Neuroscience Flashcards
What types of fibres are carried by the spinal nerves?
somatic motor and somatic sensory fibres
sympathetic fibres
What is the effect of lesions in the dorsal column pathway?
ipsilateral loss of/impaired fine touch and proprioception
What is the effect of lesions in the spinothalamic tract?
contralateral loss of/impaired pain and temperature sensation
What is a dermatome?
area of skin supplied by a single spinal nerve
What is a myotome?
muscles supplied by a single spinal nerve
What are the tests for CN II?
visual acuity - snellen chart, read through a pinhole
visual fields
fundoscopy
pupillary light reflex
colour vision (Ishihara plates)
What are the investigations for CN III damage?
look for ptosis (drooping eyelid)
eye movements (MR, SR, IR, IO)
pupillary light reflex (parasympathetic)
WHat is the test for CN IV function?
ask patient to look medially and down
What is the test for the abducens nerve (CN VI)?
ask patient to abduct their eye
(if affected there will be medial deviation due to LR paralysis)
What are the tests for the trigeminal nerve (CN V)?
facial sensation
corneal reflex (touching the cornea–> blinking)
facial muscles - check for wasting,
What are the tests for the facial nerve (CN VII)?
taste anterior 2/3
muscles of facial expression
What are the tests for the vestibulocochlear nerve (CN VIII)?
hearing (Gross hearing test, Rinne’s test, Weber’s test)
balance, gait (Vestibular testing)
caloric test
What are the tests for the glossopharyngeal nerve (CN IX)?
taste posterior 1/3 of tongue
gag reflex
What are the test for the vagus nerve (CN X)?
hoarseness of the voice? Unilateral vocal cord paralysis.
Difficulty swallowing?
Gag reflex: Light touch to the back of the pharynx (afferents = CN IX; efferents = CN X). Look for reflex contraction / elevation of the palate.
Unilateral lesion of X = palate and uvula deviate away from the side of the lesion (towards the normal side).
What are the tests for acessory nerve function? (CN XI)
test sternocleidomastoid (patient turns their head against resistance)
test trapezius (look for symmtery - atrophy?) - shrug shoulders
What is the test for the hypoglossal nerve? (CN XII)
tongue deviation (patient sticks out tongue - look for atrophy)
What are the 3 symptoms of meningism?
neck stiffness
photophobia
severe headache
What are the common bacterial causes of meningism in neonates?
E. coli
Group B streptococcus
Listeria monocytogenes
What are the common causes of bacterial meningitis in infants?
Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumoniae
What are the common causes of bacterial meningitis in young adults?
Neisseria meningitidis
Streptococcus pneumoniae
What are the common causes of bacterial meningitis in the elderly?
Streptococcus pneumoniae
Neisseria meningitidis
Listeria monocytogenes
What % of meningitis cases are caused by viruses?
80%
Which viruses can cause meningitis?
enteroviruses (echo virus, coxsackie virus)
herpes simplex virus
mumps virus
lymphocytic chorio meningitis virus
historically poliovirus
What is meningitis?
inflammation of the meninges
What are the fungal causes of meningitis?
cryptococcus, histoplasma, blastomyces
What are the risk factors for meningitis?
extremes of age
immunnocompromised
non-vaccination
crowding
exposure to pathogens
cranial anatomical defects
cochlear implants
sickle cell disease (due to impaired splenic function)
What is the pathophysiology of bacterial meningitis?
- bacteria reach the CNS by haematogenous or contiguous spread and colonise the arachnoid space
- bacterial components in the CSF induce the production of various inflammatory mediators
- this leads to an influx of leukocytes into the CSF
- the inflammatory cascade leads to cerebral oedema and increased ICP
- result is neurological damage and even death
What are the key presentations of meningitis?
meningism
fever
altered consciousness
seizures
What are the signs of meningitis?
non-blanching rash in children (meningococcal septicaemia)
Kernig sign (can’t extend knee when hip is flexed without pain)
Brudzinski sign (when neck is flexed, knees + hips automatically flexed)
What non-specific signs of meningitis can neonates present with?
hypotonia
poor feeding
lethargy
hypothermia
bulging fontanelle
What are the investigations for meningitis?
lumbar puncture + CSF analysis (sample taken from L3/4)
What is the mortality rate of treated bacterial meningitis?
5%
What are the bacterial causes of acute meningitis\?
Neisseria meningitidis (gram negative diplococci)
Strep. pneumoniae (gram positive diplococci)
Listeria spp. (gram positive rod)
Group B Strep (gram positive cocci)
Haemophilus influenzae B (gram negative rod)
E.coli (gram negative rod)
What are the bacterial causes of chronic meningitis
Mycobacterium tuberculosis (TB) (Phenol-auramine)
Syphilis §
What is the management for bacterial meningitis?
ceftriaxone/cefotaxime (3rd gen. cephalosporin)
+ steroids (dexamethasone)
What is the management for viral meningitis?
none if enteroviral cause
Aciclovir if cause is HSV or VZV
What is the management for fungal meningitis?
long course, high dose antifungals (e.g. fluconazole)
What is encephalitis?
inflammation of the cerebral cortex
What is it called when a patient has symptoms of encephalitis + meningism?
meningo-encephalitis
Which viruses can cause encephalitis?
Herpes simplex
varicella zoster
parvoviruses
HIV
mumps
measles
What are the risk factors for encephalitis?
immunocompromised
extremes of age
vaccination
post-infection
organ transplantation
animal or insect bites
location (e.g. increased risk of exposure to malaria, ebola, trypanosomiasis)
What is the pathophysiology of encephalitis?
in viral encephalitis the virus gains entry and replicates in local or regional tissue, such as the GI tract to skin and then disseminates to the CNS via haematogenous routes (enterovirus, HSV, HIV, mumps) or retrograde axonal transport (herpes virus, rabies)
Which part of the brain is most commonly affected by encephalitis? How does it present?
temporal lobe, presents with aphasia
What are the key presentations of encephalitis?
fever
headache
focal neurology
altered cognition/consciousness
focal seizures
rash
lethargy and fatigue
What are the investigations for encephalitis?
lumbar puncture + CSF analysis (viral PCR testing)
MRI head (GS)
EEG recroding
swabs
HIV testing
What is the management for encephalitis?
aciclovir
What are the complications of encephalitis?
lasting fatigue and prolonger recovery
change in mood/personality
changes to memory and cognition
chronic pain
What is the definition of a stroke?
acute neurological deficit lasting more than 24hrs of cerebrovascular cause
What percentage of strokes are ischaemic/haemorrhagic?
Ischaemic - 80%
Haemorrhagic - 20%
What are the pathological subtypes of ischaemic strokes?
large vessel disease (50%)
small vessel disease (25%)
cardioembolic (20%)
cryptogenic/rarities (5%)
What is the TOAST classification for types of ischaemic stroke?
1) large-artery atherosclerosis
2) cardioembolism
3) small-vessel occlusion
4) stroke of other determined etiology
5) stroke of undetermined etiology
What are the pathological subtypes of haemorrhagic stroke?
primary intracerebral haemorrhage
subarachnoid haemorrhage
What are the causes of ischaemic stroke?
thrombus formation or embolus
atherosclerosis
shock
vasculitis
What are the causes of haemorrhagic stroke?
trauma
hypertension
berry aneurysm rupture
What are the risk factors for stroke?
CVD
previous stroke or TIA
atrial fibrillation
carotid artery disease
hypertension
diabetes
smoking
vasculitis
thrombophilia
combined contraceptive pill
over 55 years
FHx
What is the pathophysiology of ischaemic stroke?
blood supply in a cerebral vascular territory is critically reduced due to occlusion or critical stenosis of a cerebral artery
What is the pathophysiology of haemorrhagic stroke?
cerebral vascular rupture causes bleeding into the brain parenchyma resulting in a primary mechanical injury to the brain tissue
What are the key presentations for stroke?
unilateral sudden onset of:
weakness of limbs
facial weakness
onset dysphagia
visual or sensory loss
headache
What is the FAST acronym for stroke recognition?
F-face
A - arm
S - speech
T - time (act fast and call 999)
What are the investigations for stroke?
Non-contrast CT head
Bloods - serum glucose, electrolytes, U+Es, cardiac enymes, FBC
ECG
PT and aPTT
carotid doppler
ECHO
CT or MR angiogram
What is the ROSIER tool?
Recognition Of Stroke In the Emergency Room
What are the differential diagnoses for stroke?
hypoglycaemia
hypertensive encephalopathy
TIA
What is the management for ischaemic stroke?
Thombolysis with alteplase
Thrombectomy (mechanical removal of clot)
What is the management for haemorrhagic stroke?
IV mannitol for ↑ICP
What is the secondary prevention for stroke?
clopidogrel 75mg OS
atorvastatin 80mg
carotid endarterectomy or stenting in patients with carotid artery disease
What is the action of alteplase?
A tissue plasminogen activator which rapidly breaks down clots and can reserve stroke effects if given in time
What is the definition of TIA?
Transient ischaemic stroke - an episode of neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia without acute infarction
What is a crescendo TIA?
2 or more strokes in one week, carries very high risk of developing into a stroke
What are the causes of TIAs?
carotid thrombo-emboli (29%)
small-vessel occlusion (16%)
in situ thrombosis of intracranial artery-to-artery embolism of thrombus as a result of stenosis or unstable atherosclerotic plaque (16%)
What are the risk factors for TIA?
AF
valvular disease
carotid stenosis
congestive heart failure
hypertension
diabetes mellitus
smoking
alcohol abuse
advanced age
What are the key presentations of TIAs?
sudden onset and brief duration of symptoms
unilateral weakness of paralysis
dysphagia
ataxia, vertigo or loss of balance
amaurosis fugax
homonymous hemianopia
diplopia
What are the investigations for TIAs
Often clinical diagnosis
blood glucose, FBC, platelets, PT, INR, lipids, electrolytes, ECG
What are the differential diagnoses for TIA?
stroke
hypoglycaemia
seizure
complex migraine
What is the management for TIA
aspirin 300mg daily
secondary prevention for CVD/stroke
What is a subarachnoid haemorrhage?
rapidly developing signs of neurological dysfunction and/or headaches due to bleeding into the subarachnoid space
What are the causes of subarachnoid haemorrhage
MC: berry aneurysm rupture in the circle of willis
trauma
What are the risk factors for subarachnoid haemorrhage?
hypertension
smoking
family history
Autosomal dominant polycystic kidney disease (ADPKD)
alcohol /drug use
Marfan
Ehlers-danlos syndrome
Pseudoxanthoma elasticum (connective tissue disorder)
Neurofibromatosis type I
What are the key presentations for subarachnoid haemorrhage?
severe sudden onset headache
Kernig sign (cant extend leg when knee is flexed)
Brudzinski sign (knees automatically flex when neck is elevated)
Depressed consciousness/loss of consciousness
Nerve palsies CN III/VI (III - fixed dilated pupil, VI - non-specific signs of ↑ICP)
neck stiffness and muscle aches
eyelid, drooping, diplopia with mydriasis, orbital pain
What are the investigations for subarachnoid haemorrhage?
CT head (star shape bleed)
If CT head is indicative –> CT angiogram
If CT head is uncelar –> lumbar puncture (xanthochromia)
What is the management for subarachnoid haemorrhage?
1st line = neurosurgery (endovascular coiling)
+ Nimodipine (CCB, ↓vasospasm + ↓BP)
What are the causes of subdural haemorrhage?
caused by rupture of a bridging vein
often due to deceleration injuries
also seen in abused children (e.g. shaken baby syndrome)
What are the risk factors for subdural haemorrhage
trauma
child abuse
cortical atrophy (e.g. dementia)
coagulopathy
anticoagulant use
advanced age (65+)
What is the pathophysiology of subdural haemorrhage
typically result from torsional or shear forces causing disruption of bridging cortical veins emptying into dural venous sinuses
What are the key presentations of subdural haemorrhage
gradual onset with latent period –> small amount of bleeding which accumulates over time + autolysis of blood –> symptoms after days/weeks/months
What are the signs of ↑ICP?
Cushing’s triad: bradycardia, increased pulse pressure, irregular breathing + fluctuating GCS + papilloderma
What are the symptoms of subdural haemorrhage?
nausea/vomiting
headache
diminished eye/verbal/motor responses
confusion
What is the investigation for subdural haemorrhage/
NCCT head (banana, crescent-shaped haematuria)
What is the management for subdural haemorrhage?
sugery: burr hole + craniotomy
IV mannitol to ↓ICP
What is an extradural haemorrhage?
an acute haemorrhage between the dura mater and inner surface of the skull
What is the aetiology of extradural haemorrhage?
most commonly caused by skull trauma in the temporoparietal region, typically following a fall, assault or sporting injury
can also occur secondary to vein rupture, arteriovenous abnormalities or bleeding disorders
What are the risk factors for extradural haemorrhage?
head trauma
age 20-30yrs
What are the key presentations of extradural haemorrhage?
reduced GCS (with lucid interval intially)
headaches
vomiting
confusion
seizures
pupil dilation
What is the gold standard investigation for extradural haemorrhage?
NCCT (lemon/lens shaped haematoma)
What is the management for extradural haemrorrhage?
Urgent surgery (craniotomy + vessel ligation)
IV mannitol to ↓ICP
What are the differentials for extradural haemorrhage?
epilepsy
carotid dissection
carbon monoxide poisoning
subdural haematoma
subarachnoid haemorrhage
What is amaurosis fugax?
also known as retinal transient ischaemic attack
= a sudden, short-term, painless loss of vision in one eye
What are the causes of amaurosis fugax
stenosis or occlusion of internal carotid artery or central retinal artery
inflammation of optic nerve or nervous system
giant cell arteritis in individuals >60yrs old
What is multiple sclerosis?
chronic and progressive neurological disorder caused by demyelination of the myelinated neurons in the CNS
What are the types of MS?
Relapsing-remitting = symptoms then incomplete recovery then symptoms return
Primary progressive = gradual deterioration without recovery
Secondary progressive = relapsing remitting –> primary progressive (around 75% of RR cases evolve to this)
What is the aetiology of MS?
unclear but thought to be a combination of:
- multiple genes
- Epstein-Barr virus
- Low vitamin D
- Smoking
- Obesity
What are the risk factors for MS?
female
20-40yrs
autoimmune disease
FHx
EBV
vitamin D deficiency
What is the pathophysiology of MS?
Inflammation around the myelin covering nerves in the CNS and infiltration of immune cells causes damage to the myelin and affects the way the electrical signals travel along the nerves
What are the key presentations of MS?
optic neuritis (mc)
eye movement abnormalities (double vision, internuclear ophthalmoplegia, conjugate lateral gaze disorder)
focal weakness (Bell’s palsy, Horner’s syndrome, limb paralysis, incontinence)
focal sensory symptoms (trigeminal neuralgia, numbness, paraesthesia, Lhermitte’s sign)
ataxia (sensory or cerebellar)
What are the atypical symptoms of MS?
aphasia, hemianopia, extrapyramindal movement disorders, severe muscle wasting, muscle fasciculation
What are the investigations for MS?
McDonald criteria (2 attacks disseminated in time (separate events) + space (different parts of CNS affected)
MRI scan (GS)
What is the management for MS?
acutely (during symptomatic episodes) –> IV methylprednisolone
patient education
prophylaxis –> B interferon (DMARDs, biologic therapies)
What is the epidemiology of MS?
More common in women
20-40 most common age for diagnosis
More common in white
More common in northern latitudes
Symptoms will improve in pregnancy and post-partum period
What is Uhthoff’s phenomenon?
worsening of MS symptoms following a rise in temperature, such as a hot bath
What is optic neuritis?
demyelination of the optic nerve which presents with:
- unilateral reduced vision
- central scotoma
- pain on eye movement
- impaired colour vision (red)
What is the McDonald criteria based on ?
2 or more relapses and either:
- objective evidence of two or more lesions
- objective evidence of one and a reasonable history of a previous relapse
‘objective evidence’ = abnormality on neurological exam, MRI or visual evoked potentials
What is used to treat a MS relapse?
oral or IV prednisolone
plasma exchange: to remove disease-causing antibodies
What is used for maintenance of MS?
flare ups - IV methylprednisolone
DMARDs - ocrelizumab
Beta-interferon - decreases the level of inflammatory cytokines
Monoclonal antibodies
Glatiramer acetate (immunomodulator)
Fingolimod
What are the stroke symptoms from anterior circulation strokes?
either hemisphere:
hemiparesis
hemisensory loss
visual field defect
dominant hemisphere (usually left)
language dysfunction
- expressive dysphasia
- receptive dysphasia
- dyslexia
- dysgraphia (inability to write)
non-dominant hemisphere
anosognosia (impaired ability to comprehend illness)
- neglect of paralysed limb
- denial of weakness
visuospatial dysfunction
- geographical agnosia
- dressing apraxia
- contructional apraxia
What are the posterior circulation symptoms of stroke?
- unsteadiness
- visual disturbance
- slurred speech
- headache
- vomiting
- others e.g. memory loss, confusion
What are some examples of stroke mimics?
epileptic seizure
space occupying lesion (subdural, tumour, arteriovenous malformation)
infection
metabolic (e.g. hyponatraemia/hypoglycaemia/alcohol/drugs)
multiple sclerosis
functional neurological disorder (FND)
migraine
What is the most common cause of ischaemic strokes in under 45 yr olds?
carotid or vertebral dissection
What is a primary intracerebral haemorrhage (PICH)?
leakage of blood directly into brain tissue due to :
- hypertension (weakens deep perforating blood vessels)
- amyloidosis
- arteriovenous malformation
- aneurysm rupture
What are the causes of secondary intracerebral haemorrhages? Are they classed as strokes?
trauma
warfarin
bleeding into a tumour
Not classed as strokes but can cause similar symptoms
WHat are the eligibility criteria for mechanical thrombectomy?
previously independent (MRS <3 able to walk unaided)
large proximal arterial occlusion (internal carotid or M1 or proximal M2)
procedure can be achieved within 6 hours of onset (or up to 24hrs if sufficient penumbra on CT perfusion imaging)
What are the eligibility criteria for mechanical thrombectomy?
previously independent (MRS <3 able to walk unaided)
large proximal arterial occlusion (internal carotid or M1 or proximal M2)
procedure can be achieved within 6 hours of onset (or up to 24hrs if sufficient penumbra on CT perfusion imaging)
What is a primary brain tumour?
abnormal growth originating from cells within the brain (gliomas, germ cell tumours, meninigiomas)
What is the incidence of brain tumours?
18 per 100,000
What percentage of brain tumours are malignant?
55%
What is the aetiology of brain tumours?
majority no cause found
ionising radiation
5% family history (associated genetic syndromes (neurofibromatosis, tuberose sclerosis, Von Hippel-Lindau disease)
immunosuppression
What are the risk factors for brain tumours?
ionising radiation
FHx
other cancer
immunosuppression
older age
obesity
What are the prognostic factors for low grade gliomas?
histology type
age
size of tumour
rate of growth
location
cross midline
presenting features
performance status
What is the median age for low grade glioma diagnosis?
35 yrs old
What is the average survival length for low grade glioma patients?
10 yrs
What is the most common type of brain cancer/
High grade glioma (85% of all new cases of malignant primary brain tumour)
What are the red flags for brain tumour?
headache + features of raised ICP and/or focal neurology
new onset focal seizure
rapidly progressive focal neurology
past history of other cancer
What is the prognosis for high grade lymphoma?
6 months (no treatment)
18 months (with treatment)
What is the median survival for low grade lymphoma?
10 years with early treatment
What is a glioblastoma multiforme?
a grade IV glioma, which is a fast-growing and aggressive brain tumour
What are the types of glioblastoma
multifocal - can be seen to have multiple areas of high grade cancerous formations joined together by other abnormal brain tissue (2-20% of all glioblastomas)
multicentric - more than one GBM tumour that has arisen in the brain at the same time, or within a very short timeframe which have normal brain tissue between them
What are the key presentations of brain tumours?
Wide variation depending on tumour type, grade and site
Headache (woken by headache, worse in the morning, associated with N/V, exacerbated by coughing, sneezing, drowsiness)
Seizures
Focal neurological symptoms (symptoms specific to site in the brain e.g. loss of right arm motor function due to damage to left side motor cortex) - hemiparesis, hemisensory loss, visual field defect, dysphasia
Other non-focal symptoms (personality change/behaviour, memory disturbance, confusion)
Signs of ↑ICP - altered mental state, visual field defects, seizures, unilateral ptosis, 3rd and 6th nerve palsies, papilloedema (on fundoscopy)
How can low grade and high grade brain tumours be differentiated clinically?
low grade - typically present with sezures (can be incidental finding)
high grade - rapidly progressive neurological deficit + symptoms of raised intracranial pressure
What are the investigations for brain tumours?
1st line - contrast CT
GS - MRI
other - functional MRI
What is the management for high grade brain tumours?
Steroids - reduce oedema
Palliative care
Chemotherapy - temozolamide, PCV
Radiotherapy - mainstay, radical vs palliative
Surgery - biopsy or resection
What is the management for low grade brain tumour?
Surgery - early resection
Radiotherapy and early chemotherapy
What is the grading for brain tumours?
1: slow growing, non-malignant, and associated with long-term survival
2 - have cytological atypia. These tumours are slow growing but recur as higher-grade tumours
3 - have anaplasia and mitotic activity. These tumours are malignant
4 - anaplasia, mitotic activity with microvascular proliferation, and/or necrosis. These tumours reproduce rapidly and are very aggressive malignant tumours.
What is the action of sodium valproate in epilepsy treatment?
increases the activity of GABA which has a relaxant affect on the brain by stopping the release of excitatory neurotransmitters
What is status epilepticus?
medical emergency defined as seizures lasting more than 5 minutes or more than 3 seizures in one hour