Neuro Infections 1- MJ

Question 1

Infectious agents can gain access to CNS through what 3 major pathways?

Answer 1

• Invasion of the blood stream
• Retrograde neuronal pathway
• Direct contiguous spread

Question 2

Most CNS infections can be categorized into what 3 types?

Answer 2

1. Meningitis
2. Encephalitis (involving brain itself)
3. Brain abscess

Question 3

• What are the 3 contraindications for performing a lumbar puncture?
• If a contraindication is present, what test must you do before LP?

Answer 3

1. Signs or symptoms of increased ICP (papilledema, decreased LOC, focal neuro sxs)
2. Severe coagulopathy (or on anticoags)
3. Mass lesion

*if contraindications present, MUST get CT prior to LP*

Question 4

What is Cushing’s Triad (indication of increased ICP)?

Answer 4

1. Respiratory depression
2. Bradycardia
3. HTN

Question 5

CSF analysis:

• What would be the appearance of normal CSF? What does abnormal look like?

Answer 5

• Normal: crystal clear and colorless, viscosity is similar to water
• Abnormal: Cloudy, purulent or pigment-tinged

Question 6

What are 4 possible causes of RBCs in CSF on a lumbar Puncture?

Answer 6

1. Traumatic LP (CSF clears by the 3rd tube)
2. Subarachnoid hemorrhage (redness the same in all tubes)
3. Intracerebral hemorrhage
4. Cerebral infarct

Question 7

What should you be concerned for if the CSF is cloudy?

Answer 7

Bacterial Meningitis

Question 8

CSF analysis:

Bacterial infections are usually associated w/ a predominance of what type of cells?

Answer 8

PMN leukocytes

(neutrophils)

Question 9

LP w/ CSF analysis:

What are the 4 possible causes of WBS on a CSF analysis?

Answer 9

1. Bacterial infection
2. Vasculitis
3. Lekemic infiltration
4. “Traumatic tap”

Question 10

What is encephalitis?

Answer 10

Acute inflammation of the brain parenchyma causing abnormalities in brain function

Question 11

Which of the following describes primary encephalitis vs post-infectious encephalitis?

• _______= Virus present and can be cultured/identified; (+) neuronal involvement
• ________= Virus not present; demyelination occurs; (-) neuronal involvement–> this is a secondary inflammation in the brain

Answer 11

• \_Primary_\__= Virus present and can be cultured/identified; (+) neuronal involvement
• __Post-infectious__= Virus not present; demyelination occurs; (-) neuronal involvement

Question 12

What is the most common etiology of encephalitis?

Answer 12

Viruses (70%)

Question 13

What puts a person at high risk for encephalitis? (4)

Answer 13

• Outdoors (forestry workers, campers, hunters)
• Travel to endemic areas
• Compromised immunity
• Lack of vaccines

Question 14

Which virus is associated wtih post-infectious encephalitis?

Answer 14

Measles

Question 15

The following are possible viral etiologies of what condition?

1. HSV
2. Arthropod-borne viruses (West Nile, Colorado tick fever, etc)
3. Rabies
4. HIV
5. Enteroviruses (coxsackie, polio)- common
6. Measles (assoc w/ post-infectious encephalitis)
7. Influenza, mumps, adenovirus

Answer 15

Encephalitis

(basically any virus can cause this)

Question 16

The following are possible bacterial causes of what condition?

1. Borrellia burgdorferi (Lyme)
2. M. tuberculosis
3. Treponema pallidum (syphilis)
4. Listeria spp.
5. Leptospirosis
6. Bartonella henselae (cat-scratch disease)
7. Streptococcus spp.
8. Klebsiella spp.
9. Staphylococcus spp.
10. Neisseria meningitides
11. Rickettsia spp. (Rocky Mountain spotted fever)

Answer 16

Encephalitis

Question 17

What are the 5 non-infectious causes of encephalitis?

Answer 17

1. Paraneoplastic syndrome
2. Drug Toxicitiy
3. Autoimmune causes (SLE, sarcoidosis, etc)
4. Radiation
5. Metabolic disorders

Question 18

The following is the clinical presentation of what condition?

• Fever
• AMS (behavior/personality changes, confused, agitated, etc)
• Seizures
• Focal neuro sxs (motor/sensory deficits, paralysis, CN palsies, exaggerated DTRs, speech disorders)
• _**NO SIGNS OF MENINGEAL IRRITATION_ (photophobia or nuchal rigidity)

Answer 18

Encephalitis

Question 19

The following are history clues of what condition?

• Geography
• Recent travel
• Recent illness
• Season
• Outdoor activities
• Medical hx (birth hx for neonates)
• Parotitis (Mumps), hydrophobia (rabies), Zoster rash

Answer 19

Encephalitis

Question 20

How do you differentiate between encephalitis and meningitis based on clinical presentation?

Answer 20

Meningitis has signs of meningeal irritation (photophobia, nuchal rigiditiy) and encephalitis does NOT

Question 21

What might you see on fundoscopy in a patient with Encephalitis?

Answer 21

• Papilledema
• Retinitis

Question 22

Why is it important to perform a skin exam on a patient with Encephalitis?

Answer 22

You are looking for a rash that could give you a clue to the underlying pathogen.

(Vesicular eruption for HSV, VZV, Erythema nodosum for TB/histo/sarcoid, etc)

Question 23

How do you diagnose Encephalitis?

Answer 23

MRI is preferred but start w/ a CT w/wo contrast if patient is SICK

***Negative CT does NOT c/o encephalitis***

Question 24

What might you find on MRI in a patient with encephalitis?

Answer 24

• May be negative
• +/- hyperintensity in areas of edema
• +/- demyelination post infectious

Question 25

**MRI findings in encephalitis:** In **what lobe** of the brain would you see hyperintensity in areas of edema if the etiology is **herpesvirus**?

Answer 25

Temporal lobe

Question 26

On CSF analysis of viral Encephalitis, what color would the CSF be?

Answer 26

clear or cloudy, straw colored

Question 27

On CSF analysis of viral Encephalitis, what would the opening pressure be?

Answer 27

Normal to increased

Question 28

On CSF analysis of viral Encephalitis, What would the WBC count be? (increased or decreased)

Answer 28

Increased

Question 29

On CSF analysis of viral Encephalitis, what differential cells woul be seen?

Answer 29

Lymphocytes (b/c viral)

Question 30

On CSF analysis of viral Encephalitis, what would the RBC count be?

Answer 30

0 | (increased if pathogen is herpes)

Question 31

On CSF analysis of viral Encephalitis, would there be normal, increased or decreased proteins?

Answer 31

Normal to increased

Question 32

On CSF analysis of viral Encephalitis, would glucose be normal, increased or decreased?

Answer 32

Normal

Question 34

What are the 3 most important diagnostics for Encephalitis?

Answer 34

1. MRI (Textbook- preferred choice) 2. CT (what you will actually order in practice) 3. LP

Question 35

What is the gold standard for the diagnosis of Encephalitis?

Answer 35

**Brain biopsy** | (NOT routinely performed)

Question 36

What 2 specialties should get involved STAT if you have a patient with encephalitis?

Answer 36

1. Infectious Disease 2. Neurology

Question 37

What is the management and treatment of Encephalitis? (6 steps)

Answer 37

1. **_Stabilize the patient_** (ET tube, ventilator, circulatory support, monitor electrolytes) 2. Empiric antiviral treatment- **_Acyclovir_** 3. Identify and tx offending agent (isolate pt until cause is found) 4. Prevent & manage secondary bacterial infections 5. DVT/GI (ulcer) prophylaxis 6. Tx elevated ICP- consider **corticosteroids and mannitol**

Question 38

What is the **empiric medication** used to treat encephalitis? (this will be on exam)

Answer 38

* Start early! * _**\*Acyclovir**_ 10mg/kg IV q8hrs * (Decreases morbidity/mortality due to HSV/VZV)

Question 39

What is **primary prevention** for encephalitis? (2)

Answer 39

* Avoid vectors (bug spray, avoid areas, etc) * Vaccination

Question 40

What is the prognosis of encephalitis?

Answer 40

* Varies depending on organism * Up to 75% mortality within 18 months for untreated HSV encephalitis * **Up to 90% survival with early acyclovir** * May have long-term neuromuscular and cognitive deficits * Poor prognosis in immunocompromised and extremes of age