Week 12 - Neurology Flashcards
Describe the connections of the dural venous sinuses
- The superior and inferior sagittal sinuses anastomose with the straight sinus at the confluence of the sinuses - The transverse sinus comes from the confluence and goes on to form the sigmoid sinuses - The sigmoid sinuses drain into the IJV as they leave the cranium via the jugular foramina
List the layers of the meninges
- Dura mater 2. Arachnoid mater 3. Pia mater
Describe the signs seen in upper and lower motor neurone lesions
- Lower motor neurone lesion - damage to the peripheral nerve that supplies the muscle
- Wasting
- Weakness
- Fasciculations
- Loss of tone
- Upper motor neurone lesion
- Weakness
- Increased tone - loss of inhibition of motor neurone for relaxation
- Need stimulation of motor neurons contracting and inhibition of opposite motor neurone for relaxation
Describe the arrangement of the arteries which supply the brain
Terminal branches of the vertebral and internal carotid arteries form an anastomotic circle called the Circle of Willis, which gives off branches to supply the majority of the brain
Describe the position of the central sulcus
Separates the frontal and parietal lobes
Describe the structural features of sacral vertebrae
Fused, facets for articulations w/ pelvis at sacroiliac joint
What does a loss of stretch reflexes indicate?
Loss of reflexes - sign of loss of info to spinal cord to say there has been stretch (sensory) and/or signal back to muscles to tell them to contract (motor)
List the suggested mechanisms for LB formation
- Oxidative stress
- Mitochondrial failure
- Excitotoxicity
- Protein aggregation - alpha synuclein, ubiquitin
- Interference with DNA transcription
- Nitric oxide
- Inflammation
- Apoptosis
- Trophin deficiency
- Infection
What is the purpose of cognitive assessment?
- Does this patient have cognitive impairment?
- If so, what cognitive domains are involved?
- What is the likely pathological process?
Describe the epidemiology of stroke
- Affects 150,000 people per year
- Leading cause of disability, cognitive impairment, and death in the developed world
- Accounts for 5% of NHS budget
- Mostly hospital (esp. LOS) and post-stroke costs - long rehabilitation
- Appropriate use of acute Rx reduces long-term cost
- By 2030 3-4% of the UK population over the age of 18 is projected to have had a stroke
- Between 2012 and 2030, total direct stroke-related medical costs are expected to more than double
- Effective treatment is crucial to relieve this huge burden
List cortical signs associated with large vessel strokes
- Right brain
- Right gaze preference
- Neglect
- Loss of one side of sensorium
- L sided neglect - no sensory input from L side
- No specific test
- Inattention is a milder form of neglect - attend to stimulus when applied unilaterally to bad/good side
- Stimulus on each side separately - can detect both sides
- Stimulus on both sides together - preference to undamaged side, can’t detect damaged side
- Left brain
- Left gaze preference
- Aphasia - speech hemispheres, language difficulty
- Patient looks towards side of damage
- Stroke on R side, L visual field disrupted - look towards R side
How is the function of the trigeminal nerve tested clinically?
- Sensory
- Light touch in all 3 areas (forehead, cheek, jaw) w/ wisp of cotton wool
- Motor
- Clench teeth - palpate temporalis and massester muscles
- Open mouth - deviation shows weakness of pterygoid muscles
- Jaw jerk reflex
- Corneal reflex - touch cornea with wisp of cotton wool while looking away, normal response is blinking (sensory innervation)
When is an LP done in suspected subarachnoid haemorrhage?
- If scans do not confirm diagnosis but clinical signs of subarachnoid haemorrhage present
- If signs of raised ICP LP contraindicated
Describe prophylactic therapy in migraines
- Lifestyle advice, triggers
- Identify and treat medication overuse
- Prophylaxis if >4-5 disabling headaches per month
- Use headache diaries
- For each medication, determine efficacy at 3 months (30-50% reduction in headache days?)
- If ineffective, wean medication and try another one
- If effective, continue 6-12 months
Describe the arrangement of the vertebrae in the vertebral column
33 vertebrae separated by intravertebral discs
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 (fused) sacral
- 4 (fused) coccygeal
Describe the structural differences between normal veins and the dural venous sinuses
The dural venous sinuses lack smooth muscle and valves
How is primary progressive MS diagnosed in comparison to secondary progressive MS?
- Primary progressive MS
- At least 1 year of disease progression
- MRI scan supports diagnosis of MS
- Oligoclonal bands support diagnosis of MS
- Secondary progressive MS
- RRMS in past but now progressive disease without relapses or inflammation on scan
What imaging should be done in strokes?
- CT scan
- Non-contrast CTH remains the most widely used modality as it’s quick, cheap, available and shows and IVH and ICH - shows bleeding well, less sensitive for infarcts (shows bruising which develops with time)
- CT with contrast may help identify aneurysms, AVMs or tumours buts is not at the moment required to determine whether or not the patient is a tPa candidate
- MRI
- Superior for showing underlying structural lesions
- Better for acute changes
- Contraindications
Multimodal Imaging:
- Multimodal CT
- Typically includes non-contrast CT, perfusion CT, and CTA
- Two types of perfusion CT
- Whole brain perfusion CT
- Dynamic perfusion CT
- Multimodal MRI
- Standard MRI sequences (T1 weighted, T2 weighted, and proton density) are relatively insensitive to changes in cerebral ischaemia
- Multimodal adds diffuse-weighted imaging (DWI) and PWI (perfusion-weighted imaging)
Describe the function of the olfactory nerve
Smell
List causes of length dependent axonal neuropathy
- Diabetes
- Alcohol
- Nutritional - folate/B12/thiamine/B6 deficiency
- Immune mediated - RA, lupus, vasculitis, polyarteritis nodosa
- Metabolic/endocrine - renal failure, hypothyroidism
- Drugs - isoniazid, cisplatin, amiodarone, gold
- Infectious - HIV, hepatitis B & C
- Inherited - Charcot-Maria-Tooth, hereditary neuropathy with liability to pressure palsy (HNPP)
- Neoplastic - myeloma
- Paraneoplastic
- Critical illness
Describe the function of the facial nerve
- Motor (derivatives of 2nd pharyngeal arch)
- Muscles of facial expression
- Posterior belly of digastric muscle
- Stylohyoid muscle
- Sensory
- Area around concha
- Special sensory
- Taste to anterior 2/3 of tongue (chorda tympani)
- Parasympathetic
- Submandibular and sublingual salivary glands (chorda tympani)
- Nasal, palatine and pharyngeal mucous glands
- Lacrimal glands
Describe the presentatin of posterior circulation strokes
Brainstem Stroke Syndromes
- Rarely presents with an isolated symptom - hard to identify origin
- Usually a combination of cranial nerve abnormalities, and crossed motor/sensory findings such as
- Double vision
- Facial numbness and/or weakness
- Slurred speech
- Difficultly swallowing
- Ataxia
- Vertigo
- Nausea and vomiting
- Hoarseness
Describe the phases of a migraine
- Prodrome (hours - days)
- Yawning, polyuria, depression, irritability, food cravings, poor concentration, sensitivity to light and sound, poor sleep
- Aura (5 - 60 minutes)
- Visual, sensory, language, motor
- Positive and negative elements
- Fully reversible
- Headache (4-72 hours)
- Throbbing headache, nausea, vomiting, photophonophia, worse with activity
- Postdrome (24 - 48 hours)
- Depression, euphoria, poor concentration, fatigue
What is status epilepticus?
- Sustained seizures e.g. due to non-compliance to medications
- Seizures have low risk of causing harm to brain, heart etc. until they persist
Describe the clinical presentation of a neuropathy
- Depends on the type and distribution of affected fibres
- Motor
- Weakness/muscle atrophy
- Sensory
- Large (myelinated) fibres - sensory ataxia, loss of vibration sense +/- numbness and tingling
- Small (thinly myelinated/unmyelinated) fibres - impaired pin prick, temperature, painful burning, numbness and tingling
- Autonomic
- Postural hypotension, erectile dysfunction, GI disturbance, abnormal sweating
- Tendon reflexes may be reduced or absent
Describe the treatment of vestibular schwannomas
Surgery
- Risks of damaging vestibulocochlear nerve and causing loss of hearing
- Also risk damaging surrounding structures e.g. facial nerve
- Use retrosigmoid approach (from behind sigmoid sinuses) to try to preserve hearing
Radiation
Observation - if small and slow growing
How is the function of the accessory nerve tested clinically?
Raised shoulders and turn cheek against resistance
List the nuclei of the basal ganglia
- Caudate nucleus
- Lentiform nucleus - globus pallidus + putamen
- Substantia nigra
- Subthalamic nucleus
Describe examination of a patient with headaches
- Blood pressure, urine dipstick, pregnancy test, temperature, weight
- GCS, mental status examination
- Palpation - skull, neck, greater occipital nerves, TMJ, temporal arteries, nuchal rigidity
- Eyes
- Acuity, visual fields (blind spot), fundi, assessment for papilloedema and spontaneous venous pulsation, movements
- Presence or absence of Horner’s 3rd, 6th nerve palsies
- Autonomic features if during an attack
- Cranial nerves, routine neurological examination
- Skin exam (rashes), cervical lymphadenopathy, tympanic examination
List the symptoms/signs of cerebellar stroke
- Ipsilateral ataxia
Where does the glossopharyngeal nerve exit the cranium?
Jugular foramen
What can be seen on examination of the optic disc during fundoscopy?
- Normal optic disc - orange/pink colour, regular clear edges
- Papilloedema
- Edges of optic disc blurred, hyperaemia
- Swelling of optic nerve related to increased ICP
- Optic atrophy
- Pale, bright optic disc
- E.g. in optic neuritis (possible MS)
List factors that can affect consciousness
- Trauma
- Elevated ICP
- Fever
- Hypothermia
- Seizure
- Hypotension/severe hypertension
- Hypoxia
- Hypercapnia
- Sepsis
- Metabolic
- Medications (e.g. sedatives)
- Etc.
List the functions of the peripheral nervous system
- Sensory input to CNS
- Motor output to muscles
- Innervation of viscera
Incoming sensory information enters spinal cord via posterior root
Motor infection exits spinal cord via anterior root
Collections of nerve cell bodies in PNS known as ganglia
Where does the vagus nerve exit the cranium?
Jugular foramen
Which anatomical landmark marks the confluence of the sinuses
Internal occipital protuberance
How can syncope be distinguished from seizures?
- Trigger
- Syncope - common
- Seizure - rare (lights, hv)
- Prodrome
- Syncope - almost always
- Seizure - common
- Onset
- Syncope - gradual (mins)
- Seizure - usually sudden
- Duration
- Syncope - 1-30 secs
- Seizure - 1-3 mins
- Convulsive jerks
- Syncope - common (brief)
- Seizure - common (prolonged)
- Incontinence
- Syncope - uncommon
- Seizure - common
- Lateral TB
- Syncope - very rare
- Seizure - common
- Colour
- Syncope - very rare
- Seizure - pale (CPS) red, blue
- Post-ictal confusion
- Syncope - rare
- Seizure - common (in amb)
- Recovery
- Syncope - rapid
- Seizure - slow (confused)
List the fibre types of the peripheral nervous system
- Large fibres (myelinated)
- Motor nerves
- Proprioception, vibration and light touch
- Thinly myelinated fibres
- Light touch, pain and temperature
- Small fibres (unmyelinated)
- Light touch, pain and temperature
List the symptoms/signs of cerebellar haemorrhage
- Vomiting (more common in ICH than SAH or ischaemic CVA)
- Haemorrhages associated w/ worse headache - feel nauseated
- Ataxia
- Eye deviation toward the opposite side of the bleed
- Small sluggish pupils
- Altered mental status
Describe the function of Broca’s area and the affect of a lesion to Broca’s area
- Broca’s - thoughts to motor speech
- Non fluent, can comprehend
- Left posterior inferior frontal gyrus (weak limbs) - next to limb strip so almost always have limb involvement
Describe induction therapy vs escalation therapy in MS treatment
Alemtuzumab is licenced as a first line therapy and some specialist centres use it as an ‘induction’ therapy for aggressive MS instead of starting with weaker treatments and ‘escalating’
Describe the path of the vertebral arteries
- Ascend the posterior aspect of the neck through the transverse foramen of the cervical vertebrae 2. Enter the cranial cavity through the foramen magnum 3. Give off branches 4. Converge to form the basilar artery which gives of branches to supply the pons and cerebellum 5. Basilar artery terminates by bifurcating into posterior cerebral arteries
Describe the general venous drainage of the brain
Veins empty into dural venous sinuses which eventually empty into the internal jugular veins
Describe the mechanism of action and use of MOA-B inhibitors in Parkinson’s disease
- E.g. Selegiline, Rasagiline
- Prevents dopamine breakdown by binding irreversibly to monoamine oxidase
- Can be prescribed as monotherapy in early disease or as adjunct in later disease
- Well tolerated
Describe the appearance of DATSCAN SPECT in Parkinson’s disease
- Normal DATSCAN SPECT - uptake highest in middle slices of striatum (light up)
- In PD - dopamine neurones are lost, less uptake (dark patches)
Describe the location of the dura mater
Outer layer of the meninges, lies directly under the bones of the skull and the vertebral column
What are the most common causes of a subarachnoid haemorrhage?
- Trauma - most common cause
- Spontaneous SAH most commonly due to aneurysm
- Localised dilatation of artery
What is seen on clinical examination in an aneurysmal subarachnoid haemorrhage?
- Photophobia
- Meningism
- Subhylaoid haemorrhages
- Between vitreous and retina, boat shaped
- Monocular blindness - bleed in vitreous
- Raised ICP - double visioin (CN VI/III affected - enlarging basilar tip)
- Vitreous haemorrhages (Terson’s syndrome)
- Speech and limb disturbance
- Pulmonary oedema
What are oligoclonal bands? How are they used in the diagnosis of MS?
- Immunoglobulin bands seen in blood and spinal fluid after protein electrophoresis
- Presence of bands in CSF but not blood suggests immunoglobulin production in CNS
- Supports diagnosis of MS but can be seen in other conditions
List the types of headaches
- Primary
- Migraine
- Trigeminal autonomic cephalgias
- Secondary
- Thunderclap headaches
- High pressure headaches
- Low pressure headaches
- The neuralgias
What investigations should be done in Parkinsonism?
- Bloods
- If tremor present - thyroid function tests, copper/caeruloplasmin
- Structural imaging
- CT/MRI brain normal in PD
- Abnormal in vascular parkinsonism, Parkinson plus disorders
- Functional imaging
- Imaging of presynaptic dopaminergic function using DAT SPECT is abnormal in degenerative parkinsonism
Describe the anatomy and function of the glossopharyngeal nerve
- Sensory
- Nucleus location - medulla
- Function - taste, proprioception for swallowing, blood pressure receptors
- Structures innervated - posterior 1/3 of tongue, pharyngeal wall and carotid sinuses
- Motor
- Nucleus location - medulla
- Function - swallow and gag reflex, lacrimation
- Structures innervated - pharyngeal muscles, lacrimal glands
- Parasympathetic
- Function - saliva production
- Structure innervated - parotid glands
What is the clinical significance of the sphenoid emissary vein
Root of spread of infection from the upper teeth to the cranial cavity
Describe the anatomy of visual processing
- Dorsal stream
- Where?
- Position of object in space (dyspraxia)
- Picking an object from a scene
- Ventral stream
- What?
- Object recognition (visual agnosia)
- Facial recognition (prosopagnosia)
List the major white matter bundles of the cerebrum
Internal capsule, corpus callosum
When does the foetal brain start functioning?
- 3 weeks gestation - functioning brain, electrical activity
What is the function of the grey matter structures of the cerebrum?
Processing and cognition
Compare endovascular coiling to neurosurgical clipping
- Endovascular coiling
- Introduce platinum coil into aneurysm using microcatheter, helps blood clot
- Seal off the aneurysm, reduce pressure on outer wall - prevent rupture
- Better for reducing long term morbidity
- Neurosurgical clipping
- Requires craniectomy
- Close the base of the aneurysm with a clip
- Decision as to which technique is employed is made on the bases of aneurysm morphology, patient characteristics and local experience
- Longer-term morbidity and mortality better in endovascular coiling
- Open surgical clipping may be favoured in cases that also require clot evacuation or decompressive surgery
Describe the cognitive domains
- Frontal lobe - executive function/language
- Temporal lobe - memory, language
- Parietal lobe - visuospatial, praxia
Describe the sections of the glasgow coma scale
- 3 subscales
- Eye
- Verbal
- Motor
What assessment should be done when faced with an unconscious patient?
- Is the environmental safe for me to enter?
- How much time do I have to think?
- A-B-C-DEFG and what is the story behind it?
3. If all is safe - where is the problem? - Assess GCS (response to environment, eyes, speech, movement)
- Moving?
- Neurological deficit?
- Bloods - U&Es, ABGs, glucose, LFTs (? + tox screen)
Where does the mandibular division of the trigeminal nerve exit the skull?
Foramen ovale
Describe the parts of the globus pallidus
Internal and external segments
List the symptoms/signs of ACA stroke
- Leg > arm weakness, grasp
- Cognitive: muteness, perseveration, abulia
What is transverse myelitis?
- Inflammation of the spinal cord
- Weakness
- Sensory loss
- Incontinence can be only symptom
- Many other causes than MS
Describe the structural features of lumbar vertebrae
- Largest - big bodies for weight bearing
- Short spinous body - point less inferiorly
How is the function of the vagus nerve tested clinically?
- With the glossopharyngeal nerve
- Speech - hoarseness/difficulty pronouncing sounds (dysphonia)
- Swallowing (dysphagia)
- Position of palate and uvula (deviation = lesion on opposite side to deviation)
- Gag reflex - not usually done
What is the function of the white matter structures of the cerebrum?
Connect the grey matter areas
Describe the anatomical course of the facial nerve
- Arises in pons - large motor and small sensory root
- Roots travel through internal acoustic meatus in temporal bone
- Enter facial canal (Z-shaped), roots fuse to give facial nerve, forms geniculate ganglion and gives off the greater petrosal nerve, nerve to stapedius and chorda tympani
- Exits cranium via stylomastoid foramen
- Gives off branches - posterior auricular nerve, nerve to posterior belly of digastric muscle and stylohyoid muscle
- Motor root continues to parotid gland, splits to form 5 terminal branches
Describe the structures which form the walls of the lateral ventricles
- L and R ventricles separated medially by the septum pellucidum
- Roof formed by the body of the corpus callosum
- Floor formed by the rostrum of the corpus callosum
- Lateral wall formed by the caudate nucleus
- Anterior wall formed by the genu of the corpus callosum
What is a stretch reflex?
Signal - stretch of muscles, spinal cord sends signal to muscles to contract to correct
Where is the supracristal line?
At the level of the iliac crest, marks the location of L4
List the main peripheral nerves of the lower limbs
- Anterior thigh – femoral nerve (quadricep)
- Some hip flexion, mostly knee extension
- Runs alongside femoral a/v
- Sciatic nerve – hamstrings (posterior m in thigh)
- Bottom of leg splits into 2 – tibial nerve posteriorly (calf), peroneal nerve round back of fibula (exposed to injury – muscles in front of shin, inability to bring foot up towards you = foot drop, common neuropathy, sensory problems over lateral shin and top of foot)
Describe the arterial supply of the dura mater
- Anterior meningeal artery - branch of ethmoidal a
- Middle meningeal artery - branch of maxillary a
- Posterior meningeal artery - branch of ascending pharyngeal a
- Accessory meningeal artery - branch of maxillary a
Describe the function of the ophthalmic nerve
Sensory innervation of the scalp, forehead and nose
How is the oculomotor nerve tested clinically?
With the trochlear and abducens nerves
What should be done if AEDs are ineffective in epilepsy management?
- Minimise side effects
- Minimise seizure severity
What is the recurrence risk after 1 seizure? After 2 seizures?
- Recurrence risk after 1 seizure
- Low risk
- Medium risk
- High risk
- Recurrence risk after 2 seizures
- 50-60%, start treatment
Describe the origins and path of spinal nerves
- Each spinal cord segment gives rise to 2 spinal nerves - L and R
- C1-7 pass through their intervertebral foramen above the level of the corresponding vertebral body
- C8 onwards exit below the level of the vertebral body
What can cause olfactory nerve dysfunction?
Neurodegenerative disorder - loss of sense of smell e.g. Alzheimer’s
Traumatic brain injury - shear olfactory nerve from cribiform plate
How is myasthenia gravis managed?
Managed with pyridostigmine (anti-acetylcholine esterase) and immunosuppressive therapies (e.g. steroids and IV immunoglobulin
Describe the function of the meninges
- Provide supportive framework for cerebral and cranial vasculature - Act with CSF to protect the CNS from mechanical damage
Describe the endosteal layer of the dura mater
Lines the inner surface of the cranial bones, only present around the brain (not in the vertebral column)
What is Uthoff’s phenomenon?
Symptoms are worse with exercise (heat) which is Uthoff’s phenomenon - seen in demyelination
What are the consequences of an aneurysmal subarachnoid haemorrhage?
- Acute cerebrovascular event
- Devastating effects on CNS
- Profound impact on several other organs
- Course of disease may be prolonged
Which clinically isolated syndromes are associated with MS?
- Single episode of neurological disability due to focal CNS inflammation
- Can include optic neuritis and transverse myelitis
- May be a first attack of MS
- Can happen after infection and not be related to MS
What should be done following a first seizure?
- Clinical diagnosis
- Investigation
- Same imaging as epilepsy
- EEG only useful for prognosis of first seizure
- Calculate recurrence risk
- Abnormal scan/EEG, presence of risk factors - risk of recurrence 60%
- Normal scan/EEG, no risk factors - risk of recurrence 20%
Describe the impact of migraines on society
- Migraine is 3rd most common disease in the world
- Migraine most disabling disorder worldwide in 15-49 y/o, 2nd overall
- Affects 1 in 7 people (females > males)
- £150 million per year by NHS
- £3.4 billion lost per year in productivity
Describe the function of the vestibulocochlear nerve
- Vestibular fibres - balance
- Cochlear fibres - hearing
List the causes of Parkinsonism other than Parkinson’s disease
- Degenerative
- Dementia with Lewy bodies
- Progressive supranuclear palsy
- Multiple system atrophy
- Corticobasal degeneration
- Secondary
- Drug-induced - chronic use of dopamine antagonists
- Cerebrovascular disease
- Toxins e.g. carbon monoxide, organophosphates, MPTP
- Post-infectious
What is the impact of migraines on individuals?
- 5 or more headache days per month - 37%
- Need for bed rest - 53.7%
- Attack related impairment - 92.8%
- At least one day of activity restriction over 3 months - 35.1%
Describe the risk of hydrocephalus following a subarachnoid haemorrhage
- Imbalance in CSF within the ventricular system
- Obstruction due to clots, underdrainage due to inflammatory change
- Increase in size of ventricles
- Can complicate management of SAH
- LP, EVD
- Shunt
Describe the functions of the occipital lobe
- Primary visual cortex
- Visual association area - vision
- Visual interpretation
List the major gyri of the cerebrum and their functional significance
- Precentral gyrus - primary motor cortex
- Postcentral gyrus - primary somatosensory cortex
- Superior temporal gyrus - inferior to lateral sulcus, primary auditory cortex
What is the half life of L-Dopa?
90 minutes
List the branches given off by the vertebral arteries and describe their functions
- Meningeal branch - supplies falx cerebri
- Anterior and posterior spinal arteries - supplies spinal cord
- Posterior inferior cerebellar a - supplies cerebellum and pons
How is MS diagnosed?
- Multiple Sclerosis is diagnosed when there is evidence of 2 or more episodes of demyelination disseminated in space and time
- There is no definitive diagnostic test for MS
- Clinical diagnosis is based on weight of evidence from history, examination and investigation
Describe the structural features of cervical vertebrae
- C2-C6/7 spinous processes bifurcate
- Transverse foramina transmit vertebral arteries to brain
- C1/2 are unique (atlas/axis) - odontoid peg
What is visuo-spatial function? What suggests a defect in visuo-spatial function from a history?
- Visual processing - where? What?
- Accurately localise objects
- From history
- Inability to recognise faces or common objects or to find objects in direct view despite good acuity, inability to operate simple implements, or orient clothing to the body
What is a partial seizure?
- Area of abnormality in otherwise normal brain
- Symptoms related to the area of the brain of focal starting point
- Positive motor phenomenon e.g. twitch, spasm
- Negative motor phenomenon e.g. weakness
- Positive sensory phenomenon e.g. burning, itching
- Negative sensory phenomenon e.g. numbness
- Positive visual phenomenon e.g. colours, shapes, memories
- Negative visual phenomenon e.g. blind spots
- Can spread across brain and lead to bilateral convulsive seizure
- Partial/localised/focal epilepsy can cause secondarily generalised seizures
Where can lesions arise that cause cranial nerve abnormalities?
- Communicating pathways to and from the cortex, cerebellum and other parts of brainstem
- Nerve nucleus
- Nerve
- Neuromuscular junction disorders
- Muscle
Describe the beginning and end of the spinal cord
- Begins as continuation of medulla oblongata, ends at conus medullaris
- Becomes cauda equina
- Cord terminates at L3/4 in newborns, L1/2 in adults - vertebral column lengthens more than spinal cord during development
List the cranial nerves
- Olfactory nerve
- Optic nerve
- Oculomotor nerve
- Trochlear nerve
- Trigeminal nerve
- Abducens nerve
- Facial nerve
- Vestibulocochlear nerve
- Glossopharyngeal nerve
- Vagus nerve
- Accessory nerve
- Hypoglossal nerve
Describe the mechanism of action of AEDS which reduce post-synaptic activity
- Perampanel blocks AMPA receptors
- Felbamate has weak affinity for NMDA receptors
- Topiramate binds both AMPA and kainate receptors
- Benzodiazepines, barbiturates, felbamate and topiramate increased the GABA A receptor activity (reduced neuronal excitability)
List the main types of strokes
- Ischaemic stroke
- Clot occluding artery - 85%
- Intracerebral haemorrhage
- Bleeding into brain - 10%
- Subarachnoid haemorrhage
- Bleeding around brain - 5%
Where do the internal carotid arteries originate?
At the bifurcation of the L and R common carotid arteries, at the level of C4
Describe the function and anatomy of the abducens nerve
- Motor
- Function - eyeball movement
- Nucleus - pons
- Structure innervated - lateral rectus muscles
- Abducts eye in horizonal plane
Describe supportive therapy in stroke management
- Glucose management
- Infarction size and oedema increase with acute and chronic hyperglycaemia
- Hyperglycaemia is an independent risk factor for haemorrhage when stroke is treated with tPA
- Blood pressure management
- In ICH, consider treatment if SBP over 150
- Higher threshold in ischaemic stroke (about 180-200)
- Labetalol or GTN used, but not much evidence
- Senior advice
Compare L-Dopa and dopamine agonists
Dopamine agonists
- Longer half-life than L-dopa
- Associated with fewer motor complications than L-dopa
Describe the use of oral treatments in MS
- Fingolimod
- Daily tablet
- Less effective than natalizumab or alemtuzumab
- Risk of infections
- May slow heart rate
- Dimethyl Fumarate
- Twice daily tablet
- Less effective than fingolimod
- Low white cell counts
- Risk of infections
- Cladribine
- Old chemotherapy drug
- Two short courses of tablets (8 days) over two years
- Targets B-cells
- May stop MS activity for many years
What are the differential diagnoses for strokes
- Migraine
- Seizure
- Hypoglycaemic, or other metabolic/toxic states
- Tumour or other space occupying lesion (onset typically more insidious)
- Cerebral metastases (can present acutely, especially if there is a bleed into a metastasis)
- Cerebral venous sinus thrombosis
- Inflammatory lesions such a demyelination (onset is not usually abrupt as in this case)
- Peripheral neuropathy and entrapment neuropathy (there is clear cortical deficit in this man, so neuropathy is not the diagnosis)
- Cardiovascular/syncope
- Functional weakness
Describe the use of stem cell transplants in MS management
- Autologous haemopoeitic stem cell transplant
- Approved in UK for very aggressive RRMS that has been treated with stronger drugs but activity ongoing
- Limited trial data
- Will not repair disability
List the causes of intracerebral haemorrhage
- Trauma
- Non-traumatic
- 36% - hypertension
- 36% - aneurysm
- 11% - AV malformation
- 17% - other
- Bleeding into tumour, hypocoagulable state, haemorrhagic infarction, iatrogenic
Describe the diagnostic criteria for cluster headaches
- At least five attacks fulfilling criteria B-D
- Severe or very severe unilateral orbital, supraorbital and/or temporal pain lasting 15-180 minutes (when untreated)
- Either or both of the following
- At least one of the following symptoms or signs, ipsilateral to the headache
- Conjunctival injection and/or lacrimation
- Nasal congestion and/or rhinorrhoea
- Eyelid oedema
- Forehead and facial sweating
- Forehead and facial flushing
- Sensation of fullness in the ear
- Miosis and/or ptosis
- A sense of restlessness or agitation
- At least one of the following symptoms or signs, ipsilateral to the headache
- Occurring with a frequency between once every other day and 8 per day
- Not better accounted for by another ICHD-3 diagnosis
Describe the location of the internal capsule
Separates the caudate nucleus and thalamus from the putamen and globus pallidus (Lentiform nucleus)
List the features of length dependent axonal neuropathy
- Diffuse involvement of peripheral nerves
- Age >50 years
- Length dependent - starts in toes/feet
- Symmetrical
- Slowly progressive
- No significant sensory ataxia
- Any weakness is distal and mild
- Most common peripheral neuropathy
Describe the use of alemtuzumab in MS management
- Two short courses over a year then further treatment if needed
- Stops relapses in 40% of patients
- High risk of secondary autoimmune problems (thyroid, ITP, good pastures)
- May improve disability
List the drugs used for prophylaxis in migraines
- Beta blockers e.g. Propranolol - start at 20mg bd, target 80mg bd NNT
- Anti-emetics e.g. Topiramate - start at 15 or 25mg daily, target 50mg bd
- Tricyclics e.g. Amitriptyline - start at 10mg, target 50mg
- Helps w/ comorbidities e.g. depression, sleep problems
- Candesartan - start at 4mg, target 16mg
- Flunarazine - 10mg
- Pizotifen - start at 1.5mg, target 3mg-4.5mg
List the side effects of dopamine agonists
Dopaminergic side effects +, somnolence, impulse control disorders (e.g. pathological gambling, hypersexuality) and nightmares
Where does the ophthalmic division of the trigeminal nerve exit the skull?
Superior orbital fissure
Describe the adverse effects of L-Dopa
- Peripheral - nausea, vomiting, postural hypotension
- Central - confusion, hallucinations
- Longer term - approx. 50% of patients develop motor complications after 5 years L-dopa
- Fluctuation in motor response
- Dyskinesia - most commonly choreiform movements at peak dose
Does ACE diagnose dementia?
- Overall score = 100
- <88/100 excludes dementia
- Sensitivity 83%, specificity 71%
- >83/100 supports dementia
- Sensitivity 82%, specificity 96%
- Always consider not only score and pattern but any potential confounders
Why should regular opioid analgesia or combination analgesia (e.g. co-codamol) be avoided in migraines?
Regular opioid analgesia or combination analgesia (e.g. co-codamol) should be avoided in migraine due to potential for developing medication overuse headache (MOH) - common cause of chronic daily headache, stopping medication results in improvement in severity and frequency of headache
Describe the clinical significance of the lumbar cistern
Site for epidural injections and lumbar punctures
How is the corneal reflex tested? What does it show?
- Lightly touch cornea with cotton wool
- Afferent - V
- Efferent VIII
- Test of pontine function
- Bilateral blinking = intact corneal response
- Patients who use contact lenses can denervate cornea
What investigations should be done in a patient presenting with headaches?
- Blood pressure
- ECG
- Urinalysis
- Bloods e.g. CRP, ESR, FBC, U&Es, thyroid function
- Ct brain/MRI brain
- Lumbar puncture (opening pressure, blood products, other constituents)
- CT angiogram/MR angiogram
- CT venogram/MRI venogram
Describe the contents of the internal capsule
- Contains ascending and descending axons, going to and from the cerebral cortex
- Large part is cortiospinal tract - carries motor information from the primary motor cortex to lower motor neurons in the spinal cord
Describe the pathophysiology of migraines
- Interaction between primary afferent nociceptive neurones/trigeminovascular system/brainstem/thalamus/hypothalamus/cortex i.e. brain disorder
- Calcitonin gene related peptide (CGRP)
- NOT a primary vascular problem
- Attacks probably due to dysfunction within sensory brainstem nuclei
- Pain results from interactions between components of the trigeminovascular system
- Pain-sensitive cranial blood vessels
- Trigeminal nerve fibres that innervate them
- The cranial parasympathetic outflow
- Functional MRI studies have shown that the aura phase of migraine is associated with reduction blood flow in hemispheric regions contralateral to affected symptoms
Describe the position of the cerebellar falx
Partially divides the cerebellar hemispheres
Describe the preparations of dopamine agonists
- Prescribed as monotherapy in early disease or in combination with L-dopa
- Longer-acting oral, transdermal and subcutaneous preparations available
How can an upper and lower motor neuron lesion affecting the face be distinguished?
Upper motor neuron e.g. stroke shows forehead sparing due to bilateral innervation of the forehead
Describe the function of the vagus nerve
- Sensory - external ear, larynx, pharynx and thoracic/abdominal viscera
- Taste from epiglottis region of tongue
- Smooth muscle of pharynx, larynx and most of GI tract
When should you consider a thunderclap headache?
- First and worst headache
- Severe headache
- Sudden onset
- Typically maximum at onset within 1 minute (but can be several minutes - SIGN and NICE define as 5 minutes)
- Typical duration >1h (dogged adherence to this rule unreliable)
What is the function of the mandibular nerve?
- General sensory of anterior 2/3 of tongue, skin over mandible, lower teeth
- Motor - muscles of mastication
How is the GCS performed in children?
Verbal scale not appropriate in non-verbal children
GCS (modified for young children)
Best verbal response (1-5)
1 - none
2 - restless, agitated
3 - persistently irritable
4 - consolable crying
5 - appropriate words, smiles, fixes/follows
List the ligaments of the vertebral column
- Anterior and posterior longitudinal ligament (run full length of vertebral column)
- Ligamentum flavum
- Interspinous/supraspinous ligaments
- Intertrasverse ligaments
Describe the appearance of an eye with a trochlear nerve lesion
Torsional (rotational) diploplia, compensatory tilted head
Describe the function of Wernicke’s area
Sensory language area - lexical processing
List the lobes of the cerebum
- Frontal
- Parietal
- Temporal
- Occipital
Describe the function and anatomy of the facial nerve
- Motor
- Nucleus location - pons
- Function - muscles of expression
- Sensory
- Nucleus location - medulla
- Function - taste
- Structure innervated - anterior 2/3 of tongue
- Parasympathetic
- Nucleus location - medulla
- Function - salivation and lacrimation
- Structure innervated - salivary and lacrimal glands
What is the significance of the falx cerebri when considering the dural venous sinuses
The falx cerebri between the L and R cerebral hemispheres (in the longitudinal fissure) contains the superior and inferior sagittal and straight sinuses
Describe the risk of rehaemorrhage following a subarachnoid haemorrhage
- Incidence highest immediately following initial bleed
- 5-10% over 1st 72 hours
- Higher in poor grade patients
- Larger aneurysms
- Immediate repair reduces rebleeding risk
Describe the structure of vertebrae
- Anterior vertebral body
- Weight bearing
- Lined by hyaline cartilage
- Separated by IVD
- Posterior vertebral arch
- Forms vertebral foramen, line up to give vertebral canal which spinal cord travels through
- Spinous processes - posterior
- Transverse processes - in thoracic articulate with ribs
- Articular processes - join one vertebra to its corresponding vertebrae superiorly/inferiorly
Describe the segmentation of the spinal cord
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Describe the pathological progression of Alzheimer’s
- Classically starts in temporal lobe - episodic memory (mild stage)
- Spreads to parietal and frontal lobes
- Moderate stage - visuo-spatial
- Severe stage - language
How is an MS relapse treated?
- Not all relapses need treatment
- Important to discuss side effects of high dose steroids with patient
- Steroids may speed up recovery from relapse with no effect on progression of disease
- Steroids should not be given if any evidence of infection
- If appropriate patient should get physiotherapy +/- occupational therapy
- Sometimes in RRMS there may be a plan to organise MRI with contrast to look for active disease and change treatment
- If patient is on treatment for RRMS the MS nurses should be informed - patient may be eligible for new treatment
Describe language disorders and how language is tested in the ACE
- Language =
- Speech (aphasia), reading (alexia), writing (agraphia)
- Example of disorders
- Progressive non-fluent aphasia (variant FTD), dominant MCA territory infarction
- Testing using ACE-r
- Naming
- Repetition
- 3 stage command (comprehension)
- Reading
List the main peripheral nerves of the upper limbs
- Radial nerve - spirals round humerus, supplies extensors of arm
- Not much sensation (back of hand – snuffbox)
- Deltoid contraction – axillary n
- Median nerve – forearm flexors, some muscles in hand
- Muscles in hand (LOAF)
- Sensation – lateral part of hand
- Ulnar nerve – fine motor movements of hand, forearm/wrist flexion minorly
- All muscles except LOAF – adduction and abduction etc.
- Sensation – rest of hand not supplied by median
Why is it important to consider the eye in facial nerve palsy?
Orbicularis oculi muscle supplied by temporal/zygomatic branches of the facial nerve, facial nerve palsy results in inability to close the eye properly, leads to drying of the cornea and damage
List the dural venous sinuses
Superior sagittal sinus, inferior sagittal sinus, straight sinus, transverse sinus, sigmoid sinus
Which genes are associated with parkinsonism?
List the motor clinical features of Parkinsonism
- Bradykinesia
- Slowness in initiation of voluntary movement with progressive reduction in speed and amplitude of repetitive actions
- And at least one of the following
- Muscular rigidity
- 406 Hz resting tremor
- Postural instability
How should a patient who is suspected to have had a stroke be assessed in the ED?
- Airway, breathing, circulation, blood glucose
- History - should not delay clinical assessment and investigations
- Probably won’t get history from patient - important to get focused history from witnesses
- Time of onset or last time seen well - need time window for reperfusion therapies
- Description of what happened, including evidence of seizure activity
- Review of PMH - susceptibility to haemorrhage, contraindications for reperfusion therapy or ischaemia
- Current medication including oral anti-coagulants
- Social history
- Probably won’t get history from patient - important to get focused history from witnesses
- Examination
- Airway, breathing and circulation stable?
- Focus on key deficits commonly found in stroke
- Should be nil by mouth until a formal speech and language therapy review is man
- When IV access is obtained, blood tests should be performed
Describe the older treatments for MS
- Injected daily, several times week or weekly
- Beta interferon, copaxone
- Less effective than fingolimod or monoclonal antibodies
- Patients often do not like injections
- Work well for some people
- May prolong life in some patients (long term data up to 16 years available)
- Less people disabled over 20 years
List the causes of a thunderclap headache
- Subarachnoid haemorrhage
- Approx. 15% of thunderclap headaches presenting to ED
- Other causes
- Intracerebral haemorrhage
- Arterial dissection (vertebral or carotid)
- Cerebral venous sinus thrombosis
- Ischaemic stroke
- Bacterial meningitis
- Spontaneous intracranial hypotension
- Pituitary apoplexy
What is the input and output for posture and voluntary movement?
- Input - cortex
- Output - cortex and brainstem
Describe the function and anatomy of the spinal accessory nerve
- Motor
- Function - head rotation and shoulder shrugging
- Nucleus location - medulla
- Structures innervated - sternocleidomastoid and trapezius muscles
Describe the mechanism of action and use of COMT inhibitors in Parkinson’s disease
- E.g. entacapone, tolcapone
- Inhibiting catechol-o-methyltransferase results in longer L-dopa half-life/duration of action
- Co-prescribed with L-dopa (available as combined table - Stalevo) in later disease
- Side effects - dopaminergic and diarrhoea
List the causes of low CSF pressure headaches
- Post-lumbar puncture
- Affects up to 1/3 cases
- 90% develop within 3 days
- Most resolve spontaneously
- Spontaneous intracranial hypotension
- Results from spontaneous dural tear
- Can occur following Valsalva
Describe the prevalence of relapse in epilepsy
- Of 780 patients
- 276 patients no remission
- 504 patients (64.6%) >12 months remission
- 399 patients (52%) no relapse
- 105 patients (13%) some relapse
- 63 patients (8%) regained remission
- 42 patients (5%) no regained remission
Describe the function of the basal ganglia
- Motor - movement
- Oculomotor - eye movement control
- Lateral orbito-frontal - social behaviour
- Dorsolateral prefrontal loop - executive functions/working memory
Basal ganglia have role in maintaining posture and initiating voluntary movement.
How is the olfactory nerve tested clinically?
Smell tested in each nostril separately, stimuli should be non-irritating and easily identifiable e.g. cinnamon, toothpaste
Describe the features of the dura mater
Thick, tough, inelastic
What is multiple sclerosis?
- Idiopathic inflammatory demyelinating disease of the CNS
- Acute episodes of inflammation are associated with focal neurological deficits
Describe resuscitation following an aneurysmal subarachnoid haemorrhage
- Bed rest
- Volume depleted
- Fluids - 2.5-3.0L normal saline
- Anti-embolic stockings (considered pro-thrombotic)
- Nimodipine - 60mg q 4Hr oral/NG or 2.5-10ml/Hr IV via central line
- Calcium channel antagonist - reduce risk of developing late ischaemia (microcirculation going into spasm)
- Analgesia
- Doppler studies
Describe the function of the optic nerve
Visual acuity and visual fields
What can be done in an ED when a patient who has had a stroke is approaching in an ambulance?
- In general ambulance crews now issue a pre-alert for all cases of hyperacute stroke (within the first few hours) - teams assessing patients w/ stroke can prepare for the arrival of the patient
- Methods of alert vary between sites and health services
- Once alerted, stroke team mobilise to the ED
- Prioritisation of acute stroke over TIA assessment
- All professionals who will be involved in the hyperacute management should be alerted
- Radiographers
- Radiologists
- Anaesthetists (id there is a thrombectomy service)
- Sometimes if sufficient clinical details, request for imaging can be submitted before the patient arrives in hospital - reduce waiting time for scan
- Designated area for assessing the patient should be cleared before they arrive
- Bay in resuscitation room or an area in the acute stroke unit
Describe the anatomy and function of the oculomotor nerve
- Motor
- Nucleus location - midbrain (oculomotor)
- Function - movement of eyeball and lens accommodation
- Structure innervated - inferior oblique, superior, medial and inferior recti muscles, levator palpebrae superioris (all extraocular muscles except superior oblique and lateral rectus)
- Parasympathetic
- Nucleus location - midbrain (Edinger Westphal)
- Function - pupil constriction
- Structure innervated - ciliary muscle and pupillary constrictor muscles
List the risk factors for small vessel stroke
- Hypertension
- Hyperlipidaemia
- Diabetes mellitus
- Tobacco use
- Sleep apnoea
List the typical sites for hypertensive ICH
- Basal ganglia
- Cerebellum
- Pons
How can lacunar stroke present?
- Pure motor stroke/hemiparesis
- Ataxic hemiparesis
- Dysarthria/clumsy hand
- Pure sensory stroke
- Mixed sensorimotor stroke
List clinical features of raised intracranial pressure
- Papilloedema on fundoscopy
- Constriction of visual fields
- Enlargement of the blind spots
- Unilateral or bilateral VI nerve palsy may be a false localising sign of in raised ICP
How is the patient assessed using the GCS?
- Glasgow Coma Scale
- Patient fully resuscitated
- Best motor, verbal and eye response
- If flex and extend give highest score
- Pain -
- Supraorbital press
- Trapezius pinch
- Sternal rub - risk damage to skin with repeated
- Distinguish between flexion and extension
- Can monitor changes in GCS over time to identify deterioration/improvement
List the main symptoms of multiple sclerosis
- Central
- Fatigue
- Cognitive impairment
- Depression
- Unstable mood
- Visual
- Nystagmus
- Optic neuritis
- Diplopia
- Speech
- Dysarthria
- Throat
- Dysphagia
- Musculoskeletal
- Weakness
- Spasms
- Ataxia
- Sensation
- Pain
- Hypoesthesias
- Parasethesias
- Bowel
- Incontinence
- Diarrhoea or constipation
- Urinary
- Incontinence
- Frequency or retention
Describe the arrangement of white and grey matter in the spinal cord
- Inner grey matter
- Dorsal horn (sensory)
- Intermediate horn
- Ventral horn (motor)
- Outer white matter
- Dorsal funiculus
- Lateral funiculus
- Ventral funiculus
What are the consequences of demyelination in multiple sclerosis?
- Demyelination results in loss of neurological function
- Weak leg
- Visual loss
- Urinary incontinence
- These deficits usually develop gradually, last for more than 24 hours and may gradually improve over days to weeks
- Later in untreated disease patients may become progressively more disabled
Describe the epidemiology of Parkinson’s disease
- UK prevalence - 180 per 100,000
- Approx. 12,000 patients in Scotland
- Prevalence 1.5x higher in men
- Prevalence rises exponentially >60 years
- 300-500 per 100,000 in >80 years
- Mean duration from diagnosis to death - 15 years
- Primarily a sporadic disorder
- Monogenic causes of PD account for about 6% of UK cases
- Significant economic burden
Describe the risk of seizures following a subarachnoid haemorrhage
- 1-7% patients may suffer seizures after initial aneurysm rupture
- Often a manifestation of re-rupture
- Short course (3-7d) may be useful in patients with heavy blood load, parenchymal clots, infarcts or >65 undergoing surgery
What are visual evoked potentials? How are they used in the diagnosis of MS?
- Measure conduction of nerve signals in optic nerve to look for subclinical optic neuritis
- Conduction will be slower if a patient has had optic neuritis in the past
Describe the components and drainage of the superficial venous system
- Primarily drains the cerebral cortex - Cortical veins - superior, middle and inferior groups - Drain into the superior sagittal sinus
What causes Horner’s syndrome?
- Results from ipsilateral disruption of cervical/thoracic sympathetic chain
- Congenital
- Brainstem stroke
- Cluster headache
- Apical lung tumour - Pancoast tumour
- Multiple sclerosis
- Carotid artery dissection
- Cervical rib
- Syringomyelia
Describe the organisation of the spinal cord
- Sensory tracts
- Dorsal columns
- Light touch, vibration, proprioception
- Crosses in lower brainstem
- Spinothalamic tract
- Pain and temperature
- Crosses as soon as spinal cord
- Dorsal columns
- Motor tracts
- Corticospinal tracts
- Cross in brainstem, descends in spinal cord on side of limb being supplied
- Anything above nerve root exit - upper motor neurone changes on that side (synapses with LMN before exits spinal cord)
- Corticobulbar tracts
- Corticospinal tracts
Describe the pathological progression of parkinson’s disease
- 1-2 = medulla/pons and olfactory nucleus
- Presymptomatic or pre-motor e.g. loss of smell
- 3-4 = midbrain - substantia nigra pars compacta
- Parkinsonism only becomes evident after extensive nigral damage
- 5-6 = neocortex involvement
- Development of PD dementia
How is semantic memory tested in the Addenbrookes Cognitive Evaluation
What DVT prophylaxis should patients recieve following a subarachnoid haemorrhage?
- SAH induces a prothrombotic state
- DVT in SAH 2-18%
- Highest incidence in poor grade SAH
- Timing of DVT prophylaxis in relation with aneurysm occlusion is controversial
- Probably safer to use sequential compression devices initially then LMWH after aneurysm secured
Which medications should be started to reduced risk of further ischaemic stroke?
Antiplatelets
- Guidelines from SIGN/NICE/European Stroke Organisation are broadly consistent
- Local guidance may vary
- Acutely - evidence that aspirin effective
- If the patient received thrombolytic therapy, then the patient should not receive this treatment for at least 24 hours, and not until a 24 hour CT scan has excluded significant haemorrhage
- Should be given at 300mg daily until day 14, or discharge - whichever is sooner
- Antiplatelets should be given for secondary prevention after
- Clopidogrel 75mg once daily regimen
- Aspirin 75mg and dipyridamole (modified release at 200mg bd) can be considered if the patient is intolerant to clopidogrel
- If evidence of arterial dissection or atrial fibrillation consider full anti-coagulation
- Combination of antiplatelet and anticoagulant not recommended for secondary prevention of stroke
Statins
- Prevent further stroke
- SIGN guidelines allow consideration of all statins including atorvastatin 80mg and simvastatin 40mg
- Benefit seen regardless of baseline cholesterol
Antihypertensives
- Lower BP to <140/85mmHg
- Started when patient is stable, generally not in the acute period
- Consider starting ACE inhibitor e.g. perindopril and a thiazide diuretic e.g. indapamide together
Where does the optic nerve exit the skull?
Optic canal
What is biotin? How is it used in MS?
- Dietary supplement
- High dose vitamin
- May lead to some symptom relief and mild improvement power
- Ongoing large clinical trials
- Gives energy to damaged nerve cells
Describe the appearance of an eye with an oculomotor nerve lesion
Ptosis, down and out deviation, fixed and dilated pupil
Describe the underlying pathophysiological process in ischaemic strokes
- Large vessel strokes usually due to vessel occlusion by thrombus
- Sources of thrombus e.g. embolism from plaques on atheromatous large vessels such as the carotid artery or aorta, or from a cardiac source
- Size of arterial occlusion depends on size of thrombus
- Occlusion impedes passage of blood, reducing cerebral blood flow to the brain territories distal to the clot
- When blood flow drops below a critical threshold, a cascade of events is set motion which may ultimately result in cell death, which occurs may 5 major mechanisms
- Exotoxicity
- Peri-infarct depolarisation
- Oxidative stress
- Inflammation
- Apoptosis
- Tissue does not die immediately but instead there is a time window when the tissue is compromised to reduced blood flow but is still potentially salvageable if there is reperfusion in a timely fashion
- In this case, can infer that thrombolytic therapy has led to recanalisation of the artery and reperfusion of the ischaemic penumbra
