Infections of nervous system Flashcards
Meningitis definition
Inflammation/infection of meninges
Encephalitis definition
Inflammation/infection of brain structure
Myelitis definition
Inlfamation/infection of spinal cord
What are the clinical features of Meningitis
Classic Triad: Fever, stiff neck, altered mental status
Short history of progressive headache
associated with: fever >38, Meningism (neck stiffness, photophobia, nausea and vomiting)
Cerebral dysfunction: common, GCS <14
Cranial nerve palsy, seizures, focal neurological deficits
Petechial skin rash (Tumbler test)
How would you test for neck stiffness
Passively bending the neck forward
What are the symptoms of cerebelar dysfunction?
Confusion, delirium, declining conscious level
What is the Tumbler test
Placing a glass over a rash
If menigitis: rash will be able to be seen through the glass
Not meningitis: rash will not be visible through the glass
What causes petechial skin rash?
Usually caused by meningococcal meningitis
can occur in viral meningitis.
What are the causes of bacterial meningitis?
Neisseria menigitidis (meningococcus)
Streptococcus pneumoniae (pneumococcus)
What are the viral causes of meningitis
Main cause enteroviruses
What is the clinical features of encephalitis
Flu-like prodrome (4-10 days)
progressive headache associated with fever
+/-meningism
progressive cerebral dysfunction
seizures
Focal symptoms/signs
What is meningism?
set of Symptoms similar to those of meningitis but is not caused by meningitis
bacterial vs viral encephalitis onset times
Viral encephalitis: slower onset, cerebral dysfunction more prominent.
Bacterial encephalitis: faster onset
What are the antibodies that can cause Auto-immune encephalitis
Anti-VGKC (voltage gated Potassium channel)
Anti-NMDA receptor
What are charaterstic symptoms of Anti-VGKC autoimmune encephalitis?
Frequent seizures
amnesia
Altered mental state
What are characteristic symptoms of anti-NMDA receptor auto-immune encephalitis?
Flu like prodrome
Prominent psychiatric features
Altered mental state and seizures
Progressing to a movement disorder and coma
what is the Investigation for meningitis
Menigitis
Blood culture: bacteraemia
Lumbar puncture (CSF culture/microscopy)
No need for imaging if no contraindications to LP
What is the investigations for encephalitis
Blood cultures
Imaging (CT +/- MRI)
Lumbar puncture (CT before)
EEG
What would be indications to do a CT before a Lumbar puncture?
Focal neurological deficit (suggest focal brain mass)
New-onset seizure
papilloedema
abnormal level of consciousness
severe immunocomprised state
What would a reduced conscious level suggest?
Raised intercranial pressure
What could a raised intercranial pressure cause
reduced conscious level.
What would the CSF findings be in bacterial meningitis
Opening pressure: increased
Cell count: High, mainly neutrophils
Glucose: reduced
Protein: high
What would the CSF findings in Viral meningitis and encephalitis
Opening pressure: normal/increased
Cell count: High, mainly lymphocytes
Glucose: Normal (60% of blood glucose)
Protein: slightly increased
How is Herpes simplex encephalitis diagnosed?
PCR of CSF for viral DNA
How would you treat HSV encephalitis
Aciclovir on clinical suspicion.
What is the mortality and morbidity of HSV encephalitis
> 70% mortality
High morbidity rate if left untreated.
How would you treat viral encephalitis
Treat with IV aciclovir + ceftriaxone for 2 weeks
What is the treatment for bacterial meningitis + encephalitis
IV Ceftraizone with IV amoxicillin
(penicillen allergy: Chloramphenicol)
What is Arbovirus Encephalitides
Transmitted to man by vector from non-human host
relevant to travel (travel history important)
Brain abscess definition
localized area of pus within the brain
What is the definition of Subdural empyema
Thin layer of pus between the dura and arachnoid membranes over the surface of the brain
What are signs and symptoms of Brain abscess and empyema
Fever, Headache
Focal symptoms/signs: seizures, dysphasia, hemiparesis etc.
Signs of raised intercranial pressure: Papilloedema (oedema in eye). false localizing signs
depressed conscious level
Meningism may be present (usually in empyema)
What can cause Brain abscess and empyemas
Penetrating head trauma
Spread from adjacent infection (dental, sinusitis, otitis media)
Blood borne infection
neurosurgical procedures
Investigations for brain abscess and empyema
Imaging CT/MRI
Investigate source
Blood cultures
Biopsy (drainage of pus)
Brain abscess constituents
Polymicrobial
Streptococci 70% of cases
Anaerobes in 40-100% of cases (bacteroides, prevotella)
What is the management of Brain abscesses?
Surgical drainage
Penicillin or Ceftriaxone to cover strep
Mentronidazole for anaerobes
High dose required
Culture and sensitivity test
What are Spirochaete that can affect the CNS
Lyme disease (Borrelia Burgdorferi)
Syphilis (Trepomena pallidum)
Leptospirosis (leptospira interrogans)
What is Trepomena pallidum
Syphilis
What is Borrelia burgodorferi
Lyme disease
What is Leptospira interrogans
Leptospirosis
Lyme disease stage 1 characteristics
Expanding rash from site of tick bite
50% flu like symptoms (day-1 week)
-fatigue, myalgia, arthralgia, headache, fever, chills, neck stiffness
Stage 2 signs + symptoms of lyme disease
weeks - months
Musculoskeletal and neurologic involvement most common
(one or more organ: haematologic or lymphatic spread)
PNS>CNS involvment
Stage 3 lyme disease
Months to years: chronic infection
same neurological involvement as stage 2 + subacute encephalopathy, encephalomyelitis
Investigation and treatment for Lyme disease
Investigation: serology tests, CSF Lymphocytosis, MRI brain/spine (if CSF involvement), nerve conduction studies
treatment antibiotic treatment: Oral doxycyline (amoxicillin in pregnancy)
IV ceftriaxone: in serious cases
Neurosyphilis features
3 stage presentation
tertiary disease years/decades after infection (uncommon)
Investigation: treponema and non-treponemal specific antibody tests
CSF: lymphocytes increased, evidence of intrathecal antibody production
Treatment: High dose penicillin
