Ventricles and Sinuses B&B

Question 1

what is the flow of CSF in the brain?

Answer 1

1. lateral ventricles
2. interventricular foramen (of Monroe)
3. third ventricles
4. cerebral aqueduct
5. fourth ventricles
6. central canal (center of spinal cord)

Question 2

CSF is produced by ______, absorbed by ______, and drained by ______

Answer 2

production: ependymal cells of choroid plexus (one in each ventricle)

absorption: arachnoid villi

drainage: superior sagittal sinus (onward to venous system)

Question 3

choroid plexus cysts are associated with…

Answer 3

chromosome abnormalities, esp. trisomy 18

however, often a normal variant

Question 4

what is the problem in communicating hydrocephalus?

Answer 4

decrease in CSF absorption by arachnoid, increasing intracranial pressure (ICP)

Question 5

what are the key clinical features of communicating hydrocephalus? (3)

Answer 5

1. headache (chief complaint)
2. papilledema (fundoscopic exam)
3. dilation of ALL ventricles (CT scan)

note PMH of meningitis is common (causes scarring)

Question 6

Pt with PMH of meningitis presents to your neurology practice complaining of severe headache. Fundoscopic exam reveals papilledema. A CT scan is ordered, which shows dilation of all the ventricles. What is the diagnosis?

Answer 6

communicating hydrocephalus

1. headache (chief complaint)
2. papilledema (fundoscopic exam)
3. dilation of ALL ventricles (CT scan)

PMH of meningitis is common (causes scarring)

Question 7

what are 3 congenital causes of non-communicating hydrocephalus?

Answer 7

1. aqueductal stenosis: congenital or intrauterine infection
2. Chiari malformations: malformations of cerebellum and brain stem
3. Dandy Walker malformation: developmental anomaly of 4th ventricle

Question 8

give 1 genetic cause and 4 infectious causes of aqueductal stenosis

Answer 8

congenital: X-linked (boys)

inflammatory due to intrauterine infection: Rubella, CMV, toxo, syphilis

[blocked drainage from 3rd to 4th ventricles —> non-communicating hydrocephalus]

Question 9

how does aqueductal stenosis present in a baby?

Answer 9

enlarging head circumference (due to non-communicating hydrocephalus)

Question 10

what is the consequence of a Chiari II malformation?

Answer 10

downward displacement and herniation of the cerebellar tonsils and medulla

causes obstruction of CSF flow from 4th ventricle —> non-communicating hydrocephalus

Question 11

Chiari II malformations are almost always associated with…

Answer 11

[downward displacement and herniation of the cerebellar tonsils and medulla —> non-communicating hydrocephalus]

associated with myelomeningocele (spina bifida) - failure of spine/meninges to close around cord

Question 12

what congenital malformation causes downward displacement and herniation of the cerebellar tonsils and medulla

Answer 12

Chiara II malformation —> non-communicating hydrocephalus

associated with spina bifida (myelomeningocele)!!!

Question 13

what are the consequences of Dandy Walker malformation? explain the 2 root causes of these

Answer 13

developmental anomaly of 4th ventricle

1. cysts —> hydrocephalus —> macrocephaly
2. very large ventricle —> hypoplasia/agenesis of cerebellar vermis, small cerebellum —> motor dysfunction (crawling/walking) —> delayed development

Question 14

Parent comes in to the office worried that their child is not crawling yet. On PE, you note the child has a very large head (macrocephaly). Delayed development and motor dysfunction is apparent. You might want to think about…

Answer 14

Dandy Walker malformation: developmental anomaly of 4th ventricle

1. cysts —> hydrocephalus —> macrocephaly
2. very large ventricle —> hypoplasia/agenesis of cerebellar vermis, small cerebellum —> motor dysfunction (crawling/walking) —> delayed development

Question 15

pseudotumor cerebri

Answer 15

idiopathic intracranial HTN —> increased ICP in absence of tumor/ other cause

causes intractable/ disabling headaches, papilledema, visual loss, pulsatile tinnitus (rushing water/ wind sound)

Question 16

what are the symptoms of pseudotumor cerebri? which one is most key?

Answer 16

idiopathic intracranial HTN —> increased ICP in absence of tumor/ other cause

causes intractable/ disabling headaches, papilledema, visual loss, pulsatile tinnitus (rushing water/ wind sound)

Question 17

who is the classic patient affected by pseudotumor cerebri?

Answer 17

idiopathic intracranial HTN

causes intractable/ disabling headaches, papilledema, visual loss, pulsatile tinnitus

classically overweight women of childbearing age

Question 18

how is pseudotumor cerebri diagnosed? how is it treated?

Answer 18

idiopathic intracranial HTN

causes intractable/ disabling headaches, papilledema, visual loss, pulsatile tinnitus

diagnose via spinal tap to measure the ICF pressure
tx: acetazolamide (mild diuretic)

Question 19

what is the key neuroimaging finding of normal pressure hydrocephalus (NPH)?

Answer 19

enlarged ventricles on imaging causing compression of the corona radiata (fibers projecting from corpus colosum)

note the CSF pressure is normal when measured (may be due to impaired absorption of CSF)

classic triad: urinary incontinence, gait disturbance, dementia (wet, wobbly, wacky)

Question 20

what is the classic triad of normal pressure hydrocephalus (NPH)?

Answer 20

enlarged ventricles on imaging causing compression of the corona radiata (but normal CSF pressure when measured)

classic triad: urinary incontinence, gait disturbance, dementia (wet, wobbly, wacky)

Question 21

how is normal pressure hydrocephalus (NPH) treated?

Answer 21

enlarged ventricles on imaging causing compression of the corona radiata (but normal CSF pressure)

tx: ventriculoperitoneal (VP) shunt - drains CSF to abdomen

Question 22

what is the cause of hydrocephalus ex vacuo?

Answer 22

ventricular enlargement that occurs with age (60+) due to shrinkage of the cortex (but may be accelerated with Alzheimer’s, Pick, HIV, etc)

Question 23

how can hydrocephalus ex vacuo be differentiated from hydrocephalus on neuroimaging?

Answer 23

hydrocephalus ex vacuo: ventricular enlargement with age

size of ventricles should increase in proportion to increasing size of sulci (as cortex atrophies) - if out of proportion, you’re dealing with hydrocephalus

Question 24

what is the function of the dural sinuses?

Answer 24

large venous channels traveling through dura, drain blood from cerebral veins and receive CSF from arachnoid granulations —> empty into internal jugular vein

Question 25

which dural sinus receives CSF first?

Answer 25

sagittal sinus

Question 26

which 6 nerves travel through the cavernous sinus? which important artery travels through the cavernous sinus?

Answer 26

between temporal/sphenoid bones, collects blood from the eye/cortex and drains into internal jugular vein nerves: CN III, IV, V1, V2, VI, sympathetics (all going to orbit) artery: internal carotid

Question 27

what are the symptoms of cavernous sinus syndrome?

Answer 27

between temporal/sphenoid bones, drains into internal jugular vein, includes: *nerves*: CN III, IV, V1, V2, VI, sympathetics (all going to orbit) *artery*: internal carotid symptoms: headache, *swollen eyes*, impairment of ocular motor nerves, Horner’s syndrome, loss of sensation supplied by V1/V2

Question 28

Pt presents to their GP with complaint of a “head cold” that has gotten worse. They complain of headache and sensory loss to their upper face. Examination reveals swollen eyes, impairment of the ocular motor nerves, and Horner’s syndrome. What is the likely diagnosis?

Answer 28

*Cavernous sinus syndrome* - due to infection spreading (septic thrombosis) between temporal/sphenoid bones, drains into internal jugular vein, includes: *nerves*: CN III, IV, V1, V2, VI, sympathetics (all going to orbit) *artery*: internal carotid

Question 29

which of the dural sinuses often becomes enlarged in patients with AV malformations?

Answer 29

artery to vein connection with no capillary bed, enlarge over time —> headaches, seizures commonly result in *Vein of Galen* enlargement

Question 30

describe the presentation of hydrocephalus in adults vs children

Answer 30

adults: headache, N/V, *papilledema + periodic visual obscurations* (transient vision loss), cranial nerve palsies (esp. *abducens/CN VI*), cognitive impairment + urinary difficulties, gait instability (*frontal lobe dysfunction*) children: non-specific signs, *head enlargement*, tense fontanelles, developmental delay, sun-setting phenomenon (*vertical gaze palsy - can’t look up*)

Question 31

what 2 findings are necessary to confirm diagnosis of hydrocephalus?

Answer 31

1. establish ventriculomegaly - are lateral ventricles more than 1/3 of the diameter of the skull? AND 2. confirm signs of increased ventricular pressure - are the *temporal horns dilated*? Is there *transependymal flow* of CSF (bright white around rim of ventricles)?

Question 32

what is a colloid cyst and what type of CNS issue does it cause?

Answer 32

*colloid cyst*: non-malignant, mucin-filled lesions in roof of *third ventricle* —> obstructs foramen of Monro —> *non-communicating hydrocephalus* can cause acute life-threatening hydrocephalus that causes hemorrhage!

Question 33

most common cause of congenital hydrocephalus

Answer 33

*aqueductal stenosis* —> non-communicating hydrocephalus

Question 34

hyperdensity on CT scan =

Answer 34

hemorrhage

Question 35

vast majority of absorption of CSF in the brain is by… [why is this relevant regarding communicating hydrocephalus?]

Answer 35

*capillaries!* not actually the arachnoid granulations! (recall CSF = ECF in brain) therefore, the real cause of communicating hydrocephalus is *loss of elasticity* of the blood vessels within the brain (decreased vascular compliance) - they have less capacity to hold a big volume of CSF, and thus more leaks out (global problem, not focal)