Neurology - Infections Flashcards
What is Herpes simplex encephalitis?
Infection by herpes simplex virus that affects the temporal lobes.
Features of herpes simplex encephalitis.
- fever
- headache
- psychiatric symptoms
- seizures
- vomiting
- aphasia
Aetiology of herpes simplex encephalitis.
HSV-1 infecting temporal and inferior frontal lobes.
Diagnostic workup for herpes simplex encephalitis.
- CSF (?lymphocytosis, elevated protein)
- PCR (?HSV)
- CT (medial temporal and inferior frontal changes)
- EEG changes
Treatment of herpes simplex encephalitits.
Early IV aciclovir.
Left untreated mortality ~80%.
Species of malaria.
- Plasmodium falciparum (most common)
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariea
Protective factors against malaria.
- sickle cell trait
- G6PD deficiency
- HLA-B53
- absence of Duffy antigens
Presentation of falciparum malaria.
- feveer (cyclical)
- n+v
- splenomegaly
- abdominal pain
- diarrhoea
- cough
- generalised body aches
- headache
- dizziness
- thrombocytopenia
- AKI
Complications of falciparum malaria.
- cerebral malaria (seizures, coma)
- acute renal failure
- acute respiratory distress syndrome
- hypoglycaemia
- DIC
Management of uncomplicated falciparum malaria.
Artesunate
plus
Mefloquine.
Features of severe falciparum malaria.
- parasitaemia >2%
- hypoglycaemia
- acidosis
- temperature >38°C
- severe anaemia
- acute complications
Management of severe falciparum malaria.
- IV artesunate
- exchange transfusion (parasite count >10%)
Haemodynamic instability usually indicates coexistant bacterial septicaemia; malaria rarely causes haemodynamic collapse.
Most common causes of meningitis.
0-3 months old.
- GBS
- E. coli
- Listeria monocytogenes
Most common causes of meningitis.
3 months - 6 years old.
- Neisseria meningitidis
- Streptococcus pneumoniae
- Haemophilus influenzae
Most common causes of meningitis.
6-60 years old.
- Neisseria meningitidis
- Streptococcus pneumoniae
Most common causes of meningitis.
> 60 years
- Streptococcus pneumoniae
- Neisseria meningitidis
- Listeria monocytogenes
Most common causes of meningitis.
Immunocompromised.
Listeria monocytogenes
Features of meningitis.
Triad of meningism:
- neck stiffness
- photophobia
- headache
Other fetures:
- fever
- nausea / vomiting
- non-blanching rash
- decreased consciousness
Pre-hospital management of suspected bacterial meningitis.
- urgent hospital transfer
- IM benzylpenicillin (as long as doesn’t delay transit to hospital)
In-hospital management of suspected meningitis.
Manage via ABCDE approach.
- IV access > take bloods and blood culture
- lumbar puncture
- IV antibiotics
- IV dexamethasone
Contraindications to lumbar puncture.
- signs of severe sepsis or rapidly evolving rash
- severe respiratory / cardiac compromise
- significant bleeding risk
- signs of raised ICP
Signs of raised ICP.
- focal neurological signs
- papilloedema
- significant fontanelle bulging
- DIC
- signs of cerebral herniation
CSF findings consistent with bacterial infection.
a) appearance
b) glucose
c) protein
d) white cells
a) cloudy
b) low (<1/2 plasma)
c) high (>1g/l)
d) raised granulocytes
CSF findings consistent with viral infection.
a) appearance
b) glucose
c) protein
d) white cells
a) clear / cloudy
b) normal
c) normal / raised
d) raised lymphocytes
IV antibiotics in meningitis.
a) 3-months to 50 years
b) >50 years
a) cefotaxime
b) cefotaxime + amoxicillin
Management of patients with signs of raised intracranial pressure.
- critical care input
- secure airway
- high flow oxygen
- IV access (bloods / blood culture)
- IV dexamethasone
- IV antibiotics
- arrange neuroimaging
Bloods taken in suspected meningitis.
- FBC
- U&Es / renal function
- glucose
- lactate
- clotting profile
- CRP
If an LP is performed, what tests should be requested?
- glucose, protein, microscopy and culture
- lactate
- meningococcal and pneumococcal PCR
Management of contacts of meningitis.
People who have been exposed to a patient with confirmed bacterial meningitis within 7 days before symptom onset should be given prophylactic antibiotics.
Single dose of ciprafloxacin used.
Causes of viral meningitis.
- non-polio enterovirus
- mumps
- HSV
- HZV
- CMV
- HIV
- measles
Risk factors for viral meningitis.
- extremes of age (<5 years, >60 years)
- immunocompromised
- IV drug user
Management of viral meningitis.
IV aciclovir if risk factors.
Generally speaking, viral meningitis is self-limiting and will spontaneously resolve within 2 weeks.
Complications of meningitis.
- sensorineural hearing loss*
- seizures
- focal neurological deficit
- sepsis
- intracerebral abscess
- brain herniation
- hydrocephalus
*all patients offered audiology assessment as soon as they have recovered, to assess for hearing impairment.
Examination findings consistent with meningitis.
Causes of brain abscess.
- extension of sepsis from middle ear / sinus
- trauma
- surgery to scalp
- penetrating head injury
- embolic events
Presenting symptoms of brain abscess.
Abscesses have considerable mass effect in the brain and raised ICP is common.
- headache
- fever
- focal neurology (e.g. oculomotor nerve palsy, abducens nerve palsy)
- nausea
- papilloedema
- seizures
Imaging for brain abscess.
- CT scanning
Management of brain abscess.
- surgical drainage
- IV antibiotics
- dexamethasone (pressure management)
Features of Lyme disease.
- bulls-eye rash (erythema migrans)
- headache
- lethargy
- fever
- arthalgia
Late features of Lyme disease.
a) cardiovascular
b) neuroloical
a) heart block; pericarditis; myocarditis
b) facial nerve palsy; radicular pain; meningitis
Investigation of Lyme disease.
Clinical diagnosis if erythema migrans is present.
ELISA test first line investigation if warranted.
Management of asymptomatic tick bites.
- remove tick if present
- do not give abx unless symptomatic
Management of symptomatic tick bites.
- remove tick
- doxycycline (or amoxicillin if pregnant)
Complication of treating Lyme disease.
Jarish-Herxheimer reaction - fever, rash and tachycardia after first dose of antibiotic.
