Viral CNS infections

Question 1

what is aseptic meningitis?

Answer 1

inflammation of the leptomeninges not caused by bacteria

Question 2

what is encephalitis?

Answer 2

inflammation of the brain tissue

Question 3

what is meningoencephalitis?

Answer 3

infection of meninges and brain

Question 4

what are the causes of aseptic meningitis?

Answer 4

viruses, fungi, TB, and infections near the CNS

Question 5

what are the most common viral causes of meningitis?

Answer 5

80% enteroviruses, 10% HSV 1 and 2 and 10% arboviruses

Question 6

what are the symptoms of aseptic meningitis? how is it differentiated from encephalitis?

Answer 6

headache, fever, stiff neck, malaise, sore throat, nausea, abdominal pain etc
does not have change in mental status like encephalitis does

Question 7

how is aseptic meningitis diagnosed?

Answer 7

elevated WBC in CSF with no bacteria. viruses may be detected

Question 8

how is aseptic meningitis treated?

Answer 8

supportive care

drugs only for HSV, fungal and mycobacterial infections

Question 9

what is the prognosis of aseptic meningitis?

Answer 9

usually resolves in 2 weeks unless encephalitis occurs

Question 10

what is brudzinki’s sign?

Answer 10

knees flex when the neck is flexed because it is so stiff

Question 11

what is the cause of damage in encephalitis?

Answer 11

immune cells influx with cerebral edema that destroys the neurons. May cause intracerebral hemorrhage
viruses can also directly kill tissue

Question 12

what are the symptoms of encephalitis?

Answer 12

altered mental status, fever, headache, vomiting, photophobia, stiff neck, confusion, and other cerebral signs

Question 13

what are urgent symptoms of encephalitis?

Answer 13

unresponsiveness, seizures, muscle weakness or neuro signs (poor judgement, flat affect and memory loss)

Question 14

how is encephalitis diagnosed?

Answer 14

CSF shows inflammation and possibly blood and/or viruses (PCR). EEG suggestive of seizures and MRI may show foci of inflammation or hemorrhage

Question 15

what is the treatment for encephalitis?

Answer 15

supportive care, acyclovir for HSV, antiseizure meds, dexamethasone to decrease inflammation and sedatives

Question 16

what is the prognosis of viral encephalitis?

Answer 16

some cases are benign, others may be fatal

Question 17

what is a complication of viral encephalitis?

Answer 17

permanent neurologic impairments

Question 18

who is most susceptible to viral CNS disease?

Answer 18

young and elderly, impaired immunity and exercise may increase dissemination to CNS

Question 19

what is acute disseminated encephalomyelitis? what is it caused by?

Answer 19

postinfectious encephalitis following viral infection by 1-2 weeks
caused by autoimmunity

Question 20

what diseases are associated with acute disseminated encephalomyelitis?

Answer 20

measles, mumps, varicella/zoster, influenza and parainfluenza viruses

Question 21

what are 4 types of CNS infections?

Answer 21

Herpes viruses, rabies, enteroviruses, and arboviruses

Question 22

which herpesviruses are neurotropic?

Answer 22

HSV 1 and 2 and VZV

Question 23

how do HSV 1 and 2 affect the CNS?

Answer 23

HSV 1 and 2 (2 more frequently) primary infections can cause meningitis
HSV 1 recurrences can cause encephalitis

Question 24

what herpesviruses cause meningitis other than HSV? what is a sequelae?

Answer 24

VZV, CMV and EBV in immunocompromized patients

in weak host- often progress to severe encephalitis

Question 25

how does HSV1 cause encephalitis?

Answer 25

most common cause of viral encephalitis
HSV from oropharynx -> trigem->CNS
reactivation in CNS

Question 26

what are the symptoms of HSV1 encephalitis?

Answer 26

altered mental status, CN deficits, hemiparesis, slurred speech, stumbling, seizures and fever

Question 27

how is HSV encephalitis diagnosed? what does MRI show?

Answer 27

PCR of CSF

MRI shows unilateral temporal lobe abnormalities

Question 28

how does rabies infect the brain?

Answer 28

replicates at bite site (incubation period), infects peripheral nerves, travels to brain and replicates

Question 29

why does postexposure immunization for rabies work?

Answer 29

because there is a long incubation period

Question 30

what are the symptoms of rabies?

Answer 30

hydrophobia, seizures, hallucinations, paralysis, coma and death

Question 31

what picornaviruses cause CNS infection?

Answer 31

poliovirus, coxsackie and enterovirus

Question 32

what togavirus arboviruses cause encephalitis? which is the worst?

Answer 32

venezualan, eastern and western equine encephalitis viruses

VEE is worst

Question 33

what flavivirus arboviruses cause encephalitis?

Answer 33

japanese encephalitis virus, west nile, st louis encephalitis virus, russian spring-summer encephalitis and powassan virus (last two tick borne)

Question 34

which arboviruses are seen only in urban areas? why?

Answer 34

venezualan and eastern equine encephalitis virus

because their vector the Aedes mosquito lives in urban areas

Question 35

what vaccines and antivirals are available for arboviruses?

Answer 35

live attenuated vaccines for yellow fever and japanese encephalitis
no antivirals

Question 36

how often does west nile cause meningoencephalitis? who is at higher risk?

Answer 36

less than 1%

cancer, diabetes, hypertension and kidney disease

Question 37

what is the prognosis of WNV meningoencephalitis?

Answer 37

recover over weeks or months- some neuro effects permanent. mortality 10%

Question 38

what viral CNS infections have predilection for the summer and fall?

Answer 38

enteroviruses and arboviruses

Question 39

what viral CNS infections have predelection for winter and spring?

Answer 39

mumps and measles

Question 40

what viral CNS infections have no seasonal preference?

Answer 40

HSV and HIV