CHAPTER 29
Neurosurgery
Test Taking Tips
Make sure that you are familiar with the Glasgow Coma Score prior to the test.
Review the neurosurgery section in the trauma chapter.
What components are present in the cranium?
Brain tissue, cerebrospinal fluid (CSF), blood vessels and blood volume, pathological volume (eg, neoplasm, hematoma, abscess, etc)
What may cause an increase in the brain tissue component (not including neoplasms)?
Edema, inflammatory, perineoplastic, vasogenic
What can be given to decrease swelling due to edema?
Mannitol, hypertonic saline
What can be given to decrease the brain tissue component if swelling is caused by inflammation or perineoplastic syndrome?
Steroids
What can be done to decrease the blood volume component?
Hyperventilation, diuretics, head elevation, remove venous obstruction
What can be done to decrease the CSF component?
Drainage (either external or internal such as a VP shunt), acetazolamide (temporary), steroids (temporary)
What can be done to decrease volume due to a mass lesion?
Evacuation or removal of the cause of the mass lesion
What is the Monro-Kelly doctrine?
The total volume of the cranial vault is fixed and thus an increase in one component must be offset by a decrease in another component.
True or false: CSF production rate is affected by intracranial pressure (ICP)?
False. CSF production rate is constant and is not affected by “back pressure.”
What is the site of CSF production?
The arachnoid granulations
What is the name of the process that maintains cerebral blood flow at a constant rate despite changes in systemic blood pressure?
Autoregulation
Define cerebral perfusion pressure:
Mean arterial pressure (MAP) – ICP
Why do older people tend to be more tolerant of mass lesions?
They tend to have larger ventricles, which are more tolerant of compression than brain tissue
What is a raised ICP with no mass lesion termed?
Pseudotumor cerebri or idiopathic intracranial hypertension
What is increased ventricular volume without increased intracranial pressure called?
Normal pressure hydrocephalus
What is a failure of proper capillary formation termed?
Arteriovenous malformation (AVM)
What is the risk of hemorrhage associated with an AVM?
4% per year
What percentage of AVM-associated hemorrhages is classified as severe?
25%
FIGURE 29-1. Cerebral angiogram demonstrating a frontal arteriovenous malformation filling from the left anterior cerebral artery. (Reproduced from Doherty GM. Current Diagnosis and Treatment: Surgery. 13th ed. http://www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.)
Berry aneurysms
What is the risk of hemorrhage with an aneurysm measuring less than 1 cm?
0.05% to 0.5% per year
What is the risk of hemorrhage with an aneurysm measuring more than 1 cm?
1% to 2% per year
If not treated, what is the risk of rebleed within 2 weeks from an aneurysm that has ruptured?
20%
Which cerebrovascular moniker derives from the Japanese term for “puff of smoke?”
Moyamoya—it is characterized by idiopathic narrowing of the major intracrainial vessels with formation of a compensatory collateral circulation.
Which medication is prescribed to reduce swelling related to brain tumors?
Dexamethasone
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