Chapter 28: Intro CNS, ICP

Question 1

• Excessive amount of CSF and ventricular enlargement
• enlarged head circumference/grotesque
• convulsions optic atrophy with blindness
• Gaze problem?
• Why are symptoms of increased ICP generally absent?
• Dx? Common cause of Dx?

Answer 1

Parinaud’s syndrome: paralysis of upward gaze

Infantile cranium sutures not yet fused, expands easily

Congenital Hydrocephalus

Atresia of the aqueduct of Sylvius (cerebral aqueduct)

Question 2

Accumulation of CSF within ventricles resulting in dilatation of these structures

Answer 2

hydrocephalus

Question 3

1) Decrease CSF absorption by arachnoid villi/granulations = increased ICP, papilledema, herniation
2) Or could have Increased CSF production

Dx? Possible Causes of 1 or 2?

Answer 3

Communicating hydrocephalus due to subarachnoid hemorrhage

1) inflammation resulting in arachnoid scarring (postmeningitic scarring), or thrombosis of dural venous sinuses, tumor
2) choroid plexus papilloma

Question 4

Structural blockage of CSF circulation in ventricular system Dx? MOST Common site of block in newborns?

Answer 4

Noncommunicating hydrocephalus atresia or stenosis of Aqueduct of Sylvius

Question 5

Headaches, confusion, drowsiness, papilledema, vomiting, might retain cognitive abilities Pathological Mechanism for herniations and hydrocephalus, due to space occupying lesions

Answer 5

Increased Intracranial Pressure

Question 6

“Wet, wobbly, wacky” Clinical triad of dementia, ataxia, urinary incontinence

Is the dementia reversible?

Answer 6

Normal pressure hydrocephalus

Yes

Question 7

Normal baseline ICP

Doesn’t result increased subarachnoid space volume

Expansion of ventricles distorts axons of corona radiata leading to symptoms of wet, wacky, wild

Dx?

Answer 7

Normal pressure hydrocephalus

Question 8

Loss of CNS tissue from another disease _____. Atrophy of gyri in frontal and hippcampal cortex, widening of sulci, compensatory enlargement of lateral ventricles and increased CSF, unrelated to obstructive lesions

Dx?

Answer 8

Alzheimer disease

Hydrocephalus ex vacuo

Question 9

You’re driving down to Scranton to meet up with your beloved. As you’re passing through Binghamton, a drunk driver slams into you from the driverside at a stop sign. You report having a severe headache and blurred vision. You order an X-ray STAT because you know your shit, also you’re in a lucid interval and know you could soon go into neurological deterioration. It shows a temporal-parietal bone fracture and you’re rushed into an emergency craniotomy. Unlike the lady in Rubin’s Q&A, the procedure is a success! What artery would have been vulnerable to be severed? What could have been found on brain autopsy if you hadn’t been so lucky?

Answer 9

Middle meningeal artery

Acute Epidural Hematoma

Epidural hemorrhage would be the active process that could happen with severed MMA.

Question 10

One hemisphere is forced under the falx cerebri S/S: confusion, drowsy, ACA (anterior cerebral artery) displaced, infarction leads to contralateral lower extremity weakness and urinary incontinence

Answer 10

Cingulate (subfalcine) herniation

Question 11

• Name the herniation!!
• Ipsilateral fixed and dilated pupil/ptosis with down and out eye (strabismus) is due to which CN palsy/crushed
• Ipsilateral hemiparesis (same side of body as offending mass) due to crushing of contralateral cerebral pedicle is called?
• Visual field disturbances are due to?
• What is the first part of the hemisphere to be displaced in this type of herniation?
• What does this part displace and what is the result?

Answer 11

• Transtentorial herniation/uncal herniation
• CN3
• Kernohan’s notch
• Compression of PCA
• Uncus
• Uncus displaces the midbrain, the midbrain to midpons is the site of secondary (Duret) hemorrhages

Question 12

Bonus: You’re an MS2 getting ready for Step 1. You were part of the summer anatomy crew who learned head & neck in 2 weeks. This means you didn’t have enough time for those LTPs to be formed in this part of your brain 1)______. You may have forgotten that the most significant artery of the external carotid system is 2)_________, a branch of the maxillary artery in the 3)______ fossa, that enters the skull through the foramen 4)_______ in order to supply the skull and 5)_______.

Answer 12

1) Hippocampus 2) Middle meningeal artery 3) infratemporal fossa 4) spinosum 5) dura

Question 13

A 3 yo boy is brought to the ER. He has persistent vomiting, a stiff neck, and decreased responsiveness. An MRI shows a posterior fossa tumor filling the 4th ventricle. Now that you know how to use a fundoscope, you want to take a look in his eyes. 1) What are you likely to find? 2) Would you perform a spinal tap? 3) Which kinds of CNS tumor could he have?

Answer 13

1) Likely to see bilateral papilledema due to increased CSF causing increased ICP. All a result of noncommunicating hydrocephalus.
2) Don’t perform a spinal tap on people with increased ICP and papilledema could result in herniation and death.
3) medulloblastoma or ependymoma.