neurologic infections (bacterial&viral&encephalitis)

Question 1

what are neurologic infections?

Answer 1

infections within the CNS

• types vary by: brain, spinal, meninges
  microbe: bacterial or viral

Question 2

CNS is well protected, so somehow the microbes must find a way to enter brain..? (4)

Answer 2

1. fracture of skull- direct entry of pathogens
2. blood brain barrier- bacteria must first survive in circulation and evade defense cells, then cross BBB
3. extension- infection in a contagious area that is adjacent/in contact with CNS
4. opening into cranium for blood vessels and nerves (microbes can travel along axon of cranial nerves to make way into brain)

Question 3

bacterial meningitis is?

Answer 3

meningeal inflammation d/t infection from bacteria entering column

Question 4

what are the meninges?

Answer 4

3 membranes that envelop the brain and spinal cord
-DURA mater (outside)
-ARACHNOID mater
PIA mater (inside)

Question 5

limited space within cranium because

Answer 5

adult cranium bones are fused together and cannot expand

Question 6

anything requiring space in the brain will

Answer 6

compromise the existing tissue function: life-threatening

Question 7

etiology of bacterial meningitis?

Answer 7

• known bacteria: any bacteria can cause bacterial meningitis (some are more common!)
• streptococcus pneumonia (more in adults)
• neisseria meningitides (more in children)
• both bacteria present in NASOPHARYNX and do not cause problem until an infection

Question 8

predisposition to bacterial meningitis?

Answer 8

• head trauma
• post neurological surgery (portal of entry)
• sinus or middle ear infection= congruent, infection in a contiguous area
• immunocompromised

Question 9

pathology of bacterial meningitis?

Answer 9

• limited space in cranium, bacteria enter, defence follows
• death of neurons, defence cells and bacteria
• —> lysis of these cells causes an accumulation of cell debris. brain= no where for this debris to go—-> inflammation—> increased exudate takes up space
• —> vessel congested —-> impeded flow —> infarction —-> neurons lost to infarction that do not recover
• meninges thicken and adhere to brain tissue and other meninges: further decrease in space
• CSF blockage= CSF accumulation d/t obstructed flow—> space occupying lesion—> hydrocephalus (abn accumulation of CSF within brain INCREASED ICP)
• PURULENT exudate mises with CSF and flows into spinal cord even MORE increased ICP

Question 10

manifestations of bacterial meningitis?

Answer 10

fever

• headache, nausea and vomiting (d/t inflammation in cranium, stimulation of vomit reflex center)
• nuchal rigidity (back of neck), back pain (r/t infm of spinal cord)
• positive brudzinsukis and kernigs sign

Question 11

what are the two signs you test for in meningeal irritation?

Answer 11

brudzinskis and kernigs

brudzinskis: pain when bringing neck up and legs bend up
kernigs: resistance to bring the knee up when supine (cannot go past 90 degrees)

Question 12

diagnosis for bacterial meningitis?

Answer 12

• history and physical
• c&s
• csf
• abs increased proteins
• exudate/pus
• WBC count, increased neutrophils
• decreased glucose (utilized by bacteria)

Question 13

treatment for bacterial meningitis?

Answer 13

• antibiotics: increase lysis of bacteria (furthers inflammation and takes up more space)
• steroids: to counter the inflammation brought by antibiotics
• monitor for thrombosis (exudate applies pressure on neural tissue, vessels dilate to compensate resulting in hyperemia, blood congests in vessels, enlarged arteries and veins… can lead to thrombosis)

Question 14

what is viral meningitis?

Answer 14

aka “aseptic meningitis”—> bacteria is not the source of infection

• less severe than bacterial (which is rare because viral are usually worse!!
• self-limiting (will resolve without treatment) but can lead to critical complications so must closely monitor

Question 15

when does viral meningitis usually resolve?

Answer 15

~ 2 weeks

Question 16

treatment of viral meningitis?

Answer 16

• symptomatic treatment, manage ICP

- monitor to make sure NO complications

Question 17

CSF analysis for viral meningitis?

Answer 17

many viruses cause this/
analysis for increased lymphocytes
increased monocytes (responding to inflm and infection)
moderately increased protein due to inflm and antibodies
normal gluose levels because viruses DO NOT metabolize glucose

Question 18

encephalitis=

Answer 18

inflammation in NEURAL tissue itself!

Question 19

what is the functional tissue in a organ called?

Answer 19

parenchyma- in brain or spinal cord

Question 20

encephalitis is usually?

Answer 20

viral, any virus entering the cranium can cause encephalitis

Question 21

2 groups of viruses that most commonly cause encephalitis?

Answer 21

1. herpes simplex type 1 (HS1 causes cold sores in the lips)

2. arboviruses (transmitted by arthropods- insects, ticks, etc) have an exoskeleton

Question 22

pathology of encephalitis?

Answer 22

very serious infection- course of illness is unpredictable, can begin without much warning

• virus disrupts genetic info within the neuron—> neurons lyse, resulting in degeneration of cell bodies and necrosis of healthy neurons
• —> blood vessels are affected thru inflammatory process and tissue damage, which can result in hemorrhaging
• –> damage is focused initially, then because generalized as it spreads
• inflammation causes exudate production resulting in edema in brain tissue

Question 23

how is arbovirus fought

Answer 23

self-limiting approx 2 weeks

Question 24

how is herpes fought

Answer 24

AGGRESSIVE treatment: IV acyclovir

Question 25

manifestations of encephalitis

Answer 25

systemic= lethargy (usually seen w infections)
local= seizures and coma d/t neurological disturbances
-fever, nuchal rigidity (back of neck) and headache (normally systemic but not here)
-increased mortality: approx 30%

Question 26

complications of encephalitis

Answer 26

• dementia, epilepsy (neurological disturbances!)
• death
• aggressive treatment is needed