Neurological emergencies (Year 5 OSCE) Flashcards
Guillain–Barré syndrome:
- Definition
- Pathophysiology
- Subtypes of GBS (brief)
- Causes
- Presentation
- Examination
- Investigations
DEFINITION:
- An acute, inflammatory polyneuropathy typically characterised by a progressive, ascending neuropathy resulting in weakness and reduced reflexes
- Rare condition
- Male predominance
PATHOPHYSIOLOGY:
- Molecular mimicry, where B cells create antibodies against antigens on the triggering pathogen, which then target proteins on peripheral neurones (myelin sheath or axons)
SUBTYPES OF GBS:
- Acute Inflammatory Demyelinating Polyradiculoneuropathy (95%)
- Acute Motor Axonal Neuropathy (rare, more common in Asians)
- Acute Motor and Sensory Axonal Neuropathy
- Miller Fisher (sensory ataxia, arreflexia, ophthalmoplegia)
CAUSES:
a) Campylobacter jejuni:
- Most common cause of GBS
- Gram-negative rod
- Common cause of food poisoning and GE
- More severe GBS
b) Other infections:
- Cytomegalovirus (CMV)
- Epstein-Barr virus (EBV)
- Hepatitis E (Hep E)
- Mycoplasma
PRESENTATION:
(onset 4 weeks after provoking infection, with peak after 2-4 weeks, and then period of recovery)
- Rapidly progressive symmetrical bilateral weakness in ascending pattern, beginning in the LLs and ULs, affecting arms, trunk, facial muscles
- Paraesthesia
- Issues with balance or coordination (especially in the lower body)
- Visual disturbances
- Dysarthria
- Dysphagia
- Facial weakness (bilateral)
- Apyrexial at onset
- PMH of infection (eg: uncooked food)
[NB: There is variation in the progression of symptoms and can take hours, days, or weeks to resolve. Symptoms will progress up to a maximum of 4 weeks]
O/E:
(often symmetrical, LMN signs due to peripheral nerve involvement)
- Reduced power which is bilateral, symmetrical, ascending from LL first up to UL, then trunk, bulbar, and ocular muscles
- Reduced sensation (mild)
- Hyporeflexia
- Bilateral facial weakness suggesting facial nerve involvement
- ANS dysfunction: arrhythmias, tachycardia, hyper/hypotension
INVESTIGATIONS:
a) Bedside:
- Spirometry to detect reduction in FVC suggestive of respiratory failure (done every 4 hours)
- ABG for T1RF/T2RF
- ECG for arrhythmias
- Throat swabs for PCR
- Stool samples for MCS
- Vital signs monitoring continuously
b) Bloods:
- FBC for baseline, may reveal infection
- U&Es: up to 50% may have SIADH, and also to exclude K+ abnormalities
- LFTs: raised ALT and AST
- BM to exclude hypoglycaemia
- Creatine Kinase to exclude polymyositis
- Anti-ganglioside antibodies (anti-GM1, C. Jejuni for AMAN; anti-GQ1B for MF)
c) Others:
- Nerve conduction studies show reduced signal through the nerves (predominantly reduced conduction velocity through motor nerves)
- Lumber puncture shows increased protein and normal cell count and normal glucose
Guillain–Barré syndrome: principles of management
GENERAL MEASURES:
(close observation as weakness is progressive)
- Spirometry: FVC* monitoring by bedside and consideration of ventilation (15-30%)
- ECGs and BP monitoring
- VTE prophylaxis with lower limb stockings/flowtrons and LMWH due to increased risk of DVT following immobility after GBS episode
- Analgesia for neuropathic pain (eg: gabapentin and carbamazepin)
- Physiotherapy to regain motor function
- NGT if dysphagic
- Catheterisation if retention
FVC MONITORING:
- Always consider referral to HDU/ITU
- 4-hourly spirometry monitoring
- Weight 55 kg and FVC < 1.1L, should warrant HDU/ITU referral
- Weight 90 kg and FVC <1.8L, should warrant HDU/ITU referral
- FVC < 20 ml/kg should warrant referral to HDU/ITU
FURTHER MANAGEMENT:
- Plasma exchange: involves plasma within the blood being removed, filtered to remove autoantibodies, and returned to circulation around the body. This decreases the severity of GBS by removing the autoantibodies within the blood damaging the nerves.
- IV immunoglobulin therapy (IVIg): an infusion of donor immunoglobulins (antibodies) which dilutes the ability of the autoantibodies to inflict damage upon the body. This therapy has proven effective in reducing recovery time.
[NB: weak evidence for corticosteroids; VTE prophylaxis should be considered]
Meningitis:
- Definition
- Bacterial causes
- Viral causes
- Risk factors
- Presentation
- Investigations
- Management
- Complications
DEFINITION:
- Inflammation of the meninges, often due to infection
BACTERIAL CAUSES:
- Neisseria meningitidis (gram-negative diplococcus, encapsulated)
- Streptococcus pneumoniae
- Haemophilus influenzae type B
- Group B streptococcus
VIRAL CAUSES:
- Enteroviruses (eg: coxsackievirus)
- Herpes simplex virus (HSV)
- Varicella zoster virus (VZV)
RISK FACTORS:
- Young age/older age (> 65 years)
- Winter season
- Splenic pathology or absence
- Immunocompromised/incomplete immunisation or vaccination
- Cancer – leukaemia and lymphoma
- Cochlear implants
- Living in overcrowded households, college dormitories, or military barracks
PRESENTATION:
- Fever (100%)
- Headache (90%)
- Cognitive issues such as irritability (80%)
- Neck stiffness
- Vomiting
- Photophobia
- Seizures
O/E:
- Reduced consciousness
- Non-blanching petechial rash in meningococcal septicaemia with N. meningitidis
- Kernig’s test (lie supine, flex one hip and knee to 90 degrees, then slowly straighten knee with hip flexed at 90 degrees; positive if lower back pain is induced due to meningeal stretching and irritation)
- Brudzinski’s test (lie supine, then lift their head and neck off the bed, flexing their chin to their chest, positive if patient involuntarily flexes hips/knees)
- Cranial nerve palsies in 10-20% due to brainstem involvement
- Seizures in 30%
- Hemiparesis
INVESTIGATIONS:
- CT head before lumbar puncture (LP) to exclude intracranial abnormality with elevated ICP due to risk of brain herniation after LP
- Lumbar puncture (LP) to sample CSF for bacterial culture, viral PCR, cell count, protein and glucose
- BM taken for comparison with CSF glucose
[NB: see image for CSF interpretation]
MANAGEMENT:
- Admit
- IM/IV benzylpenicillin stat
- For > 3 months, IV ceftriaxone 10-14 days
- For < 3 months, IV cefotaxime with amoxicillin (to cover listeria) 10-14 days
- Aciclovir is added if viral meningitis suspected (KIV s/e of crystal nephropathy)
- Dexamethasone to reduce hearing loss and neurological complications
- Notify UK Health Security Agency/PHE
- Contact tracing to identify close prolonged contacts within 7 days before the onset of the illness, for prophylactic ciprofloxacin stat dose
- Repeat LP to ensure treatment works
[NB: < 3 months for cefOtaxime + amOxicillin; gram negative organisms often need 21 days of treatment with antibiotics]
COMPLICATIONS:
- Hearing loss (a key complication)
- Seizures and epilepsy
- Cognitive impairment and learning disability
- Memory loss
- Focal neurological deficits
Encephalitis:
- Definition
- Causes (infectious vs non-infectious)
- Presentation
- Investigations
- Management
- Complications
DEFINITION:
- Inflammation of the brain parenchyma
- More likely in children and the elderly
INFECTIOUS CAUSES:
- Herpes simplex virus (HSV) is most common
- Arboviruses (eg: West Nile virus)
- Varicella zoster virus (VSV)
- Epstein barr virus (EBV)
- HIV
[NB: viral causes are more likely with encephalitis]
NON-INFECTIOUS CAUSES:
- Paraneoplastic encephalitis: abnormal immune response in the setting of cancer
- Post-infectious encephalitis following vaccination/infection; due to shared antigens between the infection and CNS, that generates autoreactive T cells that react to antigens in the CNS (more common in children)
- Autoimmune encephalitis
PRESENTATION:
- Fever
- Headache
- Seizures
- Altered mental status
- Psychotic features (eg: delusions, hallucinations)
- Mood disorders (eg: anxiety/depression)
- Brainstem dysfunction: dysphagia, dysarthria
- Memory problems
O/E:
- Reduced consciousness
- Focal neurology: hemiparesis, cranial nerve neuropathies, cerebellar ataxia
- Pyrexia
INVESTIGATIONS:
a) Imaging
- CT head to exclude acute stroke/SOL
- MRI for more detailed anatomy
b) Electroencephalogram
- Non-invasive investigation
- To detect electrical activity suggestive of encephalitis
- To exclude non-convulsive status epilepticus
c) Lumbar puncture
- Send CSF sample for protein, viral PCR, MCS, glucose, WCC and serology
- Viral PCR to confirm HSV or other viral aetiologies
- MCS to exclude bacterial meningitis
- WCC raised (lymphocytes)
- Glucose often normal
- Serology for paraneoplastic aetiologies
d) Others
- Routine bloods
- Bedside sputum and urinalysis to exclude infections
MANAGEMENT:
- Admit as emergency, treat underlying causes
- IV Aciclovir started empirically against HSV and VZV due to high mortality, and fact that HSV is most common cause anyway
- IV Ganciclovir for cytomegalovirus (CMV)
- Steroids (eg: dexamethasone) can be considered for inflammation, especially to combat raised ICP
- Repeat LP to ensure treatment works
COMPLICATIONS:
- Mortality as high as 30%
- Amnesia
- Learning disabilities
- Behavioural issues
- Autoimmune encephalitis after HSV encephalitis
Status Epilepticus:
- Definition and clinical criteria
- Subtypes of SE
- Management of SE in public
- Management of SE in hospital
- On-going management
- Complications
DEFINITION:
- Continuous seizure activity which has failed to self-terminate
CLINICAL CRITERIA:
- A convulsive seizure lasting > 5 minutes (NB: most seizures last < 3 minutes with full recovery)
- Recurring seizures without recovery
SUBTYPES OF SE:
a) Convulsive
- Sustained generalised tonic-clonic seizure (stiffening and jerking)
- Epilepsy is risk factor
b) Non-convulsive
- Absence (long or repeated) or impaired awareness (focal)
- Altered mental status
- Twitching (subtle)
- Speech disturbances
- Lack of motor signs (makes recognition difficult)
MANAGEMENT (PRE-HOSPITAL):
- STAY: remain with patient until recovery, start timer
- SAFE: move patient from harms way
- SIDE: turn patient on their side, keep airway clear, cushion head, loosen tight fitting clothes
- DON’T: restrain or place items in the mouth
- CALL 999
- CONSIDER rescue medications (eg: buccal midazolam)
MANAGEMENT OF ACUTE STATUS EPILEPTICUS:
(ensure 5 mins have passed from onset of seizure without resolution)
- ABCDE
- IV access, take bloods (prolactin is significantly raised following a seizure)
- 1st dose benzodiazepines stat (IV Lorazepam 4mg or PR Diazepam 10mg or buccal Midazolam 10 mg)
- 2nd dose benzodiazepines after 10-20 min (IV Lorazepam 4mg or PR Diazepam 10mg or buccal Midazolam 10 mg)
- IV anti-epileptic drugs with phenytoin, or sodium valporate, or levetiracetam (phenytoin is currently the only licensed drug, but check local guidelines)
- HDU/ITU admission for anaesthesia, intubation and ventilation if refractory; anaesthesia to last 12-24 hours and guided by EEG
ON-GOING MANAGEMENT:
- Neurology referral within 24 hours
- KIV maintenance AEDs
- Optimise medications
COMPLICATIONS:
- Acute = hyperthermia, cardiac arrhythmias, severe hypoxaemia, shock, cerebral oedema, death
- Chronic = epilepsy, focal neurological deficits, encephalopathy
Myasthenia CRISIS:
- Definition
- Principles of management
- Complications of MG
DEFINITION:
- Life-theatening complication of myasthenia gravis
- Often triggered by other illnesses such as infections
- Can lead to respiratory failure and death
MANAGEMENT:
- VTE stockings
- Spirometry: FVC every 4 hourly, if falling FVC < 20ml/kg, for review and KIV ventilation (don’t use PEFR)
- Acetylcholine esterase inhibitors such as pyridostigmine: onset 30 mins, peak action 1-2 hours, duration 3-6 hours; neostigmine reserved for ITU use
- Corticosteroids (start low, then titrate up), consider azathioprine as it is steroid sparring
- IV immunoglobulins and plasmapheresis for acute declines; most will respond within 7-10 days
[NB: pyridostigmine should be prescribed 45 mins before onset of meals such that peak action coincides with eating to prevent aspiration]
COMPLICATIONS OF MYASTHENIA GRAVIS:
- Myasthenic crisis
- Respiratory failure
- Aspiration and choking/pneumonitis, infection
- VTE
- Cholinergic crisis
Raised ICP:
- Causes
- Pathophysiology
- Presentation
- Investigations
- Complications
CAUSES:
- Haematomas (extradural, subdural, intracerebral)
- Haemorrhagic stroke
- Brain neoplasms (glioma, meningioma, metastasis)
- SVCO
- Abscess
- Congenital (eg: hydrocephalus)
- Cerebral oedema due to infection, infarction, ischaemia etc
- Idiopathic intracranial hypertension (IIH)
PATHOPHYSIOLOGY:
- By Monro-Kellie Doctrine, the sum of volume of brain, blood and CSF must remain constant given the fixed volume of the cranium
- Initially, venous blood and CSF is drained out of the brain as compensatory mechanisms
- As the mass increases, there is only a finite amount of CSF/venous blood that can be drained out before arterial blood is sacrificed
PRESENTATION:
- Headache starting when waking, worse on coughing or moving head
- Vomiting
- Visual disturbances
- Loss of cognition (lethargy, irritability, slow decision making)
- Weakness
- Syncope
- Seizures
[NB: photophobia, neck stifness if meningeal irritation]
O/E:
- Fundoscopy reveals blurring of the optic disc margins suggesting papilloedema
- Occulumotor nerve palsies (CN III, CN VI)
- Fixed, dilated pupil(s) due to compression on parasympathetic plial blood vessels on periphery of optic nerve to sphinter pupillae
- Ptosis (often unilateral) due to compression of blood vessels and motor fibres supplying levator palpebrae superioris
- RAPD, unilateral dilatation
- Focal neurological signs (eg: hemiparesis)
LATE SIGNS:
- Hemiparesis
- Hypertension
- Widened pulse pressure
- Slow irregular pulse
INVESTIGATIONS:
- CT head done urgently shows midline shift (subfalcine herniation), effacement of ventricles and loss of grey-white matter differentiation
COMPLICATIONS:
- Brain ischaemia
- Compression and herniation of the brain (subfalcine herniation, transtentorial herniation or tonsillar herniation)
- Cushing’s triad*
CUSHING’S TRIAD:
- Hypertension as attempts are made to maintain cerebral perfusion pressure
- Bradycardia ensues as the rise in BP is detected by baroreceptors, thereby increasing vagal tone
- Irregular breathing due to compression on cardio-respiratory centre (RPG) in the medulla
Raised ICP: principles of management
GENERAL MEASURES:
- Admit and involve neurosurgery
- Avoid pyrexia as this increases ICP
- Elevate bed to 10-15 degrees to improve jugular venous outflow
- Manage seizures
- CSF drainage, esp when an intraventricular catheter is used to monitor intracranial pressure
- Sedation usually with IV propofol or midazolam
- Analgesia with IV morphine or alfentanil
[NB: sedation and analgesia helps to decrease cerebral metabolic rate]
DEFINITIVE MEASURES:
- Mannitol (intravascular osmotic agent)
- Hypertonic saline 3-30%
- Hyperventilation: this lowers ICP by inducing hypocapnoeic vasoconstriction
OTHER MEASURES:
- Hypothermia: cooling to 35°C (rather than 33°C) is effective in lowering refractory intracranial hypertension and has fewer systemic complications
SURGERY:
- Decompressive craniectomy if medical management fails
Wernicke-Korsakoff Syndrome:
- Definition
- Presentation of Wernicke’s Encephalopathy
- Presentation of Korsakoff’s Syndrome
- Management
DEFINITION:
- Alcohol excess leads to thiamine (vitamin B1) deficiency
- Thiamine is poorly absorbed in the presence of alcohol
- Alcoholics often have poor diets and get many of their calories from alcohol
- Thiamine deficiency leads to Wernicke’s encephalopathy and Korsakoff syndrome
PRESENTATION OF WERNICKE’S ENCEPHALOPATHY:
- Altered mental status (eg: confusion)
- Ataxia (eg: gait, difficulties with coordinated movements)
- Ophthalmoplegia (eg: oculomotor disturbances)
PRESENTATION OF KORSAKOFF’S SYNDROME:
- Memory impairment (retrograde and anterograde)
- Behavioural changes
[NB: Korsakoff’s Syndrome can be mistaken for a dementia, but it isn’t by definition]
MANAGEMENT:
- Stop drinking alcohol permanently
- Psychological interventions (eg: motivational interviewing or CBT)
- Detoxication regimes
- Vitamins (particularly thiamine – vitamin B1)
- High-protein diet
- Corticosteroids may be considered to reduce inflammation in severe alcoholic hepatitis to improve short-term outcomes (but not long-term outcomes)
- Treat complications of cirrhosis (eg: portal hypertension, varices, ascites and hepatocellular carcinoma)
- Liver transplant in severe disease
