Neuro emergencies Flashcards
What is Guillain-barre syndrome
Disorder causing demyelination and axonal degeneration resulting in acute, ascending and progressive neuropathy, characterised by weakness, paraesthesiae and hyporeflexia.
What is GBS usually preceded by
75% of patients have a history of preceding infection, usually of the respiratory and gastrointestinal tract.
A large number of infections have been linked, including Campylobacter jejuni, Epstein Barr virus, cytomegalovirus, mycoplasma and human immunodeficiency virus
Risk factors for GBS
History of gastrointestinal or respiratory infection from 1-3 weeks prior to the onset of weakness.
Recently, an association has been suggested with the Zika virus
Vaccinations: live and dead vaccines have been implicated.
Malignancies - eg, lymphomas, especially Hodgkin’s disease.
Pregnancy: incidence decreases during pregnancy but increases in the months after delivery.
Presentation of GBS
Weakness Pain Areflexia sensory symptoms autonomic symptoms
Weakness in GBS
In 60% of cases, onset occurs approximately three weeks after a viral illness.
The condition usually presents with an ascending pattern of progressive symmetrical weakness, starting in the lower extremities.
This reaches a level of maximum severity two weeks after initial onset of symptoms and usually stops progressing after five weeks.
Facial weakness, dysphasia or dysarthria may develop.
In severe cases, muscle weakness may lead to respiratory failure.
Pain in GBS
neuropathic pain may develop, particularly in the legs. Back pain may be another feature.
Sensory symptoms in GBS
These can include paraesthesiae and sensory loss, starting in the lower extremities.
Autonomic symptoms in GBS
Involvement of the autonomic system may present, with reduced sweating, reduced heat tolerance, paralytic ileus and urinary hesitancy.
Severe autonomic dysfunction may occur.
Features of GBS on examination
Hypotonia.
Demonstrable altered sensation or numbness.
Reduced or absent reflexes.
Fasciculation may occasionally be noted.
Facial weakness - may be asymmetrical.
Autonomic dysfunction - fluctuations of heart rate and arrhythmias, labile blood pressure and variable temperature.
Respiratory muscle paralysis.
What might a lumbar puncture show in GBS
Most patients have an elevated level of cerebrospinal fluid (CSF) protein, with no elevation in CSF cell counts. The rise in the CSF protein may not be seen until 1-2 weeks after the onset of weakness.
What is a major determinant of need for admission to ITU in GBS
Spirometry - forced vital capacity
Management of GBS
Plasma exchange
IV immunoglobulins
Corticosteroids
DVT prophylaxis
Complications of GBS
Persistent paralysis Respiratory failure requiring mechanical ventilation Hypotension or hypertension Thromboembolism Cardiac arrhythmia Ileus
What is myasthenia gravis
Autoimmune condition that causes muscle weakness that gets progressively worse with activity and improves with rest
Which tumours are associated with myasthenia gravis
Strong link between thymoma
10-20% of patients with myasthenia gravis have a thymoma. 20-40% of patients with a thymoma develop myasthenia gravis.
Pathophys of myasthenia gravis
In around 85% of patients with myasthenia gravis, acetylcholine receptor antibodies are produced by the immune system.
These bind to the postsynaptic neuromuscular junction receptors which blocks the receptor and prevents the acetylcholine from triggering muscle contraction. As the receptors are used more during muscle activity, more of them become blocked up.
This leads to less effective stimulation of the muscle with increased activity. There is more muscle weakness the more the muscles are used. This improves with rest as more receptors are freed up for use again.
Presentation of myasthenia gravis
Most affect proximal muscles and small muscles of head/neck
Extraocular muscle weakness causing double vision (diplopia)
Eyelid weakness causing drooping of the eyelids (ptosis)
Weakness in facial movements
Difficulty with swallowing
Fatigue in the jaw when chewing
Slurred speech
Progressive weakness with repetitive movements
How can fatiguability of muscles be elicited on examination
Repeated blinking will exacerbate ptosis
Prolonged upward gazing will exacerbate diplopia on further eye movement testing
Repeated abduction of one arm 20 times will result in unilateral weakness when comparing both sides
Diagnosis of myasthenia gravis
Acetylcholine receptor (ACh-R) antibodies (85% of patients)
Muscle-specific kinase (MuSK) antibodies (10% of patients)
LRP4 (low-density lipoprotein receptor-related protein 4) antibodies
What is the edrophonium test
Patients are given an IV dose of edrophonium chloride (or neostigmine).
Normally, cholinesterase enzymes in the neuromuscular junction break down acetylcholine.
Edrophonium block these enzymes and stop the breakdown of acetylcholine.
As a result the level of acetylcholine at the neuromuscular junction increases. It briefly and temporarily relieves the weakness. This establishes a diagnosis of myasthenia gravis.
Treatment of myasthenia gravis
Reversible acetylcholinesterase inhibitors (usually pyridostigmine or neostigmine) increases the amount of acetylcholine in the neuromuscular junction and improve symptoms
Immunosuppression (e.g. prednisolone or azathioprine) suppresses the production of antibodies
Thymectomy can improve symptoms even in patients without a thymoma
Use of monoclonal antibodies in myasthenia gravis
Rituximab is a monoclonal antibody that targets B cells and reduces the production of antibodies. It is available on the NHS if standard treatment is not effective and certain criteria are met.
Eculizumab is a monoclonal antibody that targets complement protein C5. This could potentially prevent the complement activation and destruction of acetylcholine receptors. There is ongoing research and debate about whether the evidence is strong enough to offer it on the NHS. It is currently not recommended by NICE.
What is a myasthenic crisis
Severe complication of myasthenia gravis. It can be life threatening. It causes an acute worsening of symptoms, often triggered by another illness such as a respiratory tract infection. This can lead to respiratory failure as a result of weakness in the muscle of respiration.
Management of myasthenic crisis
Non-invasive ventilation with BiPAP or full intubation and ventilation
Medical treatment is with immunomodulatory therapies such as IV immunoglobulins and plasma exchange
Definition of TIA
A transient episode of neurologic dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction.
Clinical features of TIA
The clinical features are similar to those of a stroke, i.e. sudden onset, focal neurological deficit but, rather than persisting, the features resolve, typically within 1 hour.
unilateral weakness or sensory loss. aphasia or dysarthria ataxia, vertigo, or loss of balance visual problems sudden transient loss of vision in one eye (amaurosis fugax) diplopia homonymous hemianopia
Immediate pharmacological management of TIA
give aspirin 300 mg immediately, unless
- the patient has a bleeding disorder or is taking an anticoagulant (needs immediate admission for imaging to exclude a haemorrhage)
- the patient is already taking low-dose aspirin regularly: continue the current dose of aspirin until reviewed by a specialist
- Aspirin is contraindicated: discuss management urgently with the specialist team
Advice regarding specialist review for TIA
if the patient has had more than 1 TIA (‘crescendo TIA’) or has a suspected cardioembolic source or severe carotid stenosis:
discuss the need for admission or observation urgently with a stroke specialist
If the patient has had a suspected TIA in the last 7 days:
arrange urgent assessment (within 24 hours) by a specialist stroke physician
if the patient has had a suspected TIA which occurred more than a week previously:
refer for specialist assessment as soon as possible within 7 days
IX for TIA
CT brains should not be done ‘unless there is clinical suspicion of an alternative diagnosis that CT could detect’
MRI (including diffusion-weighted and blood-sensitive sequences) is preferred to determine the territory of ischaemia, or to detect haemorrhage or alternative pathologies
it should be done on the same day as specialist assessment if possible
Carotid doppler
1st line antithrombotic therapy for patients who have had a stroke
Clopidogrel
otherwise aspirin + dipyridamole
When should carotid endarterectomy be considered in TIA/Stroke management
recommend if patient has suffered stroke or TIA in the carotid territory and are not severely disabled
should only be considered if
carotid stenosis > 70% according ECST* criteria or
> 50% according to NASCET** criteria
Features of SCC
Back pain the earliest and most common symptom may be worse on lying down and coughing lower limb weakness sensory changes: sensory loss and numbness
Type of motor neurone signs exhibited by lesions above L1 in SCC
Lesions above L1 usually result in upper motor neuron signs in the legs and a sensory level.
Type of motor neurone signs exhibited by lesions below L1 in SCC
Lesions below L1 usually cause lower motor neuron signs in the legs and perianal numbness. Tendon reflexes tend to be increased below the level of the lesion and absent at the level of the lesion
IX for SCC
Whole MRI spine within 24 hrs of presentation
MX of SCC
High-dose oral dexamethasone
urgent oncological assessment for consideration of radiotherapy or surgery
Presentation of brain tumours
Dependent on location
Symptoms and signs of raised ICP
Causes of raised ICP
Brain tumours
Intracranial haemorrhage
Idiopathic intracranial hypertension
Abscesses or infection
ICP presenting features
Nocturnal
Worse on waking
Worse on coughing, straining or bending forward
Vomiting
Altered mental state Visual field defects Seizures (particularly focal) Unilateral ptosis Third and sixth nerve palsies Papilloedema
Features of papilloedema in fundoscopy
Blurring of the optic disc margin Elevated optic disc Loss of venous pulsation Engorged retinal veins Haemorrhages around optic disc Paton’s lines
Most common cancers that metastasise to the brain
Lung
Breast
Renal cell carcinoma
Melanoma
What are gliomas
Gliomas are tumours of the glial cells in the brain or spinal cord. There are three types to remember (listed from most to least malignant):
Astrocytoma (glioblastoma multiforme is the most common)
What are the meningiomas
Meningiomas are tumours growing from the cells of the meninges in the brain and spinal cord.
They are usually benign, however they take up space and this mass effect can lead to raised intracranial pressure and neurological symptoms.
What are acoustic neuromas AKA vestibular shwannomas
Acoustic neuromas are tumours of the Schwann cells surrounding the auditory nerve that innervates the inner ear.
They occur around the “cerebellopontine angle” and are sometimes referred to as cerebellopontine angle tumour
Features of acoustic neuromas
slow-growing but eventually grow large enough to produce symptoms and become dangerous
Acoustic neuromas are usually unilateral
What are bilateral acoustic neuromas associated with
Neurofibromatosis type 2
Symptoms of acoustic neuroma
Hearing loss
Tinnitus
Balance problems
Can also be associated with a facial nerve palsy
What is Lambert-eaton myasthenia syndrome(LEMS)
Causes progressive muscle weakness with increased use as a result of damage to the neuromuscular junction.
The symptoms tend to be more insidious and less pronounced than in myasthenia gravis.
In which patients does LEMS typically occur in
In patients with small-cell lung cancer
Pathophys of LEMS
Antibodies are produced by the immune system against voltage-gated calcium channels in small cell lung cancer (SCLC) cells.
These antibodies also target and damage voltage-gated calcium channels in the presynaptic terminals of the neuromuscular junction where motor nerves communicate with muscle cells.
LEMS presentation
Proximal muscles notably affected
Reduced tendon reflexes
Intraocular muscles affected causing diplopia, levator muscles affected causing ptosis and oropharyngeal muscles affected causing slurred speech and swelling problems
Symptoms of LEMS due to autonomic dysfunction
Dry mouth
Blurred vision
Impotence
Dizziness
What is post-titanic potentiation
A notable finding is that these reflexes become temporarily normal for a short period following a period of strong muscle contraction.
For example, the patient can maximally contract the quadriceps muscle for a period, then have their reflexes tested immediately afterwards, and display an improvement in the response
Treatment for LEMS
Ix for SCLC Amifampridine Immunosuppressants IV immunoglobulins Plasmapheresis
