Week 4 - Nervous system infections Flashcards
Two main infections of the NS
- Meningitis
- Encephalitis
Patient with Herpes simplex can’t stop having seizures because it affects a specific lobe of the brain, which one is it?
Temporal lobe
Encephalitis signs can be divided into 2
- Diffuse
- Focal
Inflammatory process involving the brain parenchyma + evidence of neurologic dysfunction
Encephalitis
Most common group affected by encephalitis
Infants younger than 1 year (< 5 years old)
Causes of encephalitis
- Virus
- Bacteria
- Autoimmune disease
Signs positive in meningitis
- Kering’s sign
- Brudzinski’s sign
Flexion of the hips and knees resulting in a neck flexion is a sign of…
Brudzinski’s sign
Resistance to extend the leg while the hip os flexed is a sign of…
Kering’s sign
Most common cause of encephalitis
Enterovirus
Most common bacterial cause of meningitis
Pneumococci
How does Herpes simplex 1 and 2 get to the NS
Ascends though the Trigeminal nerve
Clinical manifestations of encephalitis by Herpes simplex
- Acute
- Sporadic viral encephalitis
Treatment for Herpes simplex
Acyclovir
Pathogens infect meningeal layers
Meningitis
Pathogens infect brain parenchyma
Encephalitis
Infection starts @meninges and spreads to brain parenchyma
Meningiencephalitis
Aseptic meningitis refers to meningitis where routine bacterial cultures of CSF are -, what are some pathogens that can cause this?
- Viruses
- Mycobacteria
- Fungi
- Parasites
Most common cause of aseptic meningitis
Enterovirus: echovirus and coxsackie virus
Babies < 3 months old are most susceptible to getting bacterial meningitis from
- Group B Streptococci
- Escherichia coli
- Listeria monocytogenes
Teens between the ages of 13 and 17 years old get bacterial meningitis from
- Neisseria meningitidis
- Streptococcus pneumoniae
- Haemophilus influenzae
Children between the ages of 3 + months and 12 years + adults get bacterial meningitis from
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
Listeria monocytogenes can also cause bacterial meningitis @ another age group, which one?
> than 50 years and immunocompromised
Pure encephalitis (without meningitis) is most commonly caused by
Virus
Fungi that can cause encephalitis infections (only @ immunocompromised ppl)
- Cryptococcus neoformans
- Coccidioides immitis
Brain eating amoeba that can cause fatal meningoencephalitis
Naegleria Fowler
Another parasite that can cause meningoencephalitis and is transmitted by the tsetse fly
Trypanosoma brucei
Common triad of symptoms present in brain infections
- Headache
- Fever
- Neck rigidity
Symptoms that accompany the triad are
- Photophobia
- Nausea
- Vomiting
Petechiae are characteristic of
Neisseria meningitidis
Sign to differentiate encephalitis from meningitis
Abnormal brain function
Signs that differentiate meningitis from encephalitis
- Neck rigidity
- Kering +
- Brudzinski +
HSV encephalitis has some characteristic signs since it affects the temporal lobe, which ones?
- Aphasia
- Olfactory hallucinations
- Personality changes
Gold standard diagnosis for meningitis and encephalitis
Lumbar puncture to obtain CSF sample for analysis and culture
Instant treatment for patients with suspected encephalitis or meningitis
- IV dexamethasone: to decrease inflammatory response
- Empiric antibiotics
- Sometimes steroids to reduce the risk of mortality
If the patient has characteristic HSV encephalitis symptoms (confusion, change in personality, drowsiness, fussiness, lethargy and bulging fontanelle) start treatment with
IV acyclovir to treat HSV
Patchy signs @ brain are characteristic of
HSV infection
CSF with increased WBC count w/ neutrophil predominance
Bacterial
CSF with mild leukocytosis and a lymphocyte predominance
- Viral
- Fungal
Protein levels @ CSF change depending on the pathogen, how so?
- High protein levels @ bacterial infections
- Mild or normal protein levels @ viral and fungal infections
Glucose levels @ CSF change depending on the pathogen, how so?
- Low glucose levels @ bacterial and fungal infections
- Normal or slightly decreased @viral infections
yay fin
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