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Block 8 week 2 > Basic Neuropathology - Parks > Flashcards

Basic Neuropathology - Parks Flashcards

1
Q

List some nervous system pathology.

A
  1. contusion and necrosis caused by traumatic closed head injury
  2. cerebral edema
  3. herniation
  4. malformations such as NTD’s
  5. Hydrocephalus
  6. Developmental problems such as Arnold-Chiari malformation
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2
Q

What are contusions?

A

These are brain lesions caused by a closed head injury (like a brain bruise). Closed head injuries occur when the brain is moved around and hits the inside of the skull.

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3
Q

Contusions can lead to what clinical situation?

A

Concussions.

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4
Q

What is a concussion?

A

From Mayo Clinic - A concussion is a traumatic brain injury that alters the way your brain functions. Effects are usually temporary but can include headaches and problems with concentration, memory, balance and coordination.

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5
Q

What is a Coup contusion?

A

Brain lesions that occur at the site of impact.

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6
Q

What is a contrecoup contusion?

A

Brain lesions that occur opposite the site of impact.

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7
Q

Trauma and contusion of the brain leads to what?

A

Cell injury, cell necrosis, hemorrhage and edema (injured cells take in water).

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8
Q

What are the 2 types of cerebral edema?

A
  1. Vasogenic edema - caused by a damaged BBB following trauma. Basically the trauma causes leakage of fluid from vessels into the interstitial - the leakage is between the endothelial cells of the BBB. occurs mainly in trauma but can also occur with tumors or encephalitis.
  2. cytotoxic edema - occurs after a stroke of hypoxic-ischemic insult such as MI. Occurs because neurons and glial cells are damaged.
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9
Q

What is the mechanism of cytotoxic edema?

A
  1. injury to neurons and glial cells
  2. hypoxia occurs
  3. ATP production decreases
  4. calcium, soidum and water move into cell and potassium moves out of cell because ion pumps stop working
  5. osmotic pressure increases
  6. more water moves into cell
  7. cistern of endoplasmic reticulum distend, rupture and form vacuoles
  8. Extensive vacuolation occurs
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10
Q

What does an edematous brain look like grossly?

A

Edema will cause a flattening of gyro and a loss of sulci.

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11
Q

What are the structures that hold the brain in place?

A
  1. the skull surrounding it
  2. the falx cerebri between the hemispheres
  3. the tentorium cerebelli between the hemispheres and the cerebellum
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12
Q

What are the major herniation syndromes of the brain?

A
  1. Subfalcine or falx herniation - when brain tissue goes under the flax cerebri
  2. Transtentorial or Uncal herniation (Uncal is when the anterior medial temporal gyrus or uncus goes through) - when brain tissue goes through tentorial notch
  3. tonsillar herniation - when cerebellar tissue goes through the foramen magnum
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13
Q

Which type of herniation is most likely to affect the brainstem?

A

Uncal or transtentorial herniation.

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14
Q

How do you describe Uncal herniation grossly?

A

Uncal grooving.

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15
Q

Describe an early consequence of Uncal herniation.

A

As the uncus is pushed through and traverses the subarachnoid space it compresses CNIII causing loss of the pupillary light reflex and enlargement of the ipsilateral pupil.This happens because the parasympathetic fibers serving the pupillary muscles are located peripherally on CNIII.

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16
Q

Describe some later consequences of Uncal herniation.

A
  1. Eventually the herniation will cause compression of the midbrain against the opposite tentorial edge leading to coma
  2. Lateral displacement of the midbrain may compress the opposite cerebral peduncle producing Babinski’s sing and hemiparesis contralateral to the original hemiparesis - this is called Kernohan-Woltman sign or Kernohan notching
  3. Herniation may also compress the anterior and posterior cerebral arteries resulting in brain infarction via ischemic necrosis
  4. herniation may also entrap portions of the ventricular system resulting in hydrocephalus
  5. respiratory centers are located in the brainstem (Pons and medulla) and damage to these centers leads to death
  6. Duret hemorrhages can also occur
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17
Q

If you are worried about herniation how would you test midbrain and CNIII function?

A

Pupillary light reaction.

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18
Q

If you are worried about herniation how would you test pontine function?

A
  1. spontaneous and reflex eye movements

2. corneal-blink reflex

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19
Q

If you are worried about herniation how would you test medullary function?

A

By testing respiratory and pharyngeal responses.

20
Q

What if Duret hemorrhage?

A

A secondary brain hemorrhage that occurs in the setting of raised intracranial pressure. If Uncal herniation occurs as a result of increased intracranial pressure penetrating branches of the Circle of Willis - Paramedian branches - get stretched and torn causing hemorrhage. This is usually fatal.

21
Q

What might a central, transtentorial herniation cause?

A

Bilateral occipital infarcts. This occurs when the diencephalon gets shoved down through the tentorial notch and knocks out the posterior cerebral arteries on both sides. This will affect the occipital lobes so it will cause cortical blindness. If it also affects the parietal lobes then the cortical blindness is also accompanied by denial of blindness. This is called Anton’s syndrome.

22
Q

What part of pregnancy is critical for proper CNS development?

A

The first 5 weeks. The neural tube closes around days 28-30.

23
Q

List some neural tube defects (NTD’s)?

A
  1. Anencephaly - no brain develops
  2. cranioarchischisis
  3. open spina bifida
  4. closed spina bifida
  5. encephalocele
  6. iniencephaly
24
Q

Spina bifida occulta (closed type), meningocele and myelomeningocele are all types of spina bifida and are NTD’s. What is the difference between them?

A

Spina Bifida basically means that the bones protecting the spinal cord did not develop correctly.

  1. Spina bifida occulta - occurs when the outer part of the vertebrae have not completely closed - spinal cord is not damaged and does not protrude through the opening. Often accompanied by a tuft of hair
  2. meningocele - also occurs when outer parts of vertebrae fail to close. Spinal cord is not damaged but the meninges are damaged and they push through the openings.
  3. myelomeningocele - also occurs when the outer parts lot the vertebrae fail to close. The spinal cord and the meninges push out through the openings. Usually it is only a thinly covered fluid filled sac that can easily split. Children with this condition will have some difficulty with movement and feeling in their legs and feet and may possibly have bowel or bladder issues.
25
Q

What test helps to detect NTD’s?

A

A test for maternal serum levels of Alphafetoprotein or AFP. Babies in the womb make high amounts of AFP and if there are NTD’s the AFP may get into the amniotic fluid and then the mother’s serum. High levels are associated with a NTD.

26
Q

What is another diagnostic tool for diagnosing NTD’s in the womb?

A

Ultrasound.

27
Q

What should the mother take in order to decrease risks of NTD’s?

A

It is recommended for pregnant women to take a balanced prenatal supplement containing 30-60 mg of elemental iron and 0.5-0.8 mg of folate.

28
Q

What should pregnant women not take?

A

Megavitamins - because they may result in fetal malformation and disturbed metabolism.

29
Q

What is hydrocephalus?

A

Build-up of abnormal amounts of fluid in the brain.

30
Q

Is there such a thing as congenital hydrocephalus?

A

Yes. One way this can happen is abnormal development of the aqueduct of sylvius. These patients usually compensate for the lack of drainage of CSF so they will not have increased intracranial pressure or symptoms. The condition may cause problems however, if they get a traumatic head injury.

31
Q

Where is cerebrospinal fluid or CSF made?

A

In the choroid plexuses located in the ventricles of the brain.

32
Q

Where does CSF go?

A

It circulates in the ventricles and spaces of the brain and spinal cord and it is resorbed by arachnoid villi of the arachnoid mater.

33
Q

What are some risk factors for congenital hydrocephalus?

A
  1. lack of prenatal care
  2. gestational diabetes
  3. maternal consumption of alcohol
  4. certain infections - such as parvovirus B19
  5. maternal antidepressant use - SSRI’s
34
Q

What is one way to get hydrocephalus?

A

If the arachnoid villi are scarred -ie through meningitis - then can’t reabsorb CSF and hydrocephalus can result.

35
Q

What are the two types of hydrocephalus

A
  1. communicating - entire ventricular system enlarges. This usually occurs due to reduced CSF resorption.
  2. non-communicating - localized obstruction within the ventricular system. Only that focal ventricle enlarges while the other ventricles do not enlarge. The intracranial pressure is usually normal.
36
Q

Hydrocephalus usually occurs by what two processes?

A

Impaired resorption or obstruction. Overproduction of CSF may cause but this is rare.

37
Q

What is the triad of symptoms for hydrocephalus in adults?

A
  1. gait apraxia - like they forget how to walk
  2. urinary incontinence
  3. dementia
38
Q

Is hydrocephalus in adults acute or gradually developing?

A

It may be either. If it develops gradually then can get the triad of symptoms plus a headache. If acute then will most likely get gait apraxia,urinary incontinence then stupor and death.

39
Q

What types of tumors/structures in the Foramen of monro can cause hydrocephalus?

A
  1. gliosis

2. colloid cysts

40
Q

What types of tumors/structures in the third ventricle can cause hydrocephalus?

A
  1. chiasmal gliomas
  2. craniophryngiomas
  3. arachnoid cysts
41
Q

What types of tumors/cysts in the fourth ventricles can cause hydrocephalus?

A
  1. medulloblastomas
  2. epindymomas
  3. astrocytomas
  4. Dandy-Walker cysts
42
Q

What types of conditions can cause absorptive obstruction?

A
  1. arachnoditis (posthemorrhagic)

2. postmeningitic venous thrombosis

43
Q

What types of conditions can block the cerebral aqueduct?

A
  1. aqueductal stenosis
  2. aquductal forking
  3. subependymal gliosis
  4. periaqueductal gliomas
44
Q

What types of conditions cause basilar obstruction?

A
  1. arachnoditis

2. Chiari malformations

45
Q

What is one type of tumor that can cause hydrocephalus?

A

Pineal tumors.

46
Q

Hydrocephalus can occur secondary to what?

A

Alzheimer’s disease.

47
Q

Papilledema is a sign of increased intracranial pressure. Is it always present in hydrocephalus?

A

Not necessarily, it is a later sign for one and would not be present in non communicating hydrocephalus or in some congenital cases of hydrocephalus.

Block 8 week 2 (4 decks)

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