Trans 040 Patho Infections of CNS Flashcards
MOST COMMONLY
IN PEDIATRICS referred to as Meningimus
non bacterial aspetic meningitis
There is reaction of meninges in systemic infection but it
is not in the brain it is just a reaction
in 3 mos to 2 y/o, what is the most common cuase of bacterial meningitis?
route?
N. Meningitidis
Route: respiratory tract
Acute Pyogenic Meningitis (Bacterial Meningitis)
• In neonates, common organisms are
In adolescents and young adults, most cmmon pathogen is?
In older adults,
Escherichia
coli and group B streptococci.
N. meningitidis
Strep Pneumoniae and Listeria Monocytogenes
Modifiable Risk Factors for Bacterial Meningitis
• Not completing childhood vaccines** • Median age of diagnosis 25 years • Living in close quarters (meningococcal)** • Pregnancy (listeriosis) • Working with animals (listeriosis) • Compromised immune system (from aids, spleen removal, diabetes, use of immunosuppressant drugs **Most common in our country
MOST COMMON ROUTE OF ENTRY, bacterial mening
Hematogenous route: through arterial and venous spread
Routes of infection in bacterial mening?
• Hematogenous route: through arterial and venous spread- MOST COMMON ROUTE OF ENTRY
Mucosa → Upper respiratory tract → blood vessels (arteries) → choroid plexus →meninges
• Direct implantation
If you do lumbar puncture to some disease
Not working on sterile condition, you can introduce bacteria into CSF
o Maybe traumatic
o Rarely, iatrogenic i.e., through lumbar puncture needle
• Local extension: through air sinuses, infected tooth or surgical site
• Through peripheral nervous system as occurs with certain viruses
How does bacteria gain entry through meningitis?
It is through the choroid plexus coz CSF is produce here and choroid plexus has blood supply
CSF is a secretory product of Choroid plexus which is derived from blood circulation
Once it gains entry to CSF → break into subarachnoid space → rapid multiplication in CSF
Pathophysio of bacterial meningitis?
You get it through air that’s why easily transmissible in people who are living very close together
Bacterial transport through air → Entry → implantation (at the site where it gains entry) → multiplication → nasopharyngeal colonization in epithelial cells → Local invasion into intravascular space (viremia) → bacteremia → artery that supplies part of brain → meningitis
Suppuration in subarachnoid space → Inc. ICP → non-communicating hydrocephalus → cerebral herniation → death
Difference if bacterial invasion is via the artery vs via veins
If the bacterial invasion is into the artery it will go into brain through choroid plexus
If the bacterial invasion is venous it will drain into systemic circulation. If it drains there, you will produce a septicemic condition known as WFS or Waterhouse-Friderichsen syndrome
Complications of acute pyogenic miningitis
Phlebitis
Leptomeningeal infarction and consequent hydrocephalus
Septicemia with hemorrhagic infarction of the adrenal glands and cutaneous petechiae (known as
Waterhouse-Fridrichsen Syndrome particularly common with meningococcal meningitis)
Waterhouse-Friderichsen syndrome (WFS) syndrome or hemorrhagic adrenalitis or Fulminant meningococcemia
Focal cerebritis and seizures
Cerebral abscess
- Cognitive deficit
- Deafness
Adrenal gland failure due to bleeding into the adrenal glands
waterhouse Friderichsen syndrome
cause of waterhouse friderichsen syndrome
Caused by severe bacterial infection – most commonly the meningococcus Neisseria meningitidis
MC cause of DIC?
Septicemia
What are direct extension causes of cerebral abcess? (4)
Otitis
Paranasal Sinus
Mastoiditis
Calvarial or meningeal infection
most common cause of cerebral abcess?
septic embolization to the brain
MOST COMMON ROUTE OR SOURCE OF SEPTIC EMBOLIZATION?
congenital heart disease. Px with abnormal valves
most common source of direct extension to the brain causing cerebral abcess?
MOST COMMON SOURCE is otitis media
small subpial or subependymal foci of metastatic caseous lesion
Rich foci
complications of TB meningitis
• Hydrocephalus • Subdural effusion • Hemiplegia/Paraplegia • Late: o Intellectual impairment o Blindness o Deafness o Intracranial calcifications leading to hypothalamic and pituitary dysfunction o Growth failure o Diabetes insipidus o Failure of development of secondary sexual characteristics
MOST COMMON INFECTION OF CNS ESPECIALLY IN <1 YR
bacterial or viral?
Viral
Common viral agents?
Enterovirus coxsackie virus A e B Echovirus Arbovirus HIV HSV - 2
Herpes simplex encephalitis pathophysiology?
Brain infection is thought to occur by means of direct neuronal transmission of the virus from a peripheral site to the brain via the trigeminal or olfactory nerve.