Neuropathology 2: Raised ICP (SOL's) and Trauma Flashcards
Purpose of CSF?
Supports the brain (neutral buoyancy).
Normal volume of CSF?
120-150ml. 500ml produced every 24 hours.
Where is CSF produced?
Produced by the choroid plexus in the lateral and 4th ventricles.
Where is the CSF absorbed?
Arachnoid granulations - these are herniations of the arachnoid mater that protrude into the dura mater.
Normal appearance of CSF is a clear fluid. True/false?
True
What does increased lymphocytes in the CSF indicate?
Infection (viral or fungal), autoimmune causes.
What does increased neutrophils in the CSF indicate?
Infection (bacterial meningitis)
Definition of hydrocephalus?
Accumulation of excess CSF within the ventricular system of the brain.
How can hydrocephalus occur?
Obstruction to flow of CSF (e.g. inflammation, pus and tumours).
Decreased resorption of CSF (post SAH or meningitis).
Overproduction of CSF (very rare tumours of choroid plexus).
2 types of hydrocephalus?
Non - communicating
Communicating
What is non-communicating hydrocephalus?
When obstruction to flow of CSF occurs within the ventricular system.
What is communicating hydrocephalus?
Obstruction to CSF flow occurs outside of the ventricular system e.g. subarachnoid space or at arachnoid granulations.
If hydrocephalus develops before the closure of cranial sutures, then cranial enlargement occurs. True/false?
True
If hydrocephalus develops after closure of cranial sutures, then there is constriction of ventricles and decrease in intracranial pressure. True/false?
False
There is EXPANSION of ventricles and intracranial pressure will INCREASE.
What is hydrocephalus ex vacuo?
Occurs when a stroke or injury damages the brain and brain matter actually shrinks.
The brain may shrink in older patients or those with Alzheimer’s disease, and CSF volume increases to fill the extra space.
Ventricles are enlarged but pressure is usually normal.
Causes of raised intracranial pressure?
Increased CSF (hydrocephalus)
Focal lesion in brain (space occupying lesions)
Diffuse lesion in brain (e.g. oedema)
Increased venous volume
Physiological (hypoxia, hypercapnia, pain)
Effects of raised intracranial pressure?
Midline shift
Distortion and pressure on cranial nerves and vital neurological centres
Reduced conscious level
Impaired blood flow (CPP = MAP-ICP)
Clinical signs of raised ICP?
Nausea + vomiting
Neck stiffness
Reduced conscious level
Headache
Papilloedema - swelling of the optic disc due to elevated intracranial pressure (ICP)
Examples of SOL’s (space occupying lesions)?
Tumours - primary brain tumours/metastases
Abscesses - single/multiple
Haematomas
Localised brain swelling - e.g. swelling and oedema around cerebral infarct.
How many astrocytoma grades are there by WHO?
Grades 1- 4
WHO astrocytoma grade 1?
Grade 1 (pilocytic)
- Childhood
- Benign behaving
- Cystic areas
- Long hair-like processes
WHO astrocytoma grade 2?
Grade 2 (well differentiated)
- Nuclear atypia (abnormal appearance of cell nuclei on histology)
Average 5yr survival
WHO astrocytoma grade 3?
Grade 3 (anaplastic)
- Greater nuclear atypia
- Mitotic activity
WHO astrocytoma grade 4?
Grade 4 (glioblastoma)
- Extreme atypia
- Mitotic activity
- Necrotic and/or neovascularisation
Less than 10-12 month survival
What is the most common tumour in children?
Medulloblastoma (closely followed by pilocytic astrocytomas).
Where does medulloblastoma occur?
Midline of cerebellum, it can disrupt CSF flow leading to hydrocephalus.
How are brain abscesses diagnosed?
CT or MRI scan
Main symptoms of brain abscess?
Raised ICP
Fever
Will display symptoms depending on underlying cause
The organisms implicated depend on the underlying cause. What are some main examples of the causative organisms?
Staph aureus
Aerobic and anaerobic streptococci
Immunocompromised:
- Fungi
- Protozoa e.g. toxoplasma in AIDS
Definition of bacterial meningitis?
Inflammation of leptomeninges and CSF within subarachnoid space.
Frequently causing severe oedema and raised ICP.
Bacterial meningitis on CSF?
Abundant polymorphs and decreased glucose on CSF.
2 types of traumatic head injury?
Missile (penetrating)
Non-missile (blunt)
Blunt head injury features and causes?
Sudden acceleration/deceleration of head.
Smaller contact time = larger force
The brain moves within the cranial cavity and makes contact with the inner table of the cranium and bony protrusions.
Causes:
Road traffic accident
Falls
Assault
Alcohol (around 1/2 of cases)
Types of skull fracture?
Linear - straight sharp fracture line, that may cross sutures
Compound - associated with full thickness scalp lacerations
Depressed
Base of skull fractures - linear. True/false?
False. Compound fractures.
Coup injury?
Occurs to the brain on the side of impact
Contra-coup injury?
Diametrically opposite the point of impact
Diffuse axonal injury, definition and features?
The shearing (tearing) of the brain’s long connecting nerve fibers (axons) that happens when the brain is injured as it shifts and rotates inside the bony skull.
Reduced consciousness and coma
Can lead to vegetative state
