Neuro 1 Flashcards
Define stroke and TIA - specifying the differences
Stroke = sudden onset of focal/global neurological disturbance lasting over 24 hours
TIA = less than 24 hour neurological dysfunction caused by ischaemia without evidence of acute infarction
What heart diseases particularly predispose you to ischaemic stroke?
AF
Infective endocarditis
Valve disease
Heart failure
What can cause a haemorrhagic stroke?
Rupture of an aneurysm
High blood pressure
Head injury
When do you anticoagulate after a stroke?
2 weeks after the stroke if they have AF
What is the mechanism of aspirin?
Inhibits COX1 which suppresses production of prostaglandins and thromboxane
What is the mechanism of clopidogrel?
It irreversibly binds to ADP which prevents platelet aggregation.
It is independent of COX so it is synergistic with aspirin
What is the most common cause of ischaemic stroke in young people?
Carotid artery dissection - usually caused by hitting their chin and hyperextending their neck, rupturing the carotid artery
What can cause a central venous thrombosis?
Pregnancy
Infection
Dehydration
Malignancy
How would an infarct of the superficial division of the middle cerebral artery present?
- Expressive aphasia - Broca’s
- Receptive aphasia - Wernicke’s
- Face and arm motor weakness - motor cortex
- face and arm sensory loss - sensory cortex
How would an infarct of the lenticulostriate branches of the left middle cerebral artery present?
Right upper-motor hemiparesis - damage to basal ganglia
Aphasia
How would an anterior cerebral artery infarct present?
Leg weakness - foot drop
Leg sensory loss
Frontal lobe behavioural abnormalities
What makes up the anterior circulation of the brain?
Internal carotid arteries
Middle cerebral artery
Anterior cerebral artery
How would a total anterior circulation infarct present?
Hemiparesis (but with sparring of the forehead) Hemisensory loss Homonymous hemianopia Visuo-spatial deficit Dysphasia
What makes up the posterior circulation of the brain?
Vertebral arteries (branches from the subclavian arteries. In the cranium, the 2 vertebral arteries form the basilar artery)
Basilar artery
Posterior cerebral artery
Posterior communicating artery
How does a posterior circulation infarct present?
Cerebellar dysfunction
Homonymous hemianopia (superficial branch of posterior cerebral artery to occipital lobe)
Hemisensory loss
Hemiparesis
What percentage of strokes are due to infarction or haemorrhage?
85% - cerebral infarction
10% - primary haemorrhage
5% - subarachnoid haemorrhage
What symptoms point more towards a bleed than ischaemia?
Meningism
Severe headache
Coma
Seizure
What symptoms are in cerebellar dysfunction?
DANISH
Dysdiadokinesia Ataxia Nystagmus Intention tremor Slurred speech Hypotonia
Aside from stroke, what else can cause cerebellar syndrome?
PASTRIES
Posterior fossa tumour Alcohol MS Trauma Rare Inherited Epilepsy medication Stroke
What is the first thing that should be done in suspected stroke?
CT head within 1 hour in order to rule out haemorrhage - don’t want to thrombolyse or anticoagulate if bleeding
What is the acute management of an ischaemic stroke?
Give alteplase within 4.5 hours once haemorrhage is excluded
If post-4.5 hours, given aspirin 300mg
Thrombectomy (particularly with large artery occlusion in proximal anterior circulation)
What is alteplase? When should it not be given?
Recombinant tissue plasminogen activator
Thrombolytic drug
When should alteplase not be given?
Do not give after 4.5 hours since onset of stroke or if there is no clear onset time
Contraindications:
- Previous haemorrhage
- Aneurysm
- Recent head injury
- Known clotting disorder
- Intracranial cancer
- Acute pericarditis
- Seizure at onset of stroke (suggests haemorrhage or tumour)
- Recent lumbar puncture
- Systolic BP > 185 mmHg
What causes a unilateral progressive vision loss ‘like a curtain descending’?
Amaurosis fugax = TIA of a retinal artery
If carotid stenosis is > 70% what do you do?
A carotid endarterectomy = removal of material on inside of artery
What is the long term management post-stroke?
Clopidogrel 75mg daily
If they cannot tolerate clopidogrel, give aspirin 75mg + modified-release dipyridamole 200mg bd (inhibits phosphodiesterase to block platelet aggregation)
Statins
Blood pressure control
Diagnose: Thunderclap headache/worst headache ever
Subarachnoid haemorrhage
What usually causes a SAH?
Rupture of a Berry aneurysm in Circle of Willis.
Most are saccular aneurysms (i.e. not congenital) - elastic lamina damaged by stressors such as hypertension and smoking
What is the second most common cause of SAH?
Arterio-venous malformations
What is the most common cause of blood in the subarachnoid space?
Traumatic injury
spontaneous SAH is aneurysm though
Name some genetic disorders that can predispose you to a subarachnoid haemorrhage
Marfan’s syndrome
Autosomal dominant polycystic disease
Ehlers-Danlos syndrome
Neurofibromatosis
What can come on 6 hours after onset of SAH?
Neck stiffness
Kernig’s sign - positive when thigh is flexed at hip and knee is at 90 degrees, then subsequent extension of knee is very painful
How would an aneurysm in the posterior communicating artery present?
Pupil dilatation due to CNIII palsy (compression)
What is the most common cause of a CNIII palsy?
Diabetes
Down and out pupil
What usually causes a CNVI palsy?
Raised intracranial pressure
Why might there be hypertension in SAH?
Sympathetic reflex to intracerebral haemorrhage
What investigations should be done in suspected SAH?
Urgent CT head - detects >95% of SAH within 24 hours
LP - if CT head negative but history is suggestive - yellow CSF due to bilirubin
Angiography - to identify aneurysms
How do you manage a subarachnoid haemorrhage?
Prevent vasospasm
- Calcium channel blockers - nimodipine
Prevent rebleeding
- Clipping = craniotomy with clips around neck of aneurysm
- Coiling = obliterate aneurysm by causing clot to form in it
What does blood look like on a CT head?
Hyperdense = white - recent blood
Hypodense = dark - old blood
How do you differentiate between extradural and subdural haematoma on CT head?
Extradural haematoma
- lens shape of bleeding
- can’t cross sutures of skull
- can cross midline
Subdural haematoma
- crescent shape of bleeding
- can cross sutures of skull
- can’t cross midline
How do you differentiate between extradural and subdural haematoma with symptoms?
Extradural haematoma - LOC then lucid interval then 2nd LOC
Subdural haematoma - slow progression + confusion
What most commonly causes peripheral neuropathy?
Diabetes - poor glycaemic control
What is Guillan-Barré syndrome?
Autoimmune disorder that causes acute demyelination.
75% had prior infection usually of GI or respiratory systems e.g. Mycoplasma, EBV, Campylobacter
Presents with muscle weakness starting in feet and hands
What are some complications of Guillan-Barré syndrome? What investigation must be done?
It can affect proximal muscles e.g. trunk, respiratory and cranial nerves (progressive facial drooping)
Respiratory depression - check vital capacity (it is likely to get worse before ABG shows signs of hypoxia)
How do you treat Guillan-Barré syndrome?
IV immunoglobulins for 5 days
What should you investigate in peripheral neuropathy?
Glucose levels
B12 levels
Folate levels
Neuro-conduction studies
What is Romberg’s sign?
Sensoriataxia - when patient closes their eyes they wobble.
NOT a cerebellar test because they would wobble even with their eyes open
What drug can cause peripheral neuropathy?
Nitrofurantoin
Phenytoin
Amiodarone
Metronidazole
What congenital conditions can cause peripheral neuropathy?
Charcot-Marie-Tooth syndrome
Freidrich’s ataxia
Name some LMN signs
- Muscle paralysis
- Fasciculations - spontaneous involuntary twitching
- Hypotonia
- Reduced reflexes
- Muscle wasting
Name some UMN signs
- Spasticity - increased tone that is velocity dependent (the faster you move the muscle, the greater the resistance until it gives way like a clasp-knife)
- Pronator drift
- Babinski’s sign - dorsiflexion of foot
- Clonus - rapidly dorsiflexing the foot then many downbeats of the foot
- Hyper-reflexia
- Reduced power
What drugs can be given for peripheral neuropathy?
Tricyclic antidepressants e.g. amitryptiline
Gabapentin
What is epilepsy?
Recurrent tendency to spontaneous, intermittent, abnormal electrical activity in part of the brain, manifesting as seizures
Describe the different elements of a seizure
Prodrome (hours/days) - change in mood/behaviour
Aura - focal seizure (often from temporal lobe), deja vu, strange smells, flashing lights
Post-ictal phase - headache, confusion, myalgia, temporary weakness, dysphasia
What causes epilepsy?
2/3rd = idiopathic
Space-occupying lesion e.g. neoplasm
Head injury or cortical scarring from previous head injury
CNS infections
Stroke
Hippocampal sclerosis after febrile convulsion
Vascular malformations
Name some triggers for a seizure in epilepsy?
Alcohol
Stress
Flashing lights
What is a sign of neurofibromatosis?
Café au lait spots
What is a focal seizure?
Start in one area of one side of the brain
Often seen with underlying structural disease
What are generalised seizures? Name some different types
Involve both hemispheres of the brain
- Absence seizures - brief (less than 10 sec) pauses e.g. stares into space for 5 seconds then resumes talking
- Tonic-clonic - LOC, stiff limbs (tonic) then jerk (clonic). Tongue biting, incontinence. Post-ictal confusion and drowsiness
- Myoclonic - sudden jerk of a limb/trunk/face
- Atonic - all muscles relax and drop to floor, no LOC
What investigations should you do in epilepsy?
Anti-epileptic levels - check compliance
EEG
MRI - if focal onset or if seizures continue with medication
ECG - in all patients with altered consciousness
LP - if infection suspected
What are 1st and 2nd line treatments for focal/partial seizures?
1st line - carbamazepine or lamotrigine
2nd line - sodium valproate
What are 1st line treatment for all generalised seizures
Sodium valproate
What type of seizures should you avoid carbamazepine in ?
Myoclonic seizures - may worsen them
What are some side effects of sodium valproate?
Hair loss due to hypersensitivity - regrowth is curly hair
Nausea (always take with food)
Thrombocytopenia
Tremor
Which drug should you avoid if someone is taking sodium valproate?
Aspirin - it displaces sodium valproate from its binding sites which increases the adverse effects
Why is phenytoin no longer first line treatment for epilepsy?
Risk of toxicity –> nystagmus, diplopia, tremor, ataxia
Side effects –> reduced cognition, depression, acne, gum hypertrophy, polyneuropathy
Which anti-epileptic drug must be strictly avoided in pregnancy? Which is preferred? What must be thought about in terms of contraception?
Sodium valproate is the most teratogenic
Lamotrigine is preferred
Anti-epileptic drugs are P450 enzyme inducers so they make progesterone-only contraception unreliable.
Oestrogen-containing contraceptives lower lamotrigine levels so need increased dose.
