Ventricular System & Hydrocephalus Flashcards
What is choroid plexus?
All four ventricles contain strands of highly convoluted and vascular membranous material called choroid plexus
In what parts of the ventricular system is the choroid plexus found?
There is a band of choroid plexus in each lateral ventricle.
Are endothelial cells within the choroid plexus fenestrated or non-fenestrated?
Note: fenestrated endothelium in choroid capillary allows plasma/fluid through (green arrows), but blocks cells.
How is cerebrospinal fluid (CSF) produced and secreted?
It is produced in the choroid plexuses.
Describe the directional flow of CSF through the ventricular system, starting at the lateral ventricles and ending at the arachnoid granulations.
Lateral ventricles 3d ventricle 4 th ventricle subarachnoid space venous sinuses
Describe how CSF in the subarachnoid space is removed.
Some CSF moves into the subarachnoid space around the spinal cord. It makes its way caudally to the lumbar cistern. Most of this fluid is returned to the venous system through arachnoid villi that penetrate the dural sleeves accompanying spinal nerve roots.
Where would excess CSF volume accumulate if a blockage of CSF flow occurred at the interventricular foramina?
The lateral ventricles communicate with each other and with the 3d ventricle through the interventricular foramen (of Monroe).
If a blockage of CSF flow occurred at the cerebral aqueduct?
The 3d ventricle and hence all three communicate with the 4th ventricle through the relatively long canal – the cerebral canal aka aqueduct of Sylvius. Processes leading to obstruction of the aqueduct can block the free circulation of CS
If a blockage of CSF flow occurred at the foramina of Lushka and Magendie?
In contrast, there are three apertures in the fourth ventricle through which the ventricular system communicates freely with subarachnoid space.
The median aperture foramen of Magendie. The two lateral apertures foramina of Luschka.
What is the most common cause of hydrocephalus?
Blockage of CSF circulation (most common)
Explain the different definitions of the terms communicating hydrocephalus vs. non-communicating hydrocephalus.
Explain the different
Communicating hydrocephalus – ventricles still communicate blockage is outside
Non-communicating hydrocephalus – blockage is within the ventricles (aqueduct) In both the cause of hydrocephalus is the same: an obstruction in the path of CSF circulation.
Explain the meaning of the term “normal pressure” hydrocephalus.
In elderly 50% of cases, an idiopathic intermittent increase in ICP occurs.
Results from decreased resorbtion of CSF at the arachnoid granulations.
What are some symptoms or signs (patient presentations) of hydrocephalus?
Headache Nausea/vomiting Papilledema, except in normal pressure hydrocephalus. Changes in consciousness – from sleepiness to coma. Brain herniation - uncal and/or cerebellar tonsils, resulting in lifethreatening brain stem compression.
What clinical problem does the term “pseudotumor cerebri” refer to?
Patients present with a headache, visual disturbances such as diplopia and sixth cranial nerve (abducens) palsy.
Papilledema. Increase in ICP.
