Neuro Disease Assessment COPY Flashcards
What factors modulate cerebral blood flow (CBF)?
Cerebral metabolic rate
CPP (MAP-ICP)
PaCO2 and PaO2
drugs, pathologies
What is the approximate cerebral blood flow with autoregulation?
50 mL/100g brain tissue/min
~750mL/min
What does the intracranial and spinal vault contain?
Neural tissue
blood
CSF
What is the normal combined volume of brain tissue, intracranial CSF, and intracranial blood combined?
1200-1500mL
What is the normal intracranial pressure (ICP) range?
5-15 mmHg
What is the Monro-Kellie hypothesis?
Increase in one component must be offset by a decrease in another to prevent elevated ICP
How do homeostatic mechanisms compensate for increased ICP?
By increasing MAP to support CPP
What can happen if compensatory mechanisms for increased ICP fail?
Result in cerebral ischemia
What reflection of the dura separates the two cerebral hemispheres?
falx cerebri
What reflection of the dura lies rostral to the cerebellum and marks border between supratentorial and infratentorial spaces?
tentorium cerebelli
What is subfalcine herniation?
Hemispheric contents herniate under the falx cerebri.
What artery is compressed in subfalcine herniation?
Anterior cerebral artery
What is transtentorial herniation?
Supratentorial contents herniate past the tentorium cerebelli.
What is the consequence of transtentorial herniation?
Brainstem compression
What is the result of brainstem compression in transtentorial herniation?
AMS, gaze and ocular reflex defects, hemodynamic and respiratory compromise, and death
What is uncal herniation?
Subtype of transtentorial herniation where the uncus (medial temporal lobe) herniates over the tentorium cerebelli.
What are the manifestations of uncal herniation?
Pupillary dilatation, ptosis, lateral eye deviation, brainstem compression and death
What are the symptoms of herniation of the cerebellar tonsils?
Medullary dysfunction, cardiorespiratory instability
What are the types of brain herniation are indicated in 1-4?
- Subfalcine
- Transtentorial
- Cerebellar contents through foramen magnum
- traumatic hernation out of cranial cavity
How do tumors cause increased ICP?
- Directly due to size
- indirectly by causing edema in surrounding brain tissue
- obstructing CSF flow
How do intracranial hematomas cause increased ICP?
Similar to mass lesions
How can blood in the CSF lead to increased ICP?
Obstruct CSF reabsorption
What effect can infections like meningitis/encephalitis have on ICP?
Lead to edema or obstruction of CSF reabsorption
What positioning method encourages jugular venous outflow to decrease ICP?
Elevation of the head