Tumors of the CNS

Overview of Topics

Intracranial Tumors
Types of Intracranial Tumors
General Clinical Findings
Demographics
Symptoms
Diagnosis
Differential Diagnosis

Tumors of the Skull

Tumors of the Cranial Nerves

Intracranial Tumors

Types of Intracranial Tumors

A. Congenital:

1. Dermoid - Often cystic; may contain sebaceous waxy material, hair.
2. Teratomas - Greater amount & variety of structures, e.g., bone, muscle, fat, nerve.
   • Are calcified seen easily in X-ray; tend to lie in midline.

B. Mesodermal:

1. Meningioma - Tumor is encapsulaled; easily separated from nervous tissue - benign
   • removable if not too large.

C. Ectodermal:

1. Gliomas
   1. Glioblastoma mutiforme - Infiltrative; rapid-growing; occurs: most frequently in mid-aged; apt to involve both cerebral hemispheres via the corpus callosum; Average Survival: 1 year.
   2. Medulloblastoma - Rapidly growing tumor of the vermis of the cerebellum. Occurs usually in children; characteristically metastasizes to the surfaces of the remaining CNS via subarachnoid spaces; Average Survival, with X-rad, 15 months.
   3. Astrocytoma - Usually occurs in cerebrum of adults and cerebellum of children (but may be in adult cerebellum). Slow growing; may become cystic; star-shaped cells when under microscope; Average Survival: 6 years. May give rise to Glioblastoma multiforme within it.
   4. Oligodendroglioma - Slow growing; solid; calcified -- usually found in cerebral hemispheres of adults. Average Survival: 5 years.
   5. Astroblastoma - A rare glioma which occur in the cerebral hemispheres of middle-aged adults. Diff. Dx - it and Glioblastoma multiforme by microscopic nvestigation. Average Survival: 3 years.
   6. Spongioblastomas - Occur predominantly near the optic chiasm of children and in the pons; may give appearance of "hyperlrophy" of the pons. Ave. Survival: 1 year.
   7. Ependymomas - Occur chiefly in children; slow growing; apt to calcify; arise in or near ventricle walls; more common in the fourth ventricle than elsewhere; Average Survival: short. (4th - one going vertically cerebellum & 3rd ventricle - below Aqueduct of Sylvius.)

2. Pituitary Tumors
   1. Chromophobe - Relatively common in anterior pituitary gland of adults;compression of adjacent optic chiasm and hypothal. is common -- e.g. Pituitary adenoma.

D. Metastatic: Most common source of metastalic tumors in the brain: bronchogenic carcinoma; but also carcinoma of breast, thyroid, and G.I. tract. 10-25%, of all brain tumors from this source.

General Clinical Findings:

Presence of a tumor may give rise to early effects by

1. displacement of brain tissue
2. mild block in CSF circulation.

Headache commonly present, and is usually intensified by anything giving rise to increased intracranial CSF pressure, e.g., coughing, stooping, exercising.

Conversely, anything usually causing a reduction in CSF pressure may relieve headache.

Nausea and vomiting are common and are not necessary related to meals.

Disorientation, lethargy, easy fatiguability common with increased ICP.

Papilledema occurs, i.e. - swelling of back of eyes near exit of optic nerves.

Some areas are relatively "silent" in so far as large tumors can occur there without clinical effects -- e.g. Right frontal and temporal lobes.

Hemiplegia can occur on the side ipsilateral to a tumor.

Other Signs:

• Stiff neck
• Vasomotor & autonomic changes
• Visual disturbances - exp. in & out -- i.e. fading then good, etc.
• Hemianopsia - pituitary adenoma - bitemporal hemianopia.
• Aphasia
• Ataxia/Hemiplegia
• Sensory Disturbances
• Seizures
• Hallucinations - olfactory; visual; auditory

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Demographics

Type of Tumor	Frequency
Gliomas	43%
Meningiomas	15%
Pituitary Adenomas	13%
Acoustic Neuromas	6.5%
Metastatic	6.5%
Congenital	4%
Vascular Tumors	3%
Miscellaneous	9%

1. Age - occur predominantly at any age, especially young to middle age.
   1. Young - gliomas of cerebellum, brainstem, & optic nerve, pinealomas, craniopharyngiomas, teratomas & granutomas.
   2. Adult - mengiomas, neurofibronias, gliomas of cerebrum.
   3. Late middle life - metastatic.

2. Sex - slightly more common in men.
   1. men - cerebellar medulloblastomas, cerebral astrocytomas, & glioblastomas.
   2. women - meningiomas and acoustic neuromas.

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Symptoms

No constellation of symptoms is pathognomonic of tumors.

1. Headaches are not good for localization as they generally are in frontal or occipital localized scalp tenderness has more localizing value.
   1. headaches are usually intermittent occurring at irregular intervals from minutes to hours duration.
   2. become more frequent and of longer duration with growth in tumor.
   3. 90%, of tumor patients have headaches.
   4. Cause unknown.

2. Nausea and vomiting - much less frequent.

3. Choked discs - common finding but absence does not rule out tumors.
   1. 50-90% tumor patients have choked discs.
   2. high incidence in those patients where tumor influences cerebrospinal fluid.
   3. tumors confined to hemispheres can grow to large size with no choked discs.
   4. tumors compressing optic nerve may cause atrophy w/o evidence of choking.
   5. Foster - Kennedy's Disease - tumor on one optic nerve produces ipsilateral atrophy and contralateral choked disc.
   6. Demyelinizing diseases such as MS also cause choked disc.
   7. May lead to central or paracentral scotoma.

4. Convulsions - common with tumors of cerebrum, rare with brain stem tumors.
   1. tumor patients tend to have prolonged coma following Jacksonian focal or generalized seizure.
   2. Also may have (Todd's paralysis) transient hemiparesis.
   3. often seizures are the first sign of tumor. Tumor should be considered especially if first seizure occurs after 20 or 30 years of age.
   4. Incidence of seizures is roughly proportional to length of time tumor present.
      70% with vascular tumors of the cortex.
      50% with astrocytomas.
      40% with mcningiomas.
      25% with glioblastomas (rapidly fatal)
      

5. Mental symptoms
   1. lethargy, drowsiness, personality changes, psychotic episodes.

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Diagnosis of intracranial Tumors

A. History

1. Consider tumor whenever focal neurological symptoms develop slowly & gradually increase in severity.
2. The occurrence of convulsive seizures, headaches, dizziness, mental symptoms or the slow development of focal neurological symptoms.

B. Physical Examination

1. Choked discs and focal neurological signs.
2. Visual fields.
3. Aphasia screening.
4. With high pressure many false signs may be obtained.

C. Laboratory Examination

1. Roentgenography (X-ray)
   1. May show tumor by showing:
      • displacement of calcified pineal gland
      • absorptive changes in the bones of the skull
      • separation of the sutures in children.
   2. Calcification occurs within 12% of gliomas.
   3. 50% of meningiomas diagnosed by atrophy or hypertrophy of bone overlying tumor or by presence of abnormal vascular channels in skull.
   4. 70-80% craniopharyngiomas - diagnosed by presence of calcium in tumor.
   5. angiomas and vascular anomalies may show calcification of a curvilinear nature.

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2. Electroencephalogram - (EEG) - value in localizing tumors near surface. Slow wave activity.

3. Examination of cerebrospinal fluid
   1. increased pressure 70% above 200 mm H20
   2. increased protein content above 100 mg.

4. Echoencephalography:
   1. Echo from midline - look for displacement.
   2. also echo from pineal, interhemispheric fissure.

5. Ventriculography and Encephalography
   1. X-ray with air injection.
   2. Evaluate for displacement.

6. Angiography - injection of radiopaque dyes.
   1. produces transient seizures in 10% of cases.
   2. percutaneous puncture of carotid or vertebral arteries.

7. Radioactive Scanning
   1. tumors best seen 24 to 48 hours after injection.
   2. not effective for avascular, 3rd V and cerebellar lesions.

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Differential Diagnosis

A. CVA's - sudden onset of symptoms and lack of progression of focal signs.

1. Occasionally - sudden onset (rare).
2. Tumors are common in age group subject to arteriosclerosis, thus, this and hypertension do not rule out tumors.

B. GIiomas

Neoplasms which arise from primitive forms of glial cells.
50% of all intracranial tumors.

1. Astrocytomas
   1. 40% of gliomas - composed of astrocytes.
   2. Tend to infiltrate large areas and may undergo cystic degeneration.
   3. Grow slowly.
   4. Complete surgical removal is rare.
   5. In brain stem nuclei tend to be elongated and arranged in parallel lines as palisades (paloid astrocytoma).
   6. Unilateral or bilateral sixth nerve involvement is the most common sign.
   7. Occurs in younger patients than extrinsic tumors.
      • Presence of conjugate gaze rather than simple paralysis of rectus muscle.
      • Development of signs of injury to lung tracts.
      • Signs of BS compression.
   8. Radiation therapy (difficult to treat).

2. 0ligodendroglioma
   1. Less than 5% of all gliomas.
   2. Found chiefly in the cerebral hemispheres of young adults.
   3. More circumscribed - slower growing.
   4. Focal neurological signs and convulsive seizures common.
   5. Difficult to treat.

3. Glioblastoma Multiforme (Spongioblastoma)
   1. Most rapidly growing form of glioma.
   2. 1/3 of all gliomas.
   3. Most frequent in cerebral hemispheres of adults.
   4. Cross via corpus callosum.
   5. May seed into cerebrospinal fluid and produce tumors in remote areas.
   6. Rapidly fatal - leading to death within one year.
   7. Respond poorly to X-radiation therapy.

4. Medulloblastomas
   1. 10% of gliomas.
   2. Derived from primitive form of glia cells.
   3. Predominant in cerebellum.
   4. Most frequent in infants and young adults.
   5. Signs:
      • Increased pressure.
      • Headache, vomiting, unsteady gait are presenting symptoms.
      • Also suture separation, choked discs, and nystagmus.
   6. Rapidly growing and fatal within one year.
   7. Recurrence is almost inevitable.
   8. Radiation.

5. Ependymoma
   1. Most common in children.
   2. Relatively malignant - life two years.

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Tumors of the Skull

A. Hyperostoses

1. Local overgrowth of bones of skull.
2. May be secondary to intracranial tumors or may occur independently.
3. May involve either the outer or inner tables of the skull.
4. Unlikely to cause pressure on cerebrum.

B. Osteomas

1. May arise in the paranasal sinuses or from cortex of calavarium.
2. Cause enlargement of sinus and localized pain or headache.
3. Erosion of the dura may cause cerebrospinal fluid rhinorrhea, pneumatocele, meningitis, or abscess formation.
4. Rarely reach sufficient size to compress underlying brain tissue.

C. Hemiangiomas

1. Congenital vascular anomalies which may involve the bones of skull or SC.
2. May be single or multiple.
3. Small - no symptoms.
4. Headaches, Jacksonian or generalized seizures & focal neurological signs may result.

D. Metastatic tumors

1. May be secondary to malignant tumors elsewhere.
2. Seldom produce neurological symptoms unless located at the base - cranial nerve palsies.
3. Operative treatment is contraindicated.

E. Involvement of Skull in Systematic Diseases

1. Hand-Schiiler-Christian disease - xanthomatosis
2. Multiple Myeloma
3. Osteitis Deformans (Paget's disease).

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Tumors of the Meninges

A. Meningiomas - (meningeal fibroblastomas, leptomeningiomas, arachnoidal fibroblastomas, dural endothelioma) - tumors which are principally associated with the arachnoid villi.

1. Produce symptoms of compression of underlying nervous parenchyma.

2. Seldom break through pia.

3. Pathology - round on nodular masses.
   1. Sharply circumscribed.
   2. Invade dura and frequently bone as well.
   3. Have rich vasculature - derived from meningeal branches of ext. carotid artery.
   4. Stimulate growth in adjacent bone and occasionally erode it.
   5. Tendency to reoccur.
   6. Types (9) meningothelial without reticulin, psammomatous, and fibroblastic - most common.
   7. Less frequent - angioblastic, epitheloid, saccomatous, osteoblastic, chonodroblastic.

4. Incidence - constitute 10-15% of all intracranial tumors admitted to large neurosurgical clinics.
   1. May occur at any age but are predominantly of adult or early middle life.
      mean age onset: 38
      mean age admission: 46
   2. More common in women by ratio of 3/2.
   3. Rare in U. S. Blacks.
   4. Precipitating factors - trauma & pregnancy (high correlation w/ trauma foci).

5. Symptoms and Signs
   1. Diagnosed on basis of location and fact that they often produce proliferation of bone.

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   Located	Frequency	Symptoms
   Parasagittal	21%	General
   Convexity of hemispheres	17%
   Sphenoidal ridge	17%	Exopthalamus, visual defects
   Floor of anterior fossa	18%
   Posterior fossa	7%
   Peritorcular	4%
   Temporal fossa	3%
   Falx etc.	7%
   Spinal	6%

6. Treatment - surgery - otherwise lead to death. Complete cures are common.

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Tumors of the Cranial Nerves

A. Gliomas of the Optic Nerve

1. May occur in intraorbital division of optic nerve, post-ocular portion, or optic chiasm (most - intraorbital).
2. Occur predominantly in childhood.
3. Progressive blindness
4. Unilateral amblyopia, hemianoptic field defects - presenting symptoms.

B. Neurofibromas of 8th Cranial Nerve

1. Probably arise from swan sheath cells.

2. Pathology:
   1. Arise in peripheral portion of the vestibular division of the 8th nerve in the porus acousticus mainly intracranial and large.
   2. Tumor is composed of dense interlacing fibrous bands and loose reticular tissue in varying proportions.

3. Incidence
   1. 5-10% of all intracranial tumors.
   2. Onset between 30-60 years.
   3. Below 20 - so rare a tumor here would probably be a glioma.

4. Symptoms and Signs
   1. Loss of hearing with or without tinnitus.
   2. Tinnitus may precede other symptoms by several years.
   3. Vestibular involvement - giddiness or unsteadiness of gait.
   4. Severe vertigo attacks are rare.
   5. Horizontal nystagmus present in almost all cases.
   6. Involvement of one or more other cranial nerves is almost always present.
   7. Loss of corneal reflex is most common sign of trigeminal involvement.
   8. Signs of pressure on brain stem and cerebellum - present - later stages (ataxia,incoordination).
   9. Neck stiffness (headaches, nausea, choked discs, dulled mental functions, indication of internal hydrocephalus).

5. Laboratory Findings
   1. Increased pressure during later stages.
   2. Increased protein content. 150 mg/cc +

6. Differential Diagnosis
   1. Signs of 8th c.n. and BS and cerebellum.
   2. Mortality rate with surgery - 33%

C. Neurofibromas of 5th C.N.