Neurology/Neurosurgery Flashcards
What are the two types of brain injury?
Focal
Diffuse
Give examples of focal brain injuries
Contusion
Haematoma
Give an example of a diffuse brain injury
Diffuse axonal injury
What is the mechanism behind diffuse axonal injury?
Physical shearing forces following deceleration cause disruption and tearing of axons
What are contusions?
Micro-haemorrhages into brain parenchyma?
What are coup and contra-coup contusions?
Coup - adjacent to side of impact
Contra-coup - contralateral to impact
Give examples of secondary brain injury?
Cerebral oedema Ischaemia Infection Tonsillar herniation Tentorial herniation
How does the disruption of normal cerebral auto-regulatory processes following trauma affect the brain?
Renders the brain more susceptible to blood flow changes and hypoxia
What is the Cushing’s reflex?
Bradycardia and Hypertension
What is Cushing’s triad?
- Bradycardia
- Cheyne-Stokes respirations
- Widened pulse pressure
How does increased ICP activate Cushing reflex?
- As ICP increases, it becomes greater than Mean Arterial Pressure. (ICP must be less than MAP for adequate cerebral perfusion)
- This causes decreases Cerebral Perfusion Pressure
- Decreased cerebral perfusion pressure activates sympathetic system
- HTN and initially tachycardia
- HTN triggers carotid and aortic baroceptors to activate parasympathetic nervous system
- Parasympathetic leads to bradycardia
- Continually increasing ICP causes brainstem dysfunction -> Cheyne-Stokes breathing
How do you treat raised ICP?
IV Mannitol
How does mannitol work?
osmotic diuretic
What is normal ICP?
7-15mmHg in supine position
How do you calculate Cerebral perfusion pressure?
MAP - ICP
What are the symptoms of raised ICP?
Headaches Vomiting Reduced consciousness Papilloedema Cushing's reflex: - Bradycardia - Cheyne-Stokes breathing - Widened pulse pressure
How do you monitor ICP?
Invasive monitoring:
- Catheter placed into the lateral ventricles
- Catheter may also be used to collect CSF samples/drain CSF to reduce pressure
What is the cut-off used to determine if further treatment is required to reduce ICP?
> 20mmHg
How is raised ICP treated?
- Treat underlying cause
- Head elevation to 30º
- IV mannitol
- Controlled hyperventilation
- CSF removal
How does controlled hyperventilation aid in reducing CSF pressure?
Reduces PCO2 -> vasoconstriction of cerebral arteries -> reduced ICP
Why is caution needed when using controlled hyperventilation to reduce ICP?
May reduce blood flow to parts of brain which are already ischaemic
List 3 ways of removing CSF
- Drain from intraventricular monitor
- Repeated lumbar puncture (used in idiopathic intracranial hypertension)
- Ventriculoperitoneal shunt (hydrocephalus)
Where is the falx cerebri?
Fold of dura between cerebral hemispheres of brain
What structures are involved in subfalcine herniation?
Cingulate gyrus displaced beneath the falx cerebri
What is central herniation?
Downwards displacement of brain
What is transtentorial/uncal herniation?
Uncus of the temporal lobe is displaced beneath the tentorium cerebelli (tent above cerebellum)
What are the clinical consequences of transtentorial herniation?
Third nerve parasympathetic compression - ipsilateral fixed dilated pupil, looking down and out
Compression of cerebral peduncle - contralateral paralysis
What is tonsillar herniation?
Displacement of cerebellar tonsils through foramen magnum (aka coning - brainstem compression)
What are the two main causes of tonsillar herniation?
Raised ICP
Chiari malformation
What happens as a result of tonsillar herniation due to raised ICP?
Respiratory depression. Does not occur with chiari malformation
What is the calvaria?
Top part of skull
What is transcalvarial herniation?
Brain is displaced through defect in skull (eg fracture or craniotomy site)
What are the cerebral peduncles?
connect the cerebrum with spinal cord (compression causes contralateral paralysis)
Binocular vision post-facial trauma is suggestive of fracture of what? (+pain on opening mouth)
Depressed fracture of the zygomatic bone
What is the most sensitive investigation for diffuse axonal injury?
MRI brain
What are the layers of the dura?
Periosteal layer
Meningeal layer
Where does the haematoma form in a subdural haematoma?
In the potential space between the dura and the arachnoid
How do you test for each nerve root?
C5,6 pick up sticks (biceps reflex)
C7,8 lay them straight (triceps reflex)
S1,S2 buckle my shoe (ankle reflex)
L3/L4 kick the door (patellar reflex)
What nerve is at risk in a Smith’s fracture?
Median nerve
How can you test for median nerve damage following a Smiths fracture?
Thumb opposition (loss of function of the thenar eminence
Which nerves are at risk during axillary dissection (eg in mastectomy and lymph node clearance)?
Intercostobrachial - if damaged, loss of cutaneous axillary sensation
What nerve is responsible for fore-arm pronation?
Median nerve - also responsible for thumb opposition and thenar eminence muscles
What is pituitary apoplexy?
Haemorrhage in the pituitary gland - usually due to a pituitary adenoma
How does pit. apoplexy present?
Sudden onset headache, similar to SAH
Visual field defects
Evidence of pituitary insufficiency - hypoadrenalism
How are prolactinomas treated?
Cabergoline
How would hypoadrenalism present?
Caused by pituitary tumour
hyponatraemia
hypotension
How can neuroleptic malignant syndrome affect the kidneys?
Can cause AKI
- abnormal U&Es
What is the most common complication following meningitis?
Sensorineural hearing loss
When are triptans contra-indicated?
Coronary artery disease
Why are triptans contra-indicated in coronary artery disease?
Can cause vasospasm
Which vitamin in pabrinex can prevent Wernicke’s encephalopathy
B1
Which sign, if positive, points to a diagnosis other than Carpal tunnel syndrome?
Hoffmann’s sign
Which anaesthetic agents are likely to be ineffective in patients with myasthenia gravis?
Suxamethonium (Sucks in MG)
Which anaesthetic agent would you need to reduce the dose for for a patient with myasthenia gravis?
Rocuronium (Rocks in MG)
What is the best initial treatment for MG (if no myasthenic crisis)
Pyridostigmine
What happens in a myasthenic crisis?
Respiratory muscles affected - treat with IVIg and plasmapheresis
How to differentiate between chronic and acute subdural haematoma?
Acute = HYPERdense Chronic = HYPOdense
How is Bell’s palsy treated
If presented within 3 days of onset - prednisolone + artificial tears + advise eye taping at night
If not, artificial tears +advise eye taping at night
What is Lambert-Eaton syndrome?
Paraneoplastic syndrome associated with SCLC
What are the features of lambert eaton syndrome?
autonomic symptoms = dry mouth, impotence, difficulty micturating
limb-girdle weakness - waddle gait (lower limbs affected first)
hyporeflexia
How is LEMS managed?
treat cancer
immunosuppression with pred/azathioprine
3,4 diaminopyridine is trialled
IVIg and plasmapheresis may be beneficial
How to check if fluid draining from nose is CSF in basal skull fracture?
Check for glucose
What happens in Lhermitte’s sign?
parasthesiae in limbs on neck flexion
What are the most common cause of brain mets?
Lung Ca
how does acoustic neuroma present?
- sensorineural hearing loss
- vertigo
- tinnitus
- absent corneal reflex
- sense of fullness in ear
what investigations for acoustic neuroma
audiogram
MRI cerebellopontine angle
what treatment for acoustic neuroma
conservative
radiotherapy
surgery
what risks associated with treatment in acoustic neuroma
- facial nerve or vestibulocochlear nerve damage
what symptoms in bells palsy
- unilateral facial nerve paralysis (forehead affected)
- hyperacusis
- altered taste
- postauricular pain
- dry eyes
when should referral be considered in bell’s palsy
if no sign of improvement in 3 weeks ENT referral
if months - plastic surgery referral
what causes of brain abscess
- emboli from infective endocarditis
- extension of infection from middle ear/sinuses
- penetrating head injury
- trauma/injury to scalp
- neurotoxoplasmosis infection
what symptoms of brain abscess
- headache
- fever
- pressure effects - focal neuro: oculomotor/abducens nerve palsy
raised ICP features:
seizures
nausea
papilloedema
how are brain abscess managed
- surgical drainage
- IV cefotaxime and metronidazole
- dexamethasone for raised ICP
what cancers met to brain
breast skin kidney pancreas lung
what types of diabetic neuropathy
- sensory peripheral polyneuropathy
- autonomic neuropathy
- mononeuritis multiplex
- diabetic amyotrophy
what symptoms/signs of diabetic peripheral neuropathy
- glove and stocking, burning pain, pins and needles
- worse at night
- no ankle reflex
- no vibration sense
what features of ischaemic diabetic foot
- claudication and pain at rest
- trophic changes - pale pulseless hairless cold paraesthesia paralysis
- painful ulcers on heels/toes
what features of neuropathic diabetic foot
- usually painless
- high arched foot, clawed toes
- warm, bounding pulses
- painless ulcers at soles where shoes rub
what is autonomic neuropathy in diabetes
- gastroparesis - bloating, vomiting, erratic BM control
- chronic diarrhoea worse at night
- GORD (decreased LOS pressure)
- postural hypotension
- erectile dysfunction
- urinary retention/incontinence
- gustatory sweating
how can gastroparesis be treated in diabetic neuropathy
metoclopramide, domperidone or erythromycin
how can hypotension be treated in diabetic neuropathy
fludrocortisone or midodrine
what are the main side effects of valproate
teratogenic liver damage tremor weight gain curly hair drug interactions (CYP450)
what are the main side effects of carbamazepine
agranulocytosis
aplastic anaemia
CYP450 inducer
what are the main side effects of lamotrigine?
steven johnson syndrome
leukopaenia
what are the main side effects of phenytoin
folate deficiency - megaloblastic anaemia
vit D deficiency - osteopaenia
define status epilepticus
seizure lasting more than 5 minutes
more than 3 seizures in an hour
how is status treated
IV lorazepam
buccal midazolam
rectal diazepam
if established, refractory - IV phenytoin/phenobarbital
if unable to control seizure activity, induce general anaesthesia.
what differential diagnoses of essential tremor
WILSON'S DISEASE parkinson's MS Huntington's chorea hyperthyroidism fever drug induced - antipsychotics
what are the symptoms of essential tremor
symmetrical tremor affecting mainly upper limbs, head voice, worse when arms outstretched/in attempt to carry out voluntary movements
exacerbated by stress, caffeine
better with rest/alcohol
what mode of inheritance in essential tremor
autosomal dominant
what mgmt of essential tremor
- propranolol
- primidone
what happens in a third nerve palsy
eye down and out
ptosis
pupil FIXED AND DILATED
what causes lyme disease
Borrelia burgdorferi a spirochaete spread by ticks
what symptoms of lyme disease
- erythema migrans (bullseye rash)
- headache, fever, lethargy, arthralgia
- myocarditis, pericarditis, heart block
- facial nerve palsy, radiculopathy, meningitis
what investigations for lyme disease
elisa
immunoblot
what management of early lyme disease
doxycycline
what management of disseminated lyme disease
ceftriaxone
what reaction can occur after Abx treatment in lyme disease and syphilis
jarisch-herxhaimer reaction - fever, rash, tachy
what are the main umn and lmn signs
umn signs:
hypertonia, spasticity
hyperreflexia
upgoing plantars
lmn fasciculations muscle wasting hypotonia hyporeflexia downgoing plantars
how can mnd present
- mixture of umn and lmn signs
- muscle wasting (tibialis anterior, small muscles of hand)
- weakness, fatigue when exercising
- clumsiness, tripping over, dropping things
- fasciculations
- dysarthria
- no cerebellar signs
- no sensory signs
- external ocular muscles not affected
what investigations can be done for MND and what would they show?
nerve conduction - normal motor conduction
EMG - reduced number of action potentials, but higher amplitude
MRI - exclude DCM/cervical cord compression
what symptoms of MS
lethargy, uhthoff’s phenomenon
- optic neuritis
- abducens lesions:
- internuclear ophthalmoplegia
- conjugate lateral gaze disorder
- focal weakness:
- bell’s palsy
- Horner’s syndrome
- Limb paralysis
- Incontinence
- focal sensory signs
- Lhermitte’s sign - shooting pain down spine limbs on neck flexion
- trigeminal neuralgia
- numbness, paraesthesia
- ataxia: cerebellar or proprioceptive (positive Romberg)
what investigations for MS
- Contrast-enhanced MRI brain and spine
- LP for CSF - oligoclonal bands
- visual evoked potentials - delayed, but well-preserved waveform
what MRI changes in MS
- high signal hyperintense T2 lesions
- periventricular lesions
- Dawson’s fingers projecting from near the corpus callosum
how are MS relapses treated
steroids - high dose methylpred
orally or IV
what treatments for MS
beta-interferon
galatiramer acetate
natalizumab
fingolimod
what treatment for MS fatigue
amantadine
what treatment for MS spasticity
baclofen
gabapentin
what treatment for MS incontinence
- if significant residual post-void volume, intermittent self-catheterisation
- if urge incontinence - oxybutynin/tolterodine. (anticholinergics can worsen cognitive impairment)
what is oscillopsia in MS and how is it treated
visual fields appear to oscillate
treat with gabapentin
what is uhthoff’s phenomenon?
worsening of symptoms following rise in body temp (when taking a hot bath)
what is internuclear ophthalmoplegia and how does it present
lesion in the median longitudinal fasciculus (3rd, 4th, 6th CNs)
causes:
- impaired adduction of eye on same side of lesion
- horizontal nystagmus of abducting eye on contrallateral side
what is conjugated lateral gaze disorder
eye on same side of lesion unable to abduct. double vision.
explain pathophys of myasthenia gravis
- auto-antibodies against post-synaptic Ach receptors at neuromuscular junction
what symptoms of myasthenia gravis
- fatigability following repetitive movements, slow improvement with rest
- ptosis
- diplopia
- slurred speech
- weakness in chewing
- dysphagia
- proximal limb girdle, head, shoulder and neck muscles
what investigations for myasthenia gravis
- single fibre EMG
- anti-AChR antibodies
- anti-Muscle-specific tyrosine kinase antibodies
- CT thorax to exclude thymoma
- Creatinine Kinase - normal
tensilon no longer used (edrophonium) as risk arrhythmias
how is myasthenia gravis treated
- pyrodostigmine (long acting acetylcholinesterase inhibitor)
- can add immunosuppressants (pred, aza, mycophenolate mofetil)
In myasthenic crisis, plasmapharesis, IVIg
what is a myasthenic crisis?
- acute worsening of symptoms often triggered by other illness e.g. respiratory tract infection
- respiratory muscle weakness
how is myasthenic crisis treated
plasmapharesis, IVIg
needs ventilatory support, either NIV (bipap) or full intubation and ventilation
explain briefly pathophys of parkinsons
alpha synuclein deposits
loss of dopaminergic neurons in substantia nigra
what features of parkinson’s disease
asymmetrical: TRAP: tremor rigidity akinesia postural instability
- impaired olfaction
- mask like face
- flexed posture
- reduced arm swinging
- depression, dementia, psychosis, sleep disorders
- micrographia
- autonomic instability - postural hypotension
what drug classes can be used to treat parkinson’s
- levodopa (co-careldopa carbidopa (decarboxilase inhibitor) to prevent peripheral breakdown of levodopa before it reaches the brain)
- dopamine agonists
- COMT inhibitors
- MAOB inhibitors
- amantadine
list some dopamine agonists
cabergoline
bromocriptine
pergolide
ropinirole
give an example of a comt inhibitor
entacapone
list some maob inhibitors
silegiline
rasagiline
what is amantadine and how does it work in parkinsons
works against dyskinesia and rigidity
what side effects of dopamine agonists?
- cabergoline, bromocriptine
- impulse control disorders
- hallucinations
- excessive daytime sleepiness
- pulmonary/cardiac fibrosis
why must parkinsons medication not be missed?
prevent akinesia, acute dystonia, neuroleptic malignant syndrome
how should orthostatic hypotension in parkinsons be treated
midodrine
how should drooling in parkinsons be treated
glycopyrrhonium
what investigations for raised icp
- MRI/CT to find underlying cause
- invasive ICP monitor with catheter in ventricles
what treatment for raised ICP
- treat underlying cause
- raise head to 30degrees
- controlled hyperventilation
- drain CSF
- via ICP monitor
- repeated LP (idiopathic intracranial hypertension)
- ventriculoperitoneal shunt (NPH)
- IV mannitol/dexamethasone
how does controlled hyperventilation decrease ICP
decreased CO2 causes vasoconstriction of cerebral arteries therefore reduced ICP
what is LEMS
antibodies against voltage gated calcium channels in presynaptic terminal at neuromuscular junction
what symptoms of lems
- muscle weakness (improves after repetitive contractions) but then weakens again
- hyporeflexia
- hyporeflexia improves after sustained muscle contraction (post-tetanic potentiation)
- autonomic symptoms - dry mouth, difficulty micturating, impotence, blurred vision, dizziness
what investigation for LEMS
EMG - incremental response to repeated electrical stimulaiton
what treatment for LEMS
treat underlying ca (SCLC, brca, ovarian ca)
amifampridine
immunosuppressants (steroids etc.)
plasmapharesis and IVIg
which medications can exacerbate myasthenia gravis
- lithium
- suxamethonium
- penicillamine
- beta blockers
- phenytoin
- procainamide, quinidine
- Abx: gentamicin, quinolones, macrolides, tetracyclines
what treatment for neuroleptic malignant syndrome
dantrolene or bromocriptine (dopamine agonist)
what are some side effects of levodopa
dyskinesia psychosis on-off effect worsening effectiveness with time postural hypotension cardiac arrhythmias reddish discolouration of urine when standing nausea and vomiting
what staining for cryptococcus in HIV neuroinfection
india ink
