L38- Nervous System and Special Senses Infections II Flashcards
define aseptic meningitis
meningitis that is caused by a pathogen that will not grow on culture w/in 48hrs:
- atypical bacteria
- viruses
- fungi
- parasites
list the types of Tb meningitis based on geography
High-incidence regions:
- tuberculous meningitis
- intracranial tuberculoma
- spinal tuberculous arachnoiditis
Low-incidence regions (US, Europe):
-tuberculous meningitis
list the complications from Tb meningitis- basilar meningitis
- hydrocephalus
- vasculitis –> can cause arterial or venous occlusion / stroke
- CN deficit
list the symptoms of Tb meningitis based on stage of the disease (include timing)
1) Early, days - wks: NO NEURO DEFICITS or altered consciousness, fatigue, malaise, lethargy, behavior changes
2) Intermediate, wks - mos: meningeal irritation, minor neuro deficits — mainly CNs
3) Late, mos - yrs: abnormal movements, convulsions, stupor to coma, severe neuro deficits
CSF sample results in Tb meningitis:
- (1) appearance
- (elevated/depressed) WBC + type
- (elevated/depressed) proteins
- (elevated/depressed) glucose
1- fibrin-web like
2- elevated, lymphocytes
3- elevated
4- depressed
______ are the common causes of Spirochete meningitis
Lyme Disease —- Borrelia burgdorferi
Syphilis, Treponema pallidum
list the results of CSF sample in Lyme disease meningitis (WBC type, protein levels, glucose levels)
- lymphocytic pleocytosis (inc lymphocytes)
- elevated protein
- normal glucose
diagnosis of Lyme disease starts with (1) and is confirmed with (2)
1- ELISA
2- western blot (Igs)
list the four main clues into a suspected diagnosis of Lyme Disease meningitis
- travel to endemic region // tick bite
- ECM (erythema chronicum migrans)
- facial palsy
- papilledema
list the results of CSF sample in Syphilitic meningitis (WBC type, protein levels, glucose levels)
(treponema pallidum)
- lymphocytic pleocytosis (inc lymphocytes)
- elevated protein
- low glucose
describe diagnosing procedure for Syphilitic meningitis
1) serum + CSF serology
2) (confirmation) fluorescent treponemal Ab absorption (FTA-ABS)
______ is the most common cause of meningitis in general (start broad and include subtypes)
Viral, 85% enterovirus:
- coxsackievirus A, B
- echovirus
Coxsackievirus A, B meningitis:
- (1) route of transmission
- (2) predominant season
- (3) describe brief pathogenesis
1- fecal-oral
2- summer-fall (Jun-Oct) // year round in tropical/sub-tropical areas
3:
i) naspharynx –> lymph
ii) infects LNs –> 1st viremia
iii) target tissue (many, but in this case meninges or brain) –> 2nd viremia
______ is defined as recurrent episodes of aseptic meningitis- include most likely cause
Mollaret’s meningitis- HSV-2
Herpesviruses and meningitis:
- (1) are the most common causes
- (2) is most common cause of neonatal herpes infection
- (3) are infrequently associated with meningitis
1- HSV1 > HSV2
2- HSV2 (75%)
3- VZV, EBV, CMV, HHV6, HHV7
herpesviruses general viral features
dsDNA, enveloped –> latency
LCMV = (1) — meningitis:
- (2) family, genome, structure
- (3) source / transmission
- (4) predominant season
1- lymphocytic choriomeningitis virus
2- Arenavirus, enveloped, (-)ssRNA
3- rodents
4- winter mos
Influenza A, B:
- (1) family, genome, strucure
- (2) predominant season
- (3) population is at most risk
1- orthomyxovirus, (-)ssRNA, enveloped
2- winter mostly (Jan-Feb)
3- children <5yr via Influenza A
Rabies:
- (1) family, genome, structure, shape
- (2) transmission, (3) is most common reservoir in US
- causes (meningitis/encephalitis)
1- rhabdovirus, (-)ssRNA, enveloped, bullet shaped
2- bites or inhalation
3- raccoons
4- meningoencephalitis
Rabies meningoencephalitis:
- incubation period
- symptoms in each stage
Incubation: typically 20-60 days, can be 6 days - 7 yrs
1) Prodromal, 2-10 days: non-specific; fever, n/v/d
(note Tx must occur in prodromal phase)
2) Furious: agitation, disorientation, seizures, twitching, (neck / pharyngeal spasms –> painful swallowing = hydrophobia)
3) Dumb: paralysis, disorientation, stupor
describe diagnosis of rabies meningoencephalitis (samples, testing)
-usually based on Sxs and post-mortem
- saliva and brain tissue with virus (Ags in serum, brain, CSF, corneal scrapings via IF)
- **Intracellular eosinophilic inclusion bodies = Negri bodies
describe Rabies treatment
passive and active post-exposure prophylaxis, must occur w/in first week or two of prodromal Sxs:
1) passive immunity via Antisera —- Human Rabies Immune Globulin (HRIG) at wound and IM
2) active immunity via inactivated vaccine — doses depends on preventative or post-exposure
list the arboviruses that can cause viral meningitis by family
Flavivirus (enveloped, (+)ssRNA): **WNV (west nile), *SLE (St. Louis virus)
Bunyavirus (enveloped, (-)ssRNA): La Cross virus
Togavirus (enveloped, (+)ssRNA): EEE virus (eastern equine encephalitis), WEE virus (western equine encephalitis)
WNV is transmitted via ______ (bonus- include what else it transmitts)
Culex mosquito —- all flaviviruses
describe the presentation of Arbovirus meningitis
1) asymptomatic or prodromal / flu-like Sxs with variable severity
2) Range: febrile HA in aseptic meningitis - to - encephalitis [Note- indistinguishable from other causes]
Fungal meningitis usually affects (1) population with (2) as the predominant cause
Note- rare, usually chronic
1- immuno-compromised
2- cryptococcus (bird droppings)
Cryptococcus Neoformans - fungal meningitis:
- (1) is hallmark microscopic feature
- usually affects AIDS patients with (2) CD4+ T cell count
- (3) describe diagnostic sequence
- (4) results on imaging
1- encapsulated yeast
2- <100 cells/mm^3
3- neurological exam –> *serum cryptococcal antigen (CrAg) –> lumbar puncture
4- no pattern / variable – not helpful
(1) are the clinically important parasitic causes of meningitis
(2) is a rare, but dangerous cause associated with swimming
1- Taenia solium (pork tapeworm), Toxoplasma gondii (opportunistic)
2- Naegleria fowleri – amebic meningitis
Taenia solium:
- (1) parasite type
- (2) port of entry
- (3) CNS effect
1- tapeworm, cestode
2- ???? possibly transported w/in WBCs
3- epileptic seizures
Toxoplasma gondii:
- (1) parasite type
- (2) port of entry
- (3) CNS effect
1- intracellular protozoa via cat feces or many other environments
2- transported w/in WBCs with active infiltration thru BBB endothelium
3- necrotizing encephalitis –> microglia forms nodules + chronic meningitis
Neurocysticercosis:
- (1) cause
- most patients present with (2)
- 1/3 pts present with elevated (3)
Note- most common parasitic CNS infection
1- Taenia solium – pork tapeworm via ingestion
2- seizures
3- raised ICP
list the types of neurocystcercosis presentations (T. solium): indicate most common form + incubation period
- *Intraparenchymal cysticerci- most common, usually 3-5yr incubation, but up to 30yrs
- seizures and or HA
Extraparenchymal cysticeri- elevated ICP sxs (HA, n/v) + altered mental status —— involves ventricles, subarachnoid space, spine, and or eyes)
Neurocystcercosis (T. solium) diagnosis:
- (1) is main unique finding on routine CBC, LFTs
- (2) parasitic response cell is importantly absent
- (3) is not useful additional test as it might not be present at time of Dx
- (4) is useful- include results
1- n/a
2- no eosinophilia
3- stool (no viable intestinal tapeworm may be present)
4- imaging: starry-sky appearance on CT/MRI = innumerable hyperdensities w/ eccentric calcific foci in both cerebral hemispheres
______ is the hallmark feature for diagnosing Neurocystcercosis
(Taenia solium)
starry-sky appearance on CT/MRI: innumerable hyperdensities w/ eccentric calcific foci in both cerebral hemispheres
Toxoplasma gondii is most serious in (1) populations as it usually presents as (2) is most people.
1- immuno-compromised or congenitally infected
2- asymptomatic (immuno-competent)
(1) are the late clinical manifestations of untreated congenital Toxoplasmosis
(2) is the evaluation process of newborn with suspected infection
1- chorioretinitis, neurological abnormalities (motor abnormalities, intellectual disability, hearing loss)
2- maternal hx + serology –> complete PE –> T. gondii serology –> other ophthalmologic / neurological exams not in PE
describe the diagnosis of toxoplasma gondii infection (hint- labs, imaging)
Labs:
- CSF: mild/moderate protein elevation, mononuclear CSF pleocytosis (monocytes)
- PCR
Imaging:
- intracranial calcifications = single / multiple scattered throughout brain [multiple abscess like ring enhanced structures]
- hydrocephalus (secondary to periaqueductal involvement)
- cortical atrophy
