Histopathology 19: Cerebrovascular Disease And Trauma Flashcards
What are the 2 types of hydrocephalus ?
Non-communicating
Communicating
What is the main cause of non-communicating hydrocephalus ?
- Get obstruction of flow to CSF
- Due to the choroid plexus getting stuck in the cerebral aqueduct (between 3rd and 4th ventricle)
- NB most common form in neonate
What is a common cause of communicating hydrocephalus?
- NOT due to obstruction
- Instead to do with reabsorption of CSF into venous sinuses
- Caused by meningitis infection - causes inflammation of the meninges which blocks csf reabsorption into the venous sinuses
What are the 3 main types of herniation in the brain ?
- Subfalcine herniation
- Transtentorial (Uncal) herniation (medial temporal lobe down through the tentorial notch)
- Tonsillar herniation (coning)- cerebellum is pushed through the foramen magnum
What features can be seen on histology suggesting AVM (atrioventricular malformation) ?
Complex intertwining vessels
What is the characteristic sign of Cavernous Angioma on MRI ?
Target sign on T2 weighted MRI
What is a non-traumatic Intra-parenchymal haemorrhage ?
Haemorrhage into the brain parenchyma due to rupture of a small intraparenchymal vessels
Most commonly into the basal ganglia
2 types of Cerebral Oedema (XS fluid accumulation in brain, causing RAISED ICP)
- Vasogenic- disruption of the blood brain barrier (breakdown of tight junctions of BBB)
- Cytotoxic- secondary to cellular injury e.g. hypoxia/ ischaemia
What channels can increase development of cerebral oedema?
aquaporin 4 channels at the end feet of the astrocytes
How to reverse cerebral oedema
- reverse the activity of the AQP4 channels at the astrocytic end feet- so you want water going back into the vasculature
- can also move fluid into subarachnoid space
What you see on MRI in cerebral oedema
small gaps between the gyri and sulci which are very tight (all just a smooth brain with no notches)
Mx of non-communicating hydrocephalus
ventriculo-peritoneal shunt
Process of CSF from the point it is made
- Made: choroid plexus (mainly in the lateral horns of the lateral ventricles)
- goes from the lateral ventricles, through the intraventricular foramina, into the 3rd ventricle (slit-like ventricle in middle of the brain)
- then goes down the cerebral aqueduct (which is in the midbrain) into the 4th ventricle
- floor of the 4th ventricle is the pons and the roof is the cerebellum (so the 4th ventricle sits in the posterior cranial fossa)
- Some CSF then flows down into the medulla and further down into the central canal of the spinal cord
- Relatively little CSF volume will go down the spinal cord because most of it exits via a number of apertures in the 4th ventricle, into the subarachnoid space
- CSF will then circulate through the subarachnoid space and via the arachnoid granulations which pierce the superior sagittal sinus, thereby returning the CSF to the venous sinuses which allow resorption and recycling of CSF
Normal ICP
What happens if raised ICP?
7-15 mmHg
Get brain herniation
Herniation when cortex is pushed under the rigid falx cerebri of the dura
Subfalcine herniation
Brain herniation where there is herniation of the medial temporal lobe through the tentorial notch
Transtentorial (Uncal) Herniation
Brain herniation where the medial aspect of the cerebellum (tonsil) is pushed through the foramen magnum
Tonsillar Herniation
NB puts pressure on the medulla and can kill
When the BBB integrity is disrupted, what is the resulting oedema described as?
Vasogenic