NS 9: Strokes, CNS Imaging and Head trauma Flashcards
3 areas involved in producing clinical signs with raised intracranial pressure causing damage to these and adjacent compression?
cingulate gyrus
uncus
cerebellar tonsils
arteries comprising the anterior circulation of the brain?
anterior cerebral
middle cerebral
ICA
posterior communicating
arteries comprising posterior circulation of brain?
posterior cerebral
basilar
vertebral
branches of ICA?
opthalmic
posterior communicating
anterior choroidal
how does the middle cerebral artery from the ICA supply the basal ganglia?
gives rise to the lateral striate arteries
which artery supplies most of brainstem?
basilar artery from united vertebral arteries at causal border of pons
structures supplied by the posterior cerebral arteries which go around the midbrain?
thalamus
midbrain
temporal and occipital lobes
Aetiology and clinical presentation of a total anterior circulation stroke (20% of strokes)?
Proximal occlusion (ICA or proximal MCA)
Large volume infarct
Superficial and deep territories
Presentation= contralateral hemiparesis (weakness) +/- contralateral hemianaesthesia
contralateral hemianopia
Higher cerebral dysfunction e.g. dysphasia, dyspraxia- inability to carry out skilled, purposeful movements= cortical signs
What is dysphasia?
Disorder of language
2 types: Receptive dysphasia= often have language that is fluent with a normal rhythm and articulation but it is meaningless as they fail to comprehend what they are saying.
Expressive dysphasia are not fluent and have difficulty forming words and sentences. There are grammatical errors and difficulty finding the right word. In severe cases they do not speak spontaneously but they usually understand what is said to them. Know the word they want to say but can’t say it. Aphasia= can’t think of the word.
Aetiology and clinical presentation of a partial anterior circulation stroke (35% of strokes)?
Occlusion of MCA branch Restricted infarct 2 of 3 found in total anterior OR Restricted motor deficit (face OR arm OR leg only) OR isolated cortical signs High early recurrence rate
Aetiology and clinical presentation of a lacunar stroke (20% of strokes)?
Single perforating artery Basal ganglia/pons Pure motor, pure sensory, sensorimotor, ataxic hemiparesis silent, underdiagnosed
clinical presentation of a posterior circulation stroke (25% of strokes)?
Brainstem, cerebellar or occipital involvement, cranial nerve signs
complex presentation, thrombosis
2 secondary complications of a SA haemorrhage?
communicating hydrocephalus- could treat with a ventriculo-peritoneal shunt
cerebral ischaemia- to prevent give nimodipine (Ca2+ antagonist- *link to amlodipine- used in hypertension)- prevent vascular spasm and so cerebal ischaemia.
appearance of an extradural haematoma on a CT scan and why?
lentiform (lens shape)= convex appearance, as ED haematoma occurs with arterial disruption e.g. pterion fracture= depressed skull fracture highlighted as bone discontinuity on CT, which tears the A division of the middle meningeal artery from maxillary from ECA, so high pressure arterial blood forces periosteal layer of dura mater away from calvaria (not normally a space here.)
Lens shaped white appearance as blood and bone appear white on CT
what colour does CSF appear on CT?
black
*water also appears black, so an arachnoid cyst would appear black.
appearance of a subdural haematoma on CT scan and why?
white concavity, blood follows brain contours as torn cerebral veins, so low pressure venous blood following brain surface.
which members of the population is a subdural haematoma common in?
elderly- as brain shrinks as you get older, so cerebral veins are put under tension, weakened and prone to rupture with minute head trauma e.g. a fall.
appearance of a SA haemorrhage on CT and why?
white appearance around brain, follows sulci, blood fills gravity dependent spaces.
Commonly result of aneurysm withing arterial circle of Willis.
Can cause a communicating hydrocephalus as blood remains, in space, and rbc block the arachnoid granulations, blocking CSF from moving from the SA space into the dural venous sinuses. This would raise intracranial pressure.
Signs of raised IC pressure?*
headache-worse on a morning
nausea-worse on a morning and vomiting
irritable
papiiloedema
what is a stroke?
abrupt onset of a focal neurological defecit, lasts >24hrs
why MUST and ECG be carried out in suspected stroke?
Look for AF= absent P waves, irregularly irregular
additonal emboli may occur producing repeat ischaemic strokes.
managment of a SA haemorrhage?
nimodipine= Ca2+ antagonist- prevents vasospasm and cerebral ischaemia
phenytoin- prevent spread of seizure activity, *CYP450 inducer
may give a vasodilator to treat hypertension that could result in further haemorrhage
referral to specialist unit, usually neurosurgical, within 24 hrs
symptoms of SA haemorrhage?
- a sudden headache, may last a few s or even a fraction of a second. The patient may even look round and accuse someone of hitting them on the back of the head.
- SAH should be considered in any patient presenting with sudden-onset, severe and unusual headache with or without any associated alteration in consciousness.[11]
- The headache is often diffuse.
- The dominant feature is the severity, rather than the suddenness, of the headache, often being described as the most severe ever experienced.
- It usually lasts a week or two. Occipital headache.
- Vomiting may occur
- Seizures, which occur in only about 7% but,when they do, are highly suggestive of a haemorrhage
why might a patient have white blobs within their ventricles on a CT scan, commonly in older patients?
presence of a glomus= calcified bits of choroid plexus within the ventricles. This is normal in older patients.
