Raise ICP, SOLs and trauma Flashcards
What is the normal volume of CSF?
120-150ml
500ml a day
What produces CSF?
Choroid plexus in the lateral and 4th ventricles of the brain
What absorbs CSF?
Arachnoid granulations
What do lymphocyres in the CSF suggest?
Infection; viral or fungal
Autoimmune infection
Inflammation
What do neutrophils in the CSF suggest?
Bacterial meningitis
What is the definition of hydrocephalus?
Accumulation of excessive CSF within the ventricular system of the brain
What can cause hydrocephalus?
Obstruction to flow: inflammation, pus, tumours
Decreased reabsorption; post SAH, meningitis
Overproduction; very rare cause due to choroid plexus tumour
What is non-communicating hydrocephalus?
Obstruction to flow of CSF occuring within the ventricular system
What is communicating hydrocephalus?
Obstruction to flow of CSF outside of the ventricular system e.g. in subarachnoid space or at the arachnoid granulations
What occurs if hydrocephalus occurs before the closure of the cranial sutures?
Cranial enlargement occurs
What occurs if hydrocephalus occurs after the closure of the cranial sutures?
Expansion of the ventricles with an increase in intracranial pressure
What is hydrocephalus ex vacuo?
Dilation of the ventricular system and an increase in compensatory CSF volume secondary to the loss of brain parenchyma for example in alzheimer’s disease
What are the causes of increased ICP?
Hydrocephalus SOL Diffuse lesion in brain e.g. oedema Increased venous volume Physiological; hypoxia, hypercapnia, pain
What are the consequences of raised ICP?
Intracranial shifts and herniations Midline shift Distortion and pressure on CNs and vital neurological centres Impaired blood flow Reduced level of consciousness
How is cerebral perfusion pressure calculated?
MAP - ICP; therefore ICP is too high, it will reduce blood flow
What are the 4 types of shifts and herniations within the brain?
Subfalcine
Tentorial
Cerebellar
Transcalvarial
What is a subfalcine herniation?
Unilateral or asymmetrical expansion of the cerebral hemisphere which displace the cingulate gyrus underneath the falx cerebri
What does a subfalcine herniation result in?
Compression of the anterior cerebral artery resulting in weakness and/or sensory loss on the contralateral side
What is a tentorial herniation?
Medial aspect of the temporal lobe (uncus) herniates over the tentorium cerebellar
What will a tentorial herniation result in?
Compression of the ipsilateral CN3; resulting in a blown pupil with impairment of ocular movement on the side of the lesion
What is a tonsillar herniation?
Displacement of the tonsillar cerebellum through the foramen magnum
What will a tonsillar herniation result in?
Compression of the respiratory centers of the medulla oblongata
What is a transcalvarial herniation?
Brain herniating through any defect in the skull e.g. fracture
What are the clinical signs of an increased ICP?
Papilloedema
Headache
N+V
Neck stiffness
What are the different types of SOLs?
Tumours; primary brain tumours, mets
Abscess; single/multiple
Haematomas
Localised brain swelling; swelling and oedema around cerebral infarct
What are the Si/Sy of brain tumours?
Sy: focal, headache, vomiting, seizures, visual disturbances
Signs; focal deficit, papilloedema
What is the difference in location of brain tumours between children and adults?
Children; 70% below tentorium cerebelli
Adults; 70% above tentorium cerebelli
What common cancers will metastasize to the brain?
Breast, bronchus, kidney, thyroid, colon and melanomas
What is used to grade primary brain tumours?
Mitoses
Neovascularization
Necrosis
Atypia, cellularity
What are the common malignant primary intracranial tumours?
Astrocytoma Oligodendroglioma Ependymoma Medulloblastoma Haemangioblastoma Lymphoma Pineal
What are the common benign primary brain tumours?
Meningioma
Schwannoma
Craniopharyngioma
Pituitary adenoma
What is the commonest brain tumour in children?
Medulloblastoma
Astrocytoma; pilocytic
Describe a pilocytic grade 1 astrocytoma
Common in children
Benign behaving
Long hair like processes
Cystic area
Describe a grade 2; low grade astrocytoma
Nuclear atypia
Describe a grade 3 anaplastic astrocytoma
Greater nuclear atypia
Mitotic activity
Describe a grade 4 glioblastoma
Extreme nuclear atypia
Mitotic activity
Necrosis
Neovascularization
What can be seen histologically from a glioblastoma?
Anaplastic
Proliferation; numerous mitotic figures
Necrosis with assoc nuclear palisading
Neoangiogenesis
Describe a medulloblastoma?
20% of paeds CNS neoplasms
Poorly differentiated/embryonal
Occurs in midline of cerebellum and can easily disrupt CSF flow resulting in hydrocephalus
How are medulloblastomas treated?
Radiotherapy
What can result in a single brain abscess?
Local extension from:
Mastoditis, chronic otitis media, paranasal sinusitis, nasal facial and dental infection
Direct implantation: skull fracture
What can result in multiple brain abscesses?
Haematogenous spread; bronchopneumonia, bacterial endocarditis, bronchiectasis, lung abscesses, congenital heart disease (left to right shunt)
PWID
Where will multiple brain abscesses occur?
Grey and white matter boundary
What will occur with brain abscesses?
Central necrosis Oedema Fibrous capsule Hypoxia and ischaemia Excitotoxic injury
What are the symptoms of a brain abscess?
Fever
Increased ICP
How are brain abscesses diagnosed?
CT or MRI
How are abscesses treated?
Aspiration for culture and treatement
What is bacterial meningitis?
Inflammation of the leptomeninges and SF within the subarachnoid space
What can be seen on an LP from bacterial meningitis?
Abundant polymorphs and neutrophils
Decreased glucose
What can arachnoiditis result in?
Lack of CSF absorption
Hydrocephalus
Increased ICP
What organism causes bacterial meningitis in neonates?
E.coli; gram negative rods
What organism causes bacterial meningitis in infants and children?
Haemophilus influenzae; gram negative cocco-bacilli
What organism causes bacterial meningitis in adolescents and young adults?
Neisseria meningitis; gram negative diplococci
What organism causes bacterial meningitis in older adults or children?
Streptococcus pneumoniae; gram positive cocci in chains
What organism causes bacterial meningitis in older adults and those immunocompromised?
Listeria monocytoggene; gram positive rod
How can head trauma be classified?
Missile or non-missile (penetrating or blunt)
What can result from head trauma?
Skull #
Parenchymal and vascular injuries
What will a penetrating head trauma result in?
Focal damage
Lacerations in region of brain damage
Haemorrhage
What does the severity of a blunt injury rely on?
Initial velocity and the contact time; the smaller the contact time, the larger the force
What are causes of blunt head injuries?
RTCs
Falls
Assaults
Alcohol related injuries
What will the primary (impact) injury do?
Injury to neurones
Irreversible
Preventative measures; wearing a helmet and seat belts for example
What are the secondary head injuries?
Haemorrhage
Oedema
Potentially treatable
What is the clinical hallmark of head injuries?
Immediate change in conscious level is dependent on the scale of neuronal damage
What are examples of primary head injuries?
Scalp lesions Skull fractures Surface contusions and lacerations Diffuse axonal injury Diffuse vascular injury Petechial haemorrhages
What are the 3 types of skull fractures?
Linear
Compound
Depressed
What is a linear skull#?
Straight sharp fracture line, that may cross sutures
What is a compound skull#
Assoc with full thickness scalp lacerations
Are base of skull fractures open or closed?
ALWAYS consider compound because there is a high change that base of skull fractures will lacerate the paranasal sinuses giving bacteria a route for entrance to the cranium
What is a contra-coup injury?
Injury to the non-impact side diametrically opposite the point of impact
Occurs as a rebound
What is a diffuse axonal injury?
Occurs at the moment of injury due to shearing strains on the axonal bulbs
Affects central areas
What will a diffuse axonal injury lead to?
Reduced consciousness and coma
Lead to vegetative state
What are secondary head injuries?
Intracranial haemorrhage Reduced brain flow Hypoxic brain damage Excitotoxicity Oedema Raised ICP Infection
What oedema is assoc with trauma?
Vasogenic oedema
What are the percentages surrounding traumatic intracranial haematoma?
20% are extradural
80% are intradural
What does a traumatic extradural haematoma result from?
Fracture of pterion rupturing the middle meningeal artery
What causes an acute SAH?
Disruption of bridging veins that extend from the surface of the brain into the subdural space
What are chronic subdural haematomas assoc with?
Brain atrophy
What is a chronic subdural haematoma composed of?
Liquefied blood/ yellow tinged fluid separated from inner surface of dura mater and underlying brain by neomambrane
