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Meningitis Flashcards

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1
Q

Broad causes of meningitis

A
  • Infection
  • Systemic inflammation (autoimmune)
  • Medications (called “chemical meningitis”, especially NSAIDs, IVIG, and bactrum)
  • Malignancy (leptomeningeal metastasis)
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2
Q

Most infectious meningeal processes predominantly affect the ___, whereas most inflammatory processes predominantly affect the ___

A

Most infectious meningeal processes predominantly affect the leptomeninges (arachnoid and pia), whereas most inflammatory processes predominantly affect the pachymeninges (dura mater)

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3
Q

Carcinomatous meningitis

A

Typically refers to meningitis caused by leptomeningeal metastasis

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4
Q

____ tend to be acute in onset and evolution, whereas ___are more commonly subacute or chronic in onset and evolution

A

Bacterial meningitis and viral meningitis tend to be acute in onset and evolution, whereas fungal meningitis, tuberculous meningitis, inflammatory meningitis, and carcinomatous meningitis are more commonly subacute or chronic in onset and evolution

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5
Q

“Aseptic meningitis”

A

Refers to chemical or viral meningitis

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6
Q

How do bacteria reach the meninges to cause bacterial meningitis?

A
  • Most commonly sinus infections or the inner ear
  • Hematogenously
  • Directly via an opening from trauma
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7
Q

In infants less than 1 month of age, ___ are the most common causes of bacterial meningitis

A

In infants less than 1 month of age, Listeria, E. coli, and Streptococcus agalactiae (group B) are the most common causes of bacterial meningitis.

Mnemonic: LESS; Listeria, E. coli, Streptococci

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8
Q

In children and adults, ___ are the most common causes of bacterial meningitis.

A

In children and adults, Streptococcus pneumoniae and Neisseria meningitidis are the most common causes of bacterial meningitis.

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9
Q

___ should always be considered as an etiology of bacterial meningitis in immunocompromised patients or patients above the age of 50.

A

Listeria should always be considered as an etiology of bacterial meningitis in immunocompromised or elderly patients.

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10
Q

Rhombencephalitis

A

Inflammation of the brainstem, often symptomatic and producing cranial nerve and cerebellar deficits.

Note that Listeria may cause either meningitis or rhomboencephalitis, and represents a common and dangerous cause of rhomboencephalitis.

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11
Q

____ was once a dominant cause of meningitis in children, and should still be considered in children, although this is now rare due to widespread vaccination in childhood.

A

Haemophilus influenzae was once a dominant cause of meningitis in children, and should still be considered in children, although this is now rare due to widespread vaccination in childhood.

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12
Q

In the setting of meningitis associated with head trauma, ___ are worth consideration as possible etiologies.

A

In the setting of meningitis associated with head trauma, Staphylococcus aureus and gram negative bacteria are worth consideration as possible etiologies.

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13
Q

How severe does head trauma need to be to allow bacteria to enter the meninges?

A

Not very severe! There does not even need to be an open wound.

Basilar skull fracture can create a communication between the meninges and the outside world.

A skull defect should be considered as a cause of bacterial meningitis if a patient with prior neurosurgery or head trauma presents with cerebrospinal fluid (CSF) leak (clear fluid from the nose or ears) and/or recurrent meningitis.

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14
Q

A patient presents with recurrent bacterial meningitis and an oozy nose. How do you tell if the oozy nose is leaking CSF, or just wet mucus?

A

CSF can be distinguished from nasal secretions by testing fluid for beta-2-transferrin (present in CSF but not mucus) or for glucose (present in CSF but not mucus, although CSF glucose may be extremely low in bacterial meningitis, limiting utility of this test)

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15
Q

Clinical features of bacterial meningitis

A
  • May be rapidly fatal
  • Classically fever, neck stiffness, headache, and altered mental status
    • However, there is a broad range of presentations, and most patients won’t even have half of these symptoms at initial presentation
  • Photophobia, nausea/vomiting may also be seen
  • Meningitis caused by Neisseria meningitidis is often accompanied by a pruritic rash
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16
Q

Meningitis is always a possibility in patients presenting with headache and fever. But, of course, these symptoms are very nonspecific. In which patients should you have high clinical suspicion for meningitis?

A
  • The elderly, who may have minimal or no fever, and whose neck stiffness may be attributed to osteoarthritis
  • Febrile infants, in whom mental status may be difficult to assess.
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17
Q

Utility of the Kernig and Brudzinski signs

A

Both are highly specific when present, but not very sensitive

Both signs demonstrate meningismus by causing traction on the inflamed meninges

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18
Q

The Kernig sign

A
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19
Q

The Brudzinski sign

A
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20
Q

If bacterial meningitis is being considered as a possibility. . .

A

. . . you should start treatment right away before doing diagnostic procedures. It is a true medical emergency and you do not want to delay antibiotics.

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21
Q

The theoretical concern that antibiotics should be delayed so as not to alter the CSF results is. . .

A

. . . not founded.

Studies have shown that antibiotics do not act quickly enough to reduce the sensitivity and specificity of lumbar puncture tests significantly.

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22
Q

Diagnosing bacterial meningitis

A
  • Lumbar puncture to test CSF
    • Blood counts, antigen tests, chemistry, flow cytometry, gram stain, culture
  • Blood tests (in many patients with meningitis, blood studies are also positive for microbe antigens)
    • Also useful because it can be drawn at the time of empiric antibiotic administration, to save time
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23
Q

Empiric treatment of bacterial meningitis

A
  • Should be started prior to CSF and blood results, and be given in addition to corticosteroids (unless HIV is suspected)
  • Ceftriaxone and vancomycin combination is first-line for community-acquired meningitis to cover N. meningitidis and Streptococcus pneumoniae. Vancomycin covers ceftriaxone-resistant strains of S. pneumo
  • Ampicillin should be added if patient is <1 month old, >50 years old, or immunocompromised to cover Listeria
  • If Hx includes head trauma/neurosurgery or immunocompromise, cefepime or ceftazidime should be used in place of ceftriaxone for wider gram negative coverage including Pseudomonas aeruginosa.
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24
Q

Treating penicillin-allergic patients for empiric bacterial meningitis

A

Regimens may include fluoroquinolones, chloramphenicol, and/or trimethoprim-sulfamethoxazole.

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25
Q

If there is uncertainty in presentation of clinical suspicion of encephalitis in addition to meningitis, ___ should be added to empiric treatment regimens.

A

If there is uncertainty in presentation of clinical suspicion of encephalitis in addition to meningitis, acyclovir should be added to empiric treatment regimens.

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26
Q

When should head CT be considered prior to lumbar puncture?

A

If the diagnosis of meningitis/encephalitis itself is in question or if the patient is felt clinically to be at risk for a mass lesion (abscess) or diffuse cerebral edema that could raise the risk of herniation with LP

Symptoms/signs that suggest this would be: focal deficit, seizure, papilledema, depressed mental status, immunocompromise, known intracranial mass lesion, or age greater than 60

27
Q

Classic findings of bacterial meningitis on lumbar puncture

A
  • Elevated opening pressure
  • Extremely elevated protein
  • Extremely elevated WBC w/ neutrophil predominance
  • Decreased glucose (<40% serum level is threshold, but it is often much lower)
  • CSF gram stain and culture (+ special stainings if necessary, such as India ink for cryptococci)
28
Q

The differential diagnosis for an acute neurologic change in a patient with bacterial meningitis

A
  • Seizures, including nonconvulsive seizures, for which continuous EEG may be necessary to make a diagnosis
  • Acute ischemic stroke due to infectious vasculitis
  • Venous sinus thrombosis
  • Cerebral edema
  • Abscess formation (intracerebral or subdural empyema), which may require surgical drainage
29
Q

Chronic complications in patients with bacterial meningitis

A
  • Hearing loss
  • Epilepsy
  • Cognitive impairment
  • Hydrocephalus
30
Q

Isolation of Patients With Bacterial Meningitis and Prophylaxis of Contacts

A
  • While awaiting microbiologic diagnosis, patients should be placed on droplet precautions (mask and face protection for providers), but only patients with N. meningitidis meningitis require isolation and droplet precautions and prophylaxis of close contacts.
    • If N. meningitidis is found to be the etiology, close contacts should receive a single dose of intramuscular ceftriaxone or 2 days of rifampin.
31
Q

Viruses that may cause viral meningitis

A
  • It is a LONG list, but in short, the most common are:
    • HSV-1 or -2
    • VZV
    • lymphocytic choriomeningitis virus (LCMV)
    • HIV
    • Enteroviruses
    • Arboviruses
32
Q

Presentation of viral meningitis

A
  • Presents similarly to bacterial meningitis with headache, fever, neck stiffness, and photophobia
  • But, typically less severe than bacterial meningitis and does not usually cause alterations in consciousness UNLESS there is associated encephalitis
  • CSF protein and WBC count are generally elevated, but less so than in bacterial meningitis, and with lymphocyte predominance (though neutrophils may be present at early stages)
33
Q

Diagnosis and Treatment of viral meningitis

A
  • Diagnosis made w/ PCR on CSF and sometimes help from IgG/IgM
  • Care is supportive with the exception of HSV and VZV, which are of course treated with IV acyclovir.
34
Q

Aseptic meningitis and HIV

A

Aseptic meningitis may occur at the time of HIV seroconversion, so patients with viral meningitis should be screened for HIV risk factors

35
Q

Mollaret’s meningitis

A

Recurrent viral meningitis, most commonly caused by HSV-2

36
Q

Fungal meningitis

A
  • Most common in immunocompromised
  • More subacute than viral or bacterial forms, emerging over days to weeks
  • Cranial nerve palsies and seizures may also be seen, especially in advanced cryptococcal meningitis
  • Headache is almost always present, but the inflammatory aspects of meningitis such as fever and neck stiffness may be minimal or even absent if the patient is immunocompromised
    • ​Thus, high index of suspicion for potential fungal meningitis must be maintained in patients who develop headaches while on chronic immunosuppressive therapy
37
Q

Immunocompromised patients are ____.

A

Immunocompromised patients are immunocompromised!!!!

So they won’t have fever/inflammation in response to infection, and may lack the classic meningitis signs like stiff neck and fever.

38
Q

Cryptococcal meningitis

A
  • Most common fungal meningitis in immunocompromised patients
  • Due to meningeal inflammation, communicating hydrocephalus can develop, leading to rapid changes in mental status
    • often improves with large-volume LP to relieve intracranial pressure
    • In severe cases, LP may be required daily, and patients may ultimately require ventriculoperitoneal shunting.
  • Mass lesions of cryptococci (cryptococcomas) may occur and appear as T2/FLAIR hyperintense spherical lesions on MRI.
    • Most often in basal ganglia
39
Q

Diagnosing cryptococcal meningitis

A
  • LP shows elevated pressure, increased protein and WBC, decreased glucose
  • Most sensitive tests are CSF cryptococcal antigen and CSF cryptococcal culture
  • Classically, india ink stain on CSF is used to visualize cryptococci, but this is not as sensitive as other tests and has fallen out of favor
40
Q

Treating cryptococcal meningitis

A

Treatment of cryptococcal meningitis begins with amphotericin and flucytosine induction therapy, followed by fluconazole maintenance until the CD4 count is greater than 200 cells/μL for 6 months

41
Q

Atypical causes of fungal meningitis

A
  • Aspergillus (usually only the immunocompromised, while all the below also affect immunocompetent individuals)
  • Coccidioides (endemic to southwestern US, “desert rheumatism”)
  • Histoplasma (endemic to Mississippi and Ohio River regions and Latin America)
  • Blastomyces (endemic to Southeast US)
  • Candida (especially with IV drug use)
  • Treatment of fungal meningitis caused by these pathogens is with amphotericin or azoles.
42
Q

Map of the endemic mycoses within the US

A
43
Q

Tuberculosis meningitis

A
  • Like fungal meningitis, tuberculous meningitis presents more insidiously than viral and bacterial meningitis, typically over weeks.
  • Classic signs of meningitis as well as cranial nerve palsies
  • As in cryptococcal meningitis, hydrocephalus and subcortical infarcts in the basal ganglia may develop
  • Often no Hx of pulmonary TB
44
Q

Diagnosing tuberculosis meningitis

A
  • Neuroimaging may demonstrate hydrocephalus, basal ganglia infarcts, and/or meningeal enhancement
  • Moderate CSF WBC and protein elevation, diminished glucose w/ less extreme lows than bacterial
  • Culture is insensitive and molecular testing is effective, but not widely available in areas of high incidence
    • Therefore, empiric treatment is often initiated in these areas under certain scenarios
45
Q

Indications for empiric TB treatment in areas where molecular testing is unavailable

A
  • patients who fail to improve with treatment of bacterial meningitis
  • HIV-infected patients who have a CD4 count greater than 200 cells/mm3 (making Cryptococcus unlikely)
  • patients who do not respond to treatment for cryptococcal meningitis.
46
Q

Treatment for tuberculous meningitis

A
  • 2 months of a four-drug regimen (including isoniazid, rifampin, and pyrazinamide with ethambutol or a fluoroquinolone as the fourth agent)
    • followed by an additional prolonged course of isoniazid and rifampin
  • Corticosteroids are often added during the initial 2 months
  • In patients with coexisting HIV infection who are not already on antiretroviral therapy, anti-retrovirals may be delayed until after an initial period of treatment of tuberculous meningitis due to the risk of immune reconstitution inflammatory syndrome (IRIS)
47
Q

Complications of tuberculous meningitis

A
  • Focal brain lesions (tuberculomas)
  • Pott’s Disease (spinal tuberculosis)
48
Q

Lyme meningitis

A
  • May be preceded by the target rash typical of the disease, although many patients do not develop a rash, or may not have noticed it
  • Confirmed by detecting CSF Lyme antibody, although this is insensitive
  • Facial nerve palsy or radiculitis may also be present
  • Manifestations of Lyme in other systems may be present (arthritis, carditis)
49
Q

Treatment of Lyme meningitis

A
  • Generally treated with IV ceftriaxone
  • If the only neurologic manifestation of Lyme disease is a seventh nerve palsy (i.e., no meningitis), oral doxycycline is generally used for treatment
50
Q

Syphilitic meningitis

A
  • Usually occurs within the first few years after initial infection with syphilis
  • Meningovascular syphilis can also occur months to years following initial infection, leading to strokes.
  • Late neurologic manifestations of syphilis include tabes dorsalis and dementia
51
Q

Diagnosing syphilitic meningitis

A
  • In patients in whom positive serum treponemal antibody confirms syphilis, syphilitic meningitis is diagnosed by positive CSF VDRL (Venereal Disease Research Laboratory) test.
    • CSF VDRL is highly specific but relatively insensitive
52
Q

Treating syphilitic meningitis

A
  • Treatment is with high-dose IV penicillin G
    • Also true for other neurologic manifestations of syphilis
  • Response to treatment is generally followed with CSF VDRL at 6 month intervals until the CSF normalizes.
53
Q

Encephalitis may be caused by:

A
  • Infection (most often viral)
  • Inflammation:
    • Post-infectious (e.g., acute disseminated encephalomyelitis)
    • Paraneoplastic/antibody mediated (anti-NMDA receptor encephalitis)
    • Hashimoto encephalopathy ( immune-mediated encephalitis associated with anti-thyroid antibodies)
54
Q

Presentation of encephalitis

A
  • Altered mental status and seizures may be present early in the course of the illness in addition to headache and fever
  • Meningeal signs are generally absent
55
Q

Viruses that may cause viral encephalitis

A
  • HSV
  • VZV
  • CMV
  • EBV
  • HHV-6
  • Enteroviruses
  • Arboviruses (mosquito-borne)
    • Includes EEE, West Nile Virus, St. Lous Encephalitis Virus, and Dengue Virus
56
Q

Targeted antiviral therapies for viral encephalitis

A

Only exist for certain Herpesviruses:

HSV and VZV are susceptible to acyclovir

CMV is susceptible to ganciclovir and foscarnet

57
Q

Identifying cause of suspected viral encephalitis

A
  • HSV, CMV, HHV-6 and enteroviruses are diagnosed by CSF PCR
  • VZV is diagnosed most sensitively by CSF IgG
  • The arboviruses are most sensitively diagnosed by CSF IgM.
58
Q

HSV encephalitis

A
  • Most common viral encephalitis
  • May be rapidly fatal
  • Usually caused by HSV-1 in adults and HSV-2 in infants
    • Though this is not steadfast
  • MRI demonstrates unilateral or bilateral T2/FLAIR hyperintensities limited to limbic regions (medial/inferior temporal lobe, insula, inferior frontal lobes)
  • CSF shows a viral pattern
  • CSF red blood cell (RBC) count may be increased due to the hemorrhagic nature of the infection
  • Temporal lobe periodic lateralized epileptiform discharges (PLEDs) may be present on EEG
59
Q

Diagnosing HSV encephalitis

A

Definitive diagnosis is made by CSF HSV PCR.

CSF HSV PCR may be negative early in the course of the illness, so a negative test does not exclude the diagnosis, and the test should be repeated if clinical suspicion is high

60
Q

Lumbar puncture findings in different types of meningitis (summary)

A
61
Q

You suspect an adult, non-immunocompromised patient may have bacterial meningitis. What drugs do you use?

A

Ceftriaxone and vancomycin for Abx

Corticosteroids

62
Q

You suspect a <1 month old infant may have meningitis. What antibiotics do you use?

A

Ceftriaxone, vancomycin, ampicillin for Abx

Corticosteroids

63
Q

Steroids specifically help patients with bacterial meningitis caused by ____.

A

Steroids specifically help patients with bacterial meningitis caused by S. pneumoniae

64
Q

You suspect a patient may have herpes simplex encephalitis. You order an MRI. What are you looking for on MRI?

A

T2 hyperintense lesions in the anterior temporal lobes and limbic structures

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