Central Nervous System Infections

Question 1

Two most common types of CNS infections

Answer 1

Meningitis
Encephalitis

Question 2

Meningitis

Answer 2

infection/inflammation that is confined to the meninges.

Question 3

most common causes of meningitis

Answer 3

bacteria or viruses - Outcomes tend to be much worse when the etiology is bacterial as opposed to viral

viral - most people recover in 7-10 days with no neurologic deficits

Question 4

3 Bacterial Forms of Meningitis

Answer 4

(in order of prevalence)

Pneumococcal meningitis - most common cause of SNHL

Meningococcal meningitis

Haemophilus meningitis

Question 5

causes/complications of brain damage in bacterial meningitis

Answer 5

inflammation (most common) - which leads to tissue and vascular injury, as well as thrombosis (blood clot)

brain (cerebral) edema and increased intracranial pressure (ICP), which can lead to hypoxic ischemic encephalopathy (HIE)

Question 6

long-term neurobehavioral sequelae of bacterial meningitis

Answer 6

hearing loss (11%)
intellectual disabilities (4%) spasticity/paresis (4%)
seizure disorders (4%)

50% of childhood survivors tend to have cognitive/behavioral difficulties (e.g., cognitive impairments, academic limitations, ADHD/EF, language difficulties in children contracted <1 year

Question 7

Bacterial infection acute symptoms

Answer 7

(acute = several hours)

sudden fever
severe headaches (due to inflammation of the meningeal blood vessels)
nuchal rigidity (stiff neck)
vomiting
diarrhea
convulsions
irritability

Question 8

Encephalitis

Answer 8

general term that refers to an infection of the brain tissue/parenchyma

The cause is often unknown in 1/3-2/3 of cases

Question 9

Meningitis vs Encephalitis

Answer 9

Meningitis - infection/inflammation that is confined to the meninges.

Encephalitis - general term that refers to an infection of the brain tissue/parenchyma

Question 10

Most common cause of encephalitis

Answer 10

viruses - but can be because of bacteria, fungi, and parasites

Question 11

Most common viruses that cause encephalitis

Answer 11

herpes simplex virus (HSV) - most common children
varicella zoster virus
Epstein-Barr virus
adenoviruses
enteroviruses
arboviruses (e.g., ARthropod- BOrne viruses such as from ticks and mosquitoes)
cytomegalovirus

Question 12

How is meningitis diagnosed?

Answer 12

Lumbar Puncture/Blood Work

Question 13

Neurobehavioral sequelae of encephalitis

Answer 13

Average-to-low average IQ

Higher rates of learning disabilities, attention/EF/ processing speed problems, anterograde memory difficulties (forming new memories), behavioral concerns

Question 14

Autoimmune encephalitis

Answer 14

autoimmune syndrome associated with an attack of antibodies on neuronal receptors that can occur with or without a cancer association.

Question 15

Abscesses

Answer 15

infectious pus collections that occur in the brain or surrounding spaces. These infections can originate from nearby structures (e.g., ear infections, sinusitis, dental infections)

can occur after penetrating brain injury, depressed skull fracture, or neurosurgery

an cause brain damage by increasing ICP and by causing mass effect on the brain.

Question 16

Prion diseases

Answer 16

caused by infectious proteins called prions

common prior disease: Creutzfeldt-Jacob disease (CJD)

Question 17

Creutzfeldt-Jacob disease

Answer 17

prion disease

Brain tissue develops holes that give it a sponge-like appearance.

rapidly progressive and fatal (4 to 5 months for classic CJD and 14 to 15 months for variant CJD).

Symptoms typically include rapidly progressive dementia, including memory issues, personality changes, and hallucinations and physical problems such as speech impairment and ataxia.

Question 18

HIV-associated neurocognitive disorder (HAND)

Answer 18

common (up to 50% of infected individuals)

categorized by deficits in attention, executive function, fluency, memory, and psychomotor speed.

Decreases in brain activation, particularly in left frontal attentional networks, contribute to those with HAND being unable to compensate for age-related decline.

Question 19

Neurobehavioral outcomes of children with Perinatally Acquired HIV-Infection

Answer 19

Poor working memory, slowed processing, and executive problems are most consistently reported

impaired visual memory, visuospatial reasoning and language skills also seen.

depression and conduct problems primarily

Question 20

Leptomeningitis

Answer 20

Inflammation of only the pia mater and subarachnoid space.

Question 21

HIV-associated dementia / HIV-associated AIDS dementia complex (ADC)

Answer 21

More Severe: Dementia
- described as a “subcortical” dementia (similar to Parkinsons)
- The disruption of cortical connections, specifically fronto-striatal-thalamo- cortical loops, contribute to deficits in attention, working memory, executive functioning, and learning.
- Memory impairments are also seen likely due to hippocampal pathology and the interference of hippocampal neurogenesis while damage to cortical-striatal regions causes the psychomotor slowing and motor impairments commonly seen.

Less Severe: HIV-1-Associated Minor Cognitive/Motor Disorder
- similar “subcortical” profile to HIV dementia
- found in approximately 2% of those with HIV and is associated with 0.5–1 SD impairment (relative to controls) in at least two cognitive domains.

Question 22

Rasmussen’s encephalitis

Answer 22

Inflammatory disease characterized by frequent and severe seizures, loss of speech and motor skills, hemiparesis, and cognitive deficits.

typically impacts one hemisphere. It is most prevalent in young school age children (age 6), and is characterized by inflammation in the impacted hemisphere.

Question 23

Transverse myelitis

Answer 23

Disorder caused by an inflammatory process in the spinal cord (therefore no cognitive deficits) and results in demyelination of axons.

It is not associated with neuropsychological dysfunction.

Question 24

Imaging expectations of herpes simplex virus (HSV) encephalitis:

Answer 24

temporal lobe pathology and hyperintensities in the orbitofrontal regions (these can lead to memory impairments and problems with naming – dysnomia)

Question 25

Deficits of what language skill has been most documented in herpes simplex virus (HSV) encephalitis.

Answer 25

Naming

HSV tends to preferentially affect the inferior and medial surfaces of the temporal and frontal lobes. This commonly results in memory impairments and problems with naming (i.e., dysnomia).

Question 26

What can cause ring-enhancing cerebral lesions on CT/MRI?

Answer 26

HIV/AIDS, toxoplasmosis, and fungal infections

Question 27

Most frequently occurring form of encephalitis?

Answer 27

Herpes simplex