CNS infections Flashcards

Question

Encephalitis: general features

Answer 1

* Inflammation of brain parenchyma * Syndrome similar to acute meningitis – Fever, headache, altered mental health * – Speech & behavioral disturbances * – Seizures & hemiparesis * Coexist: meningoencephalitis * – Fever, headache, altered mental health – Speech & behavioral disturbances * – Seizures & hemiparesis * Significant morbidity & mortality * – Viruses **Sx** * Irritability * Altered personality * Drowsiness * Ataxia * Excessively brisk tendon reflexes * Encephalitis usually not severe unless caused by HSV * HSV-1 reactivation in immunocompromised state of DM (focal deficit), HSV-2 results in more global deficits

Answer 2

HSV & HHV-6 encephalitisa affecting Temporal lobe & limbic **HSV-1 & 2** * HSV-1 reactivation in immunocompromised state of DM (focal deficit), HSV-2 results in more global deficits. * S2 to S5 ganglion * Causes apoptosis of neuronal cells * Stress reactivates HSV-1 * Secondary viremia allows viral access to CNS

Answer 3

VZV vasculopathy: Multifocal haemorrhagic infarctions & demyelinating lesions

Answer 4

WNV-induced encephalitis and damage to thalami and substantia nigra.

Answer 5

Enterovirus induced encephalitis causing acute disseminated or postinfectious encephalomyelitis.

Answer 6

* Herpes viruses HSV-1, HSV-2, VZV, CMV, EBV, HHV6 * Enteroviruses * Paramyxoviruses (measles, mumps) & Togavirus (rubella) * Rabies * Arboviruses: E.g., Japanese B encephalitis, St Louis encephalitis virus, West Nile encephalitis virus, Eastern, Western, and Venezuelan equine encephalitis virus, tick borne encephalitis viruses * Bunyaviruses: E.g., La Crosse strain of California virus * Reoviruses: E.g., Colorado tick fever virus * Arenaviruses: E.g., LCMV

Answer 7

* Most common: sporadic encephalitis * – 1/250,000 population/year * – 1250-2000 cases/year (US) * Immunocompetent adults: HSV-1 (90%) **Clinical features** * – Incubation period uncertain: Rapid onset – several days * – Fever (90-100%) * – Altered consciousness (97-100%) * – Headache (70-81%)

Answer 8

VZV – Remember: latency – dorsal root ganglia – Myelitis (immunocompetent focal) CMV: most common cause of encephalitis in AIDS+ – AIDS (CD4+ T cell \<50 cells/mm3) + organ transplant • HHV-6 – Immunocompromised (allogenic bone marrow transplants)

Answer 9

* Flavivirus * horses and humans are dead end hosts * US: Most common epidemic * Distribution: Africa, Europe, Middle East, US * neuroinvasive disease (\<1% & \>60 years of age) * – Brain parenchymal involvement * – CSF: pleocytosis, ↑ protein, normal glucose * – MRI: thalamus, basal ganglia, brain stem **Sx:** Poliomyelitis-like (acute flaccid paralysis) * – Motor neuron injury (anterior horn of spinal cord) * – Brain parenchymal involvement **Diagnosis** * – WNV-specific IgM in CSF by ELISA

Answer 10

* Flavivirus * Distribution: Canada, US, Central & Southern America * 1 in 300 infected individuals: symptomatic * \<20 years (40% meningitis, 50% encephalitis) * \>60 years (90% encephalitis) * CSF: pleocytosis, ↑ protein, normal glucose * MRI: normal, or substantia nigra **Dx** – Anti-SLEV IgM antibodies in serum or CSF

Answer 11

* Alphavirus (Togaviridae family) * Distribution: US, Southern America, Caribbean * Humans are deadend hosts * Brain stem involvement * – Mortality rate 33% (50% \>60 years of age) * – CSF: pleocytosis (**neutrophil predominance** (2/3)), ↑ protein, norm glucose, RBC’s common * – MRI: thalamus, basal ganglia, brain stem **Diagnosis** – EEE IgM antibodies in CSF by ELISA

Answer 12

* Alphavirus * Distribution: Western US, Western Canada, S. America * Febrile prodrome → encephalitis * – Mortality rate 4-10% (↑ infants & elderly) * – CSF: pleocytosis (lymphocytic), normal-↑ protein, normal glucose **Diagnosis** – WEE IgM antibodies in CSF or serum

Answer 13

* Alphavirus * Distribution: Southern US, Central & S. America * Rare neurologic disease * CSF: pleocytosis (lymphocytic), ↑ protein, normal-↑ glucose **Diagnosis** – VEE IgM antibodies in CSF or serum

Answer 14

* Bunyaviridae * CaliforniaEncephalitis,LaCrosse,Jamestown Canyon & Tahyna viruses * Distribution: CEV, La Crosse & Jamestown – US; Tahyna - Russia * La Crosse: Mississippi & Ohio river basins **Sx**: Focal neurologic disease – Hemiparesis, aphasia, dysarthria, chorea – CSF: pleocytosis (lymphocytic), ↑ protein, normal glucose **Diagnosis** – IgM antibodies in CSF or serum

Answer 15

* Flaviviridae * Distribution: Asia, Western Pacific, Australia * 1-2 wk incubation * – Altered consciousness & Seizures: (85% Children, 10% adults) **Sx**: Focal neurologic disease – Hemiparesis, aphasia, dysarthria, chorea – CSF: pleocytosis (lymphocytic), mildly↑ protein, normal glucose – MRI: normal **Diagnosis** – IgM antibodies in CSF by ELISA – PCR

Answer 16

* Reoviridae * Distribution:WesternUS&Canada(Mountains) * 0-2 wk incubation (3 days) * – Complications: encephalitis or meningitis (Children 5-10%) **Neurologicsigns/symptoms** – Nuchal rigidity, photophobia, mild altered mental state – CSF: pleocytosis (mildly lymphocytic), normal-mildly↑ protein, normal glucose **Diagnosis** – IgM by ELISA

Answer 17

* Aseptic meningitis, encephalitis, acute anterior poliomyelitis (muscle pain), acute cerebellar ataxia, optic neuritis, cranial neuritis * Neonates: sepsis-like (10% mortality) * Most Common * Enterovirus 71, * Echovirus 18: small non-enveloped linear single-stranded RNA virus that spreads by faecal-oral transmission in warmer months, * Coxsackieviruses

Answer 18

* Rhabdoviridae * Zoonotic disease (infected animal bite) * 150 countries worldwide * mostly Asia & Africa – Developing countries: domestic & feral animals * – Developed countries: bats, skunks, racoons, foxes **Diagnosis** – Skin biopsy: Immunohistochemical staining - Rabies Ag – Negri bodies: Intracytoplamsic inclusions in neurons – Corneal smears – Rabies Ag – Rabies virus neutralizing Ab – CSF or serum (unimmunized) Direct Ab Test **Treatment** * Postexposure prophylaxis * Wash wounds: soap & water + providone-iodine – Vaccine * Human rabies immunoglobulin (HRIG) * Wash all wounds with soap and water * 1 dose of HRIG & 4 doses of vaccine (Days 1, 3, 7 & 14 + 2 boosters on Day 0 and 3) * HRIG: Administer majority in bite wound site * remainder IM in same limb (distant to vaccination site)

Answer 19

* 0.1% cases: acute postinfectious encephalitis * 20% mortality * SSPE: sub acute sclerosing panencephalitis * – Slow progression of symptoms * – Most 5-15 years post initial infection (but the post initial infection can range from 1 month to 27 years ) * Immunization:

Answer 20

* RNA virus * Faecal-oral transmission * Pharyngeal spread (epidemics) **Sx** * Inapparent-mild 90% cases * – Non-paralytic: Meningitis 8% cases (self-limiting) – Paralytic disease 1% cases * – Polio encephalitis: Rare * – Incubation 1-2 wks * – Infection & death anterior horn cells (grey matter) **Dx** * – CSF: PMN early→lymphocytes, ↑protein, normal glucose * – CSF: RT-PCR

Answer 21

**Bacteria Etiology mostly:** – Staphylococci (epidermidis & aureus) – Gram negative bacteria (E. coli, Klebsiella, Proteus & Pseudomonas) – Streptococci – Diphtheroids (Propionibacterium acnes) – Anaerobes – Mixed culture **Pathogenesis** * – Retrograde infection * – Skin * – Haematogenous seeding * – Colonization at surgery

Answer 22

* Focal, intracerebral infection – Fatality rate: 0-24% * Both bacterial and fungal causes * continguous infections (sinusitis, otitis media) most common **Causative agents** * Streptococcus pneumoniae * Other aerobic & anaerobic streptococci * Haemophilus influenza * Staph. aureus * Clostridia from surgery **Etiopath** #1. Direct extension from contiguous site (Most common, ~50%) * Sinusitis * Dental abscess * Otitis * Mastoiditis #2. Hematogenous from distant site * Endovascular * Respiratory tract #3. External * Postoperative * Trauma **Symptoms:** * **Rapid but Subacute: less severe than acute, lasting longer** * Recognition of predisposing conditions important (see fig. below) * Headache, Changes in mental status, Generalized seizure, nausea, vomiting, incr ICP **Dx** * – CT scan * – Hypodense centre * – Peripheral uniform ring * – Brain oedema

Answer 23

* 15-20% localized cranial infections * Sinusitis: male:female (3:1) **Etiology** * – Streptococci (25-45%) * – Staphylococci (10-15%) * – Enterobacteriacea (3-10%) * – Anaerobic bacteria (33%) * – Polymicrobial **Sx: **Fever (↑39oC), headache **Dx: **MRI showing high density interhemispheric fissure

Answer 24

– Less common (\<2%) – SDE often accompanies **Etiology: **Similar to SDE **Clinical presentation:** Similar to SDE **Diagnosis:** MRI pachymeningeal enhancement, superficial area of diminished intensity

Answer 25

– Normal cellular glycoprotein: PrPc (↑

Answer 26

* Entamoeba histolytica – normally found in large intestine – can become invasive (primarily liver) * Free-living Amoebas (see fig below)

Answer 27

* Actinomyces * Nocardia Athas lecture 73

Answer 28

* Aerobe * Partially AFB + * Catalase + * Urease + * Found in soil * filamentous rod * Ubiquitous in the environment * AFB due to Mycolic acids in cell wall * Delayed up to 7 days * Colonies appear dry, waxy, white, or pigmented; beaded apperance **Clinical illness in immunocompromised:** * Skin * Lung – patient likely had Nocardia pneumonia * CNS * Indolent course * Cough * Skin nodules * CNS symptoms when lesion enlarges

Answer 29

* Gram +ve filamentous rod * Anaerobe * AFB – * Respiratory/GI tract **Clinical illness:** * **Jaw/recent dental work,** lung, intraabdominal infection * Fistula formation * formation of sinus tracts **Dx**: Sulfur granules (yellow) Rx: Penicillin G

Answer 30

* Causative agent: JC virus * Demyelinating disease of white matter * Reactivation of virus when individual becomes immunosuppressed * HIV (CD4 \<50 mm3), organ transplantation, chemotherapy **Clinical presentation** * Ataxia * Cerebellar involvement * Visual disturbance * Cranial nerve or occipital lobe disease **Dx** * Lumbar puncture: * “Bland” CSF * Detection of myelin basic protein * As result of demyelination * Also seen in multiple sclerosis * CSF JC virus PCR * ?Biopsy * MRI: Multiple nonenhancing lesions Treatment: Reversal of immunosuppression & ARVs

Answer 31

* Lymphoma CD4 \<50 mm3 * EBV * Toxoplasmosis CD4 \<100 mm3