Herniations

Question 1

Epidural hematoma

Answer 1

Tentorial herniation

1. profuse high- pressured bleeding rapidly expands the epidural space, thereby pressing upon the adjacent cerebral hemisphere and
   
   1. herniating the cerebrum under the falx cerebri (falx herniation)
   2. through the tentorial notch
   3. hernates the uncus through the incisura compresses and displaces the midbrain.
      
      1. Bilateral compression of the midbrain reticular formation results in a progressive decrease in the level of consciousness.

Question 2

uncal herniation

Answer 2

common subtype of transtentorial herniation

the innermost part of the temporal lobe, the uncus, can be squeezed so much that it moves towards the tentorium and puts pressure on the brainstem, most notably the midbrain.

Question 3

Subfalcial herniation

Answer 3

is displacement of the cingulate gyrus from one hemisphere to the other, under the falx cerebri. Subfalcial herniation can compress the pericallosal arteries, causing an infarct in their distribution.

Question 4

cerebellar tonsillar herniation

Answer 4

Pressure on the posterior fossa contents from above or from within compresses the pons against the clivus and displaces the cerebellar tonsils into the foramen magnum (cerebellar tonsillar herniation). This may cause stiffness of the neck and head tilt. Compression of the pons and medulla damages vital centers for respiration and cardiac function, resulting in cardiorespiratory arrest.

Question 5

1. a fixed and dilated pupil
2. collapse of the ipsilateral posterior cerebral artery
3. cortical blindness

Answer 5

1. herniation of the medial temporal lobe from the middle into the posterior fossa, across the tentorial opening. The uncus of the temporal lobe is forced into the gap between the midbrain and the edge of the tentorium.
2. This compresses the ipsilateral oculomotor nerve, causing a fixed and dilated pupil
3. collapses the ipsilateral posterior cerebral artery, causing an infarct in its distribution.
4. Cortical blindness resulting from this infarct is a false localizing sign because it gives the erroneous impression that the primary lesion is in the occipital lobe.

Question 6

cardiorespiratory arrest, stiffness of the neck

Answer 6

Pressure on the posterior fossa contents from above or from within compresses the pons against the clivus and displaces the cerebellar tonsils into the foramen magnum (cerebellar tonsillar herniation). This may cause stiffness of the neck and head tilt. Compression of the pons and medulla damages vital centers for respiration and cardiac function, resulting in cardiorespiratory arrest.

Question 7

herniation can compress the pericallosal arteries, causing an infarct in their distribution.

Answer 7

1. Subfalcial herniation
   
   1. displacement of the cingulate gyrus from one hemisphere to the other, under the falx cerebri. Subfalcial herniation can compress the pericallosal arteries, causing an infarct in their distribution.

Question 8

superiorly displaces the superior portion (anterior lobe) of the cerebellum through the tentorial notch and compression the midbrain and related structures.

Answer 8

tonsillar herniation

Question 9

through the incisura

Answer 9

uncal herniation

Question 10

through the foramen magnum

Answer 10

Tonsillar Herniation

Question 11

can compress the lower medulla/upper cervical spinal cord

Answer 11

tonsillar herniation