Infections of the Nervous System

Question 1

What are the three cardinal findings of bacterial meningitis?

Answer 1

fever, headache and neck stiffness

Question 2

What are two classically described physical exam findings associated with meningitis (but not specifically the bacterial form)?

Answer 2

Kernig’s sign

Brudzinski’s sign

Question 3

What is Kernig’s sign?

Answer 3

pain upon attempted passive extension at the knee when the hip is flexed

Question 4

What is Brudzinski’s sign?

Answer 4

an involuntary flexion of the hips when the neck is flexed

Question 5

What are the most common bacteria associated with bacterial meningitis?

Answer 5

Strep pneumoni
neisseria meningitides
haemophilus influenzae

Question 6

How do the bacteria usually reach the CNS in bacterial meningitis?

Answer 6

they typically reach the subarachnoid space bia hematogenous spread from the respiratory tract, but can also get there by direct extension from trauma or through the sinuses

Question 7

What are the classic findings on CSF analysis for bacterial meningitis?

Answer 7

elevated WBC with a predominance of PMNs
elevated protein
low glucose (less than 2/3rds of the serum glucose)
CSF gram stain with bacterial

Question 8

What are the typical antibiotics used empirically for bacterial meningitis?

Answer 8

Ampicillin, Ceftriaxone and Vancomycin

+ steroids in children to prevent long-term complications

Question 9

How does a brain abscess present clinically?

Answer 9

The same way any other focal intracranial lesion presents: headache, focal neurologic signs, seizures, and potentially signs of increased ICP

sometimes fever, but not always

Question 10

Solitary brain abscesses are usually caused by what? How about multiple brain abscesses?

Answer 10

solitary abscesses are usually from invasion of the intracranial space from neighboring areas of infection like the sinuses

multiple brain abscesses are seen as a result of hematogenous dissemination, such as from infective bacterial endocarditis

Question 11

What will a brain abscess look like on MRI or CT?

Answer 11

a mass lesion surrounded by ring enhancement and signs of central necrosis

Question 12

How will a spinal epidural abscess present?

Answer 12

neck or back pain with focal neurologic signs consistent with spinal cord compression or cauda equina involvement

fever is not necessarily present

Question 13

What are the three ways tuberculosis can affect the CNS?

Answer 13

1. tuberculous meningitis
2. intracranial tuberculomas
3. Pott disease

Question 14

M. tuberculosis has a predilection for what part of the CNS?

Answer 14

the basal meninges

Question 15

How will M. tuberculosis meningitis present in comparison to other bacterial meningitides?

Answer 15

will have cranial nerve palsies in addition to the usual fever, HA and nuchal rigidity

can also get hydrocephalus or brain infarcts from inflammation affecting cerebral vessels at the base of the brain

also tends to have a more subacute or chronic insidious presentation than acute bacterial meningitis

Question 16

What will tuberculous meningitis look like on CSF analysis?

Answer 16

leukocytosis with lymphocytic predominance (rather than PMNs)

CSF glucose will be very low

Acid fast bacilli staining can identify the mycobacterium and you can do PCR for mycobacterial antigens

Question 17

Describe Pott disease.

Answer 17

It’s tuberculosis of the vertebral bodies that can extend directly into the epidural space causing neurologic symptoms

note: extension through the disk spaces to adjacent vertebral bodies suggests pott disease as opposed to metastatic disease

Question 18

What are some of the ways Lyme disease can affect the CNS?

Answer 18

lyme-associated meningitis
cranial nerve palsies (bell’s palsy particularly)
a syndrome of polyradiculopathy
lyme encephalopathy

Question 19

What will a CSF analysis show in a lyme infection affecting the CNS?

Answer 19

lymphocytic pleocytosis
elevated protein
normal glucose

PCR assay for spirochetal antigen

Question 20

What is the typical CSF profile in a viral meningitis?

Answer 20

lymphocytic predominance of WBCs
elevated protein
normal glucose

negative gram stain and culture obviously

Question 21

Treatment of viral meningitis is usually just supportive unless what?

Answer 21

unless HSV1 is suspected, in which case you give IV acyclovir

Question 22

Viral encephalitis from HSV-1 has a predilection for what part of the brain?

Answer 22

the base, specifically the medial temporal lobes and orbitofrontal regions

Question 23

Describe the clinical presentation of HSV encephalitis.

Answer 23

limbic dysfunction with complex partial seizures of mesial temporal lobe origin, olfactory hallucinations and memory disturbances in addition to the usual headache, fever, and altered LOC.

Question 24

What will the CSF in HSV1 encephalitis show in addition to the usual leukocytosis?

Answer 24

elevated RBCs (and thus needs to be distinguished from a traumatic tap)

can also run a PCR for HSV1

Question 25

What might an EEG show in HSV encephalitis?

Answer 25

periodic epileptiform discharges over one or both temporal regions

Question 26

What is the CSF profile of most fungal CNS infections?

Answer 26

lymphocytic predominance of WBCs
elevated protein
low glucose

Question 27

How do immunocompromised patients typically pick up cryptococcal CNS infections?

Answer 27

inhaling the fungus (present in soil or pigeon droppings) and then disseminates hematogenously to the CNS

Question 28

How can we make the diagnosis of cryptococcal CNS infection?

Answer 28

India ink staining of the CSF or more likely a rapid latex agglutination assay for cryptococcal antigen

Question 29

What are the two main parasitic infections of the CNS?

Answer 29

toxoplasmosis (toxoplasma gondii)

neurocysticercosis (taenia solium)

Question 30

What group of patients typically gets CNS toxoplasmosis?

Answer 30

AIDS patients

Question 31

How are humans usually exposed to toxoplasma gondii?

Answer 31

cat feces or eating undercooked meat

Question 32

What will imaging show in CNS toxoplasmosis?

Answer 32

multiple ring-enhancing lesions in the basal ganglia or at the gray-white matter junction

(may need to do a biopsy to differentiate from primary CNS lymphoma)

Question 33

How do we get taenia solium?

Answer 33

it’s a tapework we can get by eating undercooked pork (endemic in Central and South America)

Question 34

What will imaging show in neurocysticercosis?

Answer 34

multiple cystic lesions which can be ring-enhancing or calcified and often with surrounding edema

Question 35

What’s the treatment for neurocysticercosis?

Answer 35

albendazole and steroids to control the inflammation and edema

Question 36

How does neurocysticercosis usually present?

Answer 36

new-onset focal seizures

Question 37

List the ways HIV can affect the CNS

Answer 37

1. opportunistic infection with toxoplasmosis, cryptococcal meningitis, JC virus (and subsequent PML)
2. HIV-associated dementia
3. vacuolar myelopathy
4. risk for primary CNS lymphoma

Question 38

Describe the dementia you get with HIV.

Answer 38

it’s a late complication with subcortical dementia - primarily cognitive impairment and psychomotor slowing

MRI will show patchy T2 hyperintensity in the white matter with cerebral atrophy

Question 39

Describe vacuolar myelopathy

Answer 39

It’s a late complication that resembles subacute combined degeneration syndrome - patients develop posterior column signs (loss of vibration and joint position sense with sensory ataxia) and signs of corticospinal tract dysfunction (spasticity and hyperreflexia)

Question 40

Primary CNS lymphoma is associated with what virus?

Answer 40

EBV