Why does uncal herniation cause ipsilateral hemiparesis?
The mass lesion causing the uncal herniation usually causes a contralateral hemiparesis, but as the pressure increases, the opposite cerebral peduncle is compressed against the tentorium, which causes an ipsilateral hemiparesis (Kernohan’s sign).
Is uncal herniation the same as Transtentorial?
Uncal herniation is a subtype of transtentorial downward brain herniation that involves the uncus, usually related to cerebral mass effect increasing the intracranial pressure.
What are clinical symptoms of central herniation?
Symptoms
- High blood pressure.
- Irregular or slow pulse.
- Severe headache.
- Weakness.
- Cardiac arrest (no pulse)
- Loss of consciousness, coma.
- Loss of all brainstem reflexes (blinking, gagging, and pupils reacting to light)
- Respiratory arrest (no breathing)
What is ipsilateral pupil dilation?
A unilateral, ipsilateral (on the same side as the lesion), fixed dilated pupil is the initial focal sign, followed by bilateralfixed dilated pupils, occurring anything from minutes to hours later.
What is kernohan notch phenomenon?
Kernohan’s notch phenomenon is the ipsilateral hemiplegia caused by compression of the contralateral cerebral peduncle against the tentorial edge by a supratentorial mass. Diffusion tensor imaging (DTI) and transcranial magnetic stimulation (TMS) could be useful for exploring the state of the corticospinal tract (CST).
What is Transtentorial uncal herniation?
Can you survive an uncal herniation?
The outlook varies, depending on where in the brain the herniation occurs. Without treatment, death is likely. There can be damage to parts of the brain that control breathing and blood flow. This can rapidly lead to death or brain death.
What is ipsilateral and contralateral?
Contralateral is defined as ‘pertaining to the other side’. Ipsilateral is considered the opposite of contralateral and occurs on the same side.
What is Transtentorial herniation?
A transtentorial herniation is the movement of brain tissue from one intracranial compartment to another. This includes uncal, central, and upward herniation. These are life-threatening and time-critical pathologies that may be reversible with emergent surgical intervention and medical management.
What is pupillary asymmetry in cerebral herniation?
Pupillary asymmetry is a well-recognized sign of impending cerebral herniation [ 1, 2 ]. Pupillary asymmetry may be ipsilateral, bilateral [ 1, 2 ], or uncommonly, the contralateral pupil dilates first [ 3, 4 ].
What is unilateral uncal herniation?
Uncal herniation may be unilateral or bilateral 1,2. Uncal herniation occurs secondary to large mass effect (that can occur from traumatic or non-traumatic hemorrhage, malignancy, etc.) that will lead to increased intracranial pressure and herniation. Masses are typically supratentorial.
What is ipsilateral hemiparesis?
Ipsilateral Hemiparesis this is due to compression of Kernohans notch. This is compression of the cerebral peduncles (white matter conducting the longer fibre tracts) Note the corticospinal tracts decussate above the pyramid hence any weakness will be contra-lateral and ipsilateral weakness is a false localising sign.
What is unilateral descending tentorial herniation?
Uncal herniation can be suggested on CT, however, MRI is the gold standard. Features of unilateral descending tentorial herniation include: Bilateral transtentorial herniation: Uncal herniation carries a bad prognosis due to the direct compression of the vital midbrain centers.