13: CNS infections Flashcards
Meningitis- cc
Bacteria- S. pneumonia, N. meningitidis, H. influenzae
Virus- Echo, Enterovirus, HSV, HIV, CMV, EBV
Protozoa- Naegleria fowleri, Acanthamoeba
Spirochetes- Neurosyphilis
Chronic meningitis
At least 4 weeks of sx*
0-4 weeks
S. agalactiae (group B strep)*
Listeria
4-12 weeks
S agalactiae* (group B strep)
E coli
H influenzae
3month- 18yrs
N meningitidis*
S pneumoniae
18-50yrs
S pneumoniae*
N meningitidis
> 50yrs and Immunocompromised
S pneumoniae*
N meningitidis
Listeria
Aerobic Gram (-) bacilli
Intracranial manipulation
S aureus*
Goagulase (-) staph
Aerobic Gram (-) bacilli
Basilar skull fracture
S pneumoniae*
H influenzae
CSF shunts
S aureus* Aerobic Gram (-) bacilli
Acute meningitis
Hrs to a few days of onset
Signs of meningeal irritation
Kernigs sign (elevate the leg and extend the knee-> pain at the back of the thigh) Brudzinski sign (Flex the neck and the hips and knee will also bend) Nuchal rigidity (less severe in viral)
the 2 signs are absent in viral infection
Signs of ICP
Deteriorating level of consciousness
Papillaedema (blurring of optic disc margins)
Dilated, poorly reactive upil
Cushing’s reflex (Bradycardia, Hypertension, Irregular respiration)
Systemic keys to the etiology
Direct extension- Sinusitis or Otitis
Basilar skull fracture- Rhinorrhea or Otorrhea
Infective endocarditis- Murmur
Erythematous maculopapular rash- Meningococcemia
Lumbar puncture
Key- Posterior superior iliac spine-> gap is L3-L4
Puncture on either L3-4 or L4-5 with more space
Bacterial- dx
WBC: 100-5000; >80% PMNs
Glucose: 100
Viral- dx
WBC: 10-300; lymphocytes
Glucose: Normal
Protein: Normal
Tuberculous- dx
WBC: 100-500; lymphocytes
Glucose: same as bacteria
Protein: same as bacteria
S pneumoniae- tx
DOC: 3rd generation cephalosporins (ceftriaxone or cefotaxime) + vancomycin for 2 weeks
or PenG
N meningitidis- tx
DOC: PenicillinG or Ampicillin x 7days
for Resistant strains-> Ceftriaxone or Cefotaxime
H influenzae- tx
DOC: Ceftriaxone or Cefotaxime
Aerobic Gram(-) bacilli- tx
DOC: Ceftriaxone or Cefotaxime x3wks
P aeruginosa- tx
DOC: Ceftazidime (still 3rd gen but others are not effective**)
Staphylococcus species- tx
Nafcillin or Oxacilliin
Vancomycin-> MRSA, Coagulase(-) Staph
Use of Steroids
To attenuate the detrimental effects of inflammatory response due to IL-1 and TNF
MUST be given BEFORE the antibiotic therapy (killing of bacteria will worsen the immune response-> suppress immune before killing bugs)**
20mins before first dose of antimicrobial agent**
Most important dx tool for CNS viral infection
PCR amplification
Investigation of choice for Enteroviruses, HSV, CMV, EBV
Viral meningitis- tx
Acyclovir for HSV
Vaccination: MMR, VZV
Viral encephalitis- cc
They show tropism to specific tissue
Arbo virus
Enterovirus (Polio: LMN)
HSV-1 (Limbic system in Temporal lobe)
Arbo virus
US: Eastern Equine Encephalitis virus (EEE)
World: Japanese Encephalitis virus
HSV-1 encephalitis- sx
Olfactory hallucinations
Personality changes
due to its effect on Limbic system/ Temporal lobe
Perivascular inflammatory infiltrates and Inclusion bodies usually present
Encephalitis- dx
CSF PCR**
EEG: Periodic lateralized epileptiform discharges (PLEDs)**- sudden repeated spikes
MRI: most sensitive
Cerebral abscess- sites
Temporal lobe: Otits media, Mastoiditis
Posterial frontal/parietal lobe: Hematogenous spread
Interface of gray-white matter: Metastatic abscess
Cerebral abscess- cc
S aureus- MC**
Mycobacteria, Toxoplasma gondii, Cryptococcus- Immunocompromised*
Cerebral abscess- stages
1: Early cerebritis stage (day 1-3)
2: Late cerebritis stage (day 4-9)
3: Early capsule formation stage (day 10-13)- ring enhancing capsule on MRI
4: Late capsule formation stage (>14 days)
Cerebral abscess- tx
3rd gen cephalosporins
Surgical aspiration and drainage for lesion >2.5cm*
Anti-convulsant
Steroids (Dexamethasone)
