Infections of the CNS

Question 1

Presumable pathogenesis of acute meningitis

Answer 1

Nasopharyngeal colonization then local invasion then bacteremia then seeding of the meninges

Question 2

Clinical presentation of acute meningitis

Answer 2

Rapid onset nuchal rigidity, headaches, photophobia, nausea, vomiting and seizures

Question 3

LP findings with acute meningitis

Answer 3

Elevated intracranial pressure protein and mostly PMN WBCs, depressed glucose, and usually positive gram stain

Question 4

Most common acute meningits agents from birth to 3 months old

Answer 4

Strep agalactiae and E. coli from mother GU flora (screening and prophylaxis), and Listeria monocytogenes (age extremes and immunocompromised)

Question 5

Most common acute meningits agents from 3 months to 18 years old

Answer 5

Neisseria meningitides from living in close quarters, H. flu when not vaccinated, and Strep pneumoniae from pneumonia/sinusitis/otitis (treat empirically until susceptibility testing)

Question 6

Most common acute meningitis agents from 18 to 50 years of age

Answer 6

Neisseria meningitides from living in close quarters and Strep pneumoniae from pneumonia/sinusitis/otitis (treat empirically until susceptibility testing)

Question 7

Most common acute meningits agents for those over 50 years old

Answer 7

Gram negative bacilli, Strep pneumoniae from pneumonia/sinusitis/otitis (treat empirically until susceptibility testing), and Listeria monocytogenes (age extremes and immunocompromised)

Question 8

What type of antibiotics are empirically used if acute meningitis is suspected

Answer 8

bactericidal drugs with good CNS penetration

Question 9

How is aseptic meningitis different from acute meningitis

Answer 9

CSF cultures are usually negative, symptoms are milder, WBCs are mostly lymphocystes and they are less elevated, glucose is not depressed

Question 10

Causes of aseptic meningitis other than bacteria

Answer 10

Enteriviruses and medications such as NSAIDs trimethoprim-sulfamethoxazole, and IV Ig

Question 11

Clinical presentation of chronic meningitis

Answer 11

Slow onset headache, nuchal rigidity, mental status changes, nausea, vomiting, incontinence, and seizures

Question 12

Why is chronic meningitis caused by Mycobacterium tuberculosis hard to diagnose

Answer 12

There may not be pulmonary TB, CSF acid-fast stain is usually negative, and cultures take 4-6 weeks

Question 13

Encephalitis

Answer 13

Inflammation of brain parenchyma

Question 14

Noninfectious cause of encephalitis

Answer 14

Vasculitis

Question 15

Clinical presentation of encephalitis

Answer 15

Mental status changes, depressed consciousness, motor weakness, hyperreflexia, and seizures

Question 16

Most common cause of sporadic encephalitis

Answer 16

Herpes simplex type 1 virus usually in the fronto-temporal region which can be seen as a hypodensity on a CT and explains the personality changes; diagnose with PCR, CSF culture, or brain biopsy

Question 17

Definitive diagnosis of encephalitis

Answer 17

brain biopsy

Question 18

Brain abscess

Answer 18

Focal infection in parenchyma cause by direct extension of strep/staph/Haemophilus/anaerobes from nearby structures or hematogenous spread

Question 19

Clinical presentation of a brain abscess

Answer 19

Focal neurological signs, siezures and signs of increased intracranial pressure

Question 20

Diagnosis of brain abscess

Answer 20

Space occupying lesion on CT of MRI

Question 21

Epidural abscess

Answer 21

Localized infection between dura matter and bone in the spinal cord or brain

Question 22

Symptomatic differences between epidural abscesses in the brain vs the spinal cord

Answer 22

Signs of increased intracranial pressure vs localized back pain, nerve root pain and focal neurological deficits