A11. Clinical manifestation of increased intracranial pressure. Herniations.

Question 1

Causes of raised ICP

Answer 1

1. Space-occupying lesions (eg. tumor, abscess, hemorrhage) - treat with surgery
2. CSF disorders (occlusive hydrocephalus) - treat with CSF drainage
3. Cerebral edema (vasogenic, cytotoxic, interstitial)

Question 2

Space-occupying lesions - how to treat

Answer 2

(eg. tumor, abscess, hemorrhage) - treat with surgery

Question 3

CSF disorders (occlusive hydrocephalus) - how to treat

Answer 3

treat with CSF drainage

Question 4

Clinical manifestations of increased ICP

Answer 4

● Progressive headache (one of leading complaints)
● Vomiting
● Milder and atypical symptoms in elderly due to brain atrophy
● Papilloedema + blurred vision
● Always global cerebral dysfunction due to global cerebral ischemia.
* Cerebral cortex most sensitive → drowsiness, altered behaviour, slow thinking
* Focal symptoms if focal space occupying lesions

Question 5

Treatment ICP

Answer 5

● Treat underlying etiology
● Osmodiuretics (mannitol, glycerol)
● Loop diuretics decrease CSF production
● ICU:
○Controlled hyperventilation
○Barbiturate narcosis
● Decompressive craniectomy

Question 6

Treatment ICP in ICU

Answer 6

○Controlled hyperventilation
○Barbiturate narcosis

Question 7

what diuretics are used to decrease ICP

Answer 7

● Osmodiuretics (mannitol, glycerol)
● Loop diuretics decrease CSF production

Question 8

Monroe-Kellie principle- what is it about

Answer 8

• 3 main components of intracranial volume:
  1. brain tissue
  2. CSF
  3. and blood.
  These are in a state of equilibrium, and an increase in one must be compensated by a decrease in another.

Question 9

• 3 main components of intracranial volume:

Answer 9

1. brain tissue
2. CSF
3. and blood.

Monroe-Kellie principle

Question 10

Cerebral blood flow is maintained by the difference of

Answer 10

arterial and venous pressure

which is called
cerebral perfusion pressure.

Question 11

correlation between Intracranial pressure and cerebral venous pressure

Answer 11

Intracranial pressure and cerebral venous pressure are equal, thus the rise
of intracranial pressure always leads to the rise of cerebral venous pressure of equal degree

Question 12

• how will the rise
  of intracranial pressure (ICP) affect the cerebral venous pressure(CVP)
• what will happen to cerebral perfusion pressure?
• how will body compensate?

Answer 12

• always leads to the rise of cerebral venous pressure of equal degree
• As a consequence, cerebral perfusion pressure is decreased.
• in order to maintain cerebral blood
  flow, cerebral arterioles dilate causing the increase of intracerebral blood volume as well, which further
  increases intracranial pressure. This positive feedback mechanism – called vasodilatory cascade –
  eventually leads to global cerebral ischemia.

Question 13

vasodilatory cascade - what is it

Answer 13

• positive feedback mechanism
• eventually leads to global cerebral ischemia
• if Cerebral perfusion pressure is decreased
• -> in order to maintain cerebral blood flow, cerebral arterioles dilate
• –> causing the increase of intracerebral blood volume as well,
• –> which further
  increases intracranial pressure

Question 14

Intracranial pressure (physiologic range)

Answer 14

10 mmHg

Question 15

Intracranial pressure is regulated mainly by

Answer 15

• production
• and absorption
  rate of the cerebrospinal fluid - slow mechanism.

Question 16

fast mechanisms to compensate raised intracranial pressure

Answer 16

• The displacement of CSF
  via the foramen magnum into the spinal canal is the principle compensatory mechanism under
  physiological circumstances (e.g. Valsalva maneuver)
• decrease of cerebral blood volume . This mechanism
  does NOT operate under physiological conditions, but it can be artificially activated by applying:
  *controlled hyperventilation, *barbiturate narcosis and *hypothermia in intensive care units.

Question 17

how does Hyperventilation affect
the partial pressure of blood CO2,

Answer 17

Hyperventilation decreases
the partial pressure of blood CO2,
* which results in:
*arteriolar constriction
*and the decrease of cerebral
blood volume.

Question 18

How can Barbiturate narcosis and hypothermia decrease ICP

Answer 18

lead to a
* decrease of cerebral metabolism, which causes the
* further reduction of cerebral blood volume

Question 19

Brain herniations

Answer 19

4 types of herniations may occur;
1. subfalcial,
2. central
3. uncal-transtentorial
4. foraminal

Question 20

Subfalcial herniation

Answer 20

• (cingular herniation)
• Cingular gyrus in pressed under the falx.
• May compress circumferential branches of anterior cerebral artery (pericallosal, collosomarginal) if mass
  effect is considerable

Question 21

complication of subfacial herniation

Answer 21

• May compress:
  1.circumferential branches of anterior cerebral artery (pericallosal, collosomarginal) if mass
  effect is considerable
  → contralateral hemiparesis (predominantly lower limbs)

2. Contralateral hemisphere → obstruction of the foramen of Monro → hydrocephalus

Question 22

Subfalcial herniation Symptoms:

Answer 22

○ Progressive decrease in motivation (may lead to akinetic mutism)
○ Paraparesis
○ Urinary incontinence
○ Frontal release signs (primitive reflexes reappear - eg. sucking and grasping reflex)

Question 23

Central herniation- what is it

Answer 23

• mass effect caused by bilateral or midline supratentorial lesions or severe brain edema → downward displacement of the diencephalon, midbrain, and pons
• Compression of diencephalon.
• Severity is proportional to lateral or axial shift of diencephalon.

Question 24

Severity of Central herniation is proportional to

Answer 24

lateral or axial shift of diencephalon.

Question 25

Central herniation Symptoms: ○ Early phase

Answer 25

■ Indifference, concentration and memory problems ■ Frequent yawning

Question 26

Central herniation Symptoms in Later phase

Answer 26

■ Drowsiness → unconsciousness ■ Cheyne-Stokes respiratory pattern ■ **Decorticate posture** with **bilateral Babinski reflex** * Oculomotor nerve compression → oculomotor nerve palsy with fixed and dilated pupils * Brain stem dysfunction → decerebrate or decorticate posture, cardiac arrest, respiratory failure → vegetative state or death * Stretching or tearing of basilar artery perforating branches → Duret hemorrhages

Question 27

Central herniation General Symptoms:

Answer 27

■ Pupils are symmetric, constricted and reactive ■ Ciliospinal reflex is brisk (pinch skin over trapezius muscle evokes mydriasis) ■ Muscle tone is frequently increased (paratonia

Question 28

Central herniation are symptoms reversible?

Answer 28

Symptoms are still reversible if treatment is applied, but if not: transtentorial herniation occurs with irreversible symptoms

Question 29

Transtentorial herniation- can be divided into

Answer 29

* Uncal herniation: mass effect caused by a supratentorial lesion → medial and downward displacement of the uncus at the tentorial incisure * Central herniation: mass effect caused by bilateral or midline supratentorial lesions or severe brain edema → downward displacement of the diencephalon, midbrain, and pons Compression of mesencephalon in tentorial incisure - damaged blood supply of mesencephalon and secondary intraparenchymal bleedings.

Question 30

Transtentorial Uncal herniation early manifestation

Answer 30

Early manifestations * Ipsilateral posterior cerebral artery compression→ cortical blindness with contralateral homonymous hemianopia * Ipsilateral oculomotor nerve compression → Hutchinson pupil (ipsilateral fixed and dilated pupil) * Ipsilateral cerebral peduncle compression → contralateral hemiparesis * Midline shift → altered consciousness

Question 31

Transtentorial Uncal herniation Late manifestation

Answer 31

* Contralateral cerebral peduncle compression against the tentorial notch → Kernohan phenomenon (a rare false localizing sign consisting of hemiparesis ipsilateral to the brain lesion) * Downward shift of the brainstem → brainstem hemorrhages → focal deficits, impaired consciousness, death

Question 32

abnormal Pupillary reactions in Uncal Transtentorial herniation

Answer 32

■ Axial: moderate dilation + react to light ■ Lateral: anisocoria + loss of light reflex (hippocampal uncus compress ipsilateral CN3)

Question 33

in uncal Transtentorial herniation Unconsciousness is due to

Answer 33

damage to ARAS (ascending reticular activating system

Question 34

uncal Transtentorial herniation - how is muscle tone

Answer 34

○ Increased extensor muscle tone ○ Increased bilateral Babinski sign

Question 35

Kernohan's notch phenomenon | Uncal Transtentorial herniation

Answer 35

* Contralateral cerebral peduncle compression against the tentorial notch → Kernohan phenomenon (a rare false localizing sign consisting of hemiparesis ipsilateral to the brain lesion)

Question 36

Ipsilateral posterior cerebral artery compression→ | Uncal Transtentorial herniation

Answer 36

cortical blindness with contralateral homonymous hemianopia

Question 37

Ipsilateral oculomotor nerve compression | Uncal Transtentorial herniation

Answer 37

→ Hutchinson pupil (ipsilateral fixed and dilated pupil)

Question 38

Ipsilateral cerebral peduncle compression | Uncal Transtentorial herniation

Answer 38

→ contralateral hemiparesis

Question 39

Midline shift | Uncal Transtentorial herniation

Answer 39

→ altered consciousness

Question 40

Transforaminal herniation/tonsillar herniation /Foramen magnum herniation

Answer 40

Structures of the posterior fossa (e.g., cerebellar tonsils, medulla) herniate through the foramen magnum > compression of medulla

Question 41

Transforaminal herniation/tonsillar herniation symptoms

Answer 41

* Impaired consciousness * Decerebrate posturing * Impaired circulation * Death * Upper extremities become flaccid, and lower extremities flexed ○ Neck stiffness and head tilt (tonsillar impaction on foramen magnum) ○ Respiration: Apnea → completely irregular → gasping ○ Vestibuloocular reflex is lost ○ Blood pressure drops ○ Death from respiratory and cardiac arrest

Question 42

posture in Transforaminal herniation/tonsillar herniation

Answer 42

Decerebrate