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Flashcards in CNS Infections Deck (51):

Acute Bacterial Meningitis - Delayed Treatment

-Meningococcal meningitis: kill in 6-12 hrs, patient may deteriorate in ER while undergoing diagnostic testing
-treat empirically & as soon as you suspect diagnosis


Acute Bacterial Meningitis - Pathogenesis

-blood born (bacteremia, sepsis)
-nearby infection (sinusitis, ear infection)
-CSF communication with outside (cranial trauma, neurosurgical procedure, myelomeningocele, spinal dermal sinus)


Acute Bacterial Meningitis - Pathophysiology

-bacterial surface (capsule, pili) penetrate endothelial cells & cross BBB
-meningeal inflammation
-brain ischemia, infarction, & edema
-raised intracranial pressure
-brain herniation
-cardiovascular collapse


Exudative (Pus) Meningitis

-it's not the pathogen that causes the CNS damage
-meningeal inflammation is responsible
-abx - lyse bacteria - wall fragments - cytokines interleukins, & inflammatory cascade - vasculitis & thrombophiebitis

-Dexamethasone inhibits inflammatory cascade & reduces CNS damage


Causes of Meningitis: Community Acquired

-streptococcus pneumoniae (pneumococcus)
-neisseria meningitidis (meningococcus)


Causes of Meningitis: Neonates

-Group B Strep
-E. coli


Causes of Meningitis: Immune Suppressed, Pregnancy, Elderly

-Listeria monocytogenes


Causes of Meningitis: Trauma, post-neurosurgical

-Straphylococcus aures
-Gram neg (E. coli)


Meningococcal Meningitis

-colonizes nasopharynx in 5% "normal" pop.
-spread by respiratory droplets, close contact
-epidemics in military, boarding schools, (3 ft rule)
-Fluminant course: shock, Waterhouse-Friderichsen syndrome - hemorrhagic necrotic adrenals


Pneumococcal Meningitis

-chronic otitis
-sinusitis, mastoiditis
-CSF leaks (head trauma)
-Pneumococcal pneumonia
-Sickle cell disease


Listeria Meningitis

-up to 10% of all meningitis
-older patients above 50
-immune-suppressed: autoimmune, organ transplant, pregnant women, neonates & elderly
-Chronic illness: renal failure, liver disease
-Unpasteurized diary
-Meat counters, hot dogs


Clinical Presentation of Bacterial Meningitis in Infants?

-high pitched cry
-bulging fontanel


Clinical Presentation of Bacterial Meningitis in Older Kids, Adults?

-URI prodrome, sore throat
-stiff neck
-lethargy & confusion
-cranial neuropathy
-seizures, coma


Physical Exam for Bacterial Meningitis?

-VItal Signs: high fever, shock (low BP, high pulse)
-Skin: petechiae, purpura, dermal sinus
-Cranial: trauma, CSF leak, otitis, sinusitis, mastoiditis, ventricular shunt
-Neck: stiff, Kerning's & Brudzinski signs

-ausculate for pneumonia, endocarditis
-urinary tract infection



-neck stiffness, rigid & hard to move
-Kerning's sign: + if knee can't be fully extended when patient lies supine with hip flexed at 90 deg.
-Brudzinski sign: + when passive neck flexion causes reflex flexing of both legs & thighs


Aseptic Meningitis

-Drug induced: Ibuprofen/NSAIDS, sulfa-containing abx (bactrim), isoniazid, immune modulation (OKT3, IVIG, Cyclocsporine)
-Craniopharyngioma (leakage of contents)
-Lead poisoning
-Parameningeal inflammation
-Viral encephalitis
-Fulminant TB or fungal meningitis
-Lyme disease, neurosyphilis, Rocky Mountain Spotted Fever


Labs for Bacterial Meningitis

-CBC & Diff.
-Electrolytes (Syndrome of Inappropriate Antidiuretic Hormone or SIADH, metabolic acidosis)
-Cultures: nasal nares, throat, sputum, skin lesions, urine, blood, CSF
-Gram stain of blood
-Blood bacterial PCR
-Much higher in bacterial meningitis than viral
Serum Procalcitonin (>2 ng/mL)
C-reactive protein (>40 mg/L)
-Cranial CT
-Lumbar Puncture


Lumbar Puncture Tests

-opening pressure, CBC/differential, Glucose, Protein, Latex agglutination, Gram Stain, Cultures for bacteria, TB, fungi & viruses, cryptococcal antigen, VDRL (veneral disease research lab), Special (PCR, IgM, IgG)


CSF Abnormalities

Purulent Bacterial: inc. WBC, neutrophils, 0-25 glucose, inc. protein

Non-purulent Bacterial: lymphs, 25-50 glucose, inc. protein


Treatment for Bacterial Meningitis

-don't wait for diagnostic studies
-Steroids 1st: dexamethasone 10mg within 15 min of abx) and next 4 days (every 6 hrs), suppresses cytokines & inflammatory cascade induced by lysed cell components (IL-1, TNF)
-ABX: empirical: Vancomycin, 3rd or 4th gen cephalosporin or meropenem, Ampicillin (Listeria), Acyclovir (Herpes virus), Doxycycline (tics)
-Gram stain directed


Treat Bacterial meningitis

-fluids, electrolytes
-ventriculostomy for high intracrainal pressure & coma
-prophylaxis for close contacts (rifampin)


Subacute Bacterial Endocarditis

-veggies, infection on heart valves, usually with gram + cocci, widespread septic embolism
-splinter hemorrhage
-Presentation: fever, delirium to coma. Possible meningeal signs, septic emboli to brain causes:
1. stroke
2. cerebritis to abscess (single/multiple)
3. Mycotic aneurysm

-streptococcus viridans 50%


Septic Emboli Cause:

1. Splinter Hemorrhages
2. Osler's Nodes
3. Janeway Lesions
4. Roth's spots (retinal hemorrhage with central clearing)


How to treat Subacute Bacterial Endocarditis

-heart failure occurs, valve replacement may be necessary
-large cerebral abscesses must be drained


Clinical Diagnosis of Cerebral Abscess

1. Headache (worse lying down, present upon awakening) "tumor headache"
2. Papilledema & transient visual obscurations
3. Seizures
4. Focal neurological deficits
5. Contract CT or MRI: ring enhancing mass with surrounding edema
6. Risk factors: pulmonary AV shunt (hereditary hemorrhagic telangiectasia), sinusitis, sepsis


Spinal Epidural Abscess: Clinical Diagnosis

1. Severe back pain, worse lying down, point tenderness
2. Fever & Malaise
3. Bowel & bladder dysfunction (incontinence or constipation) & male impotence
4. Paraparesis or quadriparesis depending on level
5. Sensory Level (absent pin prick sensation below level of involvement)
6. High sed rate
7. Elevated WBC with left shift
8. Spinal MRI or CT myelogram
9. Blood cultures


Spinal Epidural Abscess: Risk Factors

-staphylococcus is most common pathogen
1. Skin infection (IV drugs) - staphylococcus
2. Trauma (surgery) - staphylococcus
3. Osteomyelitis - staphyloccus
4. GU instrumentation - Gram - (elderly)
5. Sepsis
6. Often accompanied by local discitis & osteomyelitis


Spinal Epidural Abscess: Treatment

1. High dose steroids
2. Abx to cover staph, strep, & anaerobes
3. Surgical drainage


Rocky Mountain Spotted Fever

-gram - obligate intracellular coccalbacillary rods
-attack vascular endothelia cells
-cause systemic vasculitis
-transmitted by ticks


Rocky Mountain Spotted Fever: Symptoms

-Fever, headache, flu-like symptoms 3-14 days after bite
-early petechial rash in distal extremities
-delirium - coma - death
-nromal CSF or mild inc. lymphocytes
-IgG and IgM (indirect immunofluorescence)
-Treatment: IV doxycycline


CNS Lyme Disease (Neuroborreliosis)

-spirochete transmitted by ticks (attached for 36 hrs)
-endemic in northeast United States
-Rare in Memphis
-2-30 days: target skin rash (erythema migrans) at bite site
-weeks: flu-like sx, acute arthritis, heart block, headache, stiff neck, meningo-radiculitis, facial nerve paresis (often bilateral)
-months: encephalopathy, radiculopathy
-Diagnosed with Elisa, confirmed by Western blot
-Treat with IV ceftriaxone for 6-8 weeks


Syphilis (Treponemal pallidum)

-primary syphilis: painless genital chancre 3 weeks after infection
-secondary syphilis: 2-3 weeks after chancre, macular-papular rash on palms, soles & body, adenopathy, iridocyclitis, arthritis, meningitis or meningo-vascular stroke
-tertiary syphilis: if untreated, skin, osseous, cardiovascular, & neurologic complications occur after 15-20 yrs. (rare b/c of widely available treatment)
-immunocompromised (HIV) at higher risk for meningitis & stroke


Neurosyphilis Diagnosis

1. Serum VDRL
2. FTA (Fluorescent Treponemal ab)
3. RPR (rapid plasma reagin)
5. CSF pleocytosis


Neurosyphilis Treatment

-high dose IV penicillin & monitor CSF for improvement in abnormalities every 6 months for 2 years in HIV+ patients


Chronic Meningitis: Clinical Symptoms

1. Fever
2. Headache
3. Lethargy
4. Poor appetite/ weight loss
5. Cranial neuropathy
6. Personality change
7. Cognitive impairment


TB Meningitis - Pathophysiology

-primary lung (or GI) infection
-bacterial lodge in brain (miliary TB)
-cellular immune system encapsulates foci
-years later, tubercle reactivation (meninges)


TB Meningitis - Pathology

-Meningitis: maximum at base of brain, communicating hydrocephalus common, cranial nerves trapped in exudate
-Vasculitis: thrombosis, multiple brain infarcts
-Tuberculoma: caseating granuloma, fibrous encapsulation


TB Meningitis - Diagnosis

-early clinical features: confusion, lethargy, low grade fever, headache, vomiting, stiff neck
-late: obtundation & coma, hemiparesis, cranial nerve palsies, seizures
-Ribosomal RNA PCR test (~3 days)
-Isolating TB from CSF is volume dep. (~3 weeks)
-Repeat LP (3 x day) for total 30 cc for culture

+ chest x-ray in 75%
+ PPD in 50%
CSF: elevated opening pressure, lymphocytic pleocytosis, modestly dec. glucose, high protein
CT or MRI detects tuberculoma in 10-20%
Risk factor: 3rd world, HIV homeless alcoholics


CNS Tuberculosis - Treatment

-Isoniazid, rifampin, pyrazinamide
-Streptomycin or Ethambutol

-corticosteroids: dexamethasone taper over 6 weeks


Viral Meningitis - Etiology

-more common than bacterial
-patients don't appear extremely ill, are not encephalopathic
-80% caused by enterovirus (ECHO, Coxsackie, enterovirus 71)
-7% attributed to Mumps, even less to arborvirus, herpes simplex virus
-HSV2 (genital herpes) recurrent viral meningitis
-Herpes zoster, HIV


Viral Meningitis - Clinical

-fever & malaise, headache, neck stiffness, low back pain (overshadowed by headache)

-self-limiting, lasts 10-14 days
-if recurrent, probably due to Herpes simplex 2


Viral Meningitis - Diagnosis & Treatment

1. raised CSF opening pressure (>180 mmH20)
2. inc. CSF lymphocytes (some neutrophils)
3. Normal CSF glucose, mild inc. in protein
4. Neg. gram stain & bacterial culture
5. Differential diagnosis same as aseptic meningitis
6. CSF IgM, IgG Index (acute & one month later), PCR

Treatment: symptomatic


Early Diagnosis of HSV1 encephalitis



Viral Encephalitis - Etiology

30% arborvirus (St. Louis, West Nile)
23% enterovirus
27% Herpes Simplex Virus Type 1
Predominantly a disease of children & youth
Summer epidemics (arborviruses) transmitted by mosquitos
-Family epidemics via URI, GI flu (enterovirus)


Viral Encephalitis - Clinical Course

-the illness ranges from mild to fatal
1. Prodromal upper respiratory infection
2. Fever
3. Headache (meningismus - usually mild)
4. Lethargy
5. Confusion (parenchmal involvement)
6. Seizures
7. Stupor
8. Coma


Viral Encephalitis - Treatment & Prognosis

-outcome depends on specific virus, timely treatment, ICU care
-HSV-1 responds to acyclovir
-CMV responds to ganciclovir
-Poorer prognosis associated with California, La Cross, Eastern Europe
-Rabies is uniformly lethal


Herpes Zoster Virus

-latent HZV infection in sensory ganglia x years
-Activation: dorsal root ganglia to radiculitis (shingles), trigeminal ganglion, 1st division (ophthalmic Zoster)
-Zoster myelitis
-Zoster encephalitis
-Zoster vasculitis (giant cell angiitis of CNS & stroke)


HZV: Pathophysiology

-Risk factors: >50 yrs of age, immunosuppression (HIV, lymphoma)
-Reactivation of latent virus in a cranial nerve sensory ganglia or dorsal root ganglia
-Thoracic dermatomes most frequently involved
-Axonal transport to periphery (vesicular eruption in a dermatomal distribution)
-Pain & paresthesia precede vesicular eruption by 2-3 days
-Post-herpetic neurologia weeks later can be incapacitation


HZV: Treatment

-anti-herpetic drug acyclovir & steroids limit Zoster & prevents this major complication


HIV & Directly Related Neurologic Disease

-Acute aseptic meningitis
-chronic meningitis
-HIC dementia
-Vacuolar myelopathy
-Peripheral neuropathy
-Cranial neuropathy
-Inflammatory myopathy
-Vasculitis, Neoplasms (primary CNS lymphoma, Kaposi's sarcoma)
-Nutritional & Metabolic Disorders
-Drug toxicity of anti-retroviral therapy


Opportunistic Infections

-toxoplasmosis is by far most frequent
-cryptococcal meningitis
-JC virus (progressive multifocal leukodystrophy)