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Neurology > CNS Infections > Flashcards

CNS Infections Flashcards

1
Q

What can an untreated CNS infection cause?

A

Brain herniation and death

Cord compression and necrosis with subsequent permanent paralysis

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2
Q

What does the gross morphology of pyogenic (bacterial) meningitis show?

A

Thick layer of suppurative exudate covering the leptomeninges over the surface of the brain
Exudate in basal and convexity surface

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3
Q

What does pyogenic meningitis show microscopically?

A

Neutrophils in the SA space

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4
Q

What is the DDx for fever and altered mental status?

A 
Encephalitis
Meningitis
Meningoencephalitis
Encephalomyelitis 
Severe sepsis syndrome due to infection elsewhere
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5
Q

When does viral meningitis usually present?

A

Late summer/autumn

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6
Q

What causes viral meningitis?

A

Enteroviruses e.g. ECHO virus

Other microbes and non-infectious causes also

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7
Q

How is viral meningitis diagnosed?

A

Viral stool culture, throat swab and CSF PCR

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8
Q

What is the treatment for viral meningitis?

A

Supportive as self-limiting

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9
Q

What viruses can cause viral encephalitis?

A 
HSV (serious)
VZV
CMV
HIV
Measles
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10
Q

What is the treatment of HSV encephalitis?

A

Aciclovir IV high doses- must be recognised, admitted and treated within 6 hours

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11
Q

What is the history and treatment of VZV encephalitis?

A

History of shingles

High dose acyclovir

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12
Q

What are the travel related causes of viral encephalitis?

A

West Nile, Japanese B encephalitis, Tick Borne encephalitis

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13
Q

What are the occupational related causes of viral encephalitis?

A

Rabies

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14
Q

What are the non-infectious causes of viral encephalitis?

A

Autoimmune etc

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15
Q

What are the clinical features of encephalitis?

A 
Insidious onset-sometimes sudden
Meningismus
Stupor, coma
Seizures, partial paralysis
Confusion, psychosis
Speech, memory symptoms
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16
Q

What investigations are required in viral encephalitis?

A

LP
EEG
MRI

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17
Q

If there is a delay in investigations in suspected viral encephalitis what should be done?

A

Start pre-emptive acyclovir as prompt therapy improves outcome

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18
Q

What are the MRI findings in encephalitis?

A

Inflamed portion of the temporal lobe, involving the uncus and adjacent parahippocampa I gyrus (brightest white on MR)

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19
Q

What are the common causes of bacterial meningitis related to age?

A 
Neonates: listeria, group B streptococci, E. coli
Children: H. influenza
10 to 21: meningococcal
21 onward: pneumococcal >meningococcal
Elderly: pneumococcal>listeria
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20
Q

What are the common causes of bacterial meningitis related to RFs?

A

Decreased CMI: listeria
S/P neurosurgery or opened head trauma: Staphylococcus, Gram Negative Rods
Fracture of the cribiform plate: pneumococcal

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21
Q

What is the likely causative organism in bacterial meningitis due to an immunocompromised state?

A

S. pneumoniae
N. meningitidis
Listeria
aerobic GNR (including Ps.aeruginosa)

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22
Q

What is the likely causative organism in bacterial meningitis due to a basilar skull fracture?

A

S. pneumonia
H. influenzae
beta-hemolytic strep group A.

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23
Q

What is the likely causative organism in bacterial meningitis due to head trauma or post-neurosurgery?

A

S.aureus
S.epidermidis
aerobic GNR

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24
Q

What is the likely causative organism in bacterial meningitis due to a CSF shunt?

A

S. epidermidis
S. aureus
aerobic GNR
Propionibacterium acnes

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25
Q

What can be some long term effects of meningitis and septicaemia?

A 
Limb loss
Deafness
Blindness
Cerebral palsy
Quadriplegia 
Severe mental impairment
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26
Q

What is the pathogenesis of bacterial meningitis?

A
  1. Nasopharyngeal colonisation
  2. Direct extension of bacteria: parameningeal foci (sinusitis, mastoiditis, or brain abscess), across skull defects
  3. From remote foci of infection: (e.g. endocarditis, pneumonia, UTI etc)
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27
Q

What are some agents of meningitis in immunocompromised patients?

A 
Conventional agents- s.pneumonia, s.aureus etc
Listerio monocytogenes
Mycobacterium tuberculosis
Nocardia asteroides 
Cryptococcus neoformans (AIDS)
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28
Q

What does Neisseria meningitides cause?

A

Meningococcal meningitis

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29
Q

What are the symptoms in meningococcal meningitis due to?

A

Endotoxin from bacteria

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30
Q

In whom does Meningococcal meningitis most commonly occur?

A

Young children

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31
Q

What are military recruits vaccinated with to prevent outbreaks of meningococcal meningitis in training camps?

A

Purified capsular polysaccharide

32
Q

What type of H. influenza is the most common cause of meningitis in children under 4yo?

A

Type B

33
Q

Where is S. pneumoniae commonly found in the nasopharynx?

A

Nasopharynx

34
Q

Who are most susceptible to S. pneumonia meningitis?

A

Hospitalised patients, patients with CSF skull fractures, diabetics, alcoholics and young children

35
Q

What does the conjugate vaccine for pneumoccal pneumonia always provide protection against?

A

Pneumococcal meningitis

36
Q

What is listeria monocytogenes?

A

Gram +ve bacilli

37
Q

What cultures should be taken in suspected listeria monocytogenes meningitis?

A

Blood cultures

38
Q

Who are most likely to have listeria monocytogenes meningitis?

A

Neonates
>55yo
Immuno-suppressed esp. malignancy

39
Q

What is the antibiotic of choice in listeria monocytogenes meningitis?

A

IV Ampicillin/Amoxicillin

Ceftriaxone has no value as intrinsically resistant

40
Q

Describe tuberculous meningitis

A

Can reactivate in elderly
Often non specific ill health
Previous TB on CXR
Poor yield from CSF

41
Q

How is tuberculous meningitis treated?

A

Isoniazid + rifampicin (add pyrazinamide + ethambutol)

42
Q

Describe cryptococcal meningitis?

A

Fungal
Mainly HIV
CD4

43
Q

How should cryptococcal meningitis be treated?

A

IV Amphotericin
B/Flucytosine
Fluconazole

44
Q

What are the clinical signs of bacterial meningitis?

A

Fever
Stiff neck
Alteration in consciousness

45
Q

What are some signs and symptoms in bacterial meningitis?

A 
Headache
 Vomiting
 Pyrexia
 Neck stiffness
 Photophobia
 Lethargy
 Confusion
 Rash
46
Q

Who are signs of bacterial meningitis often absent or atypical in?

A

Very young/old

Immunocompromised

47
Q

What DDx should be suspected in possible bacterial meningitis?

A 
Meningitis
Encephalitis 
Cerebral abscess
Severe sepsis from other source 
SA haemorrhage 
Cerebral tumour
48
Q

What is the rule regarding LP’s and bacterial meningitis?

A

LP is CSF pleocytosis, not symptoms of bacterial meningitis

49
Q

What should be in each LP tube for interpretation?

A

Tube 1. Haematology: cell count, differential
Tube 2. Microbiology: gram stain, cultures
Tube 3. Chemistry: glucose, protein
Tube 4. Haematology: cell count, differential

50
Q

How should meningitis be diagnosed?

A 
Blood cultures
Throat swab (meningococci)
Blood EDTA for PCR (meningococci)
CSF (LP)
Microscopy, biochemistry, culture, antigen detection
51
Q

What bacteria will be found in the ddx of meningitis in normal patients?

A 
Enteroviruses
HSV1, HSV2
VZV
M. tuberculosis
B. burgdorferi
Pneumococci
Meningococci
H. influenza
52
Q

What bacteria will be found in the ddx of meningitis in immunocompromised patients?

A 
EBV
CMV
HHV-6/7
T. gondii
JC virus
53
Q

What are the CSF findings in viral acute adult meningitis?

A 
10^1-10^3 cells (lymphocytes)
Negative gram stain
Negative bacterial antigen detection
Normal or slightly high protein
Usually normal glucose
54
Q

What are the CSF findings in bacterial acute adult meningitis?

A 
10^1-10^4 cells (predominantly polymorphs)
Positive gram stain
Positive bacterial antigen detection
High protein
Less than 70% glucose
55
Q

What are the CSF findings in tuberculous acute adult meningitis?

A 
10^1-10^3 cells (predominantly lymphocytes)
Positive or negative gram stain
Negative bacterial antigen detection
High or very high protein
Less than 60% glucose
56
Q

What test results are predictive of bacterial meningitis with 99% accuracy?

A

WBC >2000
Neutrophils >1180
Protein >220mg/dl
Glucose

57
Q

If not bacterial meningitis, what infectious conditions may cause neutrophilic pleocytosis and low csf glucose?

A 
Viral meningitis (early phase only)
Some parameningeal foci/ cerebritis
Leakage of brain abscess into ventricle
Amebic meningoencephalitis
TB meningitis (rarely, & usu. only early)
58
Q

If not bacterial meningitis, what non-infectious conditions may cause neutrophilic pleocytosis and low csf glucose?

A

Chemical-meningitis (contrast…)
Behcet syndrome
Drug –induced ( NSAIDs, Sulfa, INH, IVIG, OKT3…)

59
Q

What is aseptic meningitis?

A

A term used to mean non-pyogenic bacterial meningitis
It describes a spinal fluid formula that has:
low number of WBC
minimally elevated protein
normal glucose

60
Q

What are some infectious treatable causes of aseptic meningitis/encephalitis syndrome?

A 
HSV 1 and 2
Syphilis
Listeria (occasionally)
Tuberculosis
Cryptococcus
Leptospirosis
Cerebral malaria
African tick typhus
Lyme disease
61
Q

What are some non-infectious treatable causes of aseptic meningitis/encephalitis syndrome?

A 
Carcinomatous
Sarcoidosis
Vasculitis
Dural venous sinus thrombosis
Migraine
Drug:
Co-trimoxazole
IVIG
NSAIDS
62
Q

What are the adult bacterial meningitis guidelines?

A

Pre-hospital management
Early inpatient management
Antimicrobial adjunctive treatment
Supportive therapy
Prevention of secondary cases of meningitis
Screening for predisposing factors to meningitis

63
Q

What management occurs in pre-hospital acute adult bacterial meningitis?

A

Look for indications for hospital admission

Pre-hospital antibiotics

64
Q

What are some indications for hospital admission of acute adult bacterial meningitis?

A

Signs of meningeal irritation
An impaired conscious level
A petechial rash
Who are febrile or unwell and have had a recent fit
Any illness, especially headache, and are close contacts of patients with meningococcal infection, even if they have received a prophylactic antibiotic

65
Q

What should happen immediately on hospital admission in acute adult bacterial meningitis, provided ABC is fine?

A

Bloods for culture and coag screen
Antibiotic treatment before pathogens are identified, and immediately after
Throat swab which should be plated soon as practical
Disrupt and swab/aspirate any petechial or purpuric skin lesion for microscopy and culture
CT/MRI for patients with papilloedema or focal neuro signs

66
Q

Who should undergo CT prior to LP?

A 
Immunocompromised
History of CNS disease
New onset seizure (within 1 wk of presentation)
Papilloedema 
Abnormal level of consciousness
Focal neurologic deficit
67
Q

What are some key warning signs in acute adult bacterial meningitis?

A 
Marked depressive conscious level (GCS 2)
Focal neurology 
Seizure before/at presentation
Shock
Bradycardia and HT
Papilloedema
68
Q

Who should undergo an LP in acute adult bacterial meningitis?

A

All adults with suspected meningitis except when a clear contraindication exists, or if there is a confident clinical diagnosis of meningococcal infection with a typical rash

69
Q

What is the empiric antibiotic therapy for acute adult bacterial meningitis?

A

IV Ceftriaxone 2g bd
Add IV Ampicillin/amoxicillin 2g qds if listeria suspected
(If pen allergic Chloramphenicol IV 25mg/kg 6-hourly with vancomycin IV 500mg 6-hourly or 1g 12 hourly

70
Q

What treatment should be given in acute adult bacterial meningitis if listeria is suspected and patient is pen. allergic?

A

Co-trimoxazole

71
Q

What additional drug therapy other than antibiotics should be given to all patients with suspected bacterial meningitis?

A

Steroids 10mg IV 15-20 min before or with first antibiotic dose, then every 6hrs for 4 days

72
Q

When should steroids not be given in bacterial meningitis?

A

Post surgical meningitis, severe immunocompromised, meningococcal or septic shock or those hypersensitive to steroids

73
Q

What indicates a poor prognosis on admission in meningococcal disease?

A 
Haemorrhagic Diatheses
Deteriorating consciousness
Multi-organ failure 
Rapidly developing rash
Age >60
74
Q

What are key interventions in management of bacterial meningitis with low GCS (2)?

A

Admit to highly supervised area- baseline investigations
Secure airway and high flow O2
IV 2G Ceftriazone stat (+- amoxicillin if >55 to cover listeria)
IV corticosteroids
Do not wait for CT/LP

75
Q

What is the standard contact prophylaxis regimen in bacterial meningitis?

A

600 mg rifampicin orally 12-hourly for four doses (adults and children over 12 years), 10 mg/kg orally 12-hourly for four doses (aged 3-11 months) (IV).

76
Q

What vaccines against organisms which can cause meningitis exist?

A

Neisseria meningitidis: serogroups A and C (W135 & Y)- travel. Group C conjugate vaccine
H. influenza (HiB vaccine)
Strep. pneumoniae- pneumocccal vaccines-polysaccharide and conjugate

77
Q

What indicates a poor prognosis on admission in all types of meningitis?

A 
Tachycardia
GCS <12 on admission
Low GCS, cranial nerve palsy
Seizures within 24hr
Hypotension on admission
Age >60

Neurology (27 decks)

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