CNS infections Flashcards

1
Q

Meningitis general features?

A

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

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2
Q

Features of acute meningitis?

A

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

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3
Q

Common bacteria affecting adults?

A

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

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4
Q

Acute viral meningitis?

A

Self limiting disease with a good prognosis
Common org
-enterovirus other than poliovirus
-mups
-HSV
-HIV

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5
Q

Clinical clues to microbial aetiology?

A

5
Purpuric rash - meningococcal
Head injury- pneumococcus,haemophillus influensa
Neurosurgery-staphylococcus
Pregnant,raw milk consumption-listeria
Elderly-listeria,gram -ve bacilli

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6
Q

Principles of mx?

A

3 (about meningococcus,^ICP,early commencement)

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7
Q

Lumbar punctures principles and values?

A

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

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8
Q

Empirical antibiotics tx?

A

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)

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9
Q

Chronic meningitis features and causative org?

A

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

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10
Q

Encephalitis common features ?

A

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

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11
Q

Acute encephalitis causes?

A

5
Arbo viruses (JE,dengue)
HSV,VZV
plasmodium falciparum
Listeria monocytogenes (especially if lymphocytic meningoencephalitis)
Rabies

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12
Q

Features and principals mx of acute encephalitis?

A

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

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13
Q

Chronic encephalitis?

A

Sub acute sclerosing pan enCephalitis (SSPE , measles)
Creutzfeldt-Jakob disease and varient CJD

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14
Q

What is abcess and Features of it?

A

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

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15
Q

Common sites of spreading infections causing cerebral abcess?

A

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

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16
Q

Mx principals of brain abcss?

A

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

17
Q

Types of CNS infections?

A

Intra cranial
-tuberculous meningitis (TBM)
-tuberculoma
-tuberculous abcess
Spinal
-spinal tuberculous arachnoiditis
-pott’s paraplegia

18
Q

Pathogenesis of CNS TB?

A

Photo

cranial nerves involvement
Brain infarction
Cord infarction
Nerve root and cord involvement (radiculitis)
CNS infarction

19
Q

Neuroimaging findings of CNS TB?

A

base of the brain gelatinous whitish image showing exudates
Ventricles enlarge

20
Q

Clinical presentation of CNS TB?

A

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

21
Q

Intra cranial tuberculoma ct appearance and clinical features?

A

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

22
Q

TB abcess features?

A

3
Develop from granuloma or spread from TB meningial foci
More accelerated course than tuberculoma
Clinical features-
Larger headache
Focal seizures
Focal neurological signs

23
Q

Spinal Tb arachnoiditis?

A

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)

24
Q

Pott’s paraplegia?

A

4
Progressively worsening local pain
Lumbar and thoarasic regions most common
Constitutional symptoms
Bone destruction leading to vertical collapse and cord compression

25
Q

Diagnosis of TBM?

A

Typical CSF finding (^ proteins,lymphocyte pleocytosis,<2/3 od serum sugar)(also found in fungal,viral and brucellosis infections)
Definitive diagnosis- mycobacterium tuberculosis in CSF (difficult)
Diagnosis is strongly suspected if,
-clinical presentation is typical with stages
-inflammatory markers ^
-mantoux +
-CXR showed evidence of TB
-CSF profile is typical
-imaging shows evidence of Tb (contrast enhance CT or MRI showing meningial enhancement,hydrocephalus,tuberculoma,tB abcess,spinal arachnoiditis,pott’s paraplegia)

Even TB PCR is only 50% sensitive
Acid fast bacilli in CSF most of the tome (-)

26
Q

Tx pointS in TBM?

A

Start immediately on strong clinical suspicion
4 drugs 2 months
2 drugs 10 months
Steroid predni 1 mg/kg/day for 3 w then tappered off gradually over the next 3 w