Neurosurgery

TEST TAKING TIPS

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%