3 CNS Infections Flashcards
(131 cards)
1
Q
Meningitis is an inflammatory disease of the ________.
A
Leptomeninges
Neurological emergency!
2
Q
Bacterial meningitis is the _____ most common infectious cause of death
A
10th
3
Q
_______ is common among survivors of bacterial meningitis
A
Neurologic sequela
4
Q
What is the most important thing about bacterial meningitis?
A
Early recognition and initiation of empiric therapy as soon as possible
5
Q
DDx for bacterial meningitis
A
Encephalitis
Brain abscess
Subarachnoid hemorrhage
Brain tumor
6
Q
What are the two ways bacteria can enter the CNS?
A
Through the blood stream
By contiguous spread (ie - from sinus infection)
7
Q
In meningitis, inflammatory damages to the blood-brain barrier cause ___________.
A
Increased permeability —> alterations in protein and glucose transport
8
Q
What causes the neurologic damage in meningitis?
A
Progressive cerebral edema with increased intracranial pressure and decreased cerebral perfusion
9
Q
Most likely etiology for bacterial meningitis:
Neonates up to 4 weeks
A
E. coli or GROUP B STREP***
From exposure during delivery (typically in moms not screened, or w/ no prenatal care)
10
Q
Most likely etiology for bacterial meningitis:
Colonization from the nasopharynx (Sinusitis, otitis media, mastoiditis)
A
STREP PNEUMO
11
Q
Most likely etiology for bacterial meningitis:
Crowded conditions (ie military, colleges)
A
Neisseria meningitides
12
Q
Most likely etiology for bacterial meningitis:
Head trauma
A
Staph spp (anytime there’s a break in the skin, think staph)
13
Q
Most likely etiology for bacterial meningitis:
Post-neurosurgical procedures
A
Staph spp, gram (-)
14
Q
70% of all bacterial meningitis is caused by
A
N. meningitides (MENINGOCOCCAL)
S. pneumoniae (PNEUMOCOCCAL)
15
Q
Bacterial meningitis due to L. monocytogenes is more common in…
A
Elderly adults and neonates (b/c immunity is low)
Risk factors = defects in cell mediated immunity, malignancy, pregnancy, chronic glucocorticoids, alcoholism
16
Q
Bacterial meningitis due to coag (-) staph is typically due to…
A
Foreign bodies - ie from surgery, ventricular drains
17
Q
Bacterial meningitis from S. aureus is more common in patients with history of…
A
Endocarditis, surgery, foreign body, ventricular drains, ulcers
18
Q
Bacterial meningitis from gram negative bacilli is more common in …
A
Elderly and neonates
Risk factors = neurosurgery w/ or w/o drains
19
Q
Bacterial meningitis from H. influenzae is more common in…
A
Unvaccinated children/adults
Risk factors = diminished humoral immunity
20
Q
Bacterial meningitis may present _________ or ________
A
PROGRESSIVELY - over a couple of days or following febrile illness
or
ACUTELY - with SSx of sepsis (rapid progressive of symptoms over several hours - assoc with cerebral edema)
21
Q
Clinical manifestations of bacterial meningitis
A
HA (severe and generalized) Photophobia N/V/Anorexia Focal neurologic deficits (weakness, cranial nerve palsies) Seizures Altered mental status Nuchal rigidity PAPILLEDEMA**** associated with inc ICP PETECHIAL RASH**** and palpable purpura (N. meningitides)
22
Q
Classic triad of Sx for bacterial meningitis
A
Fever (95%)
Nuchal Rigidity (88%)
Altered Mental Status (78%)
23
Q
These two specialized exams only have 5% sensitivity for bacterial meningitis but we still need to know them 🙄
A
Kernig’s Sign - inability or reluctance to allow full extension of knee when hip is flexed at 90˚
Brudzinski’s Sign - spontaneous flexion of hips during attempted passive flexion of neck
24
Q
This test is a much more sensitive test for bacterial meningitis
A
Jolt Accentuation Test
Patient rotates his or her head horizontally at a frequency of two times per second - a positive test is the exacerbation of an existing HA
25
What diagnostic tests do you need to order for suspected bacterial meningitis?
Blood cultures x2 (BEFORE abx)***
+/- CT (there are specific criteria)
LP for CSF analysis
CBC w/ diff, CMP, ESR, CRP
SERUM GLUCOSE to compare with CSF GLUCOSE***
+/- coag studies (esp if petechial rash)***
26
______ is the gold standard for diagnosing bacterial meningitis
CSF culture (LP)
27
CSF findings in bacterial meningitis
Increased WBC (>1,000 with neutrophil**** predominance)
Decreased glucose (<40mg/dL, <40% of blood glucose)
Increased protein (100-500)
(+) gram stain and culture****
Increased opening pressure
28
To CT or Not to CT for bacterial meningitis?
```
CT before LP in patients with ≥1 of the following RFs:
• Immunocompromised state
• Hx of CNS disease
• New onset seizure
• Papilledema
• Abnormal level of consciousness
• Focal neuro deficit
```
If increased ICP, mass lesion present can result in cerebral herniation during LP
29
Gram (+) diplococci suggests _________ infection
Pneumococcal
30
Gram (-) diplococci suggests ________ infection
Meningococcal
31
Gram (-) coccobacilli suggests _________ infection
H. influenzae
32
Gram (+) rods and coccobacilli suggests _______ infection
L. monocytogenes
33
Predictors of adverse outcomes in bacterial meningitis
Presence of altered mental status, seizures, and/or hypotension
DO NOT DELAY TREATMENT
34
What is the best way to prevent long term neuro sequela with bacterial meningitis?
Initiate dexamethasone + empiric IV abx immediately after blood cultures and LP, based on the patient’s age and most likely organisms
If LP is delayed while obtaining CT, begin empiric abx after blood cultures obtained
35
Empiric abx treatment for bacterial meningitis:
Newborns
(Suspected organisms: Group B strep, E. coli, L. monocytogenes)
Ampicillin + Cefotaxime OR gentamycin
**The only group that doesn’t get dexa**
36
Empiric abx treatment for bacterial meningitis:
1-23 month olds
(Suspected organisms: S. pneumo, H. flu, E. coli, N. meningitides)
Vancomycin + ceftriaxone OR cefotaxime + Dexamethasone
37
Empiric abx treatment for bacterial meningitis:
2-20 year olds (“the herd”)
Suspected organisms: S. pneumo, N. meningitides
Vancomycin + ceftriaxone OR cefotaxime + Dexamethasone
38
Empiric abx treatment for bacterial meningitis:
>50 years
Suspected organisms: S. pneumo, L. monocytogenes, gram (-) bacilli, N. meningitides
Ampicillin + Vancomycin + ceftriaxone OR cefotaxime + Dexamethasone
39
Empiric abx treatment for bacterial meningitis:
Immunocompromised
Suspected organisms: S. pneumo, L. monocytogenes, gram (-) bacilli, N. meningitides
Ampicillin + Vancomycin + cefepime OR meropenem + Dexamethasone
40
Empiric abx treatment for bacterial meningitis:
Penicillin allergy
Vancomycin + moxifloxacin + bactrim
41
Empiric abx treatment for bacterial meningitis:
Basilar skull fracture
Suspected organisms: Group A beta hemolytic strep, S. pneumo, H. flu
Ampicillin + cefotaxime OR gentamycin
42
Empiric abx treatment for bacterial meningitis:
Penetrating trauma/post-neuro surgery
Suspected organisms: S. aureus, pseudomonas, coag neg staph
Vancomycin + ceftazidime OR cefepime OR meropenem
43
Why do we use dexamethasone in conjunction with abx in empiric treatment of bacterial meningitis?
Used to reduce rate of hearing loss and neuro sequela and decrease morbidity/mortality
Significant benefit only in PNEUMOCOCCAL meningitis
Steroids should be initiated shortly before or at the same time that abx therapy is initiated or it does not improve outcome
44
You should only continue the dexamethasone if...
Gram stain or blood cultures are (+) for S. pneumoniae
Why? Risk of low vanco penetration if dexa is continued unnecessarily
Dose: 0.15mg/kg q6h x 4d
45
What should you add to your empiric therapy if (+) S. pneumo?
Rifampin
B/c you’ll be continuing with the dexamethasone, so you need something that can penetrate the BBB as well (the dexa will prevent vanco from penetrating)
46
Management of bacterial meningitis if patient meets ≥1 of IDSA criteria for CT before LP...
Blood cultures STAT
Dexamethasone + empiric abx
CT of head
If contraindications for LP, continue empiric abx and dexa
If no contraindications, perform LP
CSF sent for gram stain, cultures, cell count, glucose, and protein
47
Management of bacterial meningitis if patient does not meet any of IDSA criteria for CT before LP...
Blood cultures
LP
Empiric abx + dexamethasone
CSF sent for gram stain, cultures, cell count, protein, glucose
Tailor tx dependent on gram stain/culture results
48
If CSF gram stain shows gram positive diplococci...
Targeted abx therapy to S. pneumoniae
Continue dexamethasone and ADD RIFAMPIN
49
If CSF gram stain shows other gram positive bacteria...
Adjust targeted abx therapy and d/c dexamethasone
50
If CSF gram stain is negative (no bacteria seen) but other CSF findings consistent with bacterial meningitis ...
Continue empiric abx therapy and dexamethasone
51
Complications of bacterial meningitis
Septic shock
DIC
Acute respiratory distress syndrome
Possible neurologic long term complications:
• Impaired mental status or cognition
• Sensorineural hearing loss
52
Vaccinations are available to prevent meningitis due to ...
S. pneumoniae
N. meningitides
H. influenza
53
Post-exposure prophylaxis for bacterial meningitis
Cipro
Rifampin
Ceftriaxone (for pregnant patients)***
54
Clinical evidence of meningeal inflammation but negative bacterial cultures suggest...
Aseptic meningitis
Also referred to as viral meningitis (though not always viral)
55
What is the diagnostic approach to aseptic meningitis?
Similar presentation to bacterial meningitis so follow same diagnostic approach
56
Symptoms typically less severe than bacterial meningitis, supportive care is only requirement in most cases
Aseptic meningitis
Typical patient has complete recovery with no sequela
57
Most common cause of aseptic meningitis
Enterovirus - coxsackie or echovirus
Prevalent during summer and autumn
58
Viral causes of aseptic meningitis
```
Enterovirus (most common)
Herpes simplex virus (usually HSV-2)
Varicella zoster virus
Mumps
HIV
West Nile virus
EBV
CMV
```
59
Other non-viral infectious causes of aseptic meningitis
(If you see these think immunocompromise)
Mycobacteria
Fungi (Cryptococcus, coccidiomycosis)
Spirochete (Treponema pallidum, Borrelia burgdorferi)
60
Non-infectious causes of aseptic meningitis
Malignancy - uncommon but may see due to DIRECT INVASION OF THE MENINGES
Drug induced - diagnosis of excusion (very uncommon)
• Can be either delayed hypersensitivity reaction vs. direct meningeal irritation
61
Most common malignancies that can cause aseptic meningitis
```
Leukemia
Lymphoma
Melanoma
Breast cancer
Lung cancer
GI cancer
```
62
Drugs that have the ability to cause aseptic meningitis
NSAIDs****
Abx (esp bactrim)
Chemotherapy
Phenazopyridine
Stop offending med and they magically get better
63
Clinical manifestations of aseptic meningitis
```
Generally non-specific:
• HA
• Fever
• N/V
• +/- photophobia
• +/- nuchal rigidity
```
Diverse range of etiologic agents so need to look for historical and physical clues
64
Historical clues for aseptic meningitis
Travel and exposure history (ticks, TB)
Sexual activity (HSV-2, syphilis, HIV)
• Up to 36% of patients with genital lesions due to HSV-2 have findings of meningeal involvement
• 85% of patients with HSV-2 meningitis have genital lesions up to 7 days prior to onset of Sx
Get a thorough med history including OTC drugs
65
What type of aseptic meningitis?
Parotitis in an unvaccinated patient
Mumps
66
What type of aseptic meningitis?
Severe vesicular genital lesions
Primary HSV-2 infection
67
What type of aseptic meningitis?
Diffuse, maculopapular exanthema in mildly ill patient
Enteroviral infection
Primary HIV
Syphilis
68
What type of aseptic meningitis?
Oropharyngeal thrush and cervical LAD
Primary HIV
69
What type of aseptic meningitis?
Asymmetric flaccid paralysis
West Nile Virus
70
What diagnostics do you want to order for suspected aseptic meningitis?
(Want to r/o bacterial cause so same diagnostic series)
Blood cultures x2 before abx
CT (same criteria as bacterial meningitis)
LP for CSF analysis (gram stain, culture, glucose, protein, cell count)
CBC w/ diff, CMP, ESR, CRP
Other lab tests depend on clinical suspicion
71
CSF findings in aseptic meningitis
WBC <500 and >50% lymphocytes (if viral)
Normal glucose (40-80)
Normal or mildly elevated protein (15-45 or 80-100)
(-) gram stain and culture
***Order PCR***
Cultures may take 3-7 days so treat for bacterial until definitive r/o
72
Management of aseptic meningitis
Empiric abx started at presentation, may be d/c once bacterial meningitis r/o
Viral:
Self-limiting, so supportive therapy (analgesics/antipyretic)
Anti-viral only in severe cases or immunocompromised (acyclovir)
Malignancy:
If malignant cells in CSF, involve oncology
Drug-induced:
D/C offending meds and sx typically resolve within days
Other causes:
Treat accordingly, consult ID and Neurology
73
What distinguishes meningitis from encephalitis?
Presence or absence of normal brain function
74
Meningitis or Encephalitis:
Preservation of cerebral function but more commonly have fever, H/A, and meningismus
Meningitis
75
Meningitis or Encephalitis:
Abnormalities in brain function are more common - AMS, seizures, motor or sensory deficits, personality changes, speech or movement disorders
Encephalitis
76
When the line between meningitis and encephalitis gets blurred...
Meningoencephalitis!
77
DDx for encephalitis
```
Primary intracranial/metastatic tumors
Adverse effects of meds
Vasculitis (esp if hx of rheum disease)
Brain abscess
TB meningitis and fungal meningitis
```
78
What is the pathogenesis of encephalitis?
Viral infection of the CNS results in acute inflammation of the brain secondary to either primary infection or post-infection acute disseminated encephalomyelitis (ADEM)
79
Encephalitis is typically due to a primary viral infection if...
Due to direct viral invasion of CNS
Can be cultured from brain tissue
(+) neuronal involvement
80
How is post-infectious encephalitis distinguished from primary infection?
Acute disseminated encephalomyelitis (ADEM)
No virus detected
Neurons are spared
Perivascular inflammation/demyelination
Typically occurs as initial infection is resolving
81
Most common overall cause of encephalitis in the US
West Nile Virus
82
What are the different causes of encephalitis
Arboviruses:
• WNV
• St. Louis encephalitis
Influenza
Lyme disease, Rocky Mountain spotted fever, syphilis
```
Uncommon causes:
• VZV
• EBV
• HIV
• Measles, Mumps, Rubella
• Rabies
```
83
Most common cause of FATAL encephalitis?
Herpes Simplex Virus (HSV-1 usually)
Patients RAPIDLY deteriorate
84
Do this virus more frequently cause meningitis or encephalitis?
Coxsackie
Meningitis
85
Do this virus more frequently cause meningitis or encephalitis?
West Nile Virus
Encephalitis
86
Do this virus more frequently cause meningitis or encephalitis?
HSV-1
Encephalitis
87
Do this virus more frequently cause meningitis or encephalitis?
HSV-2
Meningitis
88
Do this virus more frequently cause meningitis or encephalitis?
Varicella
Both are very infrequent
89
Do this virus more frequently cause meningitis or encephalitis?
CMV
Encephalitis
90
Do this virus more frequently cause meningitis or encephalitis?
EBV
Both are infrequent
91
Do this virus more frequently cause meningitis or encephalitis?
HIV
Meningitis
92
Do this virus more frequently cause meningitis or encephalitis?
Influenza
Encephalitis
93
Do this virus more frequently cause meningitis or encephalitis?
Meningitis
Meningitis (encephalitis infrequently but not rarely)
94
Do this virus more frequently cause meningitis or encephalitis?
Measles
Meningitis
95
Clinical manifestations of encephalitis
H/A
Fever
Altered mental status (subtle to unresponsive)
Patient can be confused, agitated, obtunded
Seizures (common)
Focal neuro deficits (hemiparesis, CN palsies, inc DTRs)
Photophobia and nuchal rigidity rare with encephalitis alone but may be seen with meningoencephalitis
96
Encephalitis physical exam clues:
Ulcers or vesicles
HSV-1
97
Encephalitis physical exam clues:
Parotitis
Mumps
98
Encephalitis physical exam clues:
Flaccid paralysis and rash
West Nile Virus
99
Encephalitis physical exam clues:
Hydrophobia, hyperactivity, pharyngeal spasms
Rabies
100
Encephalitis physical exam clues:
Tremors of tongue, lips, eyelids
St. Louis virus
101
Diagnosing encephalitis
Blood cultures x2
CBC w diff, CMP
CSF PCR for HSV, enteroviruses, EBV
CSF: cell count, glucose, protein, gram stain, and culture
(RBC in CSF can be indicative of HSV-1 infection)
CSF cultures
102
Typical CSF findings in viral encephalitis
```
WBC <250
Glucose normal (40-80) UNLESS HSV (decreased)
Protein elevated (<150)
Gram stain negative
Increased lymphocytes
```
103
What diagnostic studies should you order if suspecting encephalitis?
MRI with contrast**** (study of choice)
CT with contrast if MRI unavailable
CT/MRI may or may not be abnormal acutely
Can take 3-4 days for radiologic changes to become evident
EEG (ordered by neuro) will be abnormal
104
Temporal lobe changes on MRI are suggestive of....
HSV encephalitis
105
Hydrocephalus on MRI my suggest what sort of encephalitis
Bacterial
Fungal
Parasitic
106
When would you obtain serology on a suspected encephalitis patient?
If patient is not improving or no diagnosis based on CSF, culture, PCR
IgM antibody testing is available for WNV, Mumps, EBV
107
When would you do a brain biopsy for encephalitis?
Only if etiology is unknown, and only as a last resort
108
How do you manage encephalitis?
Acyclovir 10 mg/kg IV q8h**** (Know dose) - all patients with encephalitis
• Start empiric therapy as soon as possible
• HSV is the most important to ID and treat
Seizure prophylaxis/control
Diuretics if increased ICP
• Mannitol
• Furosemide
109
What is the prognosis for encephalitis?
Poor neuro recovery and increased mortality associated with initial diffuse cerebral edema or intractable seizures
Elevated initial ICP measurement prognostic for negative outcome
Serial ICP should be documented for improvement (neuro consult)
For HSV encephalitis - 14% mortality at one year, fatal if untreated, 24% will end up with epilepsy
110
Focal area of infection with a collection of pus, resulting from infection, trauma, or surgery
Cerebral abscess
111
Examples of cerebral abscess sources from direct spread
```
(Typically single abscess)
Otitis media, mastoiditis
Meningitis
Head/facial trauma
Sinusitis
Dental infection
S/P neurosurgical or spinal procedure
```
112
Inferior lobe and cerebellar abscesses are more likely to be direct spread from...
Subacute or chronic otitis media
| Mastoiditis
113
Frontal lobes cerebral abscesses are more likely to be direct spread from...
Frontal or ethmoid sinusitis
| Dental infection
114
Examples of cerebral abscess sources from hematogenous spread
```
(Usually multiple abscesses)
Associated with bacteremia
Chronic pulmonary infection
Skin infection
Pelvic infection
Intraabdominal infection
Bacterial endocarditis
Following esophageal dilation
```
No site/underlying condition identified in 20-40%
115
Cerebral abscesses from direct spread usually result in ________ while hematogenous spread usually results in _________.
Single abscess
Multiple abscesses
116
90% of cerebral abscesses are ________
Bacterial - related to where it originated
Paranasal: Strep, Haemophilus
Odontogenic: Strep, bacteroides
Otogenic: Strep, enterobacter, pseudomonas
Penetrating head trauma: Staph aureus, enterobacter
Neurosurgery: Strep, Staph, Pseudomonas
117
In immigrants from Mexico, the most common etiology for a cerebral abscess is....
Parasites
Cysticercosis, due to Taenia sodium infection (larval stage of pork tapeworm)
Cause of 85% of brain infections in Mexico City
118
Cerebral abscesses in Immunocompromised/HIV/AIDS patients, include these in your DDx
Toxoplasma gondii
Listeria monocytogenes
Nocardia asteroides
119
Cerebral abscesses from fungal pathogens
Multiple abscesses, poor outcomes
Cryptococcus
Coccidioides
Aspergillosis
Candida spp
120
Clinical manifestations of cerebral abscesses
Usually nonspecific, resulting in diagnostic delay
UNILATERAL HEADACHE*** (69%) unless multiple abscesses
Sudden or gradual onset
Pain tends to be severe, not relieved by OTC pain meds
Fever (45-50%)***
Nuchal rigidity (15%) - more common in occipital lobe abscesses
121
Why is pain from a cerebral abscess not relieved by OTC pain meds?
B/c it’s not an inflammatory process but a space-occupying lesion
122
More serious clinical manifestations of cerebral abscess
Altered mental status*** - indicates severe edema, poor prognosis
Vomiting (if increased ICP)
Focal neuro deficits (50%)
Seizures (25%)
Papilledema (25%) - late finding
123
Diagnosing cerebral abscesses
Blood cultures x2 (before any antibiotics)
CBC w diff, CMP
MRI is imaging study of choice******
CT-guided aspiration or surgical excision for cultures
If CT is done, MUST be with contrast
124
MRI findings for Cerebral Abscess
WILL show a ring-enhancing lesion
Early (1-2 weeks) —> lesion poorly demarcated, localized edema, acute inflammation, no tissue necrosis
Late (>2 weeks) —> necrosis and liquefaction, lesion surrounded by fibrotic capsule
125
Cerebral abscess management
CT-guided aspiration or surgical excision (neurosurgery)
Abx empirically depending on suspected origin - limited penetration with oral, must be IV
Once pathogen established via culture, continue on abx for 4-8 weeks
Track regression/progression on MRI
126
What empiric antibiotics should you choose if you suspect this is the source for your patient’s cerebral abscess:
Oral
Metronidazole + pen G
127
What empiric antibiotics should you choose if you suspect this is the source for your patient’s cerebral abscess:
Otogenic or sinus source
Metronidazole + ceftriaxone OR cefotaxime
128
What empiric antibiotics should you choose if you suspect this is the source for your patient’s cerebral abscess:
Hematogenous spread
Vancomycin + Metronidazole
129
What empiric antibiotics should you choose if you suspect this is the source for your patient’s cerebral abscess:
Post-op neurosurgical patients
Vancomycin + ( ceftazidime OR cefepime OR meropenem)
130
What empiric antibiotics should you choose if you suspect this is the source for your patient’s cerebral abscess:
Penetrating trauma
Vancomycin + ceftriaxone OR cefotaxime
131
What empiric antibiotics should you choose if you suspect this is the source for your patient’s cerebral abscess:
Unknown source
Vancomycin + (ceftriaxone OR cefotaxime OR metronidazole)
