Ventricles, CSF & Hydrocephalus (Stephens) Flashcards
What compromises the ventricular system
2 Lateral Ventricle
Third Ventricle
Fourth ventricle
What drains the CSF from the lateral ventricles to the third ventricle
Interventricular foramen of Monroe
What drains the CSF from the third ventricle to the fourth ventricle
Cerebral aqueduct
How does CSF from the fourth ventricle get to the subarachnoid space
Lateral & Median apeture
Where is cerebral spinal fluid produced
Choroid plexus of the lateral, third and fourth ventricles
Route of CSF
Lateral ventricle –> (interventricular foramen) –> Third ventricle –> (cerebral aqueduct) –> fourth ventricle –> (lateral & median apeture) –> subarachnoid space —> arachnoid villi –> Superior sagittal sinus
Volume of CSF in humans
20-25 ml in ventricles
140 ml in system
600-700 ml/day (replaced every 8 hrs)
Hydrocephaly
Due to an excessive amount of CSF in the ventricular system, the subarachnoid space or both.
External Hydrocephaly
Excessive accumulation of CSF in the subarachnoid space. It may be supratentorial, infratentorial or both.
What is supratentoral external hydrocephalus
Accumulation of CSF above the tentorium cerebelli. Most commonly associated with senile atrophy of the cortex, e.g., Alzheimer’s disease (aging)
What is infratentorial external hydrocephalus
Accumulation of CSF below the tentorium cerebelli. It is seen in combination with internal (noncomminucating) hydrocephalus to pr
Internal hydrocephalus (noncommunicating hydrocephalus)
Blockage of CSF in the ventricular system. CSF does not drain into the subarachnoid space.
What does internal (noncommunicating) hydrocephlaus result in
Enlargement of the ventricles proximal to the obstruction. It may be present in combination with an infratentorial external hydrocephalus
What are the clinical signs of hydrocephalus
- Internal strabismus (abducens palsy)
- “Sundown eyes”
- Papilledema
Communicating Hydrocephalus
No blockage in ventricular system
Combination of infratentorial external and internal (noncommunicating) hydrocephalus
CSF is able to move through the ventricular system into the infratentorial subarachnoid space, but it cannot circulate to the arachnoid villi to get to the superior sagittal sinus
Cerebral spinal fluid is resorbed in the
arachnoid villi
Atrophy of the cerebral cortex may result in
External hydrocephalus
(specifically supratentoral external hydrocephalus)
Occlusion of the cerebral aqueduct would result in _____ of the ______ and _______
Hydrocephalus
Lateral ventricles
3rd
NOTE: Cerebral aqueduct drains the 3rd ventricle to the 4th ventricle so its blockage would lead to hydrocephalus of the lateral & 3rd ventricles
Occlusion of the right interventricular forman would result in _________ of the _________
Hydrocephalus
lateral ventricle
Obstruction of the subarachnoid space at the level of the tentorial notch may result in
Communicating hydrocephalus
CSF eneters the subarachnoid space via what
Medial & Lateral foramina
Secondary to a subarachnoid hemorrhage blood in the CSF may occlude the ____ and result in ____
Arachnoid villi
Secondary (chemical) meningitis
What are you seeing in this image
Internal hydrocephalus due to enlargement of the lateral ventricles which is caused by obstruction of interventricular foramina of Monroe bilaterally and/or cerebral aqueduct.
