Neurology Flashcards
Inheritance pattern of Huntington’s disease
Autosomal Dominant
Contents of the cavernous sinus
OTOMCAT: OTOM = lateral wall CA = within sinus, joining to T Occulomotor n Trochlear n Ophthalmic division of CNV Maxillary division of CNV internal Carotid artery Abducent n
Ramsay Hunt syndrome
Herpes zoster otitis - reactivation of VZV in geniculate ganglion
Ipsilateral facial paralysis, ear pain and vesicles in auditory canal
Ipsilateral facial paralysis, ear pain and vesicles in auditory canal
Ramsay Hunt syndrome
VZV reactivation in geniculate ganglion
Cause of myasthenia gravis
Antibodies to anticholine receptor at post synaptic membrane
Regulators of cerebral blood flow
Partial pressure of CO2 and O2
- hypercapnia increases flow
- hypoxia increases flow
Definition of Parkinson’s disease
Progressive neurodegenerative disorder characterised by rigidity, tremor, postural instability and bradykinesia due to a loss of dopamine in the neostriatal pathway
Pathophysiology of Parkinson’s disease
Abnormal aggregation of alpha synuclein (Lewy body constituent)
Loss of pigmented dopaminergic neurons in substantia nigra pars compacta of midbrain
-loss of DA in neostriatal pathway (esp putamen)
60% of these neurons have degenerated before clinical features develop
Clinical features of Parkinson’s disease
Tremor (resting)
Rigidity (cogwheel/leadpipe)
Akinesia/bradykinesia
Postural instability
+/- autonomic features (bowel, bladder, orthostatic dizziness)
+/- anosmia
+/- fatigue and nonspecific discomfort
+/- neuropsychiatric (anxiety, depression, sleep disruption)
Insidious onset
Parkinsonian gait features (9)
Hesitation in starting Shuffling Freezing Propulsion Retropulsion Reduced arm swing Festination (short, accelerating steps) Difficulty stoping Difficulty turning (multi point turn)
Pharmacological management options for PD
Dopamine replacement Dopamine D2 receptor agonists Combination dopaminergic/antiCh COMT inhibitors MAOB inhibitors ACh inhibitors
Dopamine replacement therapy in PD
Levo-dopa crosses BBB, converted to DA within CNS by dopa decarboxylase (DDC)
DDC inhibition to prevent L-dopa being converted in periphery
(carbidopa, benserazide) - cannot cross BBB
Standard treatment = L-dopa + peripheral DDC inhibitor
DDC inhibitors
Carbidopa, beserazide
Adverse effects of L-dopa
Nausea, vomiting
Postural hypotension
Dyskinesia
Hallucination
In long term, shorter duration of benefit and reduced efficacy as disease progresses
Benefits of L-dopa
Improves tremor, bradykinesia and rigidity
Types of dopamine D2 receptor agonists
Non-ergot derivatives: - pramipexole Ergot-derivatives: - cabergoline - pergolide - bromocriptine
Mechanism of dopamine D2 agonists in Parkinson’s disease
mimics action of DA at D2 receptors in striatum
less marked benefit than L-dopa
Benefits of D2 agonists in PD
Longer duration of action than L-dopa
Can be first-line in younger patients to delay L-dopa use OR in combination with L-dopa in late stage disease when need additional response
Adverse effects of DA D2 agonists
Nausea, vomiting
Postural hypotension
More likely to cause hallucinations and confusion than L-dopa
ergot-derivatives lead to fibrosis (especially heart valve disease)
Combined preparations for Parkinson’s
Sinemet = L-dopa + carbidopa Madopar = L-dopa + benserazide
Example of a COMT inibitor
Entacapone
Mechanism of COMT inhibitors
(catechol-O-methyltransferase - responsible for breakdown of catecholamines)
Inhibition leads to reduced peripheral breakdown of L-dopa, increasing amount delivered to CNS
Short-half life therefore administered with each dose of L-dopa
Used in late disease with “wearing off” phenomenon of L-dopa
Adverse effects of COMT inhibitors
dyskinesia
Nausea and vomiting
Dry mouth
Diarrhoea
Example of a MAOB inhibitor
selegiline
Mechanism of MAOB inhibitors in PD
inhibits MAOB - reduces breakdown of dopamine - prolongs effect of L-dopa
Used in late stage disease (wearing off phenomenon)
Adverse effects of MAOB inhibitors
Insomnia
Exaggeration of L-dopa side effects
ACh inhibition in PD
Benzotropine (e.g.)
blocks muscarinic receptors - improvement of tremor and rigidity (little effect on bradykinesia)
Mainly used in drug induced parkinsonism
Adverse effects of benzotropine
Drowsiness Confusion Restlessness Dry mouth Blurred vision Urinary retention
Drugs to consider adding to patient with PD suffering from “wearing off” phenomenon of L-dopa
MAOB inhibitor (selegiline) OR ACh inhibitor (benzotropine)
Symptoms of PD likely to respond or not to deep brain stimulation
Gait changes and freezing (especially if respond well to medications)
Severe balance problems less likely to respond to DBS
Patients in which to consider deep brain stimulation
Significant motor fluctuations difficult to control with drug therapy
Patients with early PD, who have been responding well to drugs, but having increasing difficulties threatening social/work
Definition of multiple sclerosis
A chronic autoimmune demyelinating disease of the CNS characterised by subacute neurological impairment correlated with CNS lesions separated in time and space that cannot be explained by another disease
Patterns of MS
Relapsing-Remitting (80%): relapses followed by (near)complete recovery… 50-80% will later transition to secondary progressive
Secondary progressive: progression of disability with few or no relapses
Primary progressive (20%): progression from onset of disease, typically without relapses
Pathophysiology of MS
autoimmune destruction of myelin sheaths in the CNS
Effect of pregnancy on MS
Child birth is likely to trigger a relapse/flare-up
breastfeeding offers some protection to relapse
Presentations of MS
Optic neuritis (visual blurring +/- pain)
Weakness or sensory disturbances
Incoordination, dysarthria and intention tremor
Trigeminal neuralgia
Bladder or bowel symptoms (urgency or incontinence)
Diagnosis of MS
MRI brain and spinal cord
- more than 3 lesions greater than 6mm diameter
- oval shaped
- located in periventricular area, corpus callosum and posterior fossa
- gadalonium-enhancing lesions indicate new attacks
Lumbar puncture in MS
Non-specific, rarely used if MRI positive
- lymphocytic raised WCC
- oligoclonal bands
- raised IgG/albumin index
Primary and secondary prevention of MS
Vitamin D - reduces risk of development in susceptible individuals (e.g. family history) by 70% and reduces relapse
Management of acute exacerbation for MS
high-dose IV methlyprednisolone 5 days
(followed by oral corticosteroids if optic neuritis)
Plasmapheresis sometimes indicated (ask neurologist)
Disease modifying therapy in MS
First line: IFN beta OR galatiramer
Second-line natalizumab
Fingolimod
Causes of resting tremor
Parkinson disease/syndromes
Midbrain (rubral) tremor
Wilson’s disease
Severe essential tremor
Causes of postural-action tremor
Enhanced physiological tremor Essential tremor Primary writing tremor Extrapyradimal disorders (PD, Wilson's, dystonia) Cerebellar disease Peripheral neuropathy
Causes of intention tremor
(Cerebellar outflow)
- Cerebellar disease
- Multiple sclerosis
- Midbrain stroke
- Midbrain trauma
Causes of stroke
Ischaemic - 90%
- Cardioembolic - 30%
- Artery-artery embolism (atherosclerotic plaques)
- In situ thrombosis
Haemorrhagic (10%) - SAH or ICH
- hypertensive small vessel disease
- amyloid angiopathy
- congenital vascular malformations (young people)
Haemodynamic (hypovolaemic)
- circulatory failure (hypotension, cardiac arrest)
Cerebral vein thrombosis - inc. pressure into brain due to congestion - swollen - haemorrhage
Investigations to perform in stroke
General:
- CXR
- ECG ?AF
- CBE - ?hypercoagulable state
- ESR - ? vascultis
CT MRI Diffusion weighted MRI or FLAIR Cardiac imaging (TOE) Imaging of cerebral vessels (Carotid doppler, CTA, MRA, catheter angiogram)
CT findings in stroke
Not very sensitive in first few hours
- Normally should see “cortical ribbon (line running around brain between gyri) - lost early after stroke
- Loss of grey-white differentiation
Infarction = hypodense (DARK)
Acute haemorrhage = hyperdense (WHITE)
What is a FLAIR scan and what is it’s role?
Fluid attenuation inversion recovery MRI
Shows all cerebral damage (post-traumatic, scarring, demyelination etc.)
Non specific
Does not differentiate acute from chronic ischaemia
Role of diffusion weighted imaging in stroke
MRI scan
Measures acute cytotoxic oedema
Circulation of water particules through an area of damage - accumulated in acute damage (appears bright on scan!)
Is able to differentiate acute from chronic damage
Imaging for lacunar or brainstem infarcts
MRI - much more sensitive than CT