Neurology Flashcards
Describe the corticospinal tracts
Descending pathway for motor control
Located in the white mater of the spinal cord, laterally or ventrally (anterior)
The UMN travels from the primary motor cortex through the internal capsule, the 85% of the fibres decussate at the medulla to from the lateral corticospinal tract (remainder form the ventral tract)
They synapse with the LMN in the ventral grey horn and the axons leave in the spinal nerve
What does a lesion of the corticospinal tract cause?
Ipsilateral weakness of muscles
Describe the dorsal column pathway
An ascending tract for touch, proprioception, and vibration
Located in the dorsal white matter of the spinal cord
The cuneate fasciculus (more lateral) carries information from the upper limbs, and the gracile fasciculus (more medial) carries information from the lower limbs
Primary sensory neurons ascend in the ipsilateral dorsal columns and synapse with the 2nd neuron at the cuneate/gracile nucleus (in medulla)
The 2nd neuron decussates in the medulla then ascends to the thalamus, where is synapses with the 3rd neuron, which then projects to the somatosensory cortex
What does a lesion of the dorsal column pathway cause?
Ipsilateral impairment/loss of fine touch, proprioception, and vibration
Describe the spinothalamic tract
An ascending tract for pain and temperature
Located in the ventrolateral white matter of the spinal cord
The primary sensory neuron synapses with the 2nd neuron in the grey horn, and this decussates then ascends
It synapses with the 3rd neuron in the thalamus which then projects to the somatosensory cortex
What does a lesion in the spinothalamic tract cause?
Contralateral impairment/loss of pain and temperature sensation
Define cerebrovascular event (stroke)
A clinical syndrome caused by disruption of blood supply to the brain (due to infarction or haemorrhage), characterised by rapidly developing signs of focal or global disturbance of cerebral functions, lasting for more than 24 hours or leading to death
Define ischemic stroke
An episode of neurological dysfunction caused by focal cerebral, spinal, or retinal infarction (cell death due to lack of blood supply)
What are the 5 types of ischemic stroke?
Large vessel disease (atherosclerosis/thrombosis)
Small vessel disease (microathermoma, lacunes)
Cardioembolic (caused by AF, endocarditis, mural thrombus)
Other (rare causes e.g. vasculitis, venous thrombosis, carotid dissection)
Undefined
Define stroke due to primary intracerebral haemorrhage
Rapidly developing clinical signs of neurological dysfunction because of a focal collection of blood within the brain parenchyma or ventricular system, which is not caused by trauma
*secondary intracerebral haemorrhage = due to trauma, blood thinners etc.
Define stroke due to subarachnoid haemorrhage
Rapidly developing signs of neurological dysfunction and/or headache (thunderclap) because of bleeding into the subarachnoid space, which is not caused by trauma
What are the risk factors for strokes?
Lifestyle factors:
- smoking
- alcohol misuse
- physical inactivity
- poor diet
Established CVD:
- hypertension
- AF
- infective endocarditis
- IHD
- congestive heart failure
- structural defects
Other medical conditions:
- migraine
- hyperlipidaemia
- diabetes mellitus
- hypercoagulable disorders
- connective tissue disorders
Non-modifiable factors:
- older age
- male sex
- personal/family history of stroke/TIA
- lower level of education
What are the signs/symptoms of a stroke in the anterior circulation?
Either hemisphere (symptoms contralateral):
- hemiparesis (upper limb = MCA, lower limb = ACA)
- hemisensory loss (upper limb = MCA, lower limb = ACA)
- visual field defect
Dominant hemisphere (usually LEFT hemisphere)
- language dysfunction (expressive/receptive dysphasia, dyslexia, dysgraphia)
Non-dominant hemisphere (usually RIGHT hemisphere)
- visuospatial dysfunction (geographical agnosia, dressing apraxia, constructional apraxia)
- anosognosia (impaired understanding of their illness, neglect of paralysed limb, denial of weakness)
What are the signs/symptoms of a stroke in the posterior circulation?
Unsteadiness
Visual disturbance
Slurred speech
Disorder of perception
Headache
Vomiting
Others e.g. memory loss, confusion
What investigations are needed for a stroke?
CT head (1ST LINE, without contrast, ideally within 1 hour)
MRI brain with diffusion weighted imaging (GOLDSTANDARD)
Blood tests (FBC, U&E, ESR, TFTs, glucose, lipids to asses general health and exclude other causes)
ECG (look for arrhythmias and cardiac causes)
ECHO (may show mural thrombus, valvular lesions)
Carotid Doppler ultrasound, or CT/MRI angiogram (asses carotid artery stenosis)
What are the treatments for an ischemic stroke?
ABCDE
Oxygen as needed
Maintain blood pressure and glucose
Antiplatelets (e.g. aspirin) - only once haemorrhagic stroke is ruled out
Thrombolysis - only within 4.5 hours of onset, and if haemorrhagic stroke is ruled out, most effective in 1st 90 mins
Thrombectomy - for larger arterial occlusions
What is the primary prevention for strokes?
Control risk factors:
- asses and treat hypertension, DM, hyperlipidaemia, cardiac disease
- smoking cessation
- exercise
Long term anticoagulants
- e.g. warfarin/DOAC
- in AF or prosthetic heart valves
What is the secondary prevention for a stroke?
Antiplatelets: short-term = aspirin, long-term = clopidogrel
Anticoagulants if cardiac cause (warfarin/DOAC)
Investigate and treat risk factors: hypertension, hyperlipidaemia, cardiac disease, carotid artery stenosis, etc.
Define TIA
Transient ischemic attack:
Transient (less than 24 hours) neurological dysfunction caused by focal cerebral, spinal, or retinal infarction
What are the signs/symptoms of TIA?
*symptoms come on suddenly and usually resolve after 1 hour but can persist up to 24 hours
Focal neurological defects:
- unilateral weakness/sensory loss
- dysphasia
- ataxia, vertigo, loss of balance
Cranial nerve defects
Amaurosis fugax (sudden transient loss of vision in one eye
What are the treatments for a TIA?
Control cardiovascular risk factors (blood pressure, lipids, glucose)
Antiplatelets: short-term aspirin, long-term (secondary-prevention) = clopidogrel
Anticoagulants (warfarin/DOAC) is cardiac cause
Carotid endarterectomy (reduce stenosis)
How is the risk of having a stroke after a TIA assessed
ABCD2 =
Age (>60)
Blood pressure (>140/90)
Clinical features (weakness, speech disturbance)
Duration of symptoms
Diabetes
Higher score = higher risk = urgent referral
Describe the epidemiology of brain tumours
Mostly affects younger patients
55% malignant
How are brain tumours categorised?
Cell type: gliomas (most common - e.g. astrocytoma, ependymoma, oligodendrocytoma)
Location: meninges, sellar region, germ cell tumours (pituitary/pineal region)
Cranial nerve involvement (schwannoma)
Secondary/metastatic
Molecular markers
Genetic factors
Describe the grades of brain tumour
Grade 1: slow growing, non-malignant, and associated with long-term survival
Grade 2: have cytological atypia, slow growing but recur as higher-grade tumours
Grade 3: malignant, have anaplasia and mitotic activity
Grade 4: aggressive malignant tumours, reproduce rapidly, anaplasia, mitotic activity with microvascular proliferation
What are the causes of brain tumours?
Majority no cause found
Ionising radiation
5% family history (associated genetic syndromes)
Immunosuppression (increased risk of CNS lymphoma)
What are the signs/symptoms of brain tumours?
Varied - depends on tumour type, grade and site
Headache (due to raised intracranial pressure)
Seizures (new onset)
Focal neurological symptoms (e.g. limb weakness, sensory loss, visual/speech disturbances, ataxia)
Other non-focal symptoms (e.g. behavioural/cognitive change)
What are the red flags for brain tumours?
Headache + other symptoms
New/changed headache
Headache always on one side
New onset focal seizure
Rapidly progressive focal neurology
Previous history of cancer
What investigations are needed for brain tumours?
CT (1st line, with contrast)
MRI (better detail especially for pituitary lesions)
Functional MRI
Biopsy
What are the treatments for brain cancer?
Depends on tumour type, grade and site
Treatment is non-curative (except for grade I)
High grade:
- steroids - reduces oedema
- surgery - biopsy, relief of raised ICP, debulking for radiotherapy, resection
- chemotherapy + radiotherapy
Low grade:
- early surgery
- early radiotherapy + chemotherapy
Define epileptic seizures
Paroxysmal event in which changes of
behaviour, sensation or cognitive processes are caused by excessive, hypersynchronous neuronal discharges in the brain
Define epilepsy
A chronic neurological disorder of recurrent epileptic seizures
Describe the epidemiology of epilepsy
Affects 1 in 100 (UK)
Highest risk are infants and over 50s
What are the causes of epilepsy?
Idiopathic (2/3)
Structural abnormalities (developmental, or after injury/stroke/infection)
Genetic mutation
Space occupying lesion
What are the characteristics of an epileptic seizure?
Vary varied depending on the type of seizure
Duration: 30-120s
“Positive” ictal symptoms (during in seizures, e.g. excessive limb movements)
“Negative” postictal symptoms (after seizure, paralysis, amnesia)
May occur from sleep
May be associated with other brain dysfunction
Patients can have different types of seizures, but these will stay the same
Describe focal epileptic seizures
Originating from one hemisphere, associated with structural damage
Focal aware seizures: consciousness is not impaired, no post-ictal symptoms
Focal impaired awareness: consciousness is impaired, most commonly in temporal lobe which causes post-ictal confusion
Focal to bilateral convulsive seizure: occurs in 2/3 of patients, electrical disturbance starts focally and spreads widely causing a generalised seizure
Describe generalised epileptic seizures
Electrical disturbance rapidly affecting both hemispheres, with no associated structural abnormality
Tonic-clonic seizures: muscle stiffening (tonic), then jerking (clonic), lasting <5mins, LOC, post-ictal confusion/drowsiness
Absence seizures: brief pauses (<10s) in activity, can happen in clusters, worse with coming in/out of sleep, presents in childhood
Myoclonic seizures: sudden jerking of limb, face and/of trunk, can be thrown to floor but can get up straight away
Tonic seizures: all muscles stiffen, may cause fall, extended neck, open eyes, stop breathing
Atonic seizures: all muscles relax, may cause falls, head drops forwards, knees sag, but no LOC, muscle tone returns quickly after
What investigations are needed for epilepsy?
Look for risk factors and provoking cause
EEG (records electrical activity, can’t exclude diagnosis, can be false +ve in syncope)
MRI (look for structural causes)
ECG (rule out cardiac conditions mimicking epileptic seizures)
Lumbar puncture (if infection is suspected)
Neuropsychiatric assessment
Genetic testing
What are the treatments for epilepsy?
Anti-seizure medication (ASMs):
- focal seizures: carbamazepine or lamotrigine
- generalised seizures: sodium valproate (teratogenic) or lamotrigine
- monotherapy, rarely dual therapy
- withdrawal: only under supervision of specialist, done slowly, only if >2 years seizure free
Phycological therapies:
- relaxation, CBT (don’t improve seizure frequency, so only an adjunct not alternative)
Surgical intervention:
- only if single focus is identified
Others:
- vagal nerve stimulation
- deep brain stimulation
Describe syncope
A paroxysmal event in which changes in behaviour, sensation and cognitive processes are caused by an insufficient blood or oxygen supply to the brain
Symptoms: loss of consciousness, may have clonic jerking of limbs, with nausea, pallor, sweating and narrowing of visual field occurring before
Often situational, lasting less than 2 mins, and does not occur when lying down/sleeping
Describe non-epileptic seizures
A paroxysmal event in which changes in behaviour, sensation and cognitive function caused by mental processes associated with psychosocial distress
Also called functional/dissociative seizures
Characteristics: situational, duration of 1-20 mins, can have motor symptoms of atonia, eyes closed, history of psychiatric illness
Define an extradural haemorrhage
Bleeding (arterial) between the skull and the dura
What are the causes of an extradural haemorrhage?
Usually traumatic - fractured temporal or parietal bone causing laceration of the middle meningeal artery
What are the clinical features of an extradural haemorrhage?
May present with traumatic injuries
Can have a ‘lucid period’ lasting hours-days
Rising ICP causes decreasing GCS
Symptoms include headache and drowsiness
Can cause coma and death if not treated rapidly
How does an extradural haemorrhage appear on a CT scan
Acute (fresh) blood appearing hyperdense (bright wight)
Convex - does not conform to surface of the brain, limited by dural attachments
Involves compression of the brain (midline shift of falx cerebri, compression of lateral ventricles)
Skull fracture may be seen (or picked up on X-ray)
How is an extradural haemorrhage managed?
Palin X-ray of skull
CT head
ABC management
Oxygen if needed
IV fluids to maintain circulation
Mannitol (to reduce ICP)
Surgery
Define subdural haemorrhage
Bleeding (venous) between the dura and arachnoid
What are the causes of a subdural haemorrhage?
Usually trauma - a fall or minor event causing bleeding from dural bridging veins
Could be due to low ICP or dural metastases
More likely in patients with brain atrophy (elderly, dementia, alcoholics, epilepsy)
What are the clinical features of subdural haemorrhage?
Gradual/insidious physical or intellectual slowing
Fluctuating level of consciousness
History of fall (can be minor, up to 9 months ago)
Raised ICP
Other symptoms include sleepiness, headache, personality changes, unsteadiness
Localised neurological symptoms (e.g. unequal pupils, hemiparesis) occur late
How does a subdural haemorrhage appear on a CT scan?
Chronic (old) bleed appears hypodense (dark)
Concave - conforms to surface of the brain as bleeding is not limited by dural attachments
Involves compression of the brain (midline shift of falx cerebri, compression of lateral ventricles)
A clot may be seen on CT or MRI
How is a subdural haemorrhage managed?
Bloods: check for bleeding disorders and other causes of impaired consciousness
Urgent CT
ABC management
Intubation/ventilation if unconscious
Mannitol (to reduce ICP)
Surgery
Define a subarachnoid haemorrhage
Bleeding (arterial) between the arachnoid and pia (arachnoid space)
What are the causes of a subarachnoid haemorrhage?
Usually spontaneous rupture of a berry aneurysm, or due to arterio-venous malformations
Can be traumatic but rarely
What are the clinical features of a subarachnoid haemorrhage?
Sudden-onset excruciating headache (thunder-clap)
May have vomiting, collapse, seizures, neck stiffness, or focal neurology (pupil changes, hemiparesis)
Could be conscious, reduced GCS, or unconscious
How does a subarachnoid haemorrhage appear on CT?
Acute (fresh) bleed is hyperdense (bright white)
Blood seen in fissures and cisterns +/- ventricles
How is a subarachnoid haemorrhage managed?
Urgent CT head scan
CT angiography
Nimodipine (calcium antagonist, reduces vasospasm)
Control blood pressure
Surgery (endovascular coiling or surgical clipping)
What are the complications of a subarachnoid haemorrhage?
Irritation to the meninges
Hypoxic injury (due to vasospasm of the cerebral vessels)
Hydrocephalus (due to blockage of the ventricular system)
Describe an intracerebral haemorrhage
Bleeding into the brain parenchyma
Caused by spontaneous rupture of aneurysm/vessel
Occurring in small perforating vessels prone to rupture, especially if hypertensive
Clinical features: determined by size and location of bleed - weakness (facial/limbs), seizure, coma
CT: acute hyperdense blood, within substance of brain, with mass effect (midline shift) if large
Define meningitis
Inflammation of the meninges
What are the causes of meningitis?
Infective:
- bacteria
- viral
- fungal
- parasitic
Non-infective:
- paraneoplastic
- drug side effects
- autoimmune (e.g. vasculitis/SLE)
Which pathogens cause acute meningitis?
Bacterial:
- Neisseria meningitidis (gram -ve cocci)
- Streptococcus pneumoniae (gram +ve cocci)
- Haemophilus influenzae B, E.coli (gram -ve bacilli)
- Listeria monocytogenes (gram +ve bacilli)
Viral:
- Herpes Simplex Virus (HSV)
- Varicella Zoster Virus (VZV)
- Enterovirus
Describe the transmission of meningitis
The most common organism causing meningitis (Neisseria meningitidis and Streptococcus pneumoniae) are normal commensals of the nasopharynx
These are spread by aerosol, droplets, or direct contact with secretions
Which pathogens cause chronic meningitis?
Bacterial:
- Mycobacteria tuberculosis
- Syphilis
Fungal:
- Cryptococcal
Other:
- non-infective
- parasitic
- Lyme disease
What are the signs/symptoms of meningitis?
Fever
Headache
Photophobia (eye discomfort in bright light)
Neck stiffness (“meningism”)
Non-blanching purpuric rash
Later/rare:
- shock (hypotension, prolonged capillary refill time)
- reduced GCS or coma
- seizures
What are the investigations needed for meningitis?
Blood cultures
Nose and throat swabs: for culture and PCR
Lumbar puncture (microscopy and culture of CSF):
- bacterial = cloudy, neutrophils, high protein, low glucose
- viral = clear, lymphocytes, high protein, normal glucose
CT (if aged >60, immunocompromised, history of CNS disease, seizures)
Bloods: FBC, U&E, glucose, coagulation (asses general health, rule out differentials)
What are the treatments for meningitis?
Broad spectrum antibiotics (e.g. ceftriaxone unless contraindicated in penicillin allergy, immunocompromised, recent travel, expect listeria = amoxicillin)
Steroids (IV dexamethasone)
Oxygen support, fluid resuscitation, analgesia, metabolic correction (as needed)
