Neurology Flashcards
What is the classification of strokes?
Oxford stoke classification AKA the Bamford classification
The following criteria should be assessed:
1. unilateral hemiparesis and/or hemisensory loss of the face, arm & leg
2. homonymous hemianopia
3. higher cognitive dysfunction e.g. dysphasia
What indicates a total anterior circulation infarct?
Total anterior circulation infarcts (TACI, c. 15%)
involves middle and anterior cerebral arteries
all 3 of the classification criteria are present
- unilateral hemiparesis and/or hemisensory loss of the face, arm & leg
- homonymous hemianopia
- higher cognitive dysfunction e.g. dysphasia
What indicates a Partial anterior circulation infarct?
involves smaller arteries of anterior circulation e.g. upper or lower division of middle cerebral artery
2 of the classification criteria are present
- unilateral hemiparesis and/or hemisensory loss of the face, arm & leg
- homonymous hemianopia
- higher cognitive dysfunction e.g. dysphasia
What indicated a lacunar infarct?
Lacunar infarcts (LACI, c. 25%)
involves perforating arteries around the internal capsule, thalamus and basal ganglia
presents with 1 of the following:
1. unilateral weakness (and/or sensory deficit) of face and arm, arm and leg or all three.
2. pure sensory stroke.
3. ataxic hemiparesis
What indicates a Posterior circulation infarct?
Posterior circulation infarcts (POCI, c. 25%)
involves vertebrobasilar arteries
presents with 1 of the following:
1. cerebellar or brainstem syndromes
2. loss of consciousness
3. isolated homonymous hemianopia
what is lateral medullary syndrome?
Lateral medullary syndrome (posterior inferior cerebellar artery)
aka Wallenberg’s syndrome
ipsilateral: ataxia, nystagmus, dysphagia, facial numbness, cranial nerve palsy e.g. Horner’s
contralateral: limb sensory loss
What is Weber’s syndrome?
Weber’s syndrome
ipsilateral III palsy
contralateral weakness
What is Wernike’s aphasia?
Receptive aphasia
Due to a lesion of the superior temporal gyrus. It is typically supplied by the inferior division of the left MCA
This area ‘forms’ the speech before ‘sending it’ to Broca’s area. Lesions result in sentences that make no sense, word substitution and neologisms but speech remains fluent - ‘word salad’
Comprehension is impaired
What is Broca’s aphasia?
expressive aphasia
Due to a lesion of the inferior frontal gyrus. Typically supplied by the superior devision of the left MCA.
Speech in non-fluent, laboured and halting. Repetition is impaired
Comprehension is normal
What is condition aphasia?
Classically due to a stroke affecting the arcuate fasiculus - the connection between Wernicke’s and Broca’s area
Speech is fluent but repetition is poor. Aware of the errors they are making
Comprehension is normal
What is global aphasia?
Large lesion affecting all 3 of the above areas resulting in severe expressive and receptive aphasia
May still be able to communicate using gestures
What are the features of stroke?
motor weakness
speech problems (dysphasia)
swallowing problems
visual field defects (homonymous hemianopia)
balance problems
Cerebral hemisphere infarcts may have the following symptoms:
contralateral hemiplegia: initially flaccid then spastic
contralateral sensory loss
homonymous hemianopia
dysphasia
what may a brainstem infarct lead to?
may result in more severe symptoms including quadriplegia and lock-in-syndrome
What are lacunar infarcts and how do they present?
small infarcts around the basal ganglia, internal capsule, thalamus and pons
this may result in pure motor, pure sensory, mixed motor and sensory signs or ataxia
what symptoms are patients with hemorrhagic stroke more likely to have?
decrease in the level of consciousness: seen in up to 50% of patients with a haemorrhagic stroke
headache is also much more common in haemorrhagic stroke
nausea and vomiting is also common
seizures occur in up to 25% of patients
what are the investigations for stroke?
Initially - Non contact CT (this will help rule out haemorrhage stroke, and can show early signs of ischaemic stroke) such as a loss of insular ribbon or hyper dense middle cerebral artery sign)
MRI - with diffusion weight imaging - more sensitive for detecting acute ischaemia
bloods - fbc, clotting profile, electrolytes,, lipid profile, BM
Further imaging
Echo
Carotid imaging
24 hour egg monitoring
Cerebral angiography
Differential Diagnosis for Stroke?
Migraine with Aura
Bell’s palsy (weakness will include the forehead where as in stroke it would be forehead sparing)
Hypoglycaemia
What is the management of stroke?
- blood glucose, hydration, oxygen saturation and temperature should be maintained within normal limits
- BP should not be lowered in the acute phase of an ischaemic stroke unless there are complications e.g. hypertensive encephalopathy or they are being considered for thrombolysis
Aspirin 300mg should be given orally/rectally ASAP if haemorrhage stroke has been excluded
If AF - anticoagulants should not be started until 14 days has passed from the onset of the stroke
If cholesterol > 3.5mmol/l patients should be commenced on statin (delay treatment for 48 hours due to risk of haemorrhagic transformation
Thrombolysis
Thrombectomy
When is thrombolysis indicated for acute ischaemic stroke ?
The standard criteria for thrombolysis with alteplase or tenecteplase are as follows:
it is administered within 4.5 hours of onset of stroke symptoms
haemorrhage has been definitively excluded (i.e. Imaging has been performed)
The 2023 National Clinical Guideline for Stroke broadened the potential inclusion criteria.
it recommends that patients with an acute ischaemic stroke, regardless of age or stroke severity, who were last known to be well more than 4.5 hours earlier, should be considered for thrombolysis with alteplase if:
treatment can be started between 4.5 and 9 hours of known onset, or within 9 hours of the midpoint of sleep when they have woken with symptoms, AND
they have evidence from CT/MR perfusion (core-perfusion mismatch) or MRI (DWI-FLAIR mismatch) of the potential to salvage brain tissue
this should be irrespective of whether they have a large artery occlusion and require mechanical thrombectomy.
there are specific criteria in the guidelines that determine the imagine criteria that determine whether thrombolysis should be performed
Blood pressure should be lowered to 185/110 mmHg before thrombolysis.
Absolute contraindications for thrombolysis
- Previous intracranial haemorrhage
- Seizure at onset of stroke
- Intracranial neoplasm
- Suspected subarachnoid haemorrhage
- Stroke or traumatic brain injury in preceding 3 months
- Lumbar puncture in preceding 7 days
- Gastrointestinal haemorrhage in preceding 3 weeks
- Active bleeding
- Oesophageal varices
- Uncontrolled hypertension >200/120mmHg
Relative contraindications for thrombolysis?
- Pregnancy
- Concurrent anticoagulation (INR >1.7)
- Haemorrhagic diathesis
- Active diabetic haemorrhagic retinopathy
- Suspected intracardiac thrombus
- Major surgery / trauma in the preceding 2 weeks
When is thrombectomy used in acute Ischaemic stroke?
NICE recommend a pre-stroke functional status of less than 3 on the modified Rankin scale and a score of more than 5 on the National Institutes of Health Stroke Scale (NIHSS)
Offer thrombectomy as soon as possible and within 6 hours of symptom onset, together with intravenous thrombolysis (if within 4.5 hours), to people who have:
acute ischaemic stroke and
confirmed occlusion of the proximal anterior circulation demonstrated by computed tomographic angiography (CTA) or magnetic resonance angiography (MRA)
Offer thrombectomy as soon as possible to people who were last known to be well between 6 hours and 24 hours previously (including wake-up strokes):
confirmed occlusion of the proximal anterior circulation demonstrated by CTA or MRA and
if there is the potential to salvage brain tissue, as shown by imaging such as CT perfusion or diffusion-weighted MRI sequences showing limited infarct core volume
Consider thrombectomy together with intravenous thrombolysis (if within 4.5 hours) as soon as possible for people last known to be well up to 24 hours previously (including wake-up strokes):
who have acute ischaemic stroke and confirmed occlusion of the proximal posterior circulation (that is, basilar or posterior cerebral artery) demonstrated by CTA or MRA and
if there is the potential to salvage brain tissue, as shown by imaging such as CT perfusion or diffusion-weighted MRI sequences showing limited infarct core volume
Secondary prevention for stroke?
clopidogrel
Carotid endarterectomy is recommend if the patient has suffered a stroke or TIA in the carotid territory and is not severely disabled
should only be considered if the stenosis > 50% according to North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria
what environmental factors may lead to epilepsy?
Prenatal and perinatal risk factors - maternal drug use, infection during pregnancy, preterm birth, low birth weight, neonatal seizures, Hypoxic ischaemic encephalopathy
CNS infections
Cerebrovascular disease - e.g. stroke
Traumatic brain injury
Brain tumours
Mixed genetic and environmental - neurocutaneous syndromes - conditions such as tuberous sclerosis complex, neurofibromatosis type 1 and Struge weber syndrome have genetic and environmental tigers
what are the different classifications of seizures?
Focal Onset Seizure
Generalised onset seizure
Unknown onset seizure
What are the different types of focal seizures?
Focal aware seizure (previously simple partial seizures) - individual remains conscious and can recall events during the seizure.
Focal Impaired awareness seizure (previously complex partial seizure) - involves alteration in consciousness - they may start as focal aware seizures and then progress
Focal to Bilateral Tonic-Clonic Seizures: Begin in one hemisphere and spread to involve both, resulting in a tonic-clonic seizure.
What are the different types of generalised onset seizures?
These arise at some point within, and rapidly engage, bilaterally distributed networks.
Tonic-Clonic Seizures: Characterised by stiffening (tonic phase) followed by rhythmic muscle jerking (clonic phase).
Absence Seizures: Brief lapses in consciousness, often with staring. They can be sub-classified into typical and atypical absence seizures.
Tonic Seizures: Cause stiffening.
Atonic Seizures: Lead to loss of muscle control, often resulting in falls (‘drop attacks’).
Clonic Seizures: Involves repetitive jerking movements.
Myoclonic Seizures: Quick, sudden jerks of a muscle or group of muscles.
How can epilepsy be classified based on epilepsy syndromes?
Childhood Absence Epilepsy (CAE): Characterised by typical absence seizures, with onset usually between 4-10 years.
Juvenile Myoclonic Epilepsy (JME): Marked by myoclonic jerks, typically shortly after waking.
Dravet Syndrome: Severe epilepsy beginning in infancy, initially presenting as prolonged seizures with fever.
Lennox-Gastaut Syndrome: Characterised by multiple seizure types, cognitive dysfunction, and a specific EEG pattern.
What investigations for epilepsy?
Bloods - FBC, Electrolytes, glucose, LFTs U&E’s
EEG - electoencephalogram
MRI
LP, Genetic testing, prolonged EEG monitoring
Differential diagnosis for Epilepsy?
Syncope
Psychogenic non-epileptic seizures
TIA
Alcohol withdrawal seizure
Seizures secondary to metabolic/toxic disturbance
Management of epilepsy
Normally start anti-epileptics after a second seizure
Sodium valproate is considered the first line treatment for patients with generalised seizures with carbamazepine used for focal seizures.
Generalised tonic-clonic seizures
sodium valproate
second line: lamotrigine, carbamazepine
Absence seizures* (Petit mal)
sodium valproate or ethosuximide
sodium valproate particularly effective if co-existent tonic-clonic seizures in primary generalised epilepsy
Myoclonic seizures**
sodium valproate
second line: clonazepam, lamotrigine
Focal seizures
carbamazepine or lamotrigine
second line: levetiracetam, oxcarbazepine or sodium valproate
*carbamazepine may exacerbate absence seizures
**carbamazepine may exacerbate myoclonic seizures
Driving advice following seizure
Can’t drive for 6 months following a seizure. If patients have established epilepsy then they must be seizure free for 12 months.
when would anti-epileptics be started after one seizures?
the patient has a neurological deficit
brain imaging shows a structural abnormality
the EEG shows unequivocal epileptic activity
the patient or their family or carers consider the risk of having a further seizure unacceptable
What is the acute management of seizures?
For people having a tonic-clonic seizure lasting more than 5 minutes, or who have more than three seizures in an hour
- Buccal midazolam as first-line treatment in the community.
Rectal diazepam if preferred, or if buccal midazolam is not available.
Intravenous lorazepam if intravenous access is already established and resuscitation facilities are available.
Cerbebellar signs
Dysdiadochokinesia & Dysmetria (past pointing)
Inability to perform and sustain a series of rapidly alternating muscle movements. The patient overshoots when attempting to reach a point with their finger
Ataxia
Gross incoordination of muscle movements. The patient may be very unsteady on their feet towards the side of the lesion. The patient may also show rebound, where pushing down on the outstretched upper limb causes it to rebound up past its original position
Nystagmus
A repetitive, involuntary oscillation of the eyes. The patient may also complain of blurred vision
Intention tremor
A wide tremor during voluntary movements, such as holding out the hands
Slurred speech
Speech may be imprecise, slow and distorted
Hypotonia
The patient may have muscle weakness on the side of the lesion
How are acute stroke services run?
The focus on management in hyperacute stroke units and the specialist services they offer (i.e. thrombolysis and thrombectomy)
Understanding that not every hospital has a hyperacute stroke unit - and hence knowing where and how to refer in the event of a suspected stroke
The existence of specialist and dedicated acute stroke teams in hospitals - including consultants, registrars and specialist nurses, enabling rapid responses and immediate specialist expertise for suspected strokes
“Time is brain” - investigations should not delay transfer to hyperacute stroke units
what is Myasthenia Gravis?
chronic autoimmune neuromuscular disease
The hallmark of the condition is muscle weakness that increases during periods of activity and improves after rest. It primarily affects the ocular muscles, leading to ptosis and diplopia, but can also involve bulbar, limb and respiratory muscles.
what are the autoantibodies seen in Myasthenia gravis?
postsynaptic nicotinic acetylcholine receptors (AChRs) at the neuromuscular junction, impairing neuromuscular transmission. Other patients may have antibodies against muscle-specific kinase (MuSK)
Aetiology of myasthenia gravis?
Genetic predisposition - HLA-B8, DR3 haplotype has been associated with early onset MG, HLA b27/ DR15/16 linked to late onset
Environmental triggers - certain infections can trigger an autoimmune response leading to MG.
- Thymoma is found in 10-15% of patients - these tumours can induce an immune response resulting in the productive of autoantibodies against acetylcholine receptors
Hormonal influnces
Myasthenia Gravis pathophysiology
autoantibodies against components of the neuromuscular junction (NMJ), particularly the nicotinic acetylcholine receptor (nAChR).
= reduction in the number and functionality of nAChRs at the postsynaptic membrane, thereby disrupting neurotransmission at the NMJ. The diminished nAChR density leads to a decreased safety factor for neuromuscular transmission, which manifests as muscle weakness in patients with MG.
Also AB against muscle specific kinase and lipoprotein-related protein 4 (LRP4) - both essential for proper NMJ formation and maintenance.
The presence of these autoantibodies and their respective pathogenic mechanisms contribute to the heterogeneity observed in MG clinical presentation.
Clinical features of MG?
The hallmark of MG is fluctuating muscle weakness that worsens with repetitive activity and improves with rest.
ptosis (drooping of the upper eyelid), diplopia (double vision), dysarthria (difficulty speaking), dysphagia (difficulty swallowing), and proximal limb weakness.
Myasthenic crisis - respiratory involvement - life threatening
which drugs may exacerbate myasthenia?
penicillamine
quinidine, procainamide
beta-blockers
lithium
phenytoin
antibiotics: gentamicin, macrolides, quinolones, tetracyclines
Investigations for myasthenia gravis?
Repetitive nerve stimulation
Single-fiber electromyography (most sensitive test)
Anti-acetylcholine receptor (AChR) antibodies
Anti-muscle-specific kinase (MuSK) antibodies
Anti-lipoprotein-related protein 4 (LRP4) antibodies
CT chest or MRI - to assess for thymoma or thymic hyperplasia
