CSF Dynamics Flashcards
What is the major site of CSF production?
Choroid plexus in lateral, third, and fourth ventricles
What is the rate of CSF production in dogs?
0.047 ml/min
What is the rate of CSF production in cats?
0.017 ml/min
How many times per day is total CSF volume produced and absorbed?
3-5 times per day
What influences the production of CSF?
Osmotic pressure of blood
What effect does administration of hypertonic solutions have on CSF?
Reduces rate and formation of CSF
What type of cells are found in the choroid plexus?
Simple cuboidal epithelial cells
What separates the vascular epithelium from the choroidal epithelial cells?
Thin basement membrane and loosely arranged meningeal pial cells
What is a key characteristic of the endothelial cells in the choroid plexus?
Lack tight junctions and are fenestrated
What type of junctions do epithelial cells have at the ventricular surface?
Tight junctions
Compared to blood plasma, CSF has _____ potassium and calcium.
Less
Compared to blood plasma, CSF has _____ chloride, sodium, and magnesium.
More
How much less glucose does CSF have compared to blood?
20% less
What is the normal protein level in CSF?
25-30 mg/dL, predominantly albumin
What are the functions of CSF?
- Protection
- Regulate ICP
- Transport nutrients
- Transport neuroendocrine cells and NTs
- Maintain ionic balance
Where is the major site of CSF absorption?
At the arachnoid villi in the venous sinuses or cerebral veins
What acts as a one-way valve for CSF absorption?
Arachnoid villi
What are other sites of CSF absorption?
- Veins and lymphatics around spinal nerve roots
- Cranial nerves I, II, and VIII
What is the function of P-glycoprotein?
Prevents accumulation of certain drugs in brain parenchyma
What condition results from poor ventilation and induces cerebral arterial vasodilation?
Hypercapnia
What does cerebral perfusion pressure equal?
Mean arterial pressure minus ICP
What is a consequence of failure of autoregulation?
Vasogenic and cytotoxic edema
What is subfalcine herniation?
Medial displacement of one cerebral hemisphere ventral to the falx cerebri
What characterizes transtentorial herniation?
Displacement of the caudal aspect of one or both cerebral hemispheres ventral to the tentorium cerebelli
What are symptoms of transtentorial herniation?
- Constricted pupil followed by a widely dilated unresponsive pupil ipsilateral to the herniation
- Altered mentation
- Gait deficits
What is internal hydrocephalus?
Ventricular dilation with CSF accumulation
What is external hydrocephalus?
CSF accumulation in a dilated subarachnoid space
What type of hydrocephalus is caused by intraventricular obstruction of CSF flow?
Noncommunicating hydrocephalus
What characterizes communicating hydrocephalus?
Ventricular dilation secondary to an extraventricular obstruction of CSF flow or absorption
What is normotensive hydrocephalus associated with?
Normal CSF pressure
What is hypertensive hydrocephalus associated with?
Increase in CSF pressure
What is compensatory hydrocephalus?
Loss of parenchyma and CSF volume increases to occupy space previously occupied by parenchyma
What viral infections can cause hydrocephalus in utero?
- BVDV
- Akabane in cattle
What is obstructive hydrocephalus?
Obstruction to flow and absorption causes pressure to increase in ventricular system and expand
What condition involves stenosis of the mesencephalic aqueduct?
Developmental hydrocephalus
What is hypertensive noncommunicating developmental hydrocephalus often associated with?
Malformation of the mesencephalon with fusion of rostral +/- caudal colliculi
