Ventricle CSF & Hydrocephalus Flashcards
How much CSF is produced each day?
400-500 ml/day
CSF: Function
- Helps provide homeostasis, protection and buoyancy
- Prevents weight of brain from compression CNs and vasculature at the base of the skull
- Helps remove brain metabolites
- Endocrine mechanism – hormone transport
What produces CSF?
Ependymal cells in the choroid plexus (60-80%) – lateral ventricle (65% produced here), 3rd ventricle, 4th ventricle
Choroid Plexus
Consists of villous folds lined by epithelium with a central core of highly vascularized connective tissue
Choroidal Epithelium
Specialized layer of Ependymal cells that overlies villi in the Choroid Plexus
Main difference in composition of CSF compared to serum:
CSF has 0.035 g/dL protein vs. Serum has 7 g/dL protein
How do you test CSF composition?
Lumbar puncture
CSF Circulation
(1) Produced in Choroid Plexus of Lateral Ventricles
(2) Enters 3rd Ventricle via R and L Interventricular Foramen (of Monro)
(3) Enters 4th Ventricle via Cerebral Aqueduct of Sylvius
(4) Once in 4th Ventricle can enter Subarachnoid space via: Foramen of Luschka or Foramen of Magendie
(5) CSF reabsorbed by arachnoid granulations in the dural venous sinuses
Foramen of Luschka
- Two are located in the Fourth Ventricle
- Lateral Apenture
Foramen of Magendie
- One located in Fourth Ventricle
- Medial aperture
Arachnoid Granulations
Extensions of the Arachnoid Mater that allow CSF to be absorbed by the Dural Sinuses
Subarachnoid Cisterns
- Soft tissue structures that contain CSF and “anchor” the brain
- Consists of arachnoid trabeculae, vasculature, and in some instances CN roots
Cerebellomedullary Cistern (Cisterna Magna)
- Largest subarachnoid cistern
- Located between cerebellum and medulla
- Receives CSF from apertures of 4th ventricle
Interpeduncular Cistern (Basal Cistern)
Interpeduncular fossa between cerebral peduncles of midbrain
Pontocerebellar Cistern (Pontine Cistern)
- Located ventral to the Pons
- Continuous inferiorly with spinal subarachnoid space
Quadrigeminal Cistern (Cistern of Great Cerebral Vein)
- Located between the Posterior Corpus Callosum and superior surface of the Cerebellum
- Contains part of great vein of Galen
Posterior Cerebellomedullary Cistern
Located inferior to the Cerebellum
Cistern
Enlarged portions of subarachnoid space taht contain arteries, veins, CN roots and CSF
Blood supply to Choroid Plexus in Lateral and 3rd Ventricles:
Anastomosis between Anterior Choroidal Artery (ICA), Lateral Posterior Choroidal A (BA), and Medial Posterior Choroidal A (BA)
Blood supply to Choroid Plexus in 4th Ventricle:
AICA (BA) and PICA (VA)
Hydrocephalus
Increased amounts of intracranial pressure (ICP_ and ventricular dilation due to an excessive amount of CSF accumulation in the ventricles and/or subarachnoid spaces
Communicating (Nonobstructive) Hydrocephalus
- Failure to reabsorb CSF
- Communication between the ventricles and the subarachnoid space is intact
- Usually caused by a deficiency in the absorption of CSF into the sinus – can happen as a result of damage to the arachnoid granulations (ex. consequence of purulent bacterial meningitis)
- CSF still produced and circulates normally, but absorption into the venous sinus is impaired
Non-Communicating (Obstructive) Hydrocephalus
- Failure to circulate CSF to Subarachnoid Space
- Excessive amounts of CSF in the cerebral ventricles and enlargement of the head
- Caused by overproduction of CSF, obstruction of CSF flow, or interference with CSF absorption
- Dilates the ventricles, thins the cerebral cortex, and separates the bones of the calvaria in infants
- Obstruction can occur at any place but typically occurs in the Cerebral Aqueduct or an Interventricular Foramen
Communicating Hydrocephalus on MRI
Accumulation of CSF in subarachnoid space
