of the "quadrigeminal plate" include the pineal tumors (pineocytomas, pineoblastomas). These tumors can compress the "third ventricle (cavity holding CSF just anteriorly) and result in hydrocephalus (obstruction of CSF flow in the brain).

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Radiation therapy (also called radiotherapy) uses high-energy radiation from x-rays, neutrons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy) or from materials (radioisotopes) that produce radiation that are placed in or near the tumor or in the area where the cancer cells are found (internal radiation therapy, implant radiation, or brachytherapy). Systemic radiation therapy involves giving a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body.

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The precise, focal delivery of radiation (Gray) to a target in the brain with sparing of the surrounding normal brain. The localization of the target is achieved during the "simulation" (special scan) and the planning of the treatment is achieved using special software specifically designed for radiosurgery treatments. The precision is afforded by the "stereotactic" (precise localization in space within the brain) determination of the target volume. With sub-millimeter accuracy high doses of radiation can be delivered to the isocenter. Radiosurgery is a common treatment for acoustic neuromas, meningiomas, pituitary adenomas, hemangioblastomas and gliomas. Fractionated Stereotactic Radiosurgery (FSR) is non-invasive, precise, outpatient treatment that may offer improved safety of treatment, escalation of dose and outpatient treatment.

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A type of benign brain tumor that begins in the Schwann cells that produce the myelin that protects the acoustic nerve (the nerve of hearing). The schwannoma is slow-growing. The options for treatment include surgery vs. radiosurgery.

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Seizures are uncontrolled activity of the neurons of the brain. These can result in jerking of the body (tonic clonic seizures; motor seizures), loss of consciousness or awareness with "automatisms" such as lip smacking or chewing (absence or petit mal seizures) or other types (sensory, visual). Seizures can be caused by brain tumors. Treatment of the tumor can reduce seizures. The primary (initial) treatment is medication (example: Dilantin or Phenobarbital).

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A surgically created diversion of fluid, for example blood or cerebrospinal fluid, from one area of the body to another area of the body. The shunt may be ventriculoperitoneal (brain to abdominal cavity) or ventriculoatrial (brain to heart).

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Use of a computer and scanning devices to create three-dimensional pictures. This method can be used to direct a biopsy, external radiation, or the insertion of radiation implants.

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Generally a benign tumor, arising from tissue off the fluid sacs (ventricles) of the brain. This tumor is often seen in children and some adults with a condition called Tuberous Sclerosis. Tuberous Sclerosis is characterized by seizures, certain skin abnormalities of the face, and varying degrees of mental retardation. Treatment usually consists of surgical removal, or observation if it is not causing symptoms.

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Like an ependymoma, this tumor also arises from tissue that lines the ventricles. However, it more often occurs in elderly patients. The behavior is benign. Unfortunately, subependymomas often arise from the brainstem and surgeons may have to leave some tumor behind if they are to avoid neurologic damage.

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The tentorium is the fibrous separation of the top (superior, "supratentorial") brain from the bottom (inferior, "infratentorial") brain. It is shaped like a "tent." Supratentorial vs. infratentorial is a common designation for describing the location of tumors. The tentorium arises from the temporal, parietal and occipital bones laterally and joins the midline fibrous separation called the "falx." The tentorium is not very flexible, and masses or tumors within the infratentorial space (e.g. cerebellum, cerebellopontine angle) can exert considerable pressure upon the brain with only small increases in size.

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Tinnitus is the high-pitched, "ringing" sound that is perceived by many patients having the acoustic neuroma(s). The tinnitus may be constant or intermittent, and may increase in intensity over time.

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The nucleus of the nerve stretches from the midbrain (mesencephalic n.) through the pons (main sensory nucleus and motor nucleus) to the cervical region (spinal tract of the trigeminal nerve). It provides sensory innervation for the face and supplies the muscles of mastication.

Paralysis of the first division (V1) is usually seen in the superior orbital fissure syndrome and results in sensory loss over the forehead along with paralysis of the 3rd and 4th nerves.

Paralysis of the second division (V2) results in loss of sensation over the cheek and is due to lesions of the cavernous sinus; it also results in additional paralysis of V1 and the 3rd and 4th nerves.

Isolated V2 lesions result from fractures of the maxilla. Complete paralysis of the 5th nerve results in sensory loss over the ipsilateral face and weakness of the muscles of mastication. Attempted opening of the mouth results in deviation of the jaw to the paralyzed side.

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This is a rare tumor usually seen in young adults, often found in a temporal lobe after a seizure. It tends not to infiltrate (mix) with normal brain tissue, but may spread along the meninges. The tumor and further seizures are usually controlled by its surgical removal, but it is intermediate in its' grade (i.e. degree of malignancy). Follow-up scans over time are recommended. Radiation, radiosurgery and/or re-operation may be suggested for a recurrent tumor.

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