10.1.2 Herniation Sydromes

Question 1

Define Herniation syndrome

Answer 1

Displacemnet of one part of normal brain to other anatomical area
- Supratentorial compartment (Flax cerebri)
- Infratentorial compartment (Tentorium cerebelli)
- Foramen magnum

Question 2

Causes of herniation syndrome

Answer 2

• Trauma (Traumatic hematomas; Cerebral oedema)
• Neoplasm (Primary tumor; Metastatic tumor)
• Stroke
• Hydrocephalus
• Infection (Abscess)

Question 3

Types of herniation

Answer 3

• lateral transtentorial
• subfalcine “midline” shift
• tonsillar
• central tentoral

Question 4

Lateral transtentorial herniation
Define

Answer 4

Define - Herniation of the medial temporal lobe (uncus) through the tentorial incisura with resultant compression of:
- Cranial nerve III ➡️ Ipsilateral fixed dilated pupil (unreactive to light) & “Down and out eye” {same side as mass lesion}
- Cerebral peduncle ➡️Contralateral hemiparesis {opposite side of mass lesion}
- Posterior cerebral artery (PCA) ➡️Contralateral homonymous hemianopia {opposite side}

Question 5

Subfalcine herniation

Answer 5

Herniation of the cingulate gyrus below the falx cerebri with resultant compression of:
- Contralateral cingulate gyrus
➡️ Often no focal neurology
- Ipsilateral Anterior cerebral artery
➡️ Contralateral leg weakness

Question 6

Central transtentorial herniation

Answer 6

Descent of the brainstem through the incisura with resultant stretching and tearing of small brainstem perforators:
- Decreased level of consciousness
- Abnormal flexor posturing
- Abnormal extensor response
- Inability to look up (gaze plasy)
- Pupil abnormalities
- Diabetes Insipidus
- Cushing’s response

Question 7

Tonsillar herniation

Answer 7

Downward herniation of the cerebellar tonsils through the foramen magnum and resultant compression of:
Medulla oblongata
- Decreased level of consciousness
- Hypertension
- Bradycardia
- Irregular respiration

Question 8

What is the cushing reflex?

Answer 8

• hypertension
• bradycardia
• irregular breathing / respiration

= ⬆️ ICP

If not fixed quickly, pt will die as result of resp arrest

Question 9

Transcalvarial herniation

Answer 9

• Brain herniates through a skull defect
  ➡️Cortical injury
  ➡️Axonal stretch
  ➡️Compression of cortical vessels

Causes of skull defects
- Iatrogenic
➡️Decompressive craniectomy
- Traumatic
➡️Open skull fracture