Nervous System Infections Flashcards
What is meningitis and how does it present?
Infection or inflammation of the meninges
Presents typically with neck stiffness (tested by passively lifting the head), fever (>38) and altered mental status. Headache, photophobia, nausea and vomiting.
Petechial rash that doesn’t blanch.
Cam have cranial nerve palsies, seizures or focal neural deficits.
What are some differential diagnoses of meningitis?
Other infections Sarcoidosis NSAIDS Metastatic Haematological
What are three causative organisms of meningitis?
Streptococcus Pneumoniae (Pneumococcus) Neisseria Meningitidis (Meningococcus) Enteroviruses
What investigations are done for meningitis?
Blood Cultures
Lumbar Puncture (Culture and microscopy)
Only use imaging if LP is contraindicated
What drugs are mainly used to treat meningitis?
IV Ceftriaxone
Penicillin (if sensitive pneumococcus)
What is the presentation of encephalitis?
Slower onset and more cerebral dysfunction than meningitis
Flu like prodrome for 4-10 days
Meningism, seizures, focal signs and progressive cerebral dysfunction
Commonly caused by HSV
What are some investigations for encephalitis?
Blood Cultures
LP
MRI/CT brain
EEG
What would the CSF results for bacterial meningitis show?
High neutrophil cell count
Increased opening pressure
Reduced glucose (<5)
High protein count
What would the CSF results for viral meningitis/encephalitis show?
High lymphocyte cell count
Normal/increased opening pressure
Normal glucose
Slightly increased protein count
What are contraindications for LP?
Focal Signs (not inc CN palsies)
New onset seizures
Signs of raised ICP (papilloedema or GCS<10)
Severely immunocompromised state
Suspicion of mass on spinal cord (could cause disc herniation)
Local Infection near LP site
Platelet count less than 40 times 10 to the 9
What are the two antibodies for autoimmune encephalitis?
Anti Voltage Gated Potassium Channel (AGKC) which have frequent seizures, amnesia and altered mental state.
Anti NMDA receptor which have flu like prodrome, psychiatric features and seizures which lead into a coma.
How are arbovirus encephalitides transmitted and where are they common?
Transmitted by a vector such as ticks or mosquitoes.
Common in other parts of the world so travel and immunisation history is important.
What are symptoms of brain abscess/subdural empyema?
Headache Fever Features of raised ICP Focal Symptoms Meningism (esp empyema) Dental, sinus or ear infection (possible cause)
What are four causes of brain abscesses?
Penetrating Head Trauma
Blood borne infection (bacterial endocarditis)
Spread from adjacent infection
Neurosurgical procedure
What investigations should be done for brain abscesses?
CT/MRI imaging
Blood Culture
Biopsy of drained pus
What are some causative organisms of brain abscesses?
Streptococci Milleri (constellatus, intermedius or anginosus) Anaerobes such as prevotella or bacteriodes
What is the management for brain abscesses?
Surgical drainage if possible
High dose ceftriaxone or penicillin if Strep
High dose metronidazole if anaerobic
Name three spirochaetes that can invade the CNS
Lyme Disease-Borrelia burgdorferi
Syphillis-trepomena pallidum
Leptospirosis-leptospira interrogans
What are the three stages of lyme disease?
Stage One- localised (day 1-30)
Erythema migrans (diagnostic) and 50% get flu like symptoms
Stage Two-disseminated (weeks to months)
Neurologic symptoms in PNS and musculoskeletal problems
Stage Three-chronic (months to years)
Same as stage two but occurs after a period of latency
What are the investigations and treatment for lyme disease?
Serology tests
MRI spine/brain if CNS involved
CSF lymphocytosis
Nerve conduction studies
Treat with IV ceftriaxone or oral doxycycline
What is a typical presentation of rabies and what can it lead to?
Bitten by an animal (dog or bat)
Get paraesthesia at the site and then spreads from PNS to CNS so get ascending paralysis and encephalitis.
What is the rabies post exposure treatment?
Wash the wound out
Give active rabies immunisation
Give human rabies immunoglobulin
