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
What are some investigations to make with a patient suspected of meningitis
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
26
What is the main investigation for meningitis
Lumbar puncture
27
Where is the lumbar puncture done
The space between L3 and L4
28
What are some contraindications of lumbar puncture
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
What are some management approaches to patients with bacterial meningitis
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
If you’re treating a bacterial meningitis what drug should you start with before antibiotics
Dexamethasone
31
What antiviral drug do you give for a patient with viral meningitis
Acyclovir
32
What antibiotic drug do you give for a patient with a bacterial meningitis
3rd generation cephalosporins like ceftriazone
33
What is the first and second line preventative antibiotic for meningococcal meningitis
Ciprofloxaxin 500mg stat Rifampicin 600mg bd x2
34
What is encephalitis
Inflammation of the brain parenchyma often due to infections viral or bacterial (mostly viral) or from an immune system disorder
35
What are some viruses which cause encephalitis
Herpes Enteric Paramyxo Arbo Influenza viruses, adenovirus, parvovirus, rubella virus, rabies (rare)
36
What is the most common cause of viral encephalitis in industrialized nations
HSV encephalitis
37
HSV-1 and HSV-2 Which causes about 90% cases of encephalitis
HSV-1 *HSV-2 is more common in immuno-compromised patients and neonates*
38
HSV-2 viral encephalitis is transmitted via
Genital mucosa
39
HSV-1 infects the human with encephalitis via
Oral mucosa Virus then travels along the trigeminal nerve to ganglion
40
What is the typical clinical presentation of viral encephalitis
Acute flu-like prodrome High fever Severe headache Altered consciousness (lethargy, drowsiness, confusion, coma) Seizures Focal neurological signs
41
What are some subtle presentations of viral encephalitis
Low grade fever Speech disturbances (dysphagia, aphasia) Behavioral change
42
Subacute and chronic presentations of viral encephalitis can be caused by which viruses
CMV VZV HSV
43
What are some investigations for viral encephalitis
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
What is the viral treatment for encephalitis
Acyclovir for 14-21 days
45
What is the bacterial treatment for encephalitis
Ceftriazone Metronidazone
46
What are some poor prognostic factors of encephalitis
GCS < 7 Delay in starting acyclovir (especially > 2 days)
47
What is a cerebral abscess
It is a focal pyogenic infection of the brain
48
What are some effects of cerebral abscess
Direct involvement and destruction of the brain Compression of the parenchyma Elevation of intracranial pressure (interfering with blood and/or CSF flow)
49
What is the pathophysiology of an abscess
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
List the pathogenesis of cerebral abscess
Direct spread from contiguous foci Hematogenous spread from remote foci Penetrating trauma/surgery Cryptogenic
51
Some contiguous foci include
Otitis media/mastoiditis Sinusitis Dental infection, typically molar infections Meningitis rarely complicated by brain abscess
52
How does direct spread of encephalitis spread
Direct extension through infected bones and spread through emissary veins, diploic veins and local lymphatics
53
In which artery do brain abscesses spread (hematogenous spread)
Middle cerebral artery distribution
54
List some conditions which serve as middlemen for hematogenous spread of brain abscesses
Emphysema Lung abscesses Bronchiectasis Endocarditis Wound infections Pelvic infections Infra-abdominal source
55
Which bacteria normally causes brain abscesses
Streptococci and anaerobes Staphylococcus aureus, anaerobic GNR common after trauma or surgery
56
Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the parietal lobe
Headache Visual field defects Endocrine disturbances
57
Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the cerebellum
Nystagmus Ataxia Vomiting Dysmetria
58
Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the temporal lobe
Ipsilateral headache Aphasia Visual field defect
59
Clinical manifestations of cerebral abscesses depends on the location of the lesion. What are the clinical features for lesions in the frontal lobe
Headache Drowsiness Inattention hemiparesis Motor speech disorder
60
Differential diagnosis for cerebral abscess
CVA Hemorrhage Aneurysm Subdural emphysema/Epidural abscess
61
What is the difference in an MRI between an abscess and a tumor
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
Not so a sensitive test but if air seen, consider possibility of brain abscess. What investigation test for cerebral abscess is this
Skull x-ray
63
What are imaging study investigations for cerebral abscess
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
What are some specific investigation tests for encephalitis
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
Why is lumbar picture contraindicated in patients with known or suspected brain abscesses
There is risk of herniation
66
When do you subject a cerebral abscess patient to medical treatment only
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
What are some poor prognostic markers of cerebral abscess
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)