Infections- ACUTE MENINGITIS

Question 1

With infection, damage to nervous tissue may be the consequence of** ____________________**

Answer 1

• direct injury of neurons or
• glia by the infectious agent or
• may occur indirectly through the elaboration of microbial toxins,
• destructive effects of the inflammatory response,
• or the result of immune-mediated mechanisms.

Question 2

There are four principal routes by which infectious microbes enter the nervous
system.

Answer 2

1. Hematogenous spread
2. Direct implantation of microorganisms
3. Local extension
4. peripheral nervous system

Question 3

_____________ is the most common means of entry; infectious agents ordinarily
enter through the arterial circulation, but retrograde venous spread can occur through
anastomoses with veins of the face.

Answer 3

Hematogenous spread

Question 4

Direct implantation of microorganisms is almost invariably
________________

Answer 4

traumatic or is associated with congenital malformations

(such as meningomyelocele).

Question 5

Local
extension can come from any of several adjacent structures ________________.

Answer 5

(air sinuses, an infected tooth,
cranial or spinal osteomyelitis)

Question 6

Transport along the peripheral nervous system occurs with
certain viruses, such as______________

Note :. General aspects of the pathology of
infectious agents are discussed in Chapter 8 ; here we focus on some of the distinctive forms of
CNS infections

Answer 6

rabies and herpes zoster.

Question 7

ACUTE MENINGITIS
Meningitis refers to an i

Answer 7

• Acute Pyogenic (Bacterial) Meningitis
• Acute Aseptic (Viral) Meningitis

Question 8

What is Meningitis ?

Answer 8

refers to an inflammatory process of the leptomeninges and CSF within the
subarachnoid space,

Question 9

What is while meningoencephalitis

Answer 9

It combines this with inflammation of the brain
parenchyma.

Question 10

Meningitis is usually caused by an __________, but may also occur in response to a
nonbacterial irritantintroduced into thesubarachnoid space (chemical meningitis).

Answer 10

infection

Question 11

Infectious
meningitis is broadly classified into:

on the basis of the characteristics of inflammatory exudate on CSF examination and the clinical evolution of the illness.

Answer 11

• ** acute pyogenic** (usually bacterial meningitis),
• aseptic (usually acute viral meningitis),
• and chronic (usually tuberculous, spirochetal, or cryptococcal)

Question 12

The microorganisms that cause acute pyogenic meningitis vary with the age of the affected
individual.

In neonates, they include__________ and _________

Answer 12

Escherichia coli and the group B streptococci;

Question 13

The microorganisms that cause acute pyogenic meningitis vary with the age of the affected individual. In other
extreme of life, ____________ and __________ are more common.

Answer 13

Streptococcus pneumoniae and Listeria monocytogenes

Question 14

Among adolescents and in young adults,_________- is the most common pathogen,
with clusters of cases causing frequent public health concerns.

Answer 14

Neisseria meningitidis

Question 15

The introduction of immunization
against Haemophilus influenzae has markedly reduced the incidence of meningitis associated
with this organism in the developed world; the population that was previously at highest risk
(infants) now has a much lower overall risk of meningitis, with _____________ being the most
prevalent organism.

Answer 15

S. pneumoniae

Question 16

Affected individuals typically show__________superimposed on clinical evidence
of meningeal irritation and neurologic impairment, including headache, photophobia, irritability,
clouding of consciousness, and neck stiffness.

Answer 16

systemic signs of infection

Question 17

A spinal tap yields___________, under increased pressure, with as many as_______________, an
___________ protein concentration, and a __________ glucose content.

Answer 17

• cloudy or frankly purulent CSF
• 90,000 neutrophils per cubic millimeter
• increased
• markedly reduced

Question 18

Bacteria may be
seen on a smear or can be cultured, sometimes a few hours before the neutrophils appear.
Untreated pyogenic meningitis can be fatal, while effective antimicrobial agents markedly
reduce mortality.

Question 19

The Waterhouse-Friderichsen syndrome results from ______________(
Chapter 24 .

Answer 19

• *meningitis-associated**
• *septicemia** with hemorrhagic infarction of the **adrenal glands and cutaneous petechiae **

Question 20

The Waterhouse-Friderichsen syndrome . It occurs most often with__________ and ____________

Answer 20

meningococcal and pneumococcal meningitis.

Question 21

The normally clear CSF is __________and sometimes frankly _____________ in Acute Pyogenic ( Bacterial) Meningitis.

Answer 21

cloudy

purulent

Question 22

In acute
meningitis, an exudate is evident within the____________

The meningeal vessels are engorged and stand out prominently.

Answer 22

leptomeninges over the surface of the brain

Question 23

The location
of the exudate varies; in H. influenzae meningitis, for example, it is usually_________

Answer 23

basal,

Mnemonics: HB– High blood!

Question 24

Whereas in
pneumococcal meningitis it is often densest over the cerebral convexities near the______

Answer 24

sagittal
sinus.

Question 25

From the areas of greatest accumulation, tracts of pus can be followed along blood
vessels on the surface of the brain.

What happens when the meningitis is fulminant, the inflammation may
_______________

Answer 25

extend to the ventricles, producing ventriculitis.

Question 26

On microscopic examination, neutrophils fill predominantly around the_______________ in less severe
cases.

Answer 26

leptomeningeal blood vessels

Question 27

On microscopic examination, neutrophils fill the_____________in severely affected
areas

Answer 27

subarachnoid space

Question 28

_______________ may follow pyogenic meningitis and cause hydrocephalus.

Answer 28

Leptomeningeal fibrosis

Question 29

What is chronic adhesive arachnoiditis.?

Answer 29

In some
infections, particularly in** pneumococcal meningitis**, large quantities of the capsular
polysaccharide of the organism produce a particularly gelatinous exudate that encourages
arachnoid fibrosis

Question 30

What is Aseptic meningitis?

Answer 30

It is a clinical term referring to the absence of recognizable organisms in a
patient with meningeal irritation, **fever, and alterations of consciousness of relatively acute **onset.

The name is a misnomer, as the disease is generally of viral, and rarely of bacterial or
**other, etiology. **

Question 31

What is the clinical course of acute aseptic meningitis?

Answer 31

• It is less fulminant than that of pyogenic meningitis, and
• the** CSF findings also differ;**
  
  • in aseptic meningitis there is a lymphocytic pleocytosis,
  • the protein elevation is only moderate,
  • and the glucose content is nearly always normal.
• ​The viral aseptic meningitides are usually self-limiting and are treated symptomatically.
• Remarkably, even with molecular methods for detection of pathogens, the etiologic agent is identified in only a minority of cases. [19]

Question 32

In acute aseptic meningitis, the spectrum of pathogens varies seasonally and geographically.

Question 33

An aseptic
meningitis–likepicturemay also develop subsequent to rupture of an epidermoid cyst into the
subarachnoid space or the introduction of a chemical irritant (“chemical” meningitis).

In these
cases the CSF characteristic is:

Answer 33

• CSF is sterile,
• there is pleocytosis with neutrophils
• and an increased protein concentration,
• but the sugar content is usually normal.