Subfalcine (Cingulate)

• CT : Displacement of the cingulate gyrus/septum pellucidum.

• Cingulate gyrus
  • ipsilateral cingulate gyrus is pushed under the rigid midline falx
• Compression of the ipsilateral anterior cerebral artery

• Severe headache
• Contralateral leg weakness

Lateral (Uncal)

• CT : Widening of the ipsilateral cerebellopontine angle and obliteration of the suprasellar ipsilateral cistern.

Uncus and the adjacent part of the temporal lobe (supratentorial structures) are displaced caudally across the tentorial incisura into the infratentorial compartment.

• ipsilateral Occulomotor n. (CN III)
• Cerebral peduncle
• ipsilateral posterior cerebral artery

• Ipsilateral Ptosis
• Ipsilateral Mydriasis (pupil โต)
• Homonymous hemianopia
• Contralateral hemiparesis (Cerebral peduncle)
• Ipsilateral hemiparesis : Kernohan notch คือ pressure of free edge of tentorium against opposite cerebral peduncle
• Decreased consciousness

Posterior (Tectal)

• Superior colliculi (Quadrigeminal plate)

• Bilateral ptosis
• Upward gaze paralysis

Central (axial) ie. Tonsillar herniation

• CT : effacement of the CSF cisterns surrounding the brainstem and inferior descent of the cerebellar tonsils below the foramen magnum.

Inferior descent of the cerebellar tonsils below the foramen magnum.

Obstructive supratentorial hydrocephalus may result from fourth ventricle compression.

• Perforating branches from basilar artery
• Midbrain (mid brain)
• Pons
• medulla
• Reticular formation

• Decreased consciousness (Reticular formation)
• Decerebrate rigidity (M2) : Transection of midbrain
• Impaired eye movement
• Respiratory irregularity
  Cheyne-Stokes breathing
• Apnea
• Hypertension (Wide pulse pressure : SBP สูง DBP ต่ำ)
• Bradycardia