General Neuro Flashcards
What is decorticate posturing and what does it represent?
Flexed upper limbs and extended lower limbs, spontaneous or on stimulus
Indicates an insult to the hemispheres, internal capsule and/or thalamus
Mnemonic is you “Catch a ball” with Decorti”cat(ch)”e
M3 for GCS
What is decerebrate posturing and what does it represent?
Extended upper limbs and extended lower limbs
Indicates brain stem pathology, progressive to decerebrate posturing may represent brainstem herniation
M2 for GCS
What are the causes of fixed dilated pupils?
Brain death
Significant mass effect leading to bilateral 3rd nerve compression
Generalised seizures
Severe hypothermia
Barbituates
Severe hypoxia
Anticholinergics/Adrenaline
High intrinsic catecholamine release
What are the causes of a unilateral fixed dilated pupil
Significant mass effect/tentorial herniation (3rd nerve compression)
Focal seizures
Direct eye injury
3rd nerve palsies
What are the causes of bilateral pinpoint pupils
Opiates
Organophosphate poisoning
Medullary lesions
Metabolic disorders
What is the utility of the different IV therapies for Meningitis?
Dexamethasone- reduces ICP and proven to reduce rates of deafness
Ceftriaxone- Targets main organisms of strep, meningococcus, HiB
Benzylpenicillin- Targets Strep and Listeria
Vancomycin- Targets Beta lactam resistant organisms ie MRSA or resistant strep
What is Xanthochromia?
The yellowish discolouration of the CSF due to breakdown of haemoglobin from blood into bilirubin and oxyhaemoglobin in the CSF
Xanthochromia can also occur with systemic hyperbilirubinaemia and very high CSF protein levels
When is Xanthochromia detectable and how long does it last?
Detectable as early as 2-4hrs post bleeding, although 90% of people will have this within 24hrs
Can last 2-4 weeks
What are the classic LP findings in SAH?
Elevated opening pressure
Xanthochromia
Elevated RBC count that doesnt change from tubes 1-4
- this is poorly sensitive and specific
- <2000RBCs/uL + no xanthochromia is 100% sensitive for no SAH
What are the findings in CSF with bacterial meningitis?
Low glucose (strongly sensitive but not specific)
Oligoclonal bands
Raised WCC’s with PMN predominance
Raised protein levels
Gram stain +ve
Culture +ve
What is autonomic dysreflexia?
Occurs in people with spinal cord injuries above T6
Uninhibited or exaggerated response to noxious stimuli below the level of the spinal cord lesion ie severe hypertension and tachycardia
Why does autonomic dysreflexia generally not occur below T6?
Intact splanchnic innervation allows for compensatory splanchnic bed dilatation
How is autonomic dysreflexia treated?
- Sit the patient upright to lower the BP orthostatically
- Remove any tight fitting clothing
- Treat underlying cause (constipation and bladder distension most common)
- BP lowering agents ie GTN, hydralazine and labetalol with caution
- Prevention with meds such as nifedipine and prazosin
What are the differentials for unilateral weakness/neurological symptoms (ie stroke mimics)?
Ischaemic stroke
haemorrhagic stroke/ICH
Migraine
Todds paresis
Hypoglycaemia
Functional
MS
Brain tumour
Brain abscess
Bells Palsy
Hyponatraemia
Encephalopathy (hypertensive, hyper ammonaemic etc)
RCVS
What are the stats around meningitis?
- 90% of cases occur in 1st 5yrs
- MO’s usually enter via haematogenous spread
- Mortality/Morbidity still high despite antibiotics
- Occrs in 20-100:100,000 neonates
What are the main causes of Aseptic meningitis?
Viral
- Mumps, EBV, echo, HSV, cocksackie and HIV
Bacterial
- Mycoplasma, Borrelia, syphilis, Brucella
Fungi/Parasite
- Toxoplasma, cysticercosis
Other
- Sarcoid, SLE, Wegners, NSAID’s
What does a low glucose in CSF potentially indicate?
Normal CSF glucose is 60-80% of the serum glucose
Decrease usually indicates diffuse meningeal inflammation
Viral meningitis has normal glucose except Mumps and occasionally HSV and HZV which make it low
How should CSF results be interpreted in bacterial meningitis?
- Gram stain variably sensitive, 30-90% for meningococcus, 70-90% for pneumococcus
- CSF WCC more than 100 is 99% sens
- > 80% Neuts is highly specific
- TB meningitis will be gram stain negative and have a lymphocyte predominance
How does interpretation change when a patient is pre-treated with antibiotics?
- CSF becomes sterile approx 2-10hrs post IV ABx
- > 12hrs biochemistry is altered as well with higher glucose and lower protein levels than typical for meningitis
When and how should dexamethasone be used in meningitis?
- Most effective in the pneumococcal meningitis
- Reduces cytokine mediated complications
- the dose in adults is 10mg IV QID and 0.15mg/kg IV in children
- Dexamethasone has not been shown to be effective in neonates and is not recommended
- In Children it has been shown to reduce neurological and audiological complications
What are the main Guillane-Barre variants?
Acute Inflammatory Demyelinating Polyradiculoneuropathy (AIDP)
- This is the most common (90%) and the classical GBS variant
- Acute bilateral ascending paralysis starting distally
- 85% have sensory changes
- 1/3rd get severe pain, typically back pain
Acute Motor Axonal Neuropathy
- Motor only variant of AIDP, the 2nd most common variant
Pharyngeal-Cervical-Brachial
- Bulbar dysfunction, neck and shoulder weakness but upper and lower limbs spared
Polyneuritis Cranialis
- Acute bilateral multiple cranial nerve dysfunction + peripheral sensory loss
- younger + cytomegalovirus infection
Bickerstaff Encephalitis
- Brainstem inflammation with hyper reflexia, encephalopathy, ataxia and ophthalmoplegia
Acute Pandysautonomia
- Usually occurs in children
- BP swings, dysrhythmias, bladder issues, inappropriate sweating and paralytic ileum
- altered reflexes and sensation
Miller-Fisher Syndrome
- Triad of Ophthalmoplegia, ataxia and areflexia
How does Wallenberg Syndrome present?
Lateral medullary infarction
Basics
- The most common presentation of vertebral artery occlusion/dissection, including trauma (ie whiplash injury)
- Due to occlusion of the posterior inferior cerebellar artery
Exam
- Vertigo, ophthalmoplegia
- nystagmus (horizontal + vertical)
- ipsilateral horners syndrome
- ipsilateral limb ataxia, tendency to fall towards ipsilateral side
- preserved vibration and proprioception
- Ipsilateral face pain/temp loss
- contralateral trunk and limbs pain/temp loss
- dysphagia, dysphonia
What is the most common type of BPPV?
- Posterior canal lithiasis is the most common at 88%
- Dix-Hallpike maneuover tests for posterior canal lithiasis
- When performed the lower ear will be the affected side
What does B12 deficiency do to the CNS?
Sub-acute combined degeneration of the cord
- Flaccid paralysis and loss of proprioception
- Dorsal columns and lateral tracts
What is Transverse Myelitis?
- Post infectious inflammatory disease of the cord
- Partial segmental spinal cord dysfunction
- Also associated with autoimmune disorders such as SLE, MS and RA
What causes Guillane-Barre syndrome?
- A sensitising event leads to the creation of auto-antibodies against innate nerve tissue
- Typically spinal/cranial nerve roots and peripheral nerves
- Typically have preceding infection, then symptoms develop and peak over 2-4 weeks
Pathogens
- Campylobacter (25%)
- CMV (polyneuritis cranialis), EBV, HIV, arboviruses, influenza, Hepatitis
- Mycoplasma
Vaccination
- flu, rabies, covid, VZV
Other
- Lymphoma
What are the benefits to a protocoled approach to stroke assessment/managment?
- Rapid mobilisation of important team members
- Earlier imaging
- Faster time to treatment
- Standardisation of assessment
- Allows for auditing and quality assurance
What is the definition of a migraine?
- Idiopathic recurrent headache
- Last 4-72hrs
- Typical characteristics include unilateral, pulsating, moderate to severe, aggravated by routine physical acitivity
What are the different variants of migraines?
Abdominal
- Recurrent abdominal pain, usually in kids
Hemiplegic
- stroke mimic
Vestibular
- Vertigo and nausea
Ophthalmoplegic
- Recurrent ophthalmoplegia
What are the typical treatments for Migraines?
Dexamethasone
- 8mg IV
- Reduces the rate of rebound migraine headaches
Sumatriptan
- SC 6mg or 20mg IN
D2 antagonists
- Maxalon, chlorpromzaine, drop
Stemetil
- IV 10mg or 12.5mg IM
Aspirin
- 900mg PO
NSAID’s
- 400mg PO, Ketorolac 30mg IM
Tramadol
- 50-100mg IM
What is the CHADSVASC score and what does it represent?
The factors increasing the risk of stroke in atrial fibrillation
C- Congestive heart failure
H- Hypertension
A- Age >75 (+2)
D- Diabetes
S- Stroke/TIA/thromboemolism history is +2
V- Vascular disease
A- Age 65-75 (+1)
Sc- Sex categroy (Female +1)
Thus previous thromboembolism and age >75 are the highest risk factors
What is the HASBLED score and what does it represent?
Estimates the risk of major bleeding for people on therapeutic anticoagulation
H- Hyperension (>160 SBP or uncontrolled)
A- Alcohol use (>8 std/week)
S- Stroke history
B- Bleeding predisposition or prior major bleeding
L- Labile INR or liver disease
E- Elderly >65, End stage renal disease
D- Drugs (ie aspirin or anything else which predisposes to bleeding)
What is the drug of choice for acute multiple sclerosis exacerbations?
IV Methylprednisolone 1000mg pulsed dosing
What are the potential complications of MS?
Psychiatric/Cognitive
- Depression, mania, psycosis
- Epilepsy, cognitive impairment
Urinary
- Retention, infection, urgency
Bowel
- Constipation, incontinence
Pain
- Trigeminal neuralgia, usually lower limb or thoracic nerve pain
- MS hug aka anaconda sign (gripping/squeezing pain around the lower thorax/upper abdomen)
Occular
- Anterior uveitis
- Internuclear ophthalmoplegia
- Reading fatigue
- Oscillopsia
- Diplopia
- Nystagmus
Motor
- Paraplegia, hemiplegia
- Spastic paresis, loss of co-ordination
What are the symptoms/signs suggestive of MS?
- Optic neuritis
- Acute transverse myelitis
- Heat sensitivity (Uhtoff phenomenon)
- Fatigue (including reading fatigue)
- Internuclear ophthalmoplegia
- Relapse and remission
- Age 15-50
- Lhermitte sign (an electric shock sensation on flexion of the neck, radiating down the spine into limbs and trunk)
What are the main clinical syndromes in MS?
Clnically isolated syndrome (CIS)
- Ie isolated optic neuritis
Relapsing-Remitting
- most common, 85-90%
- Diagnosed by evidence of dysfunction in 2 separate parts of the nervous system and 2 distinct points in time
Secondary progressive MS
- Relapsing remitting that becomes more constant with progressive disability instead of defined relapses
Primary Progressive
- Progressive from onset, 10% cases
Tumefactive demyelination
- AKA Marburg disease
- Defined by very large tumour like MS lesions throughout the nervouse system on MRI
What is the differential list for coma/stupor?
Metabolic
- Hypercapnoea
- Hypo/hyperthermia
- Hypoglycaemia
- Hypo/hypernatraemia
- Hypermagnaesaemia
- Hepatic encephalopathy (ie from hyperammonaemia)
- Wernickes encephalopathy
- Uraemia
- Myxedema coma
- Adrenal crisis
Toxins
- Alcohols
- Sedatives
- CO
- TCA’s
- Opioids
- Malignant catatonia from neuroleptic malignant syndrome
- Salicylate, lithium
Vascular
- Thalamic/Pontine/Basilar stroke
- Large bleed
- Large cerebral venous sinus clot
- PRES
Trauma
- ICH
- DAI, fat embolism
Infection
- Meningoenceophalitis
- ADEM
Others
- Sepsis
- Seizures (intra/post ictal)
- Hypoxia
- Hydrocephalus
what is the test of choice with myaesthenia gravis?
Ice pack test
Place ice pack over affected eye for up to 5mins, should see improvement in function post
This is due to acetylcholinesterase activity being inhibited at colder temps
What drugs can precipitate a myaesthenic crisis?
Antibiotics
- Macrolides (worst Telithromycin)
- Aminoglycosides
- Flouroquinolones
CVS
- Beta blockers (even topical)
- statins
- class 1a antiarrhytmics
Other
- D-penicillamine (bad!)
- IV magnesium
- Botulinum toxin
- paradoxically steroids
- old school iodine contrast
Suxamethonium will not worsen MG but is in itself less effective in people with MG due to its action also being blocked by the autoantibodies
What are the alternative causes of respiratory compromise in people with myaesthenia gravis?
- Myaesthenic crisis
- Cardiopulmonary disease
- Cholinergic crisis
- Adrenal crisis (ie from long term prednisolone use)
- Thyroid storm
- Myxedema coma
What is Bells Palsy? What are the risk factors and possible causes? what is the treatment?
Idiopathic isolated 7th nerve palsy
Symptoms/Signs
- Ipsilateral upper/lower facial weakness
- Ipsilateral reduced taste/salivation (Chorda tympani branch)
- Ipsilateral reduced eye tearing (petrosal branch)
- ipsilateral hyperacusis (nerve to stapedius)
RF’s
- Pregnancy, hypertension
Causes
- Idiopathic
- HSV + other viruses
- Lyme disease
- Leukaemia
- Ischaemic
- Diabetes
- Autoimmune (GBS, MS, sarcoidosis, temporal arteritis)
- Post vaccination
- Trauma
- brain tumour
MX
- PO Prednisolone 1mg/kg max 75mg for 5 days
- PO Valaciclovir 100mg TDS 7 days
- Ocular: HB score 4-6, consider nightly eye tape, ngihtly parafin ointment and PRN lubricants
- Dental: usually 4-6, for those unable to close mouth, significant oral dryness increases risk of caries
What are the features differentiating Bells palsy from more sinister causes?
What is the prognosis?
- Worsens in 1st 3 weeks then start to recover (85%)
- 71% will recover in 12 months
- 94% have complete recovery
- Higher HB scores portend risk of incomplete recovery
- May have abberant neurology on recovery (Crocodile tears etc)
Neuro referral if
- Atypical or severe symptoms
- No recovery within 4 weeks
- Incomplete recovery within 3 months
What distinguishes Labyrinthitis from Vestibular neuritis?
- Neuritis only affects balance leading to vertigo
- Labyrinthitis also affects the hearing apparatus so deafness, hyperacusis, phonophobia, tinnitus etc occur
What are the differentials for recent onset odd neurological findings?
- Guillane-Barre syndrome
- Multiple sclerosis
- Myaesthethenia gravis
- Atypical stroke syndrome
- Tick paralysis
- Snake neurotoxin
- Paraneoplastic syndromes
- Diabetic complications
- Trauma
- Manifestation of congenital issue ie metabolic abnoramlity
- Systemic vasculitis
- Poisoning (ie arsenic)
- HIV
- Neurosyphilis
- Sarcoidosis
- Psychogenic
What are the potential clinical findings in GBS?
-Motor
- Symmetrical weakness, usually ascending
- Decreased deep tendon reflexes (90% sensitive, hallmark)
Sensory
- Paraesthesia’s, often hands/feet
- Pain, often in back
Autonomic
- Ileus/diarrhoea
- HTN/hypotension
- Fever, facial flushing
- Urinary retentions
- Tachy/brady
Other clinical
- Bulbar muscle dysfunction
- Reduced FVC (Normal >60ml/kg, <30ml/kg suggestive, <20ml/kg may need intubation)
Investigations
- CSF (high protein)
- Nerve conduction studies
- MRI
If going to intubate, suxamethonium is contraindicated as risk of excessive potassium release
What are the differentials for peripheral and central vertigo?
Peripheral
- BPPV
- Labyrinthitis/Vestibular neuritis
- Menieres disease
- Perilymph fistula
- Vestibular schwannoma
Central
- Vestibular migraine
- Stroke syndromes
- Intracranial bleeds
- Post infection cerebellar ataxia
- Autoimmune (GBS, MS)
- Medications (anticholinergics, sedatives, diuretics, aminoglycosides, antihypertensives, anticonvulsants)
What are the differences on clinical examination between peripheral and central vertigo?
How is the HINT’s exam used with vertigo?
Nystagmus must be present at rest to use the HINT’s exam
What features favour a central cause over a peripheral cause for vertigo?
- Older age
- Increased CVS risk
- Male gender
- Chronic inflammatory conditions ie RA, HIV, Covid
- PHx CVA
- AF
- Focal neurology
- Altered conscious state
- Absence of N/V
- Associated headache/neck pain
- Slow onset or longer lasting
What evidence based strategies have been shown to improve outcome post stroke?
- Dual antiplatelets
- BP control
- Stroke unit +/- ICU
- Assisted swallowing to prevent aspiration
- Temp control (normothermia)
- Euglycaemia
- Physiotherapy
- DVT prophylaxis
What are the causes of low glucose in CSF (Hypoglycorrhachia)?
- Severe hypoglycaemia can cause it, although technical definition is CSF/serum ratio <0.6 (normal is approx 0.6 or greater)
- Ie hypoglycorrhacia is a relative, no absolute lack of glucose in the CSF relative to the serum
- salicylate toxicity is a rare cause
What are the risks for and treatment of post LP/epidural headache?
Risks
- larger needle size
- Cutting needle vs non-cutting needle
- Not replacing stylet prior to removal
- Not ensuring bevel of needle is parralel to the dural fibres
Treatment
- Epidural blood patch
- Caffeine 300-500mg BD
- IV fluids
- Pregabalin/Gabapentin
- GON block or sphenopalatine block
- Simple analgesia
What are the different medications that can be used for migraines and their pros/cons?
