Tumors of the CNS
Overview of Topics
Types of Intracranial Tumors
- Dermoid - Often cystic; may contain sebaceous waxy material, hair.
- Teratomas - Greater amount & variety of structures, e.g., bone, muscle, fat, nerve.
- Are calcified seen easily in X-ray; tend to lie in midline.
- Meningioma - Tumor is encapsulaled; easily separated from nervous tissue - benign
- removable if not too large.
- 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.
- 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.
- 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.
- Oligodendroglioma - Slow growing; solid; calcified -- usually found in cerebral hemispheres of adults. Average Survival: 5 years.
- 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.
- 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.
- 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.)
- Pituitary Tumors
- 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
- displacement of brain tissue
- 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.
- Stiff neck
- Vasomotor & autonomic changes
- Visual disturbances - exp. in & out -- i.e. fading then good, etc.
- Hemianopsia - pituitary adenoma - bitemporal hemianopia.
- Sensory Disturbances
- Hallucinations - olfactory; visual; auditory
|Type of Tumor
- Age - occur predominantly at any age, especially young to middle age.
- Young - gliomas of cerebellum, brainstem, & optic nerve, pinealomas, craniopharyngiomas, teratomas & granutomas.
- Adult - mengiomas, neurofibronias, gliomas of cerebrum.
- Late middle life - metastatic.
- Sex - slightly more common in men.
- men - cerebellar medulloblastomas, cerebral astrocytomas, & glioblastomas.
- women - meningiomas and acoustic neuromas.
No constellation of symptoms is pathognomonic of tumors.
- Headaches are not good for localization as they generally are in frontal or occipital
localized scalp tenderness has more localizing value.
- headaches are usually intermittent occurring at irregular intervals from minutes to hours duration.
- become more frequent and of longer duration with growth in tumor.
- 90%, of tumor patients have headaches.
- Cause unknown.
- Nausea and vomiting - much less frequent.
- Choked discs - common finding but absence does not rule out tumors.
- 50-90% tumor patients have choked discs.
- high incidence in those patients where tumor influences cerebrospinal fluid.
- tumors confined to hemispheres can grow to large size with no choked discs.
- tumors compressing optic nerve may cause atrophy w/o evidence of choking.
- Foster - Kennedy's Disease - tumor on one optic nerve produces ipsilateral
atrophy and contralateral choked disc.
- Demyelinizing diseases such as MS also cause choked disc.
- May lead to central or paracentral scotoma.
- Convulsions - common with tumors of cerebrum, rare with brain stem tumors.
- tumor patients tend to have prolonged coma following Jacksonian focal or generalized seizure.
- Also may have (Todd's paralysis) transient hemiparesis.
- often seizures are the first sign of tumor. Tumor should be considered especially if first seizure occurs after 20 or 30 years of age.
- 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)
- Mental symptoms
- lethargy, drowsiness, personality changes, psychotic episodes.
Diagnosis of intracranial Tumors
- Consider tumor whenever focal neurological symptoms develop slowly & gradually increase in severity.
- The occurrence of convulsive seizures, headaches, dizziness, mental symptoms or the slow development of focal neurological symptoms.
B. Physical Examination
- Choked discs and focal neurological signs.
- Visual fields.
- Aphasia screening.
- With high pressure many false signs may be obtained.
C. Laboratory Examination
- Roentgenography (X-ray)
- May show tumor by showing:
- displacement of calcified pineal gland
- absorptive changes in the bones of the skull
- separation of the sutures in children.
- Calcification occurs within 12% of gliomas.
- 50% of meningiomas diagnosed by atrophy or hypertrophy of bone overlying tumor or by presence of abnormal vascular channels in skull.
- 70-80% craniopharyngiomas - diagnosed by presence of calcium in tumor.
- angiomas and vascular anomalies may show calcification of a curvilinear nature.
- Electroencephalogram - (EEG) - value in localizing tumors near surface. Slow wave activity.
- Examination of cerebrospinal fluid
- increased pressure 70% above 200 mm H20
- increased protein content above 100 mg.
- Echo from midline - look for displacement.
- also echo from pineal, interhemispheric fissure.
- Ventriculography and Encephalography
- X-ray with air injection.
- Evaluate for displacement.
- Angiography - injection of radiopaque dyes.
- produces transient seizures in 10% of cases.
- percutaneous puncture of carotid or vertebral arteries.
- Radioactive Scanning
- tumors best seen 24 to 48 hours after injection.
- not effective for avascular, 3rd V and cerebellar lesions.
A. CVA's - sudden onset of symptoms and lack of progression of focal signs.
- Occasionally - sudden onset (rare).
- Tumors are common in age group subject to arteriosclerosis, thus, this and hypertension do not rule out
Neoplasms which arise from primitive forms of glial cells.
50% of all intracranial tumors.
- 40% of gliomas - composed of astrocytes.
- Tend to infiltrate large areas and may undergo cystic degeneration.
- Grow slowly.
- Complete surgical removal is rare.
- In brain stem nuclei tend to be elongated and arranged in parallel lines as palisades (paloid astrocytoma).
- Unilateral or bilateral sixth nerve involvement is the most common sign.
- 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.
- Radiation therapy (difficult to treat).
- Less than 5% of all gliomas.
- Found chiefly in the cerebral hemispheres of young adults.
- More circumscribed - slower growing.
- Focal neurological signs and convulsive seizures common.
- Difficult to treat.
- Glioblastoma Multiforme (Spongioblastoma)
- Most rapidly growing form of glioma.
- 1/3 of all gliomas.
- Most frequent in cerebral hemispheres of adults.
- Cross via corpus callosum.
- May seed into cerebrospinal fluid and produce tumors in remote areas.
- Rapidly fatal - leading to death within one year.
- Respond poorly to X-radiation therapy.
- 10% of gliomas.
- Derived from primitive form of glia cells.
- Predominant in cerebellum.
- Most frequent in infants and young adults.
- Increased pressure.
- Headache, vomiting, unsteady gait are presenting symptoms.
- Also suture separation, choked discs, and nystagmus.
- Rapidly growing and fatal within one year.
- Recurrence is almost inevitable.
- Most common in children.
- Relatively malignant - life two years.
Tumors of the Skull
- Local overgrowth of bones of skull.
- May be secondary to intracranial tumors or may occur independently.
- May involve either the outer or inner tables of the skull.
- Unlikely to cause pressure on cerebrum.
- May arise in the paranasal sinuses or from cortex of calavarium.
- Cause enlargement of sinus and localized pain or headache.
- Erosion of the dura may cause cerebrospinal fluid rhinorrhea, pneumatocele, meningitis, or abscess formation.
- Rarely reach sufficient size to compress underlying brain tissue.
- Congenital vascular anomalies which may involve the bones of skull or SC.
- May be single or multiple.
- Small - no symptoms.
- Headaches, Jacksonian or generalized seizures & focal neurological signs may result.
D. Metastatic tumors
- May be secondary to malignant tumors elsewhere.
- Seldom produce neurological symptoms unless located at the base - cranial nerve palsies.
- Operative treatment is contraindicated.
E. Involvement of Skull in Systematic Diseases
- Hand-Schiiler-Christian disease - xanthomatosis
- Multiple Myeloma
- Osteitis Deformans (Paget's disease).
Tumors of the Meninges
A. Meningiomas - (meningeal fibroblastomas, leptomeningiomas, arachnoidal fibroblastomas, dural endothelioma) - tumors which are principally associated with the arachnoid villi.
- Produce symptoms of compression of underlying nervous parenchyma.
- Seldom break through pia.
- Pathology - round on nodular masses.
- Sharply circumscribed.
- Invade dura and frequently bone as well.
- Have rich vasculature - derived from meningeal branches of ext. carotid artery.
- Stimulate growth in adjacent bone and occasionally erode it.
- Tendency to reoccur.
- Types (9) meningothelial without reticulin, psammomatous, and fibroblastic - most common.
- Less frequent - angioblastic, epitheloid, saccomatous, osteoblastic, chonodroblastic.
- Incidence - constitute 10-15% of all intracranial tumors admitted to large neurosurgical clinics.
- May occur at any age but are predominantly of adult or early middle life.
mean age onset: 38
mean age admission: 46
- More common in women by ratio of 3/2.
- Rare in U. S. Blacks.
- Precipitating factors - trauma & pregnancy (high correlation w/ trauma foci).
- Symptoms and Signs
- Diagnosed on basis of location and fact that they often produce proliferation of bone.
|Convexity of hemispheres
||Exopthalamus, visual defects
|Floor of anterior fossa
- Treatment - surgery - otherwise lead to death. Complete cures are common.
Tumors of the Cranial Nerves
A. Gliomas of the Optic Nerve
- May occur in intraorbital division of optic nerve, post-ocular portion, or optic chiasm (most - intraorbital).
- Occur predominantly in childhood.
- Progressive blindness
- Unilateral amblyopia, hemianoptic field defects - presenting symptoms.
B. Neurofibromas of 8th Cranial Nerve
- Probably arise from swan sheath cells.
- Arise in peripheral portion of the vestibular division of the 8th nerve in the porus acousticus mainly intracranial and large.
- Tumor is composed of dense interlacing fibrous bands and loose reticular tissue in varying proportions.
- 5-10% of all intracranial tumors.
- Onset between 30-60 years.
- Below 20 - so rare a tumor here would probably be a glioma.
- Symptoms and Signs
- Loss of hearing with or without tinnitus.
- Tinnitus may precede other symptoms by several years.
- Vestibular involvement - giddiness or unsteadiness of gait.
- Severe vertigo attacks are rare.
- Horizontal nystagmus present in almost all cases.
- Involvement of one or more other cranial nerves is almost always present.
- Loss of corneal reflex is most common sign of trigeminal involvement.
- Signs of pressure on brain stem and cerebellum - present - later stages (ataxia,incoordination).
- Neck stiffness (headaches, nausea, choked discs, dulled mental functions, indication of internal hydrocephalus).
- Laboratory Findings
- Increased pressure during later stages.
- Increased protein content. 150 mg/cc +
- Differential Diagnosis
- Signs of 8th c.n. and BS and cerebellum.
- Mortality rate with surgery - 33%
C. Neurofibromas of 5th C.N.