brain tumors.
Study pages 400 and 402-404; refer to Figures 15-15 and 15-16; and Tables 15-11 and 15-12.
Cranial tumors can be either primary or meta- static. Primary intracerebral tumors originate from brain substance, neuroglia, neurons, cells of the blood vessels, and connective tissue. They include astrocyto- mas, oligodendrogliomas and ependymomas. Primary extracerebral tumors originate outside the substance of the brain and include meningiomas, and neurofibromas.
Metastatic tumors can be found inside or outside the brain substance.
Cranial tumors have local and generalized clini- cal manifestations. The local effects are caused by the destructive action of a particular site in the brain and by compression that reduces cerebral blood flow. The effects are varied and include seizures, visual disturbances,
unstable gait, and cranial nerve dysfunction. The general- ized effects result from increased intracranial pressure.
Intracranial brain tumors do not metastasize as readily as tumors in other organs because there are no lymphatic channels within the brain substance. If metas- tasis does occur, it is usually through seeding of cerebral blood or CSF, during cranial surgery, or through artificial shunts.
The principal treatment for cerebral neoplasms is surgical or radiosurgical excision or surgical decompres- sion if total excision is not possible. Chemotherapy and radiotherapy may also be used. Supportive treatment is directed at reducing edema.
In an estimated 25% of persons with cancer, metas- tasis to the brain develops. One third of metastatic brain tumors arise from the lung, approximately one sixth from the breast, and a lesser number from the gastrointestinal tract and kidney. Other tumors metastasize less often.
Carcinomas are disseminated to the brain by the circula- tion. Metastatic brain tumors carry a poor prognosis. If a solitary tumor is found, surgery or radiation therapy is used; but if multiple tumors exist, only symptomatic relief is pursued.
Neurofibromas (benign nerve sheath tumors) are a group of autosomal dominant disorders. Neurofibro- matosis type 1 causes multiple cutaneous neurofibromas, café au-lait spots and freckles, and, less commonly, bone and soft tissue tumors. Inactivation of the NF1 gene results in loss of function of neurofibromin in Schwann cells and promotes tumorigenesis. In about 50% of cases, learning disabilities are present.
Neurofibromamatosis type 2 is rare. Mutations of the NF2 gene promote development of CNS schwannomas.
Most commonly affect individuals in their 20s and 30s.
The vestibular division of cranial nerve VIII is most com- monly affected and can cause hearing loss or deafness.
Spinal cord tumors are classified as intramedullary tumors, those originating within the neural tissues, or extramedullary tumors, those originating from tissues outside the spinal cord. Intramedullary tumors have the same cellular origins as brain tumors. Extramedullary tumors arise from the meninges, epidural tissue, or verte- bral structure. The most common primary extramedullary spinal cord tumors are neurofibromas and meningiomas.
The acute onset of clinical manifestations of spinal cord tumor suggests a vascular occlusion of vessels sup- plying the spinal cord. In the compressive syndrome,
Classification of Common Primary Brain Tumors
Type Frequency Age Group Feature(s)
Astrocytoma 50% (brain/spinal cord) Adults Slow-growing, invasive, infiltrative
Oligodendroglioma 10%-15% (brain) Adults Slow-growing
Ependymoma 6%-10% (brain ventricles) All ages Variable growth rate, invasive
Meningioma 30% (brain) All ages Slow-growing, circumscribed
the motor dysfunction and sensory manifestations occur as the tumor grows. Pain develops.
The irritative syndrome combines the clinical mani- festations of a cord compression with radicular pain.
This pain is in the sensory root distribution and indicates root irritation. Sensory changes include paresthesia and impaired pain and touch perception; motor disturbances include cramps, atrophy, fasciculation, and decrease or absence of deep tendon reflexes.
PRactice exaMination Multiple Choice
Circle the correct answer for each question:
1. In blunt head trauma:
a. brain tissues are exposed.
b. only focal injury occurs.
c. the dura is severed.
d. the dura remains intact.
2. In an automobile accident, an individual’s forehead struck the windshield. The coup/contrecoup injury would be in the:
a. frontal/parietal region.
b. frontal/occipital region.
c. parietal/occipital region.
d. occipital/frontal region.
3. In moderate diffuse axonal injury:
a. coma lasts more than 24 hours.
b. coma lasts less than 24 hours.
c. axons in cerebral hemispheres and those extending into the diencephalon and brain stem are disrupted.
d. tearing of axons in the cerebral hemisphere occurs.
e. Both a and d are correct.
4. Most spinal cord injuries occur in the:
a. cervical and thoracic regions.
b. cervical and lumbar regions.
c. thoracic and lumbar regions.
d. lumbar and sacral regions.
5. Injury of the cervical cord may be life threatening because of:
a. increased intracranial pressure.
b. disrupted reflexes.
c. spinal shock.
d. loss of bladder and rectal control.
e. diaphragmatic impairment.
6. Autonomic hyperreflexia is characterized by all of the following except:
a. hypotension.
b. slower heart rate.
c. stimulation of sensory receptors below the level of the cord lesion.
d. precipitation because of a distended bladder or rectum.
7. Intervertebral disk herniation:
a. usually occurs at the thoracic level.
b. in the lumbosacral area causes pain over the gluteal region and into the calf or ankle.
c. is infrequent in the lumbosacral disks.
d. Both b and c are correct.
e. a, b, and c are correct.
8. TIAs are:
a. unilateral neurologic deficits that slowly resolve.
b. generalized neurologic deficits that occur a few seconds every hour.
c. focal neurologic deficits that develop suddenly, last more than an hour, and clear without evidence of infarction.
d. neurologic deficits that slowly evolve or develop.
9. Which is a risk factor for the development of CVAs?
a. polycythemia vera b. hypertension c. diabetes mellitus d. hyperhomocysteinemia
e. All of the above are risk factors.
10. Which most typically characterizes the victims of a cerebral embolic stroke?
a. individuals older than 65 years with a history of hypertension
b. individuals with a long history of TIAs
c. middle-aged individuals with a history of heart disease
d. individuals with gradually occurring symptoms that then rapidly disappear
11. Ruptured aneurysms are most likely in which of the following cerebrovascular accidents.
a. TIA b. thrombotic c. embolic d. hemorrhagic
12. Which is not a primary intracerebral neoplasm?
a. astrocytoma b. meningioma c. oligodendroglioma d. ependymoma
13. In bacterial meningitis, the CSF has:
a. normal glucose levels.
b. an elevated number of lymphocytes.
c. neutrophilic infiltration.
d. None of the above is correct.
e. a, b, and c are correct.
14. Multiple sclerosis involves:
a. degeneration of dopaminergic receptors.
b. activation of T cells autoreactive to myelin.
c. depletion of GABA.
d. lower motor neuron muscle wasting.
15. Manifestations of subarachnoid hemorrhage include which of the following? (More than one answer may be correct.)
a. a stiff neck b. muscle flaccidity c. Kernig sign
d. a delayed age of onset
Matching
Match the injury with its characteristic:
16. Concussion a. bleeding into the brain’s parenchyma
b. bruising of part of the brain
c. violent displacement of brain tissue resulting from rotation, acceleration, or deceleration
d. arterial bleeding e. venous bleeding 17. Contusion
18. Extradural hematoma 19. Subdural hematoma 20. Intracerebral hematoma
21. Spondylolysis a. cerebral cortex
b. neural arch of vertebra c. peripheral nerve myelin d. neuromuscular junction e. ventricular system of brain f. corticospinal tracts g. CNS myelin h. muscles 22. Myasthenia gravis
23. Multiple sclerosis 24. Guillain-Barré syndrome 25. Amyotrophic lateral sclerosis Match the disease with its site of dysfunction:
Case study
Mrs. B. is an overweight 71-year-old white female who slurred to her daughter, “My right head hurts. Can you understand me?” Upon hospital admission, she exhibited some severe right-handed numbness with a weak left hand grip. Her smile was asymmetrical with right-sided facial weakness that had persisted for 48 hours. Mrs. B.
has a history of smoking moderately for 50 years. Her mother had adult-onset diabetes and died of breast cancer at age 62; one sister died of a subarachnoid hemorrhage at age 63; and another sister is hemiparetic because of a CVA. One brother is hypertensive, and three other, younger siblings are apparently healthy.
Vital signs showed a normal temperature, elevated heart rate, and normal respirations, but a severely elevated blood pressure. CSF obtained by lumbar puncture tested negative for blood with normal protein and glucose levels. Electrocardiogram findings were normal. An electroencephalogram showed localized activity in the left hemisphere. A CT scan showed increased density on the left. Blood chemistry results were normal except for elevated glucose.
How would you assess Mrs. B.’s history, her family history, and her symptoms and signs?
Complete the following table to differentiate types of cerebrovascular accidents:
Cerebrovascular Accidents Fill in the Blank
Complete the following table comparing focal to diffuse traumatic brain injury:
Focal and Diffuse Traumatic Brain Injuries
Type of Injury Characteristics
Focal Contusion Coup/contrecoup
Extradural hematoma Arterial bleeding, immediate to delayed loss of consciousness, possible herniation Subdural hematoma
Delayed intracerebral hematoma Diffuse
Mild concussion
Classic cerebral concussion Mild DAI
Moderate DAI
Severe DAI Axonal tears in both hemispheres, diencephalon, and brain stem; sensory and cognitive deficits; increased intracranial pressure
Type Thrombotic Embolic Hemorrhagic Ischemic Lacunar
Involved sites Risk factors Causes