CNS infections

Question 1

Most likely diagnosis- Stiff neck, photophobia, meningismus

Answer 1

meningitis

Question 2

Most likely diagnosis- Confusion

Answer 2

Encephalitis

Question 3

Most likely diagnosis- Focal neurological findings

Answer 3

abscess

Question 4

Meningitis infection bacteria

Answer 4

Streptococcus pneumonia (60%), group B strep (14%), Haemophilus influenzae (7%), Neisseria meningitidis (15%), and Listeria (2%). Staph occurs in those with recent neurosurgery

Question 5

Meningitis presentation

Answer 5

• fever, headache, neck stiffness, photophobia
  -presents over several hours
  focal neurological abnormalitis occur in up to 30% of patients
  -If confusion present must order CT and LP
  -Cryptococcal meningitis may be present for several weeks

Question 6

Most likely diagnosis- AIDS with <100 CD4 cell/ul

Answer 6

Cryptococcus

Question 7

Most likely diagnosis- Camper/hiker, rash shaped like a target, joint pain, facial palsy, tick remembered in 20%

Answer 7

Lyme disease

Question 8

Most likely diagnosis- Camper/hiker, rash moves from arms/legs to trunk, tick remembered in 60%

Answer 8

Rocky Mountain spotted fever (Rickettsia)

Question 9

Most likely diagnosis- Pulmonary TB in 85%

Answer 9

Tuberculosis

Question 10

Most common diagnosis- no symptoms

Answer 10

Viral

Question 11

Most common diagnosis- Adolescent, petechial rash

Answer 11

Neisseria

Question 12

CSF eval- cell count very high with neutrophils, protein level high, glucose low, stain 50-70%, culture 90%

Answer 12

Bacterial meningitis

Question 13

CSF eval- cell count 10s-100s with lymphocytes, protein level possibly elevated, glucose level possibly decreased, stain and culture negative

Answer 13

Cryptococcus, lyme, rickettsia

Question 14

CSF eval- cell count 10s-100s with lymphocytes, protein level markedly elevated, glucose level may be low, stain and culture negative

Answer 14

Tuberculosis

Question 15

cell count 10s-100s with lymphocytes, protein level usually normal, glucose level usually normal, stain and culture negative

Answer 15

Viral

Question 16

When is head CT prior to LP the correct answer?

Answer 16

If papilledema, seizures, focal neurological abnormalitis or confusion interfering with the neurological exam are present. Therefore if there is the possibility that a space=occupying lesion may cause herniation

Question 17

If contraindication to immediate LP

Answer 17

give antibiotics. Better to treat and decrease accuracy of a test than risk permanant brain damage

Question 18

When is bacterial antigen test (Latex agglutination test) indicated?

Answer 18

When the patient has received antibiotics prior to the LP and the culture may be falsely negative. Not sentative but if positive highly specific

Question 19

Most accurate test for Tuberculosis?

Answer 19

Acid fast stain and culture on 3 high-volume lumbar punctures. Centrifuge the specimen to concentrate the organisms. TB has the highest CSF protein level. An acid fast stain of a single, uncentrifuged sample of CSF has only 10% sensitivity.

Question 20

Most accurate test for Lyme and Rickettsia?

Answer 20

Specific serologic testing, ELISA, western blot, PCR.

Question 21

Most accurate test for Cryptococcus?

Answer 21

India ink 60-70% sensitive. Cryptococcal antigen is more than 95% sensitive and specific.

Question 22

Best initial treatment for bacterial meningitis?

Answer 22

Ceftriazone, Vancomycin, and steroids if thousands of neutrophils present. Add ampicillin if immunocompromised (Listeria).Tx based on cell count. Culture takes 2-3days. gram stain is useful if positive, false negative 30-50%. Protein and glucose levels to nonspecific.

Question 23

Steroids (dexamethasone) is only proven to lower mortality in?

Answer 23

S.pneumoniae

Question 24

Listeria is resistant to all _______________ but sensitive to _______________

Answer 24

cephalosporins, penicillins

Question 25

Risk factors for Listeria?

Answer 25

elderly, neonates, steroid use, AIDS/HIV, immunocompromied, including alcoholism, pregnant

Question 26

Additional management for Neisseria meningitidis.

Answer 26

Respiratory isolation, Rifampin or ciprofloxacin to close contacts to decrease nasopharyngeal carriage (close contacts include household contacts, kissing, or sharing cigarettes or eating utensils. Routine school/work contacts do not count. Healthcare workers qualify only if they intubate the patient, perform suctioning, or have contact with respiratory secretions)

Question 27

A man comes to the ED with fever, severe headache, neck stiffness, and photophobia. On PE he is found to have weakness of his left arm and leg. What is the most appropriate next step in the management of this patient?

a. ceftriaxone, vancomycin, and steroids
b. heat CT
c. Ceftriaxone
d. Neurology consultation
e. Steroids

Answer 27

A. When there is a contraindication to an immediate LP, the most important step is to initiate treatment. A head CT is important for this patient because of focal neurological deficits, but it is more important to initiate therapy. Additionally if the head CT shows a mass lesion you may never be able to perform and LP

Question 28

What is the most common neurological deficit of untreated bacterial meningitis?

Answer 28

Eight cranial n. deficit or deafness

Question 29

When is consultation the correct answer on Step 2?

Answer 29

Almost never

Question 30

Encephalitis presentation

Answer 30

acute onset of fever and confusion

Question 31

Most common cause of encephalitis

Answer 31

Herpes simplex

Question 32

Initial test in encephalitis

Answer 32

Head CT first because of the presence of confusion

Question 33

What is the most accurate test of herpes encephalitis?

a. Brain biopsy
b. PCR of CSF
c. MRI
d. Viral culture of CSF
e. Tzanck prep
f. Serology for herpes (IgG, IgM)

Answer 33

B. PCR is more accurate than a brain biopsy. Serology is useless, 95% of population will be positive. Tzanck prep can be done as the initial test on a genital ulcerative lesion. Viral culture is the most accurate test of genital or skin lesion, but not of CSF or the brain

Question 34

Best initial treatment for herpes encephalitis?

Answer 34

Acyclovir. Famciclovir and Valacyclovir are not available as IV formulations. Foscarnet is used for acyclovir-resistant herpes.

Question 35

A woman is admitted for herpes encephalitis confirmed by PCR. After 4d of acyclover her creatinine level begins to rise. What is the most appropriate next step?

a. Stop acyclovir.
b. Reduce the dose of acyclovir and hydrate.
c. Switch to oral famciclovir or valacyclovir
d. Switch to foscarnet.

Answer 35

B. Oral medications such as famciclovir and valacyclovir are insufficient for herpes encephalitis. Although acyclovir may occasionally be renal toxic because the medication precipitates in the renal tubules, foscarnet has far more renal toxicity.