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Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
Travancore Medicity, Kollam
India
editor
There are five major brain herniation syndromes
Subfalcine or cingulate herniation
Uncal herniation
Transtentorial herniation
Cerebellotonsillar herniation
Upward posterior fossa
Subfalciane herniation
It is the most common cerebral herniation pattern, characterized by displacement of the brain beneath the free edge of the falx cerebri due to raised ICP.
It can compress the ipsilateral anterior cerebral artery and lead to contralateral weakness.
Uncal Herniation
It is the most commonest.
It occurs when the uncus of the temporal lobe is displaced inferiorly through the medial edge of tentorium.
Uncal transtentorial herniation leads to compression of parasympathetic fibers running with third cranial nerve, causing an ipsilateral fixed and dilated pupil due to unopposed sympathetic tone.
Further herniation compresses the pyramidal tract, which results in contralateral motor paralysis.
Brain Herniation Types : 1 :Uncal Herniation ; 2 :Central Transtentorial Herniation 3 : Subfalcine Herniation; 4 :Transcalvarial Herniation; 5 : Upward Transtentorial Heniration 6:Tonsillar henrniation.
Attribute : "Brain herniation types-2" by Brain_herniation_types.svg: User:Delldotderivative work: RupertMillard (talk) - Brain_herniation_types.svg. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Brain_herniation_types-2.svg#mediaviewer/File:Brain_herniation_types-2.svg
Central Transtentorial Herniation
It is less common.
It occurs in the midline lesions in the frontal or occipital lobes or in the vertex.
Most prominent symptoms are initial bilateral pinpoint pupils, bilateral babinski's sign and increased muscle tone.
Fixed midpoint pupils follow along with prolonged hyperventilation and decorticate posturing.
Cerebellotonsillar herniation
Cerebellotonsillar herniation occurs when cerebellar tonsils herniate through foramen magnum.
This leads to pinpoint pupils, flaccid paralysis and sudden death.
Upward Transtentorial Herniation
Results from a posterior fossa lesion and leads to a conjugate downward gaze with absence of vertical eye movements and pin point pupils.
A Plain CT film of brain of 70 year old man presented with fever since 3 days with sudden onset of alterted sensorium with drop in GCS. On subsequent imaging revealed upward transtentorial herniation probably secondary to brainstem encephalitis.
Management of Raised ICP
Drain CSF via ventriculostomy ; Maintain ICP < 20mmHg and CPP >60 mmHg
Elevate head of the bed; midline head position.
Osmotherapy- mannitol 25 – 100gm Q 4h as needed (Serum osmalility < 320 mosmol) / Hypertonic saline
Glucocorticoids : Dexmathasone 4mg q6h for vasogenic edema from tumor, abscess (Avoid glucocorticoids in head trauma, ischemic and hemorrhagic stroke).
Sedation (Eg : morphine, propofol or midazolam); add neuromuscular paralysis if necessary (Patients who is mechanically ventilated).
Hyperventilation : Paco2 30 -35 mmHg
Pressor therapy : Phenylephrine, dopamine or norepinephrine to maintain adequate MAP to ensure CPP >60 mmHg.
Consider second tier therapies for refractory elevated ICP
High dose barbiturate therapy
Aggressive hyperventilation
Hypothermia
Hemicraniectomy
Updated on : 9/1/15
Reference
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emmedonline
Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
Travancore Medicity, Kollam
India
editor