Meningitis and Encephalitis

Question 1

What is bacterial meningitis?

Answer 1

Meningitis is an inflammatory process of the membranes that surround the brain and spinal cord. It is classified as bacterial meningitis when caused by a bacterial pathogen

Question 2

What are the most common bacterial organisms in bacterial meningitis?

Answer 2

The most common bacterial pathogens include include Streptococcus pneumoniae and Neisseria meningitidis.

Question 3

Who is more likely to get Listeria meningitis?

Answer 3

Listeria monocytogenes meningitis is a disease more common in older patients (greater than 50 years old), infants (less than 3 months old), and immunocompromised or pregnant individuals.

Question 4

What is aseptic meningitis?

Answer 4

Meningitis is classified as aseptic meningitis when the inflammation is due to other causes such as drugs or non-bacterial infections.
- Viruses most common. Enteroviruses and echoviruses. Also HSV.

Question 5

What is encephalitis?

Answer 5

Encephalitis is an infection of the brain parenchyma causing inflammation within the CNS and is often viral in origin.

Question 6

When should you start antibiotics?

Answer 6

After lumbar puncture or blood cultures if lumbar puncture is going to be delayed. Start viral treatment if HSV is suspected.

Question 7

What are the classic symptoms of meningitis?

Answer 7

fever, neck stiffness, and altered mental status.

Question 8

What are the most common initial symptoms of meningitis?

Answer 8

Nonspecific. Headache, nausea and vomiting, and neck pain

Question 9

What are the classic symptoms of meningitis and what differentiates it from meningitis?

Answer 9

The clinical presentation of patients with encephalitis can be similar to patients with meningitis, including fever, headache, or stiff neck, but the diagnosis of encephalitis is characterized by the presence of altered mental status or neurologic symptoms.

Question 10

What are the classical physical exam findings of meningitis?

Answer 10

Classically described meningeal findings include nuchal rigidity (severe neck stiffness due to meningeal irritation), Kernig’s sign (flexing the hip and extending the knee to elicit pain in the back and the legs) and Brudzinski’s sign (passive flexion of the neck elicits flexion of the hips).

Question 11

When should a CT be done before LP?

Answer 11

A CT scan of the brain before LP should be considered under the following circumstances: altered mental status, new onset seizures, an immunocompromised state, focal neurologic signs, or papilledema.

Question 12

What LP findings are diagnostic for meningitis or encephalitis?

Answer 12

Elevated numbers of white blood cells in the CSF obtained by lumbar puncture are diagnostic for meningitis or encephalitis

Question 13

Bacterial meningitis CSF findings

Answer 13

Positive Gram’s stain with identified organism
Glucose less than 40 mg/dL or ratio of CSF/blood glucose less than 0.40
Protein greater than 200 mg/dL
WBC greater than 1000/mL
Greater than 80% polymorphonuclear neutrophils
Elevated opening pressure of CSF during LP (pressure reading must be obtained with patient in the lateral decubitus position)

Question 14

Viral meningitis CSF findings

Answer 14

Normal opening pressure
< 300 WBC
1-50% neutrophils
Normal glucose
Normal protein
Nothing on gram stain

Question 15

Fungal meningitis CSF findings

Answer 15

Elevated opening pressure
< 500
1-50% neutrophils
Reduced glucose
Elevated protein
Nothing on gram stain

Question 16

CSF findings in Encephalitis

Answer 16

CSF studies for patients with encephalitis will lead to similarly abnormal results with increased numbers of white blood cells in the CSF, generally with a lymphocytic predominance. Results may also reveal increased numbers of red blood cells in the CSF due to neuronal cell death leading to edema, hemorrhage, and necrosis when encephalitis is present.

Question 17

What is HSV encephalitis treated with?

Answer 17

HSV encephalitis is the only cause of this disease with a specific treatment, and intravenous acyclovir is recommended for patients suspected to have this infection.

Question 18

When should you consider dexamethasone?

Answer 18

Consider intravenous dexamethasone every 6 hours for 4 days in adults and children 3 months and older when it is initiated before or at the same time antibiotics are given

Question 19

Should empiric antibiotics be delayed for LP?

Answer 19

Empiric antibiotics should not be delayed while waiting for a CT scan prior to an LP if meningitis is a likely diagnosis. When a CT scan is necessary, draw blood cultures and administer steroids and appropriate antibiotics before the LP.

Question 20

What are contraindications to a lumbar puncture?

Answer 20

such as an occult mass from infection or brain tumor, or signs of brain shift or herniation.