Meningitis, Encephalitis, Brain Abscess Flashcards

1
Q

What is meningitis

A

It is the inflammation of the protective membranes (meninges) surrounding the brain and the spinal cord and the CSF

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2
Q

The CSF is found in between which membranes

A

The pia and the arachnoid matter

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3
Q

Where does the spinal cord end

A

Between L1 and L2

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4
Q

Mention the protective membranes

A

Pia, dura and arachnoid mater

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5
Q

What are the types of meningitis

A

Viral meningitis
Bacterial meningitis
Parasitic meningitis
Fungal meningitis
Non-infective meningitis

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6
Q

What is the most common type of meningitis

A

Viral meningitis

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7
Q

In which seasons are viral meningitis common

A

Summer and fall

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8
Q

Which type of virus cause about 85% percent of meningitis cases

A

Enterovirus

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9
Q

Mention some viruses which can also cause meningitis

A

Coxsackievirus A and B
Echovirus

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10
Q

Mention some bacteria which cause meningitis

A

Streptococcus pneumoniae
Neiserria meningitidis
Haemophilus influenza
Listeria monocytogenes
Staphylococcus aureus

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11
Q

What is the second most common type of meningitis

A

Bacterial meningitis

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12
Q

Which type of meningitis is likely to affect people with a weakened immune system

A

Fungal meningitis

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13
Q

Mention some fungi which causes meningitis

A

Cryptococcus
Blastomyces
Histoplasma
Coccidiodes

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14
Q

Which type of meningitis is caused by other medical conditions or treatments

A

Non-infective meningitis

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15
Q

Examples of conditions which causes meningitis

A

Lupus
Cancer
Certain medications like NSAIDs for certain people

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16
Q

Which type of meningitis is rare

A

Parasitic meningitis

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17
Q

Which type of meningitis is not spread between people

A

Parasitic meningitis

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18
Q

Which type of meningitis could go away without treatment

A

Viral meningitis

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19
Q

Which type of meningitis could be chronic

A

Fungal meningitis

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20
Q

Meningitis can occurs when the meninges are covered by the infecting agent
True or false

A

True

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21
Q

What substance will increase in the CSF in meningitis

A

Proteins

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22
Q

What are some risk factors in meningitis

A

Respiratory tract infection
Otitis media
Mastoiditis
Head trauma
Splenectomy
Sickle cell disease
Immunosuppressive therapy
Immnunocompromised host
Alcoholic patients
Patients with hardware. Eg. Ventriculoperitoneal shunt

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23
Q

What are some early clinical features of meningitis

A

Headache
Leg pain
Cold hands and feet
Abnormal skin colour
Fever
Chills, nausea, vomiting

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24
Q

Which bacteria is there most common cause of petechial rash

A

Neisseria

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25
Q

What are some investigations to make with a patient suspected of meningitis

A

Lumbar puncture (measure open pressure, gram stain CSF for microscopy, culture, etc)
Blood culture (FBC , CXR, U &E, LFT, glucose, coagulation screen)
Stool sample for viruses
CT scan/MRI may show swelling or inflammation
CXR/CT SCAN of chest or sinuses

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26
Q

What is the main investigation for meningitis

A

Lumbar puncture

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27
Q

Where is the lumbar puncture done

A

The space between L3 and L4

28
Q

What are some contraindications of lumbar puncture

A

Intra-cranial mass
Focal signs. Eg. Hemiparesis
Papilloedema
Head trauma
Middle ear pathology
Major coagulopathy
Infection at the site of lumbar puncture
CT scan (mass lesion or raised ICP)

29
Q

What are some management approaches to patients with bacterial meningitis

A

Emergent CSF analysis and initiation of immediate antiadjunctive and adjunctive therapies
Empiric antimicrobial therapy should be instituted as soon as possible to eradicate the causative organism
Antimicrobial therapy should last at least 48 to 72 hours or until the diagnosis of bacterial meningitis can be ruled out
Continued therapy should be based on the assessment of clinical improvement, cultures, and susceptibility testing results.
In addition to antibiotics, dexamethasone is a commonly used therapy for the treatment of pediatric meningitis
Dexamethasone should be administered prior to the first antibiotic dose and not after antibiotics have already been started
Dexamethasone has shown to cause a significant improvement in CSF concentrations of pro-inflammatory cytokines, glucose, protein, and lactate as well as a significantly lower incidence of neurologic sequelae commonly associated with bacterial meningitis
The commonly used IV dexamethasone dose is 0.15 mg/kg every 6 hours for 2-4 days

30
Q

If you’re treating a bacterial meningitis what drug should you start with before antibiotics

A

Dexamethasone

31
Q

What antiviral drug do you give for a patient with viral meningitis

32
Q

What antibiotic drug do you give for a patient with a bacterial meningitis

A

3rd generation cephalosporins like ceftriazone

33
Q

What is the first and second line preventative antibiotic for meningococcal meningitis

A

Ciprofloxaxin 500mg stat
Rifampicin 600mg bd x2

34
Q

What is encephalitis

A

Inflammation of the brain parenchyma often due to infections viral or bacterial (mostly viral) or from an immune system disorder

35
Q

What are some viruses which cause encephalitis

A

Herpes
Enteric
Paramyxo
Arbo
Influenza viruses, adenovirus, parvovirus, rubella virus, rabies (rare)

36
Q

What is the most common cause of viral encephalitis in industrialized nations

A

HSV encephalitis

37
Q

HSV-1 and HSV-2
Which causes about 90% cases of encephalitis

A

HSV-1
HSV-2 is more common in immuno-compromised patients and neonates

38
Q

HSV-2 viral encephalitis is transmitted via

A

Genital mucosa

39
Q

HSV-1 infects the human with encephalitis via

A

Oral mucosa
Virus then travels along the trigeminal nerve to ganglion

40
Q

What is the typical clinical presentation of viral encephalitis

A

Acute flu-like prodrome
High fever
Severe headache
Altered consciousness (lethargy, drowsiness, confusion, coma)
Seizures
Focal neurological signs

41
Q

What are some subtle presentations of viral encephalitis

A

Low grade fever
Speech disturbances (dysphagia, aphasia)
Behavioral change

42
Q

Subacute and chronic presentations of viral encephalitis can be caused by which viruses

43
Q

What are some investigations for viral encephalitis

A

CSF study
Blood study
Enhanced CT/MRI with contrast
Toxoplasma tests
MRI brain: right temporal lobe (high signal in a patient with herpes encephalitis)

44
Q

What is the viral treatment for encephalitis

A

Acyclovir for 14-21 days

45
Q

What is the bacterial treatment for encephalitis

A

Ceftriazone
Metronidazone

46
Q

What are some poor prognostic factors of encephalitis

A

GCS < 7
Delay in starting acyclovir (especially > 2 days)

47
Q

What is a cerebral abscess

A

It is a focal pyogenic infection of the brain

48
Q

What are some effects of cerebral abscess

A

Direct involvement and destruction of the brain
Compression of the parenchyma
Elevation of intracranial pressure (interfering with blood and/or CSF flow)

49
Q

What is the pathophysiology of an abscess

A

It begins as a localized cerebritis (1-2 weeks)
Evolves into a collection of pus surrounded by a well-vascularized capsule (3-4 weeks)

50
Q

List the pathogenesis of cerebral abscess

A

Direct spread from contiguous foci
Hematogenous spread from remote foci
Penetrating trauma/surgery
Cryptogenic

51
Q

Some contiguous foci include

A

Otitis media/mastoiditis
Sinusitis
Dental infection, typically molar infections
Meningitis rarely complicated by brain abscess

52
Q

How does direct spread of encephalitis spread

A

Direct extension through infected bones and spread through emissary veins, diploic veins and local lymphatics

53
Q

In which artery do brain abscesses spread (hematogenous spread)

A

Middle cerebral artery distribution

54
Q

List some conditions which serve as middlemen for hematogenous spread of brain abscesses

A

Emphysema
Lung abscesses
Bronchiectasis
Endocarditis
Wound infections
Pelvic infections
Infra-abdominal source

55
Q

Which bacteria normally causes brain abscesses

A

Streptococci and anaerobes
Staphylococcus aureus, anaerobic GNR common after trauma or surgery

56
Q

Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the parietal lobe

A

Headache
Visual field defects
Endocrine disturbances

57
Q

Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the cerebellum

A

Nystagmus
Ataxia
Vomiting
Dysmetria

58
Q

Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the temporal lobe

A

Ipsilateral headache
Aphasia
Visual field defect

59
Q

Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the frontal lobe

A

Headache
Drowsiness
Inattention hemiparesis
Motor speech disorder

60
Q

Differential diagnosis for cerebral abscess

A

CVA
Hemorrhage
Aneurysm
Subdural emphysema/Epidural abscess

61
Q

What is the difference in an MRI between an abscess and a tumor

A

An abscess has a hypo-dense center with surrounding smooth thin walled capsule and areas of peripheral enhancement
Tumors have diffuse enhancements and irregular borders

62
Q

Not so a sensitive test but if air seen, consider possibility of brain abscess. What investigation test for cerebral abscess is this

A

Skull x-ray

63
Q

What are imaging study investigations for cerebral abscess

A

Skull x-ray
MRI (more sensitive for early cerebritis, satellite lesions, necrosis, edema, especially posterior fossa)
CT scan (if ring enhancing lesion(s) are seen)
99m Tc brain scan (very sensitive, useful where CT or MRI not available)

64
Q

What are some specific investigation tests for encephalitis

A

Aspirate
WBC (normal in 40%, only moderate in ~50%, and only 10% have WBC > 20,000)
CRP (almost invariably elevated)
ESR (usually moderately elevated)
Blood culture (often negative but should still be done)
Lumbar puncture

65
Q

Why is lumbar picture contraindicated in patients with known or suspected brain abscesses

A

There is risk of herniation

66
Q

When do you subject a cerebral abscess patient to medical treatment only

A

When he is a poor surgical candidate
When he has multiple abscesses in a dominant location
When his abscess size <2.5 cm with concomitant meningitis, ependymitis or early abscess (cerebritis?) which will improvement on antiboitics
Better vascularized cortical lesions are more likely to respond to antibiotics alone than subcortical/white-matter lesions that are poorly vascularized
(Serial imaging important to monitor response)

67
Q

What are some poor prognostic markers of cerebral abscess

A

Delayed or missed diagnosis
Inappropriate antibiotics
Multiple, deep or multi-loculated abscesses
Ventricular rupture (80-100% mortality)
Fungal, resistant pathogens
Neurological compromise at presentation
Short duration with severe acute meningeal signs
Rapidly progressive neurological Impairment
Immunosuppressed host
Poor localization, especially in the posterior fossa (before CT)