Hydrocephalus Flashcards
Functions of CSF
Prevent contact between delicate neural structures. Support the brain. Transport nutrients, chemical messengers, and waste products. Transduce hormones.
Is choroid permeable?
No, but other ependymal lining is permeable.
What is CSF derived from?
Blood plasma
CSF comparison to blood plasma
CSF has higher concentrations of Cl, Mg, Na.
How is NaCl transported into ventricles? Large molecules?
NaCl= Active transport, water passively follows. Large molecules = pinocytotic vesicles from basal to apical epithelial surface, then into CSF.
Average volume of CSF?
120mL
Average production of CSF/day?
450-500mL.
CSF Pathway
Lateral ventricle, through interventricular foramen of Monro into 3rd ventricle, then through the Cerebral aqueduct of Sylvius, into the 4th ventricle, then into subarachnoid cistern through foramina of Luschka and foramen of Magendie.
Arachnoid Villi
Pressure-dependent one way valves that open into dural sinuses when ICP is 3-5 cm H2O greater than dural venous pressure.
Does CSF production use ATP?
Yes, but reabsorption is passive.
How does CSF move?
Subtle pressure gradient between production and reabsorption sites. Mechanical movement due to brain shifting/arterial pulsations.
CSF constituents
50-180 mm H2O, 15-45 mg/dl protein, 50-80 mg glucose (2/3 of blood glucose), 0-5 mononuclear cells, 1 wbc/700rbc 1dl protein/1000 rbc
Complications of lumbar puncture
Low-pressure headache, herniation syndromes, infection
Where is BBB not intact?
Portions of hypothalamus (to expose it to hormones), pineal gland (to allow secretions into circulation), choroid plexus
Symptoms of hydrocephalus
headache, nausea, vomiting, papilladema, diplopia, lethargy, coma
Communicating hydrocephalus pathogenesis
Caused by problems in CSF reabsorption. Causes ventricular system to dilate, ICP rises.
Causes of communicating hydrocephalus
Absence of arachnoid villi, blockage by RBCs due to subarachnoid hemorrhage, high protein in CSF (caused by CNS tumors or inflammation), infection (meningitis)
Signs of communicating hydrocephalus
Huge head in young kids, people whose sutures have fused present with symptoms.
Choroid Plexus tumors cause?
Oversecretion of CSF, causing HC. Extremely rare– in most cases HC caused by reabsorption issues.
When do choroid plexus papillomas/carcinomas occur?
Between birth and 10 years.
Where do most choroid tumors occur?
4th ventricle (40-50%)
Hydrocephalus ex vacuo
Not a true hydrocephalus. Brain atrophy makes ventricles appear large in comparison to grey/white matter. Treatment not indicated.
Normal Pressure Hydrocephalus
Rare preventible cause of dementia. Wet wacky wobbly. Wet improves first, wacky improves last.
What improves prognoses for NPH?
If symptoms haven’t been present for that long. Treat with VP shunt.
Noncommunicating (Obstructive) Hydrocephalus Pathogenesis
Mass blocks the outflow of CSF (intraventricular bleed too causes rapid decline).
NCHC Etiologies
Aqueductal stenosis, masses, cysts, infection, hemorrhage
Ependyoma
5-6% of all glial cell neoplasms. 60-75% are found in posterior fossa, but some in spinal cord. In children under 5.
Infra vs supratentorial ependyoma symptoms
Infratentorial can cause CN palsies, both causes HC symptoms (NV, etc).
Is congenital HC genetic?
It can be! But can be caused by intrauterine infection/birth trauma.
What causes aqueductal stenosis
Pineoblastoma/meningioma.
Treatment of NCHC
remove mass–shunt can sometimes be avoided.
Use of external ventricular drain
Can’t be maintained, not permanent.
3rd ventriculostomy
Open floor of 3rd ventricle to basal cisterns.
Frequent complication of lumbar-peritoneal shunt?
Overdrainage
Pseudotumor cerebri
AKA idiopathic intracranial hypertension. Frequently seen in obese women of child-bearing age and in persons with chronic renal failure. Headache and visual disturbances due to papilledema. Also can be related to vitamin A deficiency. Increase in ICP, but without accompanying evidence on CT.
What can cause pseudotumor cerebri?
Overweight women, chronic renal failure, endocrinopathies, vitamin A deficiency.
