Neurology Flashcards
Define myasthenia gravis
A disorder of neuromuscular transmission characterised by: weakness and fatiguing of some or all muscle groups, weakness worsening on sustained or repeated exertion, or towards the end of the day, relieved by rest
Myasthenia Gravis pathophysiology
Autoimmune destruction of the nicotinic postsynaptic receptors for acetylcholine (AChR)
Clinical features of myasthenia gravis
Ptosis, muscle paresis, weakness of jaw muscles leaves mouth hanging open,, characteristic smile - myasthenic snarl, muscle wasting, hyperactive limb reflexes
Investigations for myasthenia gravis
Acetylcholine receptor antibodies (anti-AchR)
Anti-MUSK also
Anticholinesterase drugs used to confirm diagnosis - Tensilon test
CT of the thymus - thymic hyperplasia found in 70% of sufferers
Treatment for myasthenia gravis
Anticholinesterase durgs - Pyridostigmine
Muscarinic inhibitor - atropine to counter side effects
Prednisolone
Thymectomy
Define meningitis
Inflammation of the leptomeninges and underlying subarachnoid CSF
Risk factors for meningitis
Alcoholism, overcrowding, spinal procedures, diabetes mellitus, IV drug abuse, malignancy, cystic fibrosis
Causes of meningitis
Neonates= Gram -ve bacilli: E.coli, Klebsiella, H.influenzae Children= H.influenzae, Strep. pneumoniae, N.Meningitidis Adults= Strep. pneumoniae, H.influenzae,
Symptoms of meningitis
Fever, headache, stiff neck, photophobia, non-blanching petechial skin rash, Kernig’s sign, Brudzinski’s sign, seizures
Differential diagnoses of meningitis
Encephalitis, subarachnoid haemorrhage, malaria, septicaemia
Investigations for meningitis
LP - Ziehl-Neelsen stain, glucose, protein, rapid antigen screen,
U&Es, FBC, LFT
X-ray
CT scan
Treatment for meningitis
Dexamethasone + Ceftriaxone (E.Coli)/Benzylpenicillin (Pneumococcus + Meningococcus)
Define Guillain Barre syndrome
A disorder causing demyelination and axonal degeneration resulting in acute, ascending and progressive neuropathy, characterised by weakness, paraesthesiae and hyporeflexia
Causative organisms of Guillain Barre syndrome
CMV EBV Camplyobacter jejuni HIV Haemophilus influenzae
Risk factors for Guillain Barre syndrome
History of GI or respiratory infection, association with Zika virus, vaccinations, malignancies, pregnancy
Symptoms of Guillain Barre syndrome
Weakness - facial, dysphasia, dysarthria, back pain, reduced reflexes, paraesthesiae, hypotonia
Autonomic symptoms - reduced sweating, reduced heat tolerance, urinary hesitancy, tachycardia
Differential diagnosis for Guillain Barre
Stroke Encephalitis Spinal cord compression Vasculitis Myasthenia Gravis
Investigations for Guillain Barre
Confirmed with Nerve conduction studies
Electrolytes - inappropriate ADH secretion
LP - Elevated CSF: elevated protein, low WBC
ECG - T-wave abnormalities, ST depression, QRS widening
Spirometry
Management of Guillain Barre
IV immunoglobulin
Plasma exchange
Low molecular weight heparin
Define Parkinson’s disease
A progressive neurodegenerative condition caused by degeneration of dopaminergic neurons in the pars compacta of the substantia nigra - low levels of dopamine
Causes of Parkinson’s
Idiopathic Drugs - Neuroleptics, Metocloparide, Prochloperazine, sodium valproate Truma HIV Manganese/copper toxicity
Triad of symptoms of Parkinson’s
Bradykinesia - slowness of movement
Pill-rolling tremor
Cogwheel rigidity
Other symptoms of Parkinson’s
Constipation Frequency, urgency and incontinence Hallucinations Sweating Dribbling of saliva Weight loss Sleep problems Depression Anxiety
Main treatment for Parkinson’s
Levodopa (converted to dopamine)
Complications: Postural hypotension
On-off effect
What is levodopa given with?
Decarboxylase inhibitor - Carbidopa
Other treatments for Parkinson’s
Dopamine agonists - Ropinirole
MAO-B inhibitors - Rasagiline
COMT inhibitors - Tolcapone
How is meningitis spread?
By respiratory droplet
Define meningococcal septicaemia
Petechial rash + signs of sepsis
CSF findings in bacterial meningitis
Raised protein
Low glucose
CSF findings in viral meningitis
Normal protein
Normal glucose
Prophylaxis for meningitis
Rifampicin
Define TIA
Transient ischaemic attack
Sudden onset of neurological dysfunction which lasts less than 24 hours
TIA pathophysiology
Cerebral ischaemia due to arterial embolism or thrombosis in an atheromatous carotid, vertebral or cerebral artery
Risk factors for TIA
Smoking Hypertension Diabetes mellitus Increasing age Alcohol Previous TIA Hypercholesterolemia Vasculitis AF
Signs and symptoms of TIA
Hemiparesis, hemi sensory disturbance, dysphasa, amaurosis fugax
Define amaurosis fugax
Painless transient monocular visual loss - ‘a curtain coming down vertically into field of vision’
Leads to retinal hypoxia
Differential diagnosis for a TIA
Stroke
Hypoglycaemia
Migraine aura
Focal epilepsy
Diagnosis for TIA
ECG - check for AF or myocardial ischaemia
FBC, U&Es, glucose, ESR, LFTs, TSH
Echocardiogram or cardiac monitoring
Doppler ultrasound of the carotid arteries
How is risk of a stroke following a TIA assessed?
Use ABCD2 score
A - age >60
B - BP 140/90 or greater
C - Clinical features: unilateral weakness/speech disturbance without weakness
D - duration of symptoms: 60 minutes 2 points, 10-59 = 1 point
D - diabetes
High risk = 4+
Refer for specialist assessment within 24 hours. Low risk need assessment within 1 week
How is a TIA managed?
Control cardiovascular risk factors: stop smoking, improve diet, regular exercise, cut down on alcohol, lose weight Manage AF, diabetes, hypertension Aspirin Antiplatelet therapy - clopidogrel Statin - simvastatin
Define stroke
Disruption of blood to the brain lasting for more than 24 hours
Pathophysiology of a stroke
May be due to a blockage in a cerebral blood vessel leading to ischaemic infarction (70%) or due to a intracerebral haemorrhage (30%)
Causes of a stroke
Small vessel occlusion/thrombosis Cardiac emboli (AF, MI, IE) Atherothromboembolism CNS bleeds (trauma, SAH) Coronary artery dissecton Vasculitis Hyperviscosity (polycythaemia, sickle cell anaemia, myeloma)
Risk factors for a stroke
Diabetes mellitus Hypertension AF Smoker Alcohol Increasing age Previous TIA Hypercholesterolemia
Signs and symptoms of a stroke
Total anterior circulation stroke = Unilateral weakness of face, arm and leg, homonymous hemianopia, higher cerebral dysfunction (dysphagia, visuospatial disorder) Partial anterior circulation stroke: 2 of the 3 above Posterior circulation syndrome = cerebellar or brainstem syndromes, loss of consciousness, isolated homonymous hemianopia Lacunar syndrome (LACS) = unilateral weakness, pure sensory loss, ataxic hemiparesis
Diagnosis of a stroke
Urgent CT head
MRI
BP/ECG, blood glucose
Management of a stroke
ABCDE approach
Ensure hydration, keep O2 saturation >95%
Thrombolysis for ischaemic stroke = Alteplase
Antiplatelet therapy - Clopidogrel
MDT team
Define primary prevention
Risk factor control before any stroke
Define secondary prevention
Risk factor control to prevent recurrence of a stroke including lifelong antiplatelet
Define Subarachnoid haemorrhage
Bleeding into the subarachnoid space - between the arachnoid layer of the meninges and the brain parenchyma
Risk factors for a subarachnoid haemorrhage
Hypertension
Family history
Diseases which predispose to aneurysms - Polycystic kidney disease, Ehlers Danlos syndrome, coarcation of the aorta
Pathophysiology of a subarachnoid haemorrhage
Rupture of a berry aneurysm (70%), 10% are due to an ateriovenous malformation
Signs and symptoms of a subarachnoid haemorrhage
Thunder clap headache, vomiting, Kernig’s sign, neck stiffness, altered level of consciousness - drowsiness, collapse, seizures, coma, papilloedema
Diagnosis of a subarachnoid haemorrhage
CT scan
Lumbar puncture - blood xanthochromic (yellow) due to billirubin from Hb breakdown
Management of a subarachnoid haemorrhage
Dexamethasone to decrease cerebral oedema
Neurosurgery - surgical clipping or coiling of anuerysm
Nimodipine to reduce risk of vasospasm
Complications of subarachnoid haemorrhage
Rebleeding
Hydrocephalus
Hyponatraemia (SIADH)
Cerebral ischaemia due to vasospasm
Define subdural haematoma
A collection of clotting blood in the subdural space (space between the dura mater and the arachnoid mater)
Pathophysiology of subdural haematoma
Due to a rupture of a vein between the venous sinuses and the cortex, the accumulating haematoma causes raised ICP, shifting the midline structures
Risk factors for subdural haematoma
Traumatic head injury
Increasing age
Alcoholism
Anticoagulation medications
Signs and symptoms for subdural haematoma
Raised ICP - headache, nausea, vomiting, raised BP Confusion Seizure Focal neurology Alternating level of consciousness