Cerebrovascular Infections Flashcards
Common causative agents for bacterial meningitis? (Acute)
- Infants
- Unvaxxed 2mo-2yo
- Young adults
- Older adults
- Infants: E coli and GBS
- Unvaxxed young: HiB
- Young adults: Neisseria meningitidis
- Older adults: Streptococcus pneumoniae and Listeria monocytogenes
Common causative agents for bacterial meningitis? (Chronic)
Mycobacterium tuberculosis
Common causative agents for viral meningitis?
- Enterviruses
- Influenza species
- Lymphocytic choriomeningitis virus
Common causative agents for abscesses?
Streptococci and staphylococci
Common viral causative agents for encephalitis? (encephalitic syndromes)
- HSV-1,2
- CMV
- HIV
- JC Polyomavirus (progressive multifocal leukoencephalopathy)
What are 4 routes that CNS infections are spread?
- Hematogenous (most common)
- Direct implantation (trauma or congenital malformations like meningomyelocele)
- Local extension (sinuses, teeth, etc)
- PNS (viruses like rabies, herpes)
How often is there a complete exchange of CSF
Every 3-4 hours
How does TB invade CNS?
Seeding CSF from subepidural or submeningeal granulomas
Side note: There ARE lymphatics in epidural space, not in rest of CNS
How do HSV simplex and zoster invade CNS?
Produce latent infection of sensory ganglia, replicate in Schwann cells, ascend from periph to the CNS within sensory nerves
How does the rabies virus invade CNS?
Binds at or near ACh receptors at NMJ & ascends to the CNS via motor nerves
Side note: Do NOT need to get bit to get rabies
What are anatomic considerations with capillaries that are pertinent to CNS infections? (i.e. how to molecules move across)
What is something to note about immunoglobulins, complement, and antibiotics?
- Caps do not have fenestrations, molecules move across foot processes mainly by active transport and lipid solubility
- Blood brain barrier
Relative impermeability to immunoglobulins, complement, and antibiotics
What are the 5 main types of meningitis?
Examples of each
- Meningoencephalitis
- Chemical: Non-bacterial irritant in subarachnoid space like rupture of cyst
- Acute pyogenic: Bacteria
- Aseptic: Virus
- Chronic: TB, spirochetes, Cryptococcus
What can accelerate cerebral edema in response to infection?
What can slow it down?
Accelerated by products released by both living bacteria and antibiotic-lysed bacteria
Slowed and reserved by corticosteroids
Symptoms of meningitis?
Specialty tests?
How long does disease process take?
Sx: H/A, meningeal irritation, high fever, confusion, coma
ST: Kernig, Brudzinski
Full syndrome usually develops within several days but could take a few hours with a fulminant course
Where on the brain does pneumococcal meningitis usually present?
Densest over convexities near sagittal sinus (sulci)
Where on the brain does H. flu meningitis usually present?
Basal location
What is focal cerebritis?
Inflammatory cells infiltrate walls of veins & extend into brain substance
What can phlebitis lead to?
Venous thrombosis & hemorrhagic infarction of underlying brain
What can leptomeningeal fibrosis lead to?
Hydrocephalus
What can pneumococcal meningitis lead to?
Chronic adhesive arachnoiditis
What are some complications of bacterial meningitis?
- Seizures
- Encephalitis
- Hearing loss, blindness, paralysis
- Fulminant esp w meningococcemia
- Waterhouse-Friderichsen syndrome: Rash over body, hemorrhagic adrenals
What gram-stain and shape is N. meningitidis?
Gram - diplococci
What gram-stain and shape is S. pneumoniae?
Gram + diplococci
What gram-stain and shape is H. flu?
Gram - pleomorphic
What gram-stain and shape are S. aureus, S. epi, and streptococci?
Gram + cocci
What gram-stain and shape is E. coli?
Gram - bacilli
What features does bacteria in CSF have?
- Cloudy or turbid
- Inc neutrophils
- Dec glucose
- Inc protein
What features do viruses in CSF have?
- Clear, colorless
- Inc lymphocytes
- Nml glucose
- Moderate inc in protein
What are 7 things that inc risk for meningitis?
- Age <5yo or >60yo
- DM
- Immunosuppression/HIV
- Contiguous infection (sinusitis)
- IVDU
- Bacterial endocarditis
- Sickle cell anemia
Common bacterial pathogen for acute meningitis is the pt has an immunocompromised state?
- S. pneumoniae
- N. meningitidis
- L. monocytogenes
- P. aeruginosa (CF pts)
Common bacterial pathogen for acute meningitis is the pt has a basilar skull fracture?
- S. pneumonia
- H. flu
- Group A beta-hemolytic strep
Common bacterial pathogen for acute meningitis is the pt has head trauma (post neurosurg)?
- S. aureus (from skin)
- S. epidermidis (from skin)
- P. aeruginosa
Common bacterial pathogen for acute meningitis is the pt has CSF shunt
- S. aureus (from skin)
- S. epidermidis (from skin)
- P. aeruginosa
- P. acnes
What are sx of an abscess?
What does CSF show?
What are possible complications?
Tx?
Progressive focal neurological deficits w/ s&s of inc ICP
CSF: High WBC, high protein, normal glucose
Complications: Herniation, abscess rupture w ventriculitis or meningitis, venous sinus thrombosis (fatal)
Tx: Surgical drainage and abx
What is a subdural empyema? What can it do to bridging vessels? What happens with dura?
Bacterial or fungal infection of skull bones or sinuses spread to subdural space (arachnoid and subarachnoid usually not affected)
- Can cause thrombophlebitis of bridging vessels which can lead to infarct
- Causes thickened dura
What is an extradural abscess a/w? What can this cause? (emergency)
Usually a/w osteomyelitis
-Extradural abscess of the spine may cause cord compression (neurosurgical emergency)
Clinical manifestations of N. meningitidis?
Rapidly progressive septicemia w fever, hypoTN, DIC, petechial and purpuric lesions
Waterhouse-Friderichsen syndrome:
- Purpura fulminans: Hemorrhagic skin lesions which progress to gangrene in distal portions of limbs
- Hemorrhagic infarct of adrenal glands
Chronic meningitis:
- Sx
- CSF
- How dx is made
- Common pathogens
- Sx: Fever, H/A, lethargy, confusion, N/V, stiff neck
- CSF: Elevated protein, lymphocytes, low glucose
- Dx is made if sx and CSF abnormalities persist or progress for a period of at least 4 weeks
- TB, neuroborreliosis, neurosyphilis
Note: Though TB is bacterial, still has lymphocytic proliferation
Chronic meningitis: Mycobacterium TB diffuse meningoencephalitis
What is the appearance? Where does is normally appear on the brain?
What is Obliterative endarteritis? What is a tuberculoma?
- If it gets into subarachnoid space, becomes gelatinous or has fibrinous exudate
- Predilection for base of the brain (arachnoiditis); obliterates cisterns & encases cranial nerves (hydrocephalus and CN sx)
- Obliterative endarteritis: Inflamm infiltrates vessel walls; intimal thickening; arterial occlusion & infarct
- Tuberculoma: Well-circumscribed intraparenchymal mass; central caseous necrosis; inactive lesions may calcify
Note: Always get a culture in addition to a smear
Chronic meningitis: Borrelia burgdorferi
How do you get it?
What are some sx and what is the timeline?
What can this cross react with?
- Neuroborreliosis (Lyme disease)
- Neuro sx follow characteristic rash by ~4wks
- CN palsies and peripheral neuropathies
- CSF w antibodies
- Abs can cross react w infection mono, RA, SLE, syphilis
What are 3 disorders that treponema pallidum can cause?
- Meningovascular neurosyphilis
- Paretic neurosyphilis
- Tabes dorsalis
Note: Pts often show mixed picture, most often combo of tabes dorsalis & paretic disease (aka taboparesis)
How common is it for treponema pallidum to become neurosyphilis and what increases the risk?
Only about 10% of untreated pts develop
- HIV inc the risk d/t impaired cell-mediated immunity
What part of the brain does meningovascular neurosyphilis affect? What 2 things does it do to the brain?
Chronic meningitis involving base of the brain (variable convexities & spinal leptomeninges)
- Causes communicating hydrocephalus
- Causes obliterative/Heubner endarteritis
How quickly does paretic neurosyphilis set in and what mental defects are a/w it? What is a phrase a/w this?
What is granular ependymitis?
Insidious but progressive mental defects a/w mood alterations (delusions of grandeur) that end w severe dementia (aka general paresis of the insane)
- Perivascular iron deposits
Proliferation of subependymal glia under damaged ependymal lining (a/w communicating hydrocephalus)
- Granulations lose ability to reabsorb
What is tabes dorsalis? What are some sx?
Damage to sensory nerves (loss of myelin and axons) in the dorsal roots
- Impaired joint position sense & resultant ataxia
- Loss of pain sensation
- Joint damage (Charcot joints)
- “Lightning pains”
- Absence of DTRs
Aseptic (Viral) meningoencephalitis
- Clinical picture
- Cause
- CSF
- Tx
Absence of recognizable organism in pt w meningeal irritation, fever, & alterations of consciousness w relatively acute onset
- Often caused by enteroviruses
- Less fulminant than pyogenic meningitis
- CSF: Lymphocytes, mod inc in protein, glucose normal
- Tx: Usually self-limiting; supportive care
How do viruses reach CNS in meningitis and encephalitis?
- Often hematogenous
- Reach CNS thru nerves (like olfactory & trigeminal)
What are sx of west nile involving the spinal cord?
CSF?
Polio-like syndrome w paralysis
CSF: Initially shows neutrophilic pleocyotsis which rapidly converts to lymphocytes, protein elevated, glucose normal
What are two things that histology might show w west nile in the spinal cord?
Neurophagia: Single-cell neuronal necrosis w phagocytosis of the debris
Microglial nodules: Small aggregates around foci of necrosis
What are sx of HSV-1 encephalitis?
What is a feature of what it physically does to the brain?
Where does it most commonly act?
What type of inclusions can you see?
Alterations in mood. memory, behavior
Causes necrosis and hemorrhage in inferior and medial temporal lobes
Shows Cowdry Type A intranuclear viral inclusions in neurons and glia
When do we see HSV-2 encephalitis?
What does is physically do to the brain?
in 50% of neonates born by vaginal delivery to women w active primary HSV
Acute hemorrhage and necrosis
Where does herpes zoster stay during latent phase?
Sensory neurons of dorsal root or trigeminal ganglia
Reactivation limited to dermatome
What is postherpatic neuralgia syndrome?
Persistent pain as well as painful sensation following nonpainful stimuli
Who gest CMV infections?
Where does it localize?
Fetuses and immunosuppressed (HIV)
Localized in paraventricular subependymal regions
What happens in utero with CMV infections?
Periventricular necrosis -> severe brain destruction -> microcephaly & periventricular calcification
Where does poliomyelitis affect in the nerve roots? What does it cause?
Anterior horn motor neurons and causes flaccid paralysis w muscle wasting & hyporeflexia
May extend to posterior horns & occasionally produces cavitation
What is post-polio syndrome?
Develops 25-35 years after resolution of inital illness; prgressive weakness w decreased muscle mass & pain
How long does rabies incubate?
How does it travel from wound site into nervous system?
Sx?
Inclusion seen in rabies?
1-3 months depending on distance of wound to brain
Ascends along periph nerves from wound site
CNS excitability; violent motor responses, flaccid paralysis, resp center failure, hydrophobia
Inclusion: Negri bodies
What happens in HIV aseptic meningitis during acute phase?
Perivascular inflammation & some myelin loss
What happens in HIV aseptic meningitis during chronic phase?
Microglial nodules w multinucleated giant cells
What happens to the white matter in HIV aseptic meningitis?
Loses myelin (pallor), axonal swelling, gliosis
What is IRIS?
Immune reconstitution inflammatory syndrome: Paradoxical deterioration after starting antiviral therapy
What is HAND?
HIV-Associated Neurocognitive Disorders: Mild to florid cognitive changes, persisting despite effective tx
What is a cancer that HIV is associated with?
Primary CNS lymphoma (EBV + B-cell tumor)
What virus causes progressive multifocal leukoencephalopathy?
What does it infect and what is the major effect of that?
Who does it mainly infect?
JC polyomavirus
Infects oligodendrocytes and causes demyelination of subcortical areas; dec number of axons
Infects immunocompromised individuals
What pathogen causes subacute sclerosing panencephalitis (SSPE)?
What early childhood infection can cause this?
What are some sx>
Paramyxovirus
Causes cognitive decline, spasticity of limbs, seizures
- Widespread gliosis & myelin degeneration w viral inclusions and neurofibrillary tangles
Children or non-immunized adults that had prev measles (rubeola) infection
What 4 species often cause fungal meningoencephalitis?
Candida albicans, mucor species, aspergillus fumigatus, cryptococcus neoformans
Which fungal meningoencephalitis pathogen is a/w DM?
Mucormycosis
Which fungal meningoencephalitis pathogens commonly cause vasculitis?
Mucormycosis & aspergillosis (sometimes candida)
Which fungal meningoencephalitis are endemic?
Histoplasma capsulatum, coccidiodes immitis, blastomyces dermatitidis
Which fungal meningoencephalitis pathogens cause parenchyma infections?
Candida and cryptococcus
What is cryptococcus meningitis a/w?
AIDS
Who does toxoplasmosis gondii affect?
Where in the brain does is affect?
Histology?
HIV or immunocompromised, pregnant
Causes brain abscesses located near the grey-white junction of cerebral cortex and deep grey nuclei; ring-enhancing lesions
Histo: Central foci of necrosis, petechial hemorrhages surrounded by inflam, vascular proliferation
Free tachyzoites & encysted bradyzoites???
Name 6 prion diseases
What is the spongiform change in these?
- CJD
- Gerstmann-Straussler-Scheinker syndrome
- Fatal familial insomnia
- Kuru
- Scrapie
- Bovine spongiform encephalopathy
All rapidly progressive with prion protein PrP
Spongiform change is intracellular vacuoles in neurons and glia
CJD
What brain changes do we see?
What is a unique sx?
So rapid (7mo survival) that there is little, if any, gross evidence of brain atrophy
Shows startle myoclonus
What will the Kuru plaque in vCJD stain with?
+ Congo red and + PAS
Survival time for fatal familial insomnia?
Less than 3 years
