Neuro: CNS Infections Flashcards
Which part of the leptomeninges is most commonly infected in meningitis?
Arachnoid mater
What is the most common organism to cause bacterial meningitis?
Strep pneumo
What is the most common organism to cause healthcare associated meningitis?
Staph
You do a LP and find that CSF has extremely low glucose. What dx are you thinking of?
TB meningitis. Low CSF glucose is the hallmark
Increasing cause of meningitis in neonates, pregnant women, people >60, and the immunocompromised. Acquired by food contamination.
Listeria monocytogenes
How do bacteria gain access to the CSF in meningitis?
Colonize in nasopharynx, attach to epithelial cells and are then transported to the bloodstream. Once in the blood, the bacterai reach the intraventricular choroid plexus, thereby gaining access to the CSF.
What causes inflammation in meningitis?
Lysis of bacteria and release of cell wall components into subarachnoid space.
When can you expect to see TNF and IL in the CSF?
within 1-2 hours of beginning of inflammation cascade
What contributes to the permeability of the BBB in meningitis?
TNF and IL working synergistically.
What obstructs the flow of CSF in meningitis and leads to obstructive and communicating hydrocephalus in meningitis?
Subarachnoid exudate obstructs the flow of CSF
Classic triad of bacterial meningitis
Fever, nuchal rigidity, change in mental status. Do NOT have to have all 3 present, Headache is often present.
What would you look for in someone you suspect meningitis in on PE?
RASH of meningococcemia (diffuse erythematous maculopapular rash) on trunk and lower extremities, mucous membranes and conjunctiva, palms and soles
Spontaneous flexion of hips during attempted passive flexion of neck
Brudzinki sign
Inability to allow full knee extension when the hip is flexed to 90 degrees
Kernig sign
If you suspect someone has bacterial meningitis, what should your next course of action be?
Obtain blood cultures and initiate empiric antibiotic therapy and dexamethasone therapy without delay!
How is the diagnosis of meningitis done?
Examining CSF
Who might need neuroimaging prior to LP?
Altered LOC, papilledema, neuro deficits
After confirmation of diagnosis of meningitis, what’s done next?
MRI, biopsy petechial skin rash
What labs would you order in someone you suspect meningitis?
CBC
Blood cultures
LP
What would you expect to see in the lab results in someone with meningitis?
Elevated WBC (predom. neutrophils)
Elevated CSF protein
Low CSF glucose
Gram stain to show organisms
Treatment of strep pneumo and N. meningiditis meningitis infection?
Ceftriaxone IV AND Vancomycin IV AND Dexamethasone IV
What meds do you add in treatment of meningitis in patient over 50 or immunocompromised?
Ceftriaxone, Vacomycin, and Dexamethasone IV PLUS
Ampicillin IV and
Acyclovir IV (possible herpes meningitis)
What conditions worsen the prognosis for meningitis?
Decreased LOC on admission Seizure within 24 hours of admission Young age or age >50 Comorbid conditions SHock Need to mechanical ventilation Delay in dx/tx
Pt presents with fever, headache, altered MS, nuchal rigidity. LP shows mildly increased WBC and lymphocytes, normal protein, glucose and opening pressure. What’s the diagnosis?
Viral meningitis
What’s the most common cause of viral meningitis? What time of year is this most common?
Enteroviruses
Summer and fall
What is the most important test in the diagnosis of viral meningitis? What about viral CNS infections in general?
CSF exam from LP
PCR amplification of CSF
Treatment of viral meningitis?
Analgesics, antipyretics, and antiemetics, as well as fluids
Who needs to be hospitalized with viral meningitis?
ALOC, focal neuro deficits, symptoms suggesting encephalitis
Treatment of viral meningitis in HIV patients?
Should receive highly active antiretroviral therapy on top of supportive therapy
What is infected in encephalitis?
Brain parenchyma (neurons, glial cells)
True or False: Viruses and bacteria can cause encephalitis.
False, just viruses
Most common viruses that cause encephalitis
Herpesviruses (HSV, VSV, EBV)
Arbovirsues (EEV, WNV)
Infection involving the brain and spinal cord
Encephalomyelitis
Infection involving brain, spinal cord, and nerve root
Encephalomyeloradiculitis
Pt. presents with acute fever, lethargy, aphasia,ataxia, and focal seizures. What do you suspect? What do you order?
Encephalopathy
LP and examination of CSF
What are the differences in CSF examination between encephalitis and viral meningitis?
Indistinguishable. Diagnose clinically
What is the most important test for patients who are not improving and who do not have a diagnosis?
Serology studies
You perform an MRI on a patient and see temporal lobe involvement. What does this suggest?
HSV encephalitis.
Your patient has signs of encephalitis but PCR fails and have abnormal MRI, and they show continued decline on acyclovir. What should be done?
Brain biopsy
Treatment for encephalitis
Acyclovir Admit to ICU Monitor ICP Fever control Seizure precautions
Normal brain function but has associated seizures, nuchal rigidity, photophobia, headahce, N/V
meningitis
Patient is confused and has seizures, sensory/motor deficits, altered speech or behavior
Encephalitis
“global brain dysfunction”
Encephalitis
