Central Nervous System Infections Flashcards
Two most common types of CNS infections
Meningitis
Encephalitis
Meningitis
infection/inflammation that is confined to the meninges.
most common causes of meningitis
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
3 Bacterial Forms of Meningitis
(in order of prevalence)
Pneumococcal meningitis - most common cause of SNHL
Meningococcal meningitis
Haemophilus meningitis
causes/complications of brain damage in bacterial meningitis
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)
long-term neurobehavioral sequelae of bacterial meningitis
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
Bacterial infection acute symptoms
(acute = several hours)
sudden fever
severe headaches (due to inflammation of the meningeal blood vessels)
nuchal rigidity (stiff neck)
vomiting
diarrhea
convulsions
irritability
Encephalitis
general term that refers to an infection of the brain tissue/parenchyma
The cause is often unknown in 1/3-2/3 of cases
Meningitis vs Encephalitis
Meningitis - infection/inflammation that is confined to the meninges.
Encephalitis - general term that refers to an infection of the brain tissue/parenchyma
Most common cause of encephalitis
viruses - but can be because of bacteria, fungi, and parasites
Most common viruses that cause encephalitis
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
How is meningitis diagnosed?
Lumbar Puncture/Blood Work
Neurobehavioral sequelae of encephalitis
Average-to-low average IQ
Higher rates of learning disabilities, attention/EF/ processing speed problems, anterograde memory difficulties (forming new memories), behavioral concerns
Autoimmune encephalitis
autoimmune syndrome associated with an attack of antibodies on neuronal receptors that can occur with or without a cancer association.
Abscesses
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.
Prion diseases
caused by infectious proteins called prions
common prior disease: Creutzfeldt-Jacob disease (CJD)
Creutzfeldt-Jacob disease
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.
HIV-associated neurocognitive disorder (HAND)
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.
Neurobehavioral outcomes of children with Perinatally Acquired HIV-Infection
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
Leptomeningitis
Inflammation of only the pia mater and subarachnoid space.
HIV-associated dementia / HIV-associated AIDS dementia complex (ADC)
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.
Rasmussen’s encephalitis
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.
Transverse myelitis
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.
Imaging expectations of herpes simplex virus (HSV) encephalitis:
temporal lobe pathology and hyperintensities in the orbitofrontal regions (these can lead to memory impairments and problems with naming – dysnomia)
