Neurology Flashcards
What is the central nervous system?
The brain and spinal cord
What does the peripheral nervous system consist of?
12 pairs of cranial nerves, which connect the brain/brainstem and head and neck
31 pairs of spinal nerves
What are the two divisions of the autonomic nervous system?
Sympathetic
Parasympathetic
Where does sympathetic outflow come from?
The thoracic and lumbar cord
Where does parasympathetic outflow come from?
The brainstem via cranial nerves and the sacral cord
Where is the motor cortex?
At the precentral gyrus
Where is the somatosensory cortex?
At the postcentral gyrus
Where are the pyramids?
In the medulla
What is the internal capsule?
A big white matter tract running between the deep brain structures
What does the diencephalon consist of?
Thalamus
Hypothalamus
What is the thalamus responsible for?
Motor control
Sensory relay
Visual processing
What are the basal ganglia?
Caudate
Putamen
Globus pallidus
Where does the spinal cord start and end?
Starts just below the medulla
Ends at L1-L2
How many pairs of cervical nerves are there?
8
How many pairs of thoracic nerves are there?
12
How many pairs of lumbar nerves are there?
5
How many pairs of sacral nerves are there?
5
How many pairs of coccygeal nerves are there?
1
From what level does the brachial plexus originate?
C5-8 and T1
What do the spinal nerves contain?
Mixed somatic nerves comprised of motor fibres for skeletal muscles and sensory fibres (pain, temperature, touch, pressure, vibration, proprioception)
Joined by sympathetic fibres
Where within the grey matter of the spinal cord do motor neurons terminate?
In the ventral grey horn
Where within the grey matter of the spinal cord do sensory neurons terminate?
In the dorsal root ganglion
What is a dermatome?
An area of skin supplied by a single spinal nerve
What is a myotome?
Muscles supplied by a single spinal nerve
What do the ascending tracts within the cord (white matter) do?
Carry sensory information from the periphery to the CNS
What do the descending tracts within the cord (white matter) do?
Carry motor information from the CNS to the periphery
What are interneurons?
Neurons that allow reflexes by joining a sensory neuron directly to a motor neuron, bypassing the CNS.
What are the two main ascending tracts in the spinal cord?
- Spinothalamic tract
2. Dorsal column pathway
What information is carried by the dorsal column?
Touch (particularly fine touch)
Proprioception
What information is carried by the spinothalamic tract?
Pain and temperature
Crude touch
Describe the path taken by the spinothalamic tract
Cell body is in the dorsal root ganglion
–> Projects to the dorsal grey horn and synapses with a second neuron.
–> Axons decussate via ventral white commissure
–> Ascend towards thalamus
–> Synapse with 3rd neuron in the thalamus
–> Axons project to somatosensory cortex
(Tract runs contralateral to the side of the body that it receives fibres from as decussation happens almost immediately)
Describe the path taken by the dorsal column pathway
Cell body is in the dorsal root ganglion
- -> axons ascend in the dorsal columns towards the cuneate/gracile fasciculus
- -> For upper limb, synapse with second neuron in cuneate fasciculus
- -> For lower limb, synapse with second neuron in gracile fasciculus
- -> Axons decussate in the medulla then ascend in the medial lemniscus
- -> Synapse with 3rd neuron in the thalamus
- -> Axons project to somatosensory cortex
What are the key descending tracts in the spinal cord?
Lateral and ventral corticospinal tracts
Do the corticospinal tract fibres decussate and where?
Ventral corticospinal tract does not decussate
Lateral corticospinal tract fibres decussate at the pyramids
Describe the path taken by the corticospinal tracts
~85% of the fibres decussate at the pyramids to form the lateral CST
~15% of the fibres remain ipsilateral to form the ventral CST
–> upper motor neuron synapses with lower motor neuron in the ventral grey horn
–> axon leaves in the spinal nerve
Which cranial nerves arise from the brain and which arise from the brainstem?
I and II arise from the brain
III-XII arise from the brainstem
What is the mnemonic for remembering which cranial nerves carry sensory/motor or both?
Some Say Money Matters But My Brother Says Big Brains Matter Most
Which cranial nerves also carry parasympathetic fibres?
III, VII, IX, X
oculomotor, facial, glossopharyngeal, vagus
What does cranial nerve I do?
Olfactory
Sensory: smell
Axon bundles travel through cribriform plate –> olfactory bulb –> tracts –> temporal lobe
Connects with limbic system
What does cranial nerve II do?
Optic
Sensory: vision
Fibres travel from retina –> primary visual cortex (medial aspect of occipital lobe, calcarine sulcus)
Right and left visual cortices receive information from both eyes about opposite side of visual field
What does cranial nerve III do?
Oculomotor
Motor and parasympathetic
Motor to most of extraocular muscles (medial rectus, superior rectus, inferior rectus, inferior oblique, levator palpebrae superioris)
Parasympathetic: innervates sphincter to pupillae –> constriction in response to light
What does cranial nerve IV do?
Trochlear
Motor - innervates superior oblique
What does cranial nerve V do?
Trigeminal
Sensory fibres: extensive distribution in the head, touch, pressure, pain, temperature, proprioception from TMJ and muscles of mastication
Motor fibres: Muscles of mastication
3 divisions: ophthalmic (S), maxillary (S), mandibular (S&M)
What does cranial nerve VI do?
Abducens
Motor
Innervates lateral rectus
What does cranial nerve VII do?
Facial
Sensory: taste anterior 2/3 of the tongue
Motor: muscles of facial expression
Parasympathetic: Lacrimal gland, submandibular and salivary glands
What does cranial nerve VIII do?
Vestibulocochlear
Sensory
Afferents from vestibular apparatus (balance) and cochlea (hearing)
What does cranial nerve IX do?
Glossopharyngeal Sensory: Taste - posterior 1/3 of the tongue General sensation from pharynx, eustachian tube and posterior 1/3 of tongue Motor: One muscle of the pharynx Parasympathetic: parotid gland
What does cranial nerve X do?
Vagus
Sensory: General sensation external auditory meatus, tympanic membrane, pharynx, larynx, oesophagus
Motor: Muscles of soft palate, pharynx and larynx
Parasympathetic: Thoracic and abdominal viscera
What does cranial nerve XI do?
Accessory - 2 parts
- Cranial part (joins the vagus)
- Spinal part
- Arises from ventral horn spinal cord C1-C5
- Travels up through foramen magnum
- Leaves again through jugular foramen
- Innervates sternocleidomastoid and trapezius
What does cranial nerve XII do?
Hypoglossal
Motor: tongue muscles
Why do the forehead muscles still work in the case of an upper facial motor neuron lesion?
The upper part of the facial motor nerve receives input from both sides, but the lower part of the facial motor neuron receives input from only the lower side.
What are the two layers of the dura mater?
Periosteal (outer)
Meningeal (inner)
What are the deeper pockets of the subarachnoid space called?
Cisterns
Where are the meningeal vessels?
In the extradural space
Where are the bridging veins?
In the subdural space
Where is the circle of Willis and its branches?
In the subarachnoid space
What is the cauda equina?
Lower spinal nerves at the bottom of the spinal cord below L1-2 level
Where is a lumbar puncture performed?
Below L2 level (L3-4 or L4-5)
From where do the left and right vertebral arteries arise?
From the subclavian arteries
What are the terminal branches of the internal carotid artery?
Anterior cerebral artery
Middle cerebral artery
From where does the lateral surface of the brain receive its blood supply?
Mostly from the middle cerebral artery
What is Broca’s area and where is it?
On the lateral surface of the cerebrum anterior to the middle cerebral artery.
Function: motor speech
What is Wernicke’s area and where is it?
On the lateral surface of the cerebrum posterior to the middle cerebral artery.
Function: comprehension
From where does the medial surface of the brain receive its blood supply?
Mostly from the anterior cerebral artery
Where is the lower limb represented?
Medial surface of the cerebral hemisphere (anterior cerebral artery territory)
Where are the upper limb and face represented?
Lateral surface of the cerebral hemisphere (middle cerebral artery territory)
Which vessels supply the internal capsule, basal ganglia and hypothalamus?
Perforating vessels from the anterior and middle cerebral arteries
Which vessels supply the midbrain and hypothalamus?
Perforating vessels from the posterior cerebral artery
From where does the spinal cord receive its blood supply?
From paired posterior spinal arteries and one anterior spinal artery
Reinforced by supply from radicular vessels
What is the usual cause for extradural haemorrhage?
Trauma resulting in bleeding from the middle meningeal artery as a result of a skull fracture
How does extradural haemorrhage normally present?
Usually following head injury, although may be delayed
Headache, drowsiness and neurological deterioration from brain compression
How does extradural haemorrhage appear on CT?
Acute bleed appears hyperdense on CT
Convex - does not conform to surface of the brain
Bleeding limited by suture lines
Possible midline shift due to compression of the brain
What is the usual cause of subdural haemorrhage?
Trauma, typically from a fall leading to bleeding from dural bridging veins
How does subdural haemorrhage usually present?
Bleeding is low pressure, so results in a gradual rise in intracranial pressure over several weeks or months, leading to gradual cognitive deterioration. Most likely in elderly, dementia patients, alcohol abusers and shaken babies.
How does subdural haemorrhage appear on CT scan?
Chronic bleed appears hypodense (dark)
Concave shape, conforms to the surface of the brain
Bleeding crosses suture lines
Midline shift may be present due to compression of the brain
What is the most common cause of subarachnoid haemorrhage?
Ruptured aneurysm on a cerebral artery
How does subarachnoid haemorrhage present?
Sudden onset severe ‘thunderclap’ headache
May have seizures
May be conscious/unconscious, may have reduced GCS
How does subarachnoid haemorrhage appear on imaging?
Acute bleed appears hyperdense on CT (bright white)
Blood seen in fissures, cisterns and sometimes ventricles
What is the most common cause of intracerebral haemorrhage?
Aneurysm rupture
How does intracerebral haemorrhage usually present?
Depends on cause, size of bleed and brain region affected
Can cause coma, confusion, weakness, seizures
How does intracerebral haemorrhage appear on CT?
Acute bleed –> hyperdense
Blood seen in the substance of the brain
Mass effect (e.g. midline shift) seen if large
What are the possible infective causes of meningitis?
Bacterial
Fungal
Viral
Parasitic
What are the possible non-infective causes of meningitis?
Paraneoplastic
Drug side effects
Autoimmune (e.g. vasculitis/SLE)
Name three routes of infection for meningitis
- Contiguous spread e.g. from nasal carriage, otitis media, sinusitis
- Haematogenous spread (i.e. bacteraemia)
- Neurosurgical complications
Why is CNS infection so difficult for the body to clear?
The brain is protected by the blood-brain barrier, which prevents the immune system from attacking brain tissue. However, if pathogens manage to cross the barrier, they are then isolated from the immune system and can spread without resistance.
What is the classic triad or meningitis symptoms?
- Fever
- Headache
- Neck stiffness
What other symptoms besides the classic triad can meningitis cause?
- Nausea and vomiting
- Photophobia
- Irritability
- Confusion
- Sleepiness
- Lethargy
- Purpuric rash
If a patient with suspected bacterial meningitis presents to the GP, what should they do?
Administer IM benzylpenicillin immediately and send the patient to hospital
What are the first management steps in the hospital for a patient with suspected meningitis?
- Assess GCS (eye response, verbal response, motor response)
- Blood cultures
- Administer broad spectrum antibiotics - cefotaxime or ceftriaxone (assuming patient isn’t allergic to penicillin). If patient has recently travelled, administer vancomycin too due to risk of penicillin resistance.
- Steroids (IV dexamethasone) to reduce inflammation
- Lumbar puncture to give definitive diagnosis
What are the contraindications for lumbar puncture?
- Raised ICP
- Petechial rash
- Abnormal clotting/patient on anticoagulants
- Suspicion of spinal abscess
Which patients should have a CT head before proceeding to lumbar puncture?
- Those aged 60+
- Immunocompromised
- History of CNS disease
- Seizure < 1 week
- GCS < 14
- Focal neurological signs
- Papilloedema/other signs of raised ICP
Which meningitis-causing organism appears on gram film as gram negative (pink) diplococci?
Neisseria meningitidis
Why is Neisseria meningitidis the most common cause of meningitis in children and young adults?
Due to high level of nasal colonisation
What meningitis-causing organism appears as gram positive (purple) diplococci?
Streptococcus pneumoniae
What meningitis-causing organism appears as gram positive bacilli?
Listeria spp
What meningitis-causing organism appears as gram positive individual cocci?
Group B streptococcus
Which meningitis-causing organisms appear as gram negative rods?
- Haemophilus influenzae B
2. E coli
Which organisms cause chronic meningitis?
- Mycobacterium tuberculosis
- Syphilis
- Cryptococcal (fungus)
Which types of bacterial meningitis are more likely to affect neonates?
Group B strep
E coli
Which types of bacterial meningitis are more likely to affect children?
Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae B
Which types of bacterial meningitis are more likely to affect adults?
Neisseria meningitidis
Streptococcus pneumoniae
Which types of bacterial meningitis are more likely to affect the elderly?
Neisseria meningitidis
Streptococcus pneumoniae
Listeria
What are the characteristics of CSF with bacterial infection?
Cloudy appearance
High white cell count
High protein
Low glucose
What are the characteristics of CSF with viral infection?
Clear appearance
High white cell count with lymphocytes
High protein
Normal glucose
Who needs to be notified in cases of meningitis?
All cases must be reported to Public Health immediately
For Neisseria meningitidis - identify close contacts and administer single dose of ciprofloxacin or rifampicin as a prophylactic measure.
What is encephalitis?
Inflammation of the cerebral cortex
What are the usual causes of encephalitis?
Viruses, particularly HSV and VZV
How does encephalitis usually present?
A flu-like illness that progresses to altered GCS with possible confusion, drowsiness and coma
Fever, seizures and memory loss may also be present
Possible meningeal irritation too –> meningoencephalitis
How is encephalitis managed?
MRI head
Lumbar puncture with viral PCR
Mostly supportive treatment with neuro rehabilitation
IV acyclovir if caused by HSV or VZV
Which organism found globally in soil produces spores that cause tetanus?
Clostridium tetani
What toxins are produced by Clostridium tetani and what do they do?
- Tetanolysin (destroys tissue)
- Tetanospasmin (causes muscle contraction and spasms by binding to neurons and travelling retrogradely along axons)
How is symptomatic tetanus managed?
Muscle relaxants
Paracetamol
Immunoglobulin to mop up unbound toxins
Metronidazole
How is rabies managed?
Symptomatic rabies cannot be treated
Pre-exposure prophylaxis via vaccination in endemic areas
Post-exposure prophylaxis via vaccination and immunoglobulin therapy
What should all patients with CNS infections be tested for?
HIV
What are (usually) the three main branches coming off the aortic branch?
- Brachiocephalic trunk
- Left common carotid artery
- Left subclavian artery
What does the brachiocephalic trunk divide into?
Right common carotid artery
Right subclavian artery
What are the four segments of the internal carotid artery?
- Cervical (in the neck - mobile)
- Petrous (in the temporal bone - fixed)
- Cavernous (in the cavernous sinus)
- Supraclinoid (intradural)
Why were strokes a much more common consequence of road traffic collisions before the advent of seatbelts?
Because of the potential for dissection of the carotid artery at the point where it enters the skull base.
Which important vessel comes off of the cavernous internal carotid artery?
Ophthalmic artery
Why do some people have worse strokes than others?
Depends on collateral blood supply and how well it can compensate for routes being blocked.
What are the consequences of injuries to the cavernous sinus?
Pain
Cranial nerve deficits
What surrounds the internal carotid artery in the cavernous sinus?
Sympathetic plexus
Venous blood supply
Cranial nerves: III, IV, V and VI
Why do the basal ganglia and internal capsule suffer irreversible damage very quickly?
They are supplied by perforating vessels, with no alternative circulation in case of a blockage.
Dissection of which arteries can occur simply by tipping the head back too vigorously?
Vertebral arteries
Which artery supplies the medulla and inferior cerebellum?
Posterior inferior cerebellar artery
The vertebral arteries unite to form a single basilar artery. Which arteries come off the basilar artery?
- Multiple perforating arteries to the brainstem
- Bilateral anterior inferior cerebellar arteries
- Bilateral superior cerebellar arteries
From where do the posterior cerebral arteries arise?
From the terminal bifurcation of the basilar artery
Which structures are supplied by perforating arteries from the posterior cerebral artery?
Thalamus
Geniculate bodies
Cerebral peduncles
Tectum
What are the three types of primary headache?
- Migraine
- Cluster
- Tension type
Name some causes of secondary headache
Meningitis Subarachnoid haemorrhage Giant cell arteritis Idiopathic intracranial hypertension Medication overuse
Which aspects of a patient’s history of headache would prompt investigation/referral?
- Age >50
- History of HIV/cancer/trauma/cerebral vein sinus thrombosis risk factors
- Changing personality/cognitive dysfunction
- Vomiting with no other obvious cause
Which characteristics of a patient’s headache would prompt investigation/referral?
- Jaw claudication or visual disturbance
- Severe eye pain
- Changing in frequency, characteristics or associated symptoms
- Postural associations
- Sudden onset/thunderclap
- Triggered by exercise or valsalva
- Focal neurological symptoms (e.g. limb weakness, aura)
What signs on examination of a patient with headache would prompt referral/investigation?
- Fever
- Altered consciousness
- Neck stiffness
- Other abnormal neurological examination
What are the ‘red flags’ for headache, which prompt urgent investigation?
- New headache with history of cancer
- Cluster headache
- Seizure
- Significantly altered consciousness, memory, confusion, coordination
- Papilloedema
What are the ‘orange flags’ for headache, which prompt monitoring and a low threshold for investigation?
- New headache where diagnostic pattern not emerged after 8 weeks
- Exacerbated by exercise or valsalva
- Headache associated with vomiting
- Headache for some time that has changed significantly
- New headache if >50 years
- Headache that wakes patient from sleep
What are the ‘yellow flags’ for headache, which prompt management and possible follow-up?
- Diagnosis of migraine or tension type headache
- Weakness or motor loss
- Memory loss
- Personality change
What should be asked about when taking a history for headache?
- Types/number
- Time (onset/duration/frequency/pattern)
- Pain (severity, type, site, spread)
- Associated (nausea, vomiting, photophobia, phonophobia, cranial autonomic features e.g. red eye, watery eye, blocked nose)
- Triggers
- Response
- Between attacks (normal/persisting symptoms)
- Any change in attacks
What are the diagnostic criteria for migraine without aura?
5 attacks with the following features:
- Lasting 4-72 hours
2: Two of the following: unilateral, pulsing, moderate-severe, aggravation by routine physical activity - During headache at least one of the following: nausea, vomiting, photophobia and phonophobia
Also, not attributed to another disorder
What is an ‘aura’ that can sometimes accompany migraine?
Usually occurs before headache, but can occur during
Most common - visual aura e.g. zig zags, flashing lights
Also sensory aura e.g. tingling on one side
Speech/language-related aura e.g. problems saying/understanding words
What are the diagnostic criteria for tension type headache?
> 10 attacks occurring <1 day/month or <12 days a year and:
- Lasts 30 minutes to 7 days
- Two of the following: bilateral, non-pulsating, mild/moderate intensity, not aggravated by routine physical activity
- No nausea/vomiting and no more than one of photophobia/phonophobia
Also, not attributed to any other disorder
Cluster headaches are less common than tension and migraine headaches. What are the diagnostic criteria?
At least five headache attacks with the following:
- Severe or very severe unilateral orbital, supraorbital and/or temporal pain lasting 15-180 minutes if untreated
- Headache is accompanied by ipsilateral cranial autonomic features and/or a sense of restlessness or agitation
- Frequency varies from 1 every other day to 8 per day
Not attributed to another disorder
Classical trigeminal neuralgia is a common secondary cause of headache. What are the diagnostic criteria?
At least three attacks of facial pain with the following:
- Severe or very severe unilateral orbital, supraorbital and/or temporal pain lasting 15-180 minutes if untreated.
- Headache accompanied by ipsilateral cranial autonomic features and/or a sense of restlessness/agitation
- Pain has at least three of the following four characteristics:
i) Recovering in paroxysmal attacks from a fraction of a second to 2 minutes
ii) Severe intensity
iii) Electric shock-like, shooting, stabbing
iv) Precipitated by innocuous stimuli to the affected side of the face
Also - no clinically evident neurological deficit
Which drugs can be used for acute treatment of migraine?
Normal treatment: Oral triptan with NSAID/paracetamol
Consider anti-emetic
Which drugs should not be used to treat migraine?
Ergotamines (old drugs that were used in the past) and opiates
Which patients should not be prescribed triptans?
Those with heart disease
How do triptans work?
5-HT1 receptor agonists - cause vasoconstriction in the brain and inhibit the release of inflammatory peptides like CGRP and substance P.
Name some triptans
Rizatriptan Zolmitriptan Sumatriptan Almotriptan Eletriptan Naratriptan
What drugs should be offered as a first line preventative treatment for migraine?
Topiramate or propranolol
What other treatments besides topiramate and propranolol may be helpful for prevention of migraine?
Acupuncture
Amitriptyline
Riboflavin vitamin B2 (400mg once a day)
Botox type A for prophylaxis of chronic migraine if all else fails
What is the most common cause of secondary headache?
Medication overuse
How is subarachnoid haemorrhage managed?
Resuscitation
Nimodipine
Early intervention to prevent further bleeding (radiological/surgical)
Monitor for complications
What are the features of headache caused by raised intracranial pressure?
- Worse on waking, coughing, sneezing, straining, lying down
- Nausea and vomiting
- Papilloedema
What are the risk factors for idiopathic intracranial hypertension?
Obesity
Drugs e.g. tetracycline
What would CT scan and LP show in the case of idiopathic intracranial hypertension?
Both would be normal, but LP opening pressure would be high.
How is idiopathic intracranial hypertension managed?
- Lifestyle modification
- Monitor visual fields
- Drugs: acetazolamide/topiramate/diuretics
- May require repeated LPs, shunt, optic nerve sheath fenestration
What are the diagnostic criteria for giant cell arteritis?
3 of the following:
- Age >50
- New headache or new type of localised pain
- Temporal artery abnormality: tenderness, decreased pulsation
- ESR elevated >50
- Abnormal temporal artery biopsy
What kind of visual disturbances are more likely to be associated with ophthalmology rather than neurology?
Monocular visual patterns
How can we differentiate between a surgical problem and a medical problem with CN III?
CN III (oculomotor) has parasympathetic fibres running along the outside, which are responsible for pupillary light reflex. If the pupil is affected, this could mean that something is compressing the nerve as the parasympathetic fibres are affected. If only motor function is impaired, there is no surgical problem and the patient can be managed as an outpatient.
What is the normal cause of medical problems with CN III?
Microvascular disease, usually as a result of diabetes. The only treatment is to optimise diabetic control.
What is internuclear ophthalmoplegia?
Asymmetric nystagmus, which results in double vision - caused by a lesion of the medial longitudinal fasciculus, which connects CN VI nucleus to CN III nucleus to move the eyes simultaneously.
What does internuclear ophthalmoplegia almost always signify in young people?
Multiple sclerosis
What is Horner’s syndrome?
Miosis (constricted pupil), drooping eyelid and decreased sweating on one side of the face caused by damage to the sympathetic chain
What causes lateral medullary syndrome?
Acute ischaemic infarct of the lateral medulla.
What are the ipsilateral features of lateral medullary syndrome?
Horner's syndrome Limb ataxia Loss of pain and temperature sensation in the face Reduced corneal reflex Dysarthria Dysphagia
What are the contralateral features of lateral medullary syndrome?
Loss of pain and temperature sensation
What is Brown-Sequard syndrome?
A rare neurological condition with hemiparaplegia on one side and hemianaesthesia on the other caused by an incomplete spinal cord lesion.
- Ipsilateral corticospinal tract dysfunction
- Ipsilateral dorsal column dysfunction
- Contralateral spinothalamic tract dysfunction
What is multiple sclerosis?
An inflammatory demyelinating disease affecting the CNS that causes progressive disability over time following an initial relapsing/remitting course.