recorded the presence of fluid within the cavities of the brain, and was 1st to tap the ventricles
he believed that hydrocephalus was the result of chronic epilepsy
ca. 180 AD Galen
describes the ventricle and choroid plexus; however, he was incorrect in describing their functions
1543
Versalius recognized that the ventricles are filled with fluid, not gas (as Galen had described)
1664
Willis recognized that CSF was secreted by choroid plexus and drained into the venous system.
1701
Pacchioniillustrated arachnoid granulations, however he incorrectly believed that they were the source of CSF
1825
Magendie coined term "cerebrospinal fluid" and described communication between 4th ventricle and subarachnoid space
1875
Key and Retzius established that CSF was absorbed by arachnoid granulations
1891
Quincke developed the percutaneous lumbar puncture as a diagnostic and therapeutic tool.
Physiology of Cerebrospinal Fluid
present in 1st trimester
Cerebrospinal Fluid
is a plasma ultrafiltrate made by the choroid plexus located in the medial portions of the lateral ventricles, the roof of the 3rd ventricle, and part of the 4th ventricle
most CSF is from the choroid plexus; however, there is evidence of extrachoroidal secretion
CSF is constantly produced at a rate ~20cc/hr; therefore total CSF volume (~145 ccs) is turned over 3 xs daily
CSF is absorbed by the Arachnoid Granulations, concentrated in the superior midline.
Ý Absorption with Ý pressure
Function of CSF
:
To provide physical support or buoyancy for the brain (a 1500g brain suspended in CSF weighs only 50 g)
To provide an excretory role for the brain acting as a metabolic sink
To provide intracerebral transport for biologically active substances
To control the chemical environment of the CNS
Lumbar Puncture
(1) measure "opening pressure" to give an indication of CSF pressure
(2) collect fluid to perform lab analysis to yield insight into the disease process
Normally CSF does not contain RBCs or WBCs. WBC > 5/
m L is abnL.
normal CSF protein = 35 mg/dL
normal glucose = 60 mg/dL
Pathology of Cerebrospinal Fluid Hydrocephalus
Hydrocephalus
marked swelling of the ventricles that can compress the brain; three etiologies:
(1) Obstructive
Non-draining, cant get CSF out of the closed cranial container
Non-communicating
obstruction within the ventricular system
if dye injected in the lateral ventricles, it would not be apparent in CSF from a lumbar puncture
Example
: obstruction of cerebral aqueduct, preventing CSF from reaching 4th ventricle
Treatment
: Endoscopic 3rd Ventriculostomy, punch a hole in the floor of the 3rd ventricle
allows CSF communication with subarachnoid space; risky since basilar artery is just below punch site
Communicating
obstruction within the subarachnoid space
if dye injected into the ventricles, it would come out in a lumbar puncture
Treatment
: Shunt, a tube from the ventricle to the peritoneum
CWRU Neurosurgery chairman Dr. Nulson did it in 1949
addition of a valve (invented by John Holter to treat his own son) make modern shunts much better
Shunt Malfunction
is common; 25% lifetime risk of coma, 1% risk yearly of death. 40% FAIL in 1st 2 yrs
Cranial Synostosis
, head malformation due to early suture fusion, can result from shunting too much CSF
peritoneum can stop absorbing fluid and form walled-off collection of CSF in belly(usually due to infection)
NOTE:
It is important to distinguish between communicating and non-communicating by CT before doing a lumbar puncture, since a non-communicating obstructive hydrocephalus has Ý pressure above the brain. By draining CSF from the lumbar puncture, you would ß the pressure below the brain and could potentially cause herniation of the brain.
(2) Ex Vacuo
not enough brain to fill up the space, either from atrophy or maldevelopment
(3) Excess production of CSF
(rare) from choroid plexus adenoma; can become malignant (c.p. carcinoma)