Neurology Flashcards
What are the meninges layers?
- Extra -dural space = minimal/narrow, associated meningeal vessels
- Dura mater = outermost, tough, fibrous, forms folds, encloses dural venous sinuses
- Sub-dural space = narrow, contains bridging veins
- Arachnoid mater = soft, thin, loose
- Subarachnoid space = contains CSF + cerebral vessels
- Pia mater = innermost, adhered to the surface of the brain and contributes to BBB
Recap - Outline the main roles of the
a) Frontal lobe
b) Temporal Lobe
c) Parietal Lobe
d) occipital lobe
Frontal - decision making, movement, executive function, personality.
Temporal - hearing (primary auditory cortex), memory and language, smell, facial recognition
Parietal - Sensory info
Occipital lobe - Vision
Recap - What are the main responsibilities for the
a) Brainstem
b) Cerebellum
brainstem - controls Heart and breathing rate, Blood pressure and GI function, as well as consciousness
Cerebellum - Muscle coordination, and balance
Recap - what are the two arteries that supply the brain?
Internal carotid
Vertebral arteries
What does the internal carotid artery branch off to supply?
branches off to create the Anterior cerebral artery, as well as posterior communicating artery to join the circle of Willis
After this the ICA continues on as the Middle cerebral artery, which supplies the lateral portions of the cerebrum.
After entering the cranium through the foramen magnum, what branches does the vertebral artery give off? What do the 2 vertebral arteries then go on to do?
Give off Spinal arteries, supply the entire length of spine
Gives off The Posterior Inferior cerebellar artery - supplies cerebellum
also gives off a menigeal branch
But after this two vertebral arteries converge to form the basilar artery
What arteries branch off the basilar artery?
Superior cerebellar artery (SCA)
Anterior inferior cerebellar artery (AICA) - Both to supply the cerebellum
The Pontine arteries
What are the layers of the cerebellum?
- moleucular layer
- purkinje cell layer (most important as only ouput)
- granule cell layer
- white matter
What does the posterior cerebral artery go on to supply? What is it a branch of?
Supplies occipital lobe, posteromedial temporal lobes, midbrain, thalamus,
It is the terminal branch of the basilar arteries,
What does the anterior cerebral artery supply?
ANTERIOR CEREBRAL ARTERY (supplies and runs over Corpus Callosum and supplies Medial aspects of Hemispheres (anteromedial aspects of the cerebrum)
What is the cause of an extra-dural haemorrhage?
Traumatic – typically caused by bleeding from the meningeal arteries as a result of skull fracture that tears the dura
Middle meningeal runs close to the pterion
What is the weakest part of the skull?
Pterion point
What is the clinical presentation of extra-dural haemorrhage?
Patient may have extensive traumatic injuries
In other cases, patient sustains a head injury but appears to be OK for a while (‘lucid period’)
Bleeding into the extradural space > rapid rise in intracranial pressure (ICP) > brain is compressed
Headache, drowsiness, rapid neurological deterioration
Death if not treated rapidly (neurosurgical emergency
What is the imaging look like for an Extra-dural haemorrhage?
Acute (fresh) bleed appears hyperdense on CT (bright white)
Convex; does not conform to surface of the brain as bleeding is limited by dural attachments to the skull (lemon shape)
Compression of the brain – midline shift (falx cerebri, lateral ventricles)
Skull fracture may be seen
What is the cause of a sub-dural haemorrhage?
Usually caused by trauma – typically a fall leading to bleeding from dural bridging veins
Low pressure bleeding
Gradual rise in ICP (over several weeks or months)
Most likely in patients with brain atrophy (elderly, dementia, history of excess alcohol intake) – bridging veins
WHat is the clincal presentation for sub dural haemorrhage?
Typical picture is of gradual cognitive deterioration
May be a history of a fall, maybe not
Patient may have old bruising on their head (or elsewhere) suggesting frequent / recent falls
What is the appearance of imaging for sub dural?
(banana shape)
Chronic (old) bleed appears hypodense on CT (dark)
Concave; conforms to surface of the brain as bleeding is not limited by dural attachments
Compression of the brain – signs include midline shift (falx cerebri, lateral ventricles)
What are the investigations for a SDH?
Immediate CT head
WHat is the cause of a sub-arachnoid haemorrhage?
Usually spontaneous from rupture of an aneurysm on a cerebral artery
Can be traumatic, but this is less common
What is the management for a SDH?
Drainage:
- small SDH are drained via a burr hole washout a small tube called
- large SDH requires a craniotomy which is when part of the skull bone is removed
What are the complications a the raised intercranial pressure in a SDH?
Supratentorial herniation: cerebrum is pushed against the skull or the tentorium, can compress the arteries that nourish the brain leading to an ischaemic stroke
Infratentorial herniation: cerebellum is pushed against the brainstem, can compress the vital area in the brainstem that control consciousness, respiration, and heart rate
WHat is the clinical presentation for subarachnoid?
Typically present with sudden onset severe ‘worst-ever headache’ (‘thunderclap’)
Patient may:
be conscious
have reduced GCS
be unconscious (poorer prognosis)
Can be rapidly fatal
What is the appearacne of a sub-arachnoid bleed?
Acute (fresh) bleed is hyperdense on CT (bright white)
Blood seen in fissures and cisterns +/- ventricles
(not a large mass like SD and ED)
Blood in the SA space:
irritates the meninges
irritates cerebral vessels and causes vasospasm > hypoxic injury
may track back into the ventricular system > hydrocephalus
(looks like spider)
What is the cause of an intra-cerebral haemorrhage?
- Spontaneous due to aneurysm or vessel rupture
- Small perforating vessels prone to rupture, especially if hypertensive
- Clinical presentation determined by the size of the bleed and brain region affected
E.g.
Coma
Weakness (facial, limbs)
Seizure
What is the appearance of a intra-cerebral bleed on imaging?
Acute (fresh) bleed is hyperdense on CT (bright white)
Blood seen in the substance of the brain
Mass effect seen if large (e.g. midline shift)
What is an epidural haemorrhage?
Bleeding above the dura matter
(same as extra dural haemorrhage)
Who is an EDH most common in?
They usually occur in young adults
What are the symptoms of a EDH?
Reduced GCS: loss of consciousness after the trauma due to concussion
- There might be a lucid interval after initial trauma if there is a slower bleed. This is followed by rapid decline.
Headaches
Vomiting
Confusion
Seizures
Pupil dilation if bleeding continues
What are the differentials for a EDH?
Epilepsy
Carotid dissection
Carbon monoxide poisoning
Subdural haematoma
Subarachnoid haemorrhage
What is the management for a EDH
Clot evacuation
Craniotomy: part of the skull bone is removed in order to remove accumulated blood below.
Followed by ligation of the vessel.
Which part of the brain do the middle, anterior and posterior arteries supply?
Anterior = front and midline
Middle = lateral lobes
Posterior = posterior part of brain
What is Broca’s and Wernicke’s area?
Broca - motor control of speech
Wernicke - understanding of speech
What artery and location of the primary motor cortex control upper and lower limb?
Lower limb - represented the medial surface of the cerebral hemisphere = anterior cerebral artery territory
Upper limb and face represented on the lateral surface = middle cerebral artery territory
What is the difference between CNS and PNS?
CNS = brain and spinal cord
PNS = cranial nerves, spinal nerves, ganglia
Where are motor neurones located in the spinal cord?
Ventral horn = motor neurones
Where are sensory neurones located in the spinal cord?
Dorsal root ganglion
What nerve fibres are carried in the spinal cord?
Sympathetic - smooth muscle, sweat glands
Somatic motor
Somatic sensory
What are the main ascending sensory tracts?
Dorsal columns
Spinothalamic tract
What is the main descending motor tract?
Lateral corticospinal tract
What is the route of the lateral corticospinal tracts? And consequence of lesion?
Descending motor control
decussate in the medulla
enter the contralateral lateral CST
UMN synapses with LMN in the ventral grey hron
axon leaves in the spinal nerve
lesions in cord = ipsilateral weakness
What sensations does the dorsal column pathway control?
Touch, proprioception, vibration
Cuneate fasciculus – info from the UL
Gracile fasciculus – info from the LL
What sensations does the spinoithalamic tract control?
pain and temperature
- ventrolateral
What is the route of the dorsal column pathway? And consequence of lesion?
1.Sensory primary axons ascend in the ipsilateral dorsal columns (cuneate or gracile fasciculus
2. Synapse with 2nd neuron in the cuneate (UL) or gracile (LL) nucleus
3. Axons decussate in the medulla then ascend
4. Synapse with 3rd neuron in thalamus
5. Axons project to the somatosensory cortex
Lesions in the cord: ipsilateral loss of / impaired fine touch and proprioception
What is the route of the spinothalamic tract? And consequence of lesion?
(travel up on opposite side)
Sensory primary axon synapses with 2nd neuron in the grey horn
Axons decussate then ascend
Synapse with 3rd neuron in thalamus
Axons project to the somatosensory cortex
Lesions in the cord: contralateral loss of / impaired pain and temp sensation
What is the difference between a dermatome and myotome?
Dermatome = area of skin supplied by a single spinal nerve
Myotome = muscles supplied by a single spinal nerve
What is the function of cranial nerve 1?
Olfactory
- sense of smell
- receptor in nasal cavity
- travel from cribriform plate > olfactory bulb > tracts > temporal lobe
What is the function of cranial nerve 2?
optic nerve
- Fibres travel from the retina to the primary visual cortex (calcarine sulcus, medial aspect of occipital lobe)
What is the function of cranial nerve 3?
Oculomotor nerve
- innervates eye muscles except from superior oblique + lateral rectus
- parasympathetic fibres = constrict the pupil
What is the function of the 4th nerve?
Trochlear
- Superior oblique muscle
(test by looking medially and down)
What is the function of 6th cranial nerve?
Abducens
Lateral rectus = abducts the eye
What is the function of 5th cranial nerve?
Trigeminal
Sensory and motor; 3 divisions:
Ophthalmic V1 > sensory
Maxillary V2 > sensory
Mandibular V3 > sensory plus motor to the muscles of mastication
What is the function of 7th cranial nerve?
Facial
Taste anterior 2/3 tongue
Muscles of facial expression:
Muscles of the upper face bilaterally innervated by the motor cortex
Muscles of lower face contralaterally innervated by the motor cortex
Parasympathetics to the lacrimal, submandibular and sublingual salivary glands
(stimulates secretion)
What is the function of the 8th cranial nerve?
Vestibulocochlear
- hearing + balance
WHat is the function of the 9th cranial nerve?
Glossopharyngeal
Taste posterior 1/3 of the tongue
General sensation: (touch, temp, pain)
Pharynx, posterior 1/3 of the tongue
Parasympathetics to parotid gland
What is the function of the 10th cranial nerve?
Vagus
General sensation - pharynx, larynx, oesophagus.
Motor - muscles of the soft palate, pharynx and larynx – vital for swallowing and speech
Parasympathetics: thoracic and abdominal viscera
What is the function of the 11th cranial nerve?
Accessory
Motor to sternocleidomastoid and trapezius
What is the function of cranial nerve 12?
Hypoglossal
Motor to the tongue muscles.
- Nerve lesion > ipsilateral tongue muscles are paralysed
(left deviation = left hypoglossal lesion)
What is Amaurosis Fugax?
A classical syndrome of painless short-lived monocular blindness.
It is a term usually reserved for transient visual loss of ischaemic origin.
What is the aetiology of Amaurosis Fugax?
- temporary reduction in the retinal, ophthalmic or ciliary blood flow leading to temporary retinal hypoxia
- transient obstruction from emboli of ophthalmic artery
- can occur in TIA
(other causes are giant cell arteritis and central retinal artery occlusion)
What is an ischaemic stroke?
An episode of neurological dysfunction caused by focal cerebral, spinal, or retinal infarction
(cell death due to lack of blood supply)
What is a stroke due to intracerebral haemorrhage?
Rapidly developing clinical signs of neurological dysfunction attributable to a focal collection of blood within the brain parenchyma or ventricular system not caused by trauma.
What is a stroke due to subarachnoid haemorrhage?
Rapidly developing signs of neurological dysfunction and/or headache because of bleeding into the subarachnoid space
(the space between the arachnoid membraneand the pia mater of the brain or spinal cord),
which is not caused by trauma.
What symptoms does a stroke in the dominant hemisphere cause?
(usually left hemisphere - right handed)
Language dysfunction
Expressive dysphasia
Receptive dysphasia
Dyslexia
Dysgraphia
What symptoms does a stroke in a non-dominant hemisphere cause?
Non-dominant hemisphere
(usually RIGHT hemisphere)
Anosognosia
- Neglect of paralysed limb (unaware of side of body)
- Denial of weakness
Visuospatial dysfunction
- Geographical agnosia
- Dressing apraxia
- Constructional apraxia
What are the symptoms of a anterior cerebral artery stroke?
Contralateral hemiparesis and sensory loss with upper limbs > lower limbs
Homonymous hemianopia
Aphasia: if the affecting dominant hemisphere 95% of right handed people this is the left side
Hemineglect syndrome if affecting the non-dominant hemisphere patients won’t be aware of one side
What are the symptoms of posterior cerebral artery strokes?
Contralateral homonymous hemianopia with macular sparing
contralateral loss of pain and temp due to spinothalamic damage
Unsteadiness
Visual disturbance
Slurred speech
Headache (MC in posterior)
Vomiting
Others e.g. memory loss, confusion
What are the symptoms of a vertebrobasilar artery stroke?
Cerebellar signs
Reduced consciousness
Quadriplegia (affects all 4 limbs + torso) or hemiplegia (one side of body)
What is Weber’s syndrome and what are the symptoms of it?
It is a midbrain infarct that leads to oculomotor palsy and contralateral hemiplegia (lack of control in one side of body)
What are the symptoms of lateral medullary syndrome (posterior inferior cerebellar artery occlusion)
ischaemia in lateral part of medulla oblongata
Ipsilateral facial loss of pain and temperature
Horner’s syndrome: miosis (constriction of the pupil), ptosis (drooping of the upper eyelid), and anhidrosis (absence of sweating of the face)
Ipsilateral cerebellar signs
Contralateral loss of pain and temperature
What is used to classify strokes and how does it do it?
The Bamford classification and it categorises strokes based on the area of circulation affected
What is used to identify strokes in the community?
F- Face
A- Arm
S- Speech
T- Time (this is a stupid one because it is not a symptom just there to make the word fast)
What is used to identify strokes in hospital?
Recognition of Stroke in the Emergency Room (ROSIER) scale.
What are the criteria for the ROSIER scale?
Loss of consciousness
Seizure activity
New, acute onset of:
- Asymmetric facial/arm/leg weakness
- Speech disturbance
- Visual filed defect
When would a stroke be possible using the ROSIER scale and what would happen as result?
A stroke is possible if they have any of the criteria and hypoglycaemia has been excluded
WOULD REQUIRE URGENT NON-CONTRAST CT
- Aspirin 300mg stat (after the CT)
What are key features of stroke symptoms?
Onset = abrupt (secs)
Nature of symptoms = Focal (localised to an area of the brain)
Quality = negative
Maximal deficit = at the start (symptoms are worse)
What are differential diagnosis for stroke?
Epileptic seizure = history + symptoms (unconscious)
Space occupying lesion (e.g. subdural, tumour, arteriovenous malformation) = gradual onset, headache, confusion, drowsiness, deterioration
Infection (MC in elderly - can unmask deficit from previous stroke) = gradual onset, fever
Metabolic (e.g. hyponatraemia, hypoglycaemia, hypercalcaemia, uraemia) = confusion, reduced consciousness, ataxia
Multiple sclerosis = young, sub acute progression
Functional neurological disorder (FND) = inconsistencies, ‘give way’ weakness
Migraine = history, previous attacks
Hepatic encephalopathy
What investigations are done for a stroke?
1st line: CT head (rule out anything serious like a tumour or bleed - often normal after a stroke)
GOLD: MRI brain with diffusion weighted imaging (can see ischaemia when a CT can’t)
- Blood tests (metabolites, electrolytes)
- ECG +- 72 hour tape
- carotid doppler
- ECHO
- CT or MR angiogram
What are the 4 categories for ischaemic stroke?
- large vessel disease (50%)
- small vessel disease
- cardioembolic
- cryptogenic/ rarities
What are the 2 categories of haemorrhagic stroke?
- primary intracerebral haemorrhage
- subarachnoid haemorrhage
What causes ischaemic stroke in large vessel iscahemia?
- atherosclerosis
- blood vessel occlusion, thrombus
- embolism
What causes small vessel ischaemic stroke?
- small deep perforator arteries blocked
- caused by high blood pressure, diabetes, smoking, age
- in situ microatheroma or lipohyalinosis
What are the causes of cardioembolic stroke?
Cardiogenic embolus:
Mural thrombus
Atrial fibrillation
Endocarditis (vegetation can embolise)
Atrial septal defect (
What is the most common cause of stroke in young people?
Dissection (carotid or vertebral)
Risk factors:
- trauma or cervical manipulation
- vigorous physical activity (eg weightlifting)
- vasculopathy (fibromuscular dysplasia, Marfan’s)
- sympathomimetic drug abuse
(can also be spontaneous)
What is a primary intracerebral haemorrhage stroke and its causes?
leakage of blood directly into brain tissues due to
- hypetension
- amyloidosis
- arteriovenous malformation
- aneurysm rupture
What is a secondary intracerebral haemorrhage?
NOT classed as a stroke
- due to trauma, warfarin or bleeding into a tumour
- but can cause similar symptoms as primary
What are the risk factors for developing an intracerebral stroke?
Head injury
Hypertension
Aneurysm
Brain tumour
Anticoagulant
What are the presentations of an intracerebral haemorrhage?
Sudden headache is a key feature
Weakness
Seizure
Vomiting
Reduced consciousness
What does a ‘thunder clap headache signify?
Subarachnoid haemorrhage
What are the investigations for a intracerebral haemorrhage?
CT/MRI to confirm size and location of the haemorrhage
Check FBC and clotting
Angiography to visualise the exact location of the haemorrhage
What is the management for a intracerebral haemorrhage?
Consider ICU and intubation and ventilation if there is reduced consciousness
Correct any clotting abnormalities
Correct severe hypertension but avoid hypotension
Drugs to relieve intercranial pressure mannitol
What are the surgeries that can be performed for an intracerebral haemorrhage?
Craniotomy = part of the skull bone is removed to drain any blood and relieve pressure
Stereotactic aspiration = aspirate off blood and relieve intracranial pressure guided by a CT scanner. Good for bleeding that is located deeper in the brain
What is the treatment for a ischaemic stroke?
Antiplatelets: aspirin given as soon as possible once haemorrhagic stroke is excluded
Thrombolysis: alteplase (tissue plasminogen activator)- given if to re-establish blood flow is <4.5 hours of symptom onset
Thrombectomy must score > 5 on NIH Stroke Scale/Score (NIHSS) and pre-stroke functional status < 3 on the modified Rankin scale
What should be performed before thrombectomy?
CT angiogram (CTA): identifies arterial occlusion
What are secondary stroke preventions?
- Antiplatelets agents = Clopidogrel (Warfarin/DOAC superior to aspirin in AF/mural thrombus)
- statins = stabilis atherosclerotic plaque
- long term BP lowering
- carotid intervention (remove blockage to prevent it happening again)
What can cause Subarachnoid Haemorrhage?
Trauma is a key factor
Atraumatic cases are referred to as spontaneous SAH
What is the most common cause of a spontaneous SAH?
Berry aneurysm- they account for 80% of cases.
Arise at points of bifurcation within the circle of Willis; the junction between the anterior communicating and anterior cerebral artery
They are associated with PKD, coarctation of the aorta, and connective tissue disorders (Marfan)
What are the risk factors for having a SAH?
Cocaine use
Sickle cell anaemia
Connective tissue disorders
Neurofibromatosis: tumours form on your nerve tissues
PKD
Alcohol excess
What can occur as a result of a subarachnoid haemorrhage?
Blood vessels that are bathing in a pool of blood can start to intermittently vasoconstrict (vasospasm).
If this occurs in the circle of Willis it will reduce the supply of blood flow to the brain causing further injury
Over time blood in the subarachnoid space can irritate the meninges and cause inflammation which leads to scarring of the surrounding tissue.
The scar tissue can obstruct the normal outflow of CSF causing fluid to build up leading to hydrocephalous
What are the signs of a SAH?
3rd nerve palsy- if the aneurysm occurs in posterior communicating artery
6th nerve palsy a non-specific sign which indicates raised intercranial pressure
Reduced GCS
What are the symptoms of a SAH?
Thunderclap headache during strenuous activity or sex. It’s like being hit really hard on the back of the head
Neck stiffness
photophobia
Vison changes
What are the initial investigations for SAH?
FBC
Serum glucose
Clotting screening
Urgent non-contrast CT of the head.
- Blood will cause ** hyperattenuation (this means becoming more dense on CT will show as white)** in the subarachnoid space
What tests would you perform if CT is negative but a SAH is still suspeccted?
Lumbar puncture: will show RBCs or xanthochromia (yellow pigmentation due to degradation of haemoglobin to bilirubin - so need to wait till 12 hours after SAH)
What is the management to prevent vasospasm?
Nimodipine is a CCB and prevents vasospasms
What is the management to stop the bleeding?
First line: Endovascular coiling of the aneurysm
Second line: surgical clipping via craniotomy
What are the complications of a SAH?
Rebleeding 22% risk at one month
Vasospasm: accounts for 23% of deaths; at highest risk for the first 2-3 weeks after SAH; treated with (induced) hypertension,hypervolemia andhaemodilution (triple-H therapy).
Hydrocephalus: acutely managed with external ventricular drain (CSF drainage into an external bag) or a long-term ventriculoperitoneal shunt, if required
Seizures: seizure-prophylaxis is often administered (e.g. Keppra)
Hyponatraemia: commonly due to syndrome of inappropriate antidiuretic hormone secretion (SIADH)
What is the treatment for a haemorrhagic stroke?
- Admit to neurocritical care: patients will need intensive monitoring
- If features of raised intracranial pressure:
consider intubation
with hyperventilation,
head elevation (30°)
and IV mannitol (reduce ICP) - Surgical intervention:decompression may be needed
What are the risk factors for developing a stroke
Hypertension
Smoking
AF
Vasculitis
Medication e.g. hormone replacement therapy
If the anterior cerebral artery is affected in a stroke where in the body will be affected?
Feet and legs
If the middle cerebral artery is affected in a stroke where in the body will be affected?
Hands and arms
Face
Language centres in the dominant hemisphere
If the posterior cerebral artery is affected in a stroke where in the body will be affected?
The visual cortex will be affected meaning the patient won’t be able to see properly
What is a TIA?
A transient episode of neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia without acute infarction.
It usually resolves within 24 hours
What is the management for a TIA?
First line is antiplatelet initially with aspirin 300mg
Carotid endarterectomy: surgery to remove blockage of >70% on doppler
Manage cardiovascular risk with atorvastatin etc
What is a crescendo TIA?
Where there are two or more TIAs within a week. It carries a high risk of a stroke
How many people who have a TIA will go on to have a stroke
10% within 3 months
What are the two categories a haemorrhagic stroke can be split in to?
Intracerebral where the bleeding occurs within the cerebrum
Subarachnoid when bleeding occurs between the pia and arachnoid matter
What is meningitis?
Meningitis refers to inflammation of the pia and arachnoid mater. Micro-organisms infect the cerebrospinal fluid (CSF).
What are the 3 main features of ‘meningism’?
Stiffness of the neck
Photophobia
Severe headache
What other symptoms would present with bacterial or viral meningitis?
Fever
Feel unwell
Rash (characteristically haemorrhagic in meningococcal meningitis)
What are the viral causes of meningitis?
80% viral
- Enteroviruses (including Echo virus, Coxsackie virus)
- Herpes simplex virus
- Mumps virus
- varicella zoster virus
- Lymphocytic chorio meningitis virus
And historically, Poliovirus (also an enterovirus)
What are the main bacterial causes of meningitis for each age group?
Neonates = E.coli, Group B strep, Listeria monocytogenes
Infants = N.meningitis + H.influenza, Strep pneumoniae
Adults = N.meningitis + S.pneumoniae
Elderly = S. pneumoniae + N.meningitis + listeris monocytogenes
What are the causes of fungal meningitis?
Cryptococcus neoformans
Candida
What are some risk factors for developing meningitis?
Immunocompromised: such as being in the extremes of age, infection (HIV), and medication (Chemotherapy) Listeria monocytogenes
M. Tuberculosis
Non-immunised: at risk ofH. influenza, pneumococcal and meningococcal meningitis
Crowded environments: students living in halls of residence are a commonly affected demographic
What is encephalitis?
Refers to inflammation of the cerebral cortex
What are the main clinical symptoms of encephalitis?
Lethargy + fatigue
Decreased level of consciousness
Fever
Focal neurology
Occasionally there may be fits
What are the viral causes of encephalitis?
Herpes simplex virus
Varicella zoster virus
Parvoviruses
HIV
Mumps virus
Measles virus
Where are the signs of encephalitis?
Pyrexia (fever)
Reduced GCS
Aphasia
Hemiparesis
Cerebellar signs
–
What are some behavioural changes that occur in encephalitis?
Memory disturbance
Psychotic behaviour
Withdrawal or change in personality
What are some investigations for encephalitis?
Throat swab
HIV serology
MRI of head will show evidence of inflammation will be normal in 1/3 of cases
Lumbar puncture and CSF investigation including a PCR for HSV
What are some differentials for encephalitis?
Meningitis
Encephalopathy
Status epilepticus
CNS vasculitis
What is the treatment for encephalitis?
Aciclovir = should be given in all cases where it is suspected
Ganciclovirmay = be preferred in other herpesvirus infections, such as HHV-6
What lab investigations are done for enterovirus?
Nose + throat swabs
- plated out onto blood and chocolate agar
PCR
Stool
What lab investigations are done for S.pneumoniae and N.meningitidis?
Blood cultures
PCR
What CSF cell count results would signify a bacterial cause of infection?
- a neutrophil predominant leucocytosis
- a raised protein (from dying bacteria)
- reduced CSF glucose to serum glucose ratio (metabolically active bacteria, use up glucose as a source of energy)
What are the two tests to look for meningeal infection?
Kernigs Test
Brudzinski’s Test
What is Kernigs Test?
Involves patient lying on their back and flexing one hip and knee to 90 degrees and then slowly straightening the knee whilst keeping the hip flexed. This causes the meninges to stretch
A positive test will be where there is spinal pain or resistance to the movement
What is Brudzinski’s Test?
Involves lying a patient on their back and gently using your hands to lift their head and neck off the bed and flexing their chin to their chest
A positive test is when a patient involuntarily flexes their hips and knees
What is another classic sign of meningococcus meningitis?
non-blanching rash
- that everybody worries about as it indicates the infection has caused disseminated intravascular coagulopathy (DIC) and subcutaneous haemorrhages.
Other causes of bacterial meningitis do not cause this rash
What is the empirical antibiotic therapy used against bacterial causes of CNS infection in hospital?
IV cefotaxime or ceftriaxone
What medication should be prescribed alongside antibiotics for meningitis treatment?
IV dexamethasone (corticosteroids)
- reduce risk of long term neurological complications from some causes of meningitis
what medication should be given in primary care for meningitis?
IM benzylpenicillin
then admit the patient ASAP!!
What is the management for meningitis?
- Assess GCS
- blood culture
- broad spectrum antibiotics = Ceftriaxone or cefotaxime
- Steroids = IV dexamethasone
- lumbar puncture = definitive diagnosis
What are the contraindications for a lumbar puncture?
Abnormal clotting (platelets/coagulation)
Petechial rash
Raised intracranial pressure
GCS <9
Where is a lumbar puncture usually taken from?
Between L3/L4
Since spinal cord ends L1/2
When would you do a CT head before a lumbar puncture in meningitis?
Aged > 60
Immunocompromised
History of CNS disease
Seizures <1 week
GCS <14
Focal neurological signs
Papilloedema
Atypical history
What are close contacts of patients with meningitis offered?
Notified
Antibiotic prophylaxis = single dose of ciprofloxacin
What is the CSF count and culture characteristic for a viral meningitis infection?
Predominant lymphocyte response
Only moderately raised protein
CSF glucose more than 50% of the level of serum glucose
What antimicrobial agent is used to treat a viral meningitis or encephalitis infection?
IV aciclovir
How does an infection get into the brain?
- extra-cranial infection e.g. nasopharynx, ear, sinuses
- neurosurgical complications e.g. post op, infected shunts, trauma
- via blood stream e.g. bacteraemic
What is the pathophysiology of meningitis?
- bacteria in blood
- bacteria enter CSF and can be isolated from immune cells due to BBB
- replication
- blood vessels become leaky
- so WBCs can enter the CSF, meninges and brain
- meningeal inflammation +/- brain swelling
What types of meningitis are acute and which are more commonly chronic?
Bacterial and viral meningitis are usually acute
Fungal is more chronic
What will a lumbar puncture show for bacterial meningitis?
high pressure
cloudy
high WBCs
neutrophils
low glucose
high protein
What will a lumbar puncture show for viral meningitis?
normal or elevated pressure
clear
increased lymphocytes
high glucose
low protein
what will a lumbar puncture results show for fungal/TB meningitis?
elevated pressure
cloudy/fibrin web
Increased lymphocytes
low glucose
high protein
What are the common metastases for secondary brain tumours?
Lung
breast
melanoma
renal cell
GI
What are the symptoms of secondary brain tumours?
- Headache: worse in morning, when coughing or bending
- Focal neurological signs
- Ataxia
- Fits
- Nausea
- Vomiting
- Papilloedema (on fundoscopy)
What are the investigations for brain tumours?
CT/MRI
What is the management for brain tumours?
- steroids = dexamethasone (reduce cerebral oedema)
- Stereotactic radiotherapy/chemotherapy
- surgery if <75 years
- palliative care
What are mononeuropathies?
Lesions of individual peripheral or cranial nerves
- causes are usually local e.g. trauma or entrapment (tumour)
What are the features of a median nerve lesion in the wrist and anterior interosseous?
C6-T1 = nerve of precision grip + LOAF
Wrist = carpal tunnel syndrome, weakness of abductor pollicis brevis; sensory loss over the radial 3 1/2 fingers and palm
Anterior interosseous nerve lesions = weakness of flexion of the distal phalanx of the thumb and index finger
Proximal lesions = may show combined effects
What is the presentation of an ulnar nerve palsy/lesion?
C7-T1
Claw hand
(4th + 5th fingers ‘claw’ up)
- sensory loss over medial 1 1/2 fingers and ulnar side of the hand
- wasting of hypothenar eminence
What is the treatment for a ulnar nerve palsy?
Splint for elbow
simple analgesia
rest + avoid pressure on nerve
What is the presentation of a radial nerve palsy?
C5-T1
Wrist drop
Muscles involved = BEAST
Brachioradialis
Extensors
Abductor pollicis longus
Supinator
Triceps
What is the treatment for a radial nerve palsy?
Splint and simple analgesia
What are the causes of brachial plexus lesion?
- Trauma
- Radiotherapy
- Prolonged wearing of heavy rucksack
- Cervical rib
- Thoracic outlet compression
- Neuralgic amyotrophy
What are the signs of a brachial plexus lesion?
Pain/ paraesthesia and weakness in the affected arm in a variable distribution
What are the causes of a phrenic nerve lesion?
C3,4,5 keeps the diaphragm alive
- Lung cancer
- TB
- Paraneoplastic syndrome
- Myeloma
- Thymoma
- Cervical spondylosis/ trauma
- Thoracic surgery
- Infections e.g. HZV, HIV, Lyme disease
- Muscular dystrophy
What are the signs of a phrenic nerve lesion?
- Orthopnoea
- Raised hemi-diaphragm on chest x-ray
What nerve causes a ‘foot drop’?
Common peroneal nerve L4-S1
What are the effects of a tibeal nerve lesion?
L4-S3
- inability to stand on tiptoes, invert foot and flex the toes
- sensory loss over the sole
What is mononeuritis mulitplex? And causes?
- Involvement of two or more peripheral nerves
- Causes tend to be systemic: diabetes mellitus, connective tissue disorders, vasculitis, sarcoidosis, amyloidosis, leprosy
- Electromyography helps define the anatomic site of lesion
What are the signs of cranial nerve 1 lesion?
- Reduced taste and smell
- Ammonia taste remains as it stimulates the pain fibres carried in the trigeminal nerve
What are the causes of a cranial nerve lesion?
- Trauma
- Frontal lobe tumour
- Meningitis
- fracture
- Raised ICP
- Diabetes
- hypertension
What are the signs of cranial nerve 2 lesion?
- Visual field defects:
- Start as small areas of visual loss (scotomas).
- Monocular severe sight impairment: lesions of one eye or optic nerve
- Bilateral severe sight impairment
- Bitemporal hemianopia
- Homonymous hemianopia: loss of the same half (left or right) of the visual field of both eyes, on the opposite side to the lesion (eg, a right side lesion causes loss of the left side of the visual field of both eyes).
- Pupillary abnormalities
- Optic neuritis
- Pain on moving the eye
- Loss of central vision
- Afferent pupillary defect
- Papilloedema
- Optic atrophy
- Pale optic discs
- Reduced acuity
What are the signs of cranial nerve 3 lesion?
- Fixed dilated pupil which doesn’t accommodate
- Ptosis
- Complete internal ophthalmoplegia
- Unopposed lateral rectus causes outward deviation of the eye
- If the ocular sympathetic fibres are also affected behind the orbit, the pupil will be fixed but not dilated.
What are the signs of cranial nerve 4 lesion?
- Diplopia due to weakness of downward and inward eye movement (pure vertical diplopia)
- Compensation by tilting the head away from the affected side
What are the signs of cranial nerve 5 lesion?
- Reduced sensation or dysasthesia over the affected area
- Weakness of jaw clenching and side-to-side movement.
- If LMN lesion, the jaw deviates to the weak side when the mouth is opened
- May be fasciculation of temporalis and masseter
What are the causes of sensory CN5 lesions?
Trigeminal neuralgia
HSV
Nasopharyngeal carcinoma
What are the signs of cranial nerve 6 lesion?
- Inability to look laterally
- Eye is deviated medially because of unopposed action of the medial rectus muscle
What are the signs of cranial nerve 7 lesion?
- Facial weakness
- LMN lesion:
- Forehead is paralysed - the final common pathway to the muscles is destroyed
- UMN lesion:
- Upper facial muscles are partially spared because of alternative pathways in the brainstem
What is Bell’s palsy/
Neurological condition that presents with rapid onset of unilateral facial paralysis
Why is the top half of the face sometimes spared in Bell’s palsy?
The lower half of the faces only has contralateral innervation
Top half has bilateral. forehead sparing
How can you tell between an UMN and LMN Bell’s palsy?
UMN injured: means the contralateral side is weak but the forehead is not
LMN - weakness of all the muscles on the ipsilateral side of the face
What are the signs of cranial nerve 8 lesion?
- Unilateral sensorineural deafness
- Tinnitus
- Slow-growing lesions seldom present with vestibular symptoms as compensation has time to occur
What are the signs of cranial nerve 9 lesion?
- Unilateral lesions do not cause any deficit because of bilateral corticobulbar connections (wasting and deviation of tongue)
- Bilateral lesions result in pseudobulbar palsy
What are the causes of a CN9/CN10 lesion?
Jugular foramen lesion
What are the signs of cranial nerve 10 lesion?
- Palatal weakness:
- Nasal speech
- Nasal regurgitation of food
- Palate moves asymmetrically when the patient says ‘ahh’
- Recurrent nerve palsy:
- Hoarseness
- Loss of volume
- Bovine cough (non- explosive cough of someone unable to close their glottis)
What are the signs of cranial nerve 11 lesion?
Weakness and wasting of sternocleidomastoid and trapezius muscles
What are the signs of cranial nerve 12 lesion?
- LMN lesion:
- Wasting of the ipsilateral side of the tongue, with fasciculation
- Attempted protrusion of tongue causes deviation towards the affected side
What are conditions that may affect cranial nerves?
- Diabetes mellitus
- Stroke
- MS
- Tumours
- Sarcoid
- Vasculitis (e.g. polyarteritis nodosa)
- Systemic lupus erythematosus (SLE)
- Syphilis
- Chronic meningitis (malignant, TB, or fungal)
How do you get a tetanus infetion?
Inoculation through skin with Clostridium tetani spores (found globally in soil)
Clostridium tetani - gram positive anaerobe with spores
e.g. stepping on a nail, dirty wounds
What toxins does a tetanus infection produce?
Tetanolysin (tissue destruction)
Tetanospasmin (clinical features )
What are the symptoms of tetanus?
Unopposed flexion of limbs
spasm of muscles
What is the management of tetanus?
Prevention = vaccinate!!
Supportive
Muscle relaxants
Paracetamol/cooling
Immunoglobulin to mop up toxin
Metronidazole to clear any residual bacteria
How do you become infected with Rabies?
Inoculation through skin withsaliva of rabid animal(dogs, cats, foxes etc)
e.g. lick, bite, splash
Travels retrogradelyalong nerves
What is the clinical manifestation of Rabies?
Incubation depends on site and size of inoculation
symptoms can first present within Min 2 weeks to Max years!
Paraesthesia at bite site
Reaches CNS…
Furious or paralytic presentation
What is the management for rabies?
Once symptomatic invariably fatal (>99.9%)
Managed with sedatives ++++
PROPHYLAXIS IS KEY!!!
pre-exposure prophylaxis(vaccination)
post-exposure prophylaxis (vaccination and immunoglobulin)
What are polyneuropathies?
Motor and/or sensory disorder of multiple peripheral or cranial nerves
Usually symmetrical, widespread and worse distally (glove and stocking distribution)
What are the classification of polyneuropathies?
- Chronicity e.g. acute or chronic
- Function e.g. sensory, motor, autonomic or mixed
- Mostly motor e.g.
- Guillain-Barre syndrome
- Lead poisoning
- Charcot-Marie-Tooth syndrome
- Mostly sensory e.g.
- Diabetes mellitus
- Renal failure
- Leprosy
- Mostly motor e.g.
- Pathology e.g. demyelination, axonal degeneration or both
What are the causes of polyneuropathies?
- Metabolic: diabetes mellitus, renal failure, hypothyroidism, hypoglycaemia, mitochondrial disorders
- Vasculitides: polyarteritis nodosa, rheumatoid arthritis, GPA
- Malignancy: paraneoplastic syndromes, polycythaemia rubra vera
- Inflammatory: Guillain-Barre syndrome, sarcoidosis
- Infections: leprosy, HIV, syphilis, lyme disease
- Nutritional: decreased; vit B12, B1, B6, E
- Inherited syndromes: Charcot-marie-tooth, porphyria, leucodystrophy
- Drugs/toxins: lead, arsenic, alcohol, vincristine, cisplatin, metronidazole, isoniazid, phenytoin, nitrofurantoin
- Other: paraproteinaemias, amyloidosis
What are the differential diagnoses for epilepsy?
- postural syncope
- migraine
- hypoglycaemia
- benign paroxymal positional vertigo
- dystonia
- cataplexy
- TIA
- parasomnia
- cardiogenic syncope
- non-epileptic seizure
- hyperventilation
Define epilepsy?
A neurological disorder in which a person experiences recurring seizures.
(needs to have at least 2 seizures to be diagnosed as epilepsy)
What are the main excitatory and inhibitory neurotransmitters? And their function?
main excitatory neurotransmitter = glutamate
- binds to NMDA (primary receptor)
- opens ion channels that cause calcium and sodium influx.
main inhibitory neurotransmitter = GABA
- binds to GABA receptors
- inhibits the signal by opening channels that cause a chloride influx
What are the different types of seizure?
- Generalised:when both hemispheres are affected always a loss of consciousness
- Focal : when the affected area is limited to one half of the brain or sometimes even smaller like a single lobe can progress to bilateral
What are the different subtypes of generalised seizure?
Tonic
Atonic
Clonic
Tonic-clonic
Myoclonic
Absence
What are the two types of focal seizure?
Simple (without impaired awareness)
Complex (with impaired awareness)
What are the general clinical manifestations of seizures for each stage?
Prodromal phase:
Confusion, irritability or mood disturbances
Early-ictal phase:
Aura: warning felt before a seizure. These can include sensory, cognitive, emotional or behaviour changes.
Ictal phase:
Will vary depending on seizure type
Post-ictal phase:
Confused, drowsy and irritable during recovery
