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
Mx principals of brain abcss?
6
-Look for predisposing factors clinically
-if abcess is suspected, LP is contraindicated
-common IV antibiotics-benzyl penicillin + chloramphenicol/ceftriaxone/cefotaxime/metronidazole/
-consider adding cloxacillin/vncomycin if trauma/sx
-arrange brain imaging (CT or MRI)
-neurosurgical opinion
Types of CNS infections?
Intra cranial
-tuberculous meningitis (TBM)
-tuberculoma
-tuberculous abcess
Spinal
-spinal tuberculous arachnoiditis
-pott’s paraplegia
Pathogenesis of CNS TB?
Photo
cranial nerves involvement
Brain infarction
Cord infarction
Nerve root and cord involvement (radiculitis)
CNS infarction
Neuroimaging findings of CNS TB?
base of the brain gelatinous whitish image showing exudates
Ventricles enlarge
Clinical presentation of CNS TB?
prodromal phase- 5
Insidious onset of malaise,lassitude headache,low grade fever,LOW,LOA
meningitic phase- 6
Meningism (neck stiffness,kernig sign), protracted headache , vomiting,lethargy,confusion,varying degree of cranial nerves and long tract signs
Paralytic phase-
Phase of illness may accelerate rapidly,confusion gives way to stupor and coma
Intra cranial tuberculoma ct appearance and clinical features?
NCCT -ring enhancing lesion ,edema around the lesion (^ blood vessels and inflammation)
Clinical features-7
Headache,vomiting,papilloedema,focal neurological signs,insidious onset of LOA, LOW,low grade fever
TB abcess features?
3
Develop from granuloma or spread from TB meningial foci
More accelerated course than tuberculoma
Clinical features-
Larger headache
Focal seizures
Focal neurological signs
Spinal Tb arachnoiditis?
6
Subacute onset of nerve root and cord compression signs
Spinal or radiclar pain
Paraesthesia
LMN paralysis (root involvement)
Bladder and rectal sphincter dysfunction (spinal cord damage)
Thrombosis of A spinal A and infarction of the spinal cord (vasculitis)
Pott’s paraplegia?
4
Progressively worsening local pain
Lumbar and thoarasic regions most common
Constitutional symptoms
Bone destruction leading to vertical collapse and cord compression
