Neuro Infections 1- MJ Flashcards
Infectious agents can gain access to CNS through what 3 major pathways?
- Invasion of the blood stream
- Retrograde neuronal pathway
- Direct contiguous spread
Most CNS infections can be categorized into what 3 types?
- Meningitis
- Encephalitis (involving brain itself)
- Brain abscess
- What are the 3 contraindications for performing a lumbar puncture?
- If a contraindication is present, what test must you do before LP?
- Signs or symptoms of increased ICP (papilledema, decreased LOC, focal neuro sxs)
- Severe coagulopathy (or on anticoags)
- Mass lesion
*if contraindications present, MUST get CT prior to LP*
What is Cushing’s Triad (indication of increased ICP)?
- Respiratory depression
- Bradycardia
- HTN
CSF analysis:
- What would be the appearance of normal CSF? What does abnormal look like?
- Normal: crystal clear and colorless, viscosity is similar to water
- Abnormal: Cloudy, purulent or pigment-tinged
What are 4 possible causes of RBCs in CSF on a lumbar Puncture?
- Traumatic LP (CSF clears by the 3rd tube)
- Subarachnoid hemorrhage (redness the same in all tubes)
- Intracerebral hemorrhage
- Cerebral infarct
What should you be concerned for if the CSF is cloudy?
Bacterial Meningitis
CSF analysis:
Bacterial infections are usually associated w/ a predominance of what type of cells?
PMN leukocytes
(neutrophils)
LP w/ CSF analysis:
What are the 4 possible causes of WBS on a CSF analysis?
- Bacterial infection
- Vasculitis
- Lekemic infiltration
- “Traumatic tap”
What is encephalitis?
Acute inflammation of the brain parenchyma causing abnormalities in brain function
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
- \_Primary_\__= Virus present and can be cultured/identified; (+) neuronal involvement
- __Post-infectious__= Virus not present; demyelination occurs; (-) neuronal involvement
What is the most common etiology of encephalitis?
Viruses (70%)
What puts a person at high risk for encephalitis? (4)
- Outdoors (forestry workers, campers, hunters)
- Travel to endemic areas
- Compromised immunity
- Lack of vaccines
Which virus is associated wtih post-infectious encephalitis?
Measles
The following are possible viral etiologies of what condition?
- HSV
- Arthropod-borne viruses (West Nile, Colorado tick fever, etc)
- Rabies
- HIV
- Enteroviruses (coxsackie, polio)- common
- Measles (assoc w/ post-infectious encephalitis)
- Influenza, mumps, adenovirus
Encephalitis
(basically any virus can cause this)
The following are possible bacterial causes of what condition?
- Borrellia burgdorferi (Lyme)
- M. tuberculosis
- Treponema pallidum (syphilis)
- Listeria spp.
- Leptospirosis
- Bartonella henselae (cat-scratch disease)
- Streptococcus spp.
- Klebsiella spp.
- Staphylococcus spp.
- Neisseria meningitides
- Rickettsia spp. (Rocky Mountain spotted fever)
Encephalitis
What are the 5 non-infectious causes of encephalitis?
- Paraneoplastic syndrome
- Drug Toxicitiy
- Autoimmune causes (SLE, sarcoidosis, etc)
- Radiation
- Metabolic disorders
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)
Encephalitis
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
Encephalitis
How do you differentiate between encephalitis and meningitis based on clinical presentation?
Meningitis has signs of meningeal irritation (photophobia, nuchal rigiditiy) and encephalitis does NOT
What might you see on fundoscopy in a patient with Encephalitis?
- Papilledema
- Retinitis
Why is it important to perform a skin exam on a patient with Encephalitis?
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)
How do you diagnose Encephalitis?
MRI is preferred but start w/ a CT w/wo contrast if patient is SICK
***Negative CT does NOT c/o encephalitis***
What might you find on MRI in a patient with encephalitis?
- May be negative
- +/- hyperintensity in areas of edema
- +/- demyelination post infectious
MRI findings in encephalitis:
In what lobe of the brain would you see hyperintensity in areas of edema if the etiology is herpesvirus?
Temporal lobe
On CSF analysis of viral Encephalitis, what color would the CSF be?
clear or cloudy, straw colored
On CSF analysis of viral Encephalitis, what would the opening pressure be?
Normal to increased
On CSF analysis of viral Encephalitis, What would the WBC count be? (increased or decreased)
Increased
On CSF analysis of viral Encephalitis, what differential cells woul be seen?
Lymphocytes (b/c viral)
On CSF analysis of viral Encephalitis, what would the RBC count be?
0
(increased if pathogen is herpes)
On CSF analysis of viral Encephalitis, would there be normal, increased or decreased proteins?
Normal to increased
On CSF analysis of viral Encephalitis, would glucose be normal, increased or decreased?
Normal
What are the 3 most important diagnostics for Encephalitis?
- MRI (Textbook- preferred choice)
- CT (what you will actually order in practice)
- LP
What is the gold standard for the diagnosis of Encephalitis?
Brain biopsy
(NOT routinely performed)
What 2 specialties should get involved STAT if you have a patient with encephalitis?
- Infectious Disease
- Neurology
What is the management and treatment of Encephalitis? (6 steps)
- Stabilize the patient (ET tube, ventilator, circulatory support, monitor electrolytes)
- Empiric antiviral treatment- Acyclovir
- Identify and tx offending agent (isolate pt until cause is found)
- Prevent & manage secondary bacterial infections
- DVT/GI (ulcer) prophylaxis
- Tx elevated ICP- consider corticosteroids and mannitol
What is the empiric medication used to treat encephalitis?
(this will be on exam)
- Start early!
- _*Acyclovir_ 10mg/kg IV q8hrs
- (Decreases morbidity/mortality due to HSV/VZV)
What is primary prevention for encephalitis? (2)
- Avoid vectors (bug spray, avoid areas, etc)
- Vaccination
What is the prognosis of encephalitis?
- 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
