Neuro 4 Flashcards
Why does raised ICP matter?
cerebral perfusion pressure (CPP) has relationship with cerebral blood flow (CBF)
>not linear
>termed autoregulation
late reflex brainstem ischaemia in raised ICP (intracranial pressure)
>will result in increased MAP to ensure CPP is maintained (Cushing reflex)
What happens when CPP is more than 150 mg Hg?
loss of control of blood flow – ischaemic forced vasodilation
Lisa brain swelling (brain oedema) – ICP = MAP – thus no blood flow
What happens when CPP is less than 50mmHG?
cannot perfuse brain adequately with oxygen and nutrients,
>leads to loss of function
What can cause raised ICP?
information – meningitis, encephalitis, abscess
vascular causes – intracranial haemorrhage (natural disease or traumatic), brain swelling (traumatic brain injury, physical, or physiological (cardiac arrest))
tumours
hydrocephalus
What are the types of brain herniation?
Cingulate Central Uncal Cerebrotonsullar Upward Transcalvarial
How are the clinical signs of raised ICP explained by their pathology?
Glasgow coma scale – reason cortex and brainstem
pupillary dilation – squeezing stretch on cranial nerve 3
localising signs – squeeze on decussation of Corsical spinal tracks and posterior columns
Where are the common sights of brain tumours?
In adults, mostly above tentorium
In children most are below (and mostly primary)
What is ischaemic penumbra?
Tumours occupy space and therefore squeeze nearby tissue and cause local ischaemia
lead to loss of function around it,
>Removal of oedema around tumour improves function
can salvage in tumours and head injury
What is glioma (astrocytoma)
tumours resembling cells of astrocytes differentiation
CMS supporting cells with diffuse areas (not encapsulated)
>do not metastasise outside the CNS
Often young adults
What is the prognosis of glioma?
grades of differentiation predict prognosis
high-grade has worst outlook Outlook
>grows rapidly and responds poorly to surgery – median survival 36 weeks
site important outcome regardless of grade
low-grade (cystic) grows very slowly
What is medullary blastoma
the tumour of the primitive neural ectoderm – small blue round cell tumour
children especially but not exclusively
posterior fossa especially brainstem affected
poor outcome because of central site and difficult access for surgery
What is meningioma
tumour of the Arapahoe sites – those that make up coverings of the brain 2nd most common type it is a connective tissue tumour often benign do not metastasise can be locally aggressive can invade the skull
What is a nerve sheath tumour?
Around nerves in the CNS or PNS
acoustic neuroma is most common
found near CN VII can results in unilateral deafness
found in posterior fossa, often benign lesion removal to technically difficult and can cause collateral cranial nerve injury as cranial nerve VII is very close
What is a Benign tumour of the posterior pituitary in the pituitary fossa?
often secrete pituitary hormone
many non-functional squeeze normal gland stops working – panhypopituitarism
hormone secreted reflected on clinical signs (Growth hormone result in acromegaly or giantism)
grow superiorly and impinge on optic chiasma– visual signs depending on exact site
What is CNS lymphoma
high grade neoplasm, usually diffuse large B cell lymphoma
often deep in central site therefore difficult to biopsy
difficult to treat as drugs do not cross blood-brain barrier
generally do not spread outside CNS
What is capillary heamanglioblastoma?
Space occupying tumour that may bleed
most often in the cerebellar hemispheres
What are secondary tumours?
mostly carcinomas of common tumours
present with focal signs usually
some can be removed surgically although the site matters
tend to be encapsulated and surrounded by oedema
histology of the primary tumour
What are the most common tumours that metastasise to the brain?
Lung
Breast
Kidney
GI
What are the clinical features of a brain tumour?
Cerebral oedema Increased intracranial pressure Focal neurologic deficits Obstruction of flow of CSF Pituitary dysfunction Papilledema (if swelling around optic disk
What are the specific clinical features of a cerebral tumour?
Headache Vomiting unrelated to food intake Changes in visual fields and acuity Hemiparesis or hemiplegia Hypokinesia Decreased tactile discrimination Seizures Changes in personality or behaviour
What are the specific clinical features of a brainstem tumour?
Hearing loss (acoustic neuroma) Facial pain and weakness Dysphagia, decreased gag reflex Nystagmus Hoarseness Ataxia (loss of muscle coordination) and dysarthria (speech muscle disorder) (cerebellar tumours)
What can cause small pupils?
old age Bright light Miotic eyedrops opiate overdose Horner's syndrome
How do you diagnose a brain tumour?
CT
MRI
MRI angiography
PR spectroscopy
What are the clinical features of a frontal lobe tumour?
Inappropriate behavior Personality changes Inability to concentrate Impaired judgment Memory loss Headache Expressive aphasia Motor dysfunctions
What are the clinical features of a parietal lobe tumour?
Sensory deficits Paresthesia Loss of 2 pt discrimination Visual field deficits Temporal lobe Psychomotor seizures – temporal lobe-judgment, behavior, hallucinations, visceral symptoms, no convulsions, but loss of consciousness Occipital lobe Visual disturbances
What are the types of intraaxial tumours?
Gliomas Astrocytoma (Grades I & II) Anaplastic Astrocytoma(III) Glioblastoma Multiforme(IV) Oligodendroglioma Ependymomas Medulloblastoma CNS Lymphoma
What do intraaxial gliomas originate from?
Intra-axial gliomas originate from glial cells; they affect brain by invasion and infiltration.
What are the types of extraaxial tumours?
Meningioma Metastatic Acoustic neuromas (Schwannoma) Pituitary adenoma Neurofibroma
Where do extraaxial tumours orginate?
From supporting structures of CNS
How does astrocytoma present?
seizures,
headache,
slowly progressive neurological deficits
What are oligodendrogliomas?
normally about 40 years old
distinguish pathologically from astrocytoma’s by the characteristic fried egg appearance
rises from Myelin
found in frontal lobe superficially
presents with seizures, headache, slowly progressive neurological deficits
What are glioblastomas?
most common primary brain tumour in adults
presents 40 to 60 years old more common in males
has poor prognosis and can look like a butterfly lesion
tumour infiltrates a long white matter tracts and can cross corpus callosum
may arise de novo or evolve from a low grade glioma
How do glioblastomas present?
presents procedures headache and slowly progressive neurological deficits
Where are glioblastomas found?
found in frontal and temporal lobes, or basal ganglia
What is the venous drainage of the brain?
veins do not accompany arteries, large venous sinuses within dura
Fed by bridging veins from brain – cross meninges brain to skull
emissary veins into veins outside skull
What is a stroke?
focal neurological deficit – loss of function affecting specific region of central nervous system due to disruption of blood supply
causes damage to brain tissue due to lack of oxygen and nutrients
most strokes due to thrombi and pulled ischaemic strokes
one in 10 caused by ruptured blood vessels or haemorrhagic strokes
What are the key features of a stroke?
focal neurological deficit
sudden weakness or numbness – face, arm or leg, most often one side of body
others
confusion, difficulty speaking or understanding speech
difficulty seeing one or both eyes
difficulty walking, dizziness, balance coordination loss
severe headache with no known cause
unconsciousness
clinical presentation gives indication to possible anatomy of lesion
What are the different types of stroke?
transit ischaemic attack (TIA) – less than 24 hours
minor stroke – growth in 24 hours but minor neurological deficit
disabling stroke – growth in 24 hours with persistent disability that impairs independence
can occur in either carotid or Priscilla are free territory
What is the pathogenesis of ischaemic stroke?
brain very sensitive to oxygen ischaemia
cerebral blood flow takes about 15% of cardiac output
a few minutes of hypoxaemia or anoxia will cause brain ischaemia
can lead to infarction, damage to neurons is permanent, they do not regenerate
roughly 85% of strokes have potential for thrombolysis
What are the causes of ischaemia?
atherosclerosis
thrombosis
embolism
hypertension – cardiac arrest, massive blood loss
arterial spasm following Symptomatic treatment haemorrhage
Systemic vascular disease e.g. arthritis
mechanical compression – head injury causing brain swelling, spinal cord compression
venous obstruction – dual vein thrombosis, mediastinal tumour
