CNS infections Flashcards
Meningitis general features?
5
-Inflammation in sub arachnoid space
-Diagnosed pathologically by examining the CSF
-Associated with some degree of ventriculitis
-Clinically presented as faver + meningism (headache,photophobia,neck stiffness) /meningismus (meningism except infection or inflammation)
-acute or chronic
Features of acute meningitis?
4
-developps within hours to days
-most common in extremes of ages
-commonest causes are bacterial and viral
-acute bacterial meningitis is very serious,without tx fatality is >70%,even survivors have neurological defecits
Common bacteria affecting adults?
8
Streptococcus pneumoniae (pneumococcus)
Neisseria meningitides (meningococcus) (rare but look out)
Haemophilus influenza type B (rare due to hib vaccination)
Leptospira spp
Staph. Aureus
Coagulase negetive staphylococcus
Listeria monocytogenes (rare in sl)
Gram negative bacilli
Acute viral meningitis?
Self limiting disease with a good prognosis
Common org
-enterovirus other than poliovirus
-mups
-HSV
-HIV
Clinical clues to microbial aetiology?
5
Purpuric rash - meningococcal
Head injury- pneumococcus,haemophillus influensa
Neurosurgery-staphylococcus
Pregnant,raw milk consumption-listeria
Elderly-listeria,gram -ve bacilli
Principles of mx?
3 (about meningococcus,^ICP,early commencement)
Lumbar punctures principles and values?
Principles- 3
Check CSF opening P is possible
Send for gram stain and bacterial culture
Always take concurrent blood cultures
Values-
Glucose,protein,cells
Viral-sterile culture
Empirical antibiotics tx?
6
-3rd gen cephalosporins (cefotaxime or ceftriaxone) for 14-21 days
-IV acyclovir to cover viral etiology
-IV vancomycin since getting resistance to ceftriaxone
-IV ampicillin to cover listeria if >50 yrs
-adjuvant therapy
Dexamethasone (with or before 1st dose,not given in meningococcal)
-in bacterial response is rapid usually.if no response consider,
Unusual pathogen
Complications (subdural empyema)
Other prob (infected iv cannula)
Chronic meningitis features and causative org?
4
-Develop over several days to weeks
-By def CSF changes needs to be presented for over 4 weeks
-focal defecits are more common (CN palsy,body weakness)
-org
Mycobacterium tuberculosis
Treponema pallidum
Brucell abortus
cryptococcus neoformans
Non infective - carcinomatous,drug induces
Encephalitis common features ?
5
-inflammation of the brain paranchyma
-clinically identified as fever + encephalopathy (impaired consciousness)
-may occur with or without meningism (meningoencephalitis)
-acute,subacute,chronic
-pure encephalitis almost always due to virus but consider cerebral malaria in sl
Acute encephalitis causes?
5
Arbo viruses (JE,dengue)
HSV,VZV
plasmodium falciparum
Listeria monocytogenes (especially if lymphocytic meningoencephalitis)
Rabies
Features and principals mx of acute encephalitis?
Focal defecits uncommon but occur in HSV
Principals of mx-
-EEG is extremely useful.LP and CSF Ex is useful but CSF can be normal.
-care for unconscious pt is imp since cant breat and eat
-prevent ^ ICP
-recovery is long and tedious hence rehabilitation is imp
-only specific therapy is IV acyclovir
-HSV commonly causes focal defecits in temporal lobe ,which maybe seen in EEG or MRI
-PCR test for HSV in CSF is introduced to sl now
-other specific therapy
Cerebral malaria -quinine with loading dose
Listeriosis-ampicillin 12g/d
Chronic encephalitis?
Sub acute sclerosing pan enCephalitis (SSPE , measles)
Creutzfeldt-Jakob disease and varient CJD
What is abcess and Features of it?
6
-Suppuration within the cranial cavity
-Maybe epidural,subdural (empyema) or cerebral
-Clinically presenting as fever/headache and encephalitis and focal defecits
-may occur with or without meningism and encephalopathy
-epidural abcess and subdural empyema usually occurs as extension of contiguous infection (parameningeal infection)
-cerebral abcess maybe due to such extensions or hematogenous spread
Common sites of spreading infections causing cerebral abcess?
Ear disease-temporal cerebellums
Sinusitis-frontal,temporal
Dental infection-frontal
Post meningitis-frontal,cerebellum
Trauma/sx- related to the wound
Hematogenous (by lung abcess or endocarditis)-MCA teritory/related to wound
Immunodeficiency-MCA territory