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20796741 diseases of the central nervous system

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Diseases of the Central
Nervous System
Brain & Meninges
» Meningitis
» Rabies
» Encephalitis
Nerve Diseases
» Hansen’s disease
» Tetanus
» Poliomyelitis
» Transmissible Spongiform Encephalopathy
MENINGITIS
» Inflammation of the meninges
» May be bacterial or viral (aseptic)
» May result from complications of neurosurgery,
trauma, infection or the sinus or ears, or systemic
infections
Etiologic Agents
» Streptococcus pneumoniae
» Heamophilus influenza type
B
» Neisseria meningitidis
» Enterovirus
» HSV
» Mumps virus
Pathophysiology
» Initially, the infectious agent colonizes or establishes
a localized infection in the host. This may be in the
form of colonization or infection of the skin,
nasopharynx, respiratory tract, gastrointestinal tract,
or genitourinary tract. Most meningeal pathogens are
transmitted through the respiratory route, as
exemplified by the nasopharyngeal carriage of
Neisseria meningitidis (meningococcus) and
nasopharyngeal colonization with S. pneumoniae
(pneumococcus).
» From this site, the organism invades the submucosa
by circumventing host defenses (e.g., physical
barriers, local immunity, phagocytes/macrophages)
and gains access to the CNS by (1) invasion of the
bloodstream (i.e., bacteremia,
viremia, fungemia,
parasitemia) and subsequent
hematogenous seeding of the
CNS, which is the most
common mode of spread for most agents (e.g.,
meningococcal, cryptococcal, syphilitic, and
pneumococcal meningitis); (2) a retrograde neuronal
(i.e., olfactory and peripheral nerves) pathway (e.g.,
Naegleria fowleri, Gnathostoma spinigerum); or (3)
direct contiguous spread (i.e., sinusitis, otitis media,
congenital malformations, trauma, direct inoculation
during intracranial manipulation).
Epidemiology
» Most frequent in children less
than 5years old with peak rate in
the 6-12months age group.
Incubation Period
» 2-10 days (Meningococcal)
Mode of Transmission
» Person to person thru infected
droplets of respiratory secretion.
» Close contact such as household, day care centers,
nursery schools, military camps.
Signs and Symptoms
» Sudden onset of high fever for 24hours, petechiae,
red macular rashes,
nuchal rigidity (stiff
neck-pain w/neck
flexion), photophobia.
» Meningeal irritation.
» Kernig sign: In a supine
patient, flex the hip to
90°. While the knee is
flexed at 90°, an attempt
to further extend the leg
produces pain in the
hamstrings and resistance
to further extension.
» Brudzinski sign:
Passively flex the neck
while the patient is in a
supine position with
extremities extended.
This maneuver produces
flexion of the hips in
patients with meningeal
irritation.
Diagnosis
» Lumbar puncture (high
WBC, high protein, low
glucose, cloudy CSF).
» LP: insertion of a spinal
needle through the L3-L4
interspace into the lumber
subarachnoid space to
obtain CSF; the test is
contraindicated in clients
with increased ICP because this procedure will cause
a rapid decrease in pressure in the CSF around the
spinal cord, leading to brain herniation
Preprocedure: obtain informed consent;
have the client empty the bladder
During the procedure: position the client in
a lateral recumbent position and have the
client draw the knees up to the abdomen
and the chin onto the chest; assist with the
collection of specimens (label the
specimens in sequence); maintain strict
asepsis
Postprocedure: monitor V/S and
neurological signs that may indicate leakage

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of CSF; position the client flat as
prescribed; encourage fluids to replace CSF
obtained from the specimen collection or
from leakage
» G/S of petechial scraping, CSF, blood (Gram
negative diplococci).
Complications
» Deafness, ataxia, seizure, obstructive hydrocephalus,
arthritis, pneumonia, DIC, myocaarditis.
Treatment
» PenG IV
» Chloramphenicol if with allergy to Pen
» Mannitol (for cerebral edema)
» Dexamethasone (anti-inflammatory)
Nursing Interventions
» Medications as ordered
» Assess for signs of increasing ICP: widening pulse
pressure, HPN, bradycardia (Cushing’s Triad)
» Priority: airway, safety
» Strict respiratory precaution until 1st 24hours of
antibiotic treatment
» Institute seizure precautions
» Keep room dark
» Elevate the HOB 30deg; avoid neck flexion and
extreme hip flexion
» Prevent stimulation and restrict visitors
» Suctioning of secretions; hand washing
RABIES
» Severe viral infection of CNS that is communicated
to humans by the saliva of infected mammals.
» Also Hydrophobia, caused by Rhabdovirus
(neurotropic virus from Genus Lyssavirus).
Pathophysiology
» When the rabies virus enters muscles, it replicates
locally and then is transported through peripheral
sensory nerves to the spinal ganglia, where it
replicates and travels up the spinal cord to the brain.
The virus migrates to the gray matter of the brain and
predominates in the neurons of the limbic system,
midbrain, and hypothalamus. Efferent nerves
transport virus to the acinar glands of the
submaxillary salivary glands, where it achieves high
concentrations.
Epidemiology
» 4.4/100,000 population
» Highest incidence in R
IV,V,VII
» Source: saliva of rabid
dogs, bats, cats, cattle
Incubation Period
» 5days-6years (average 2-8 weeks); variation in
length of incubation period depend on severity of
bite, site of bite in relation to the richness of nerve
supply and distance from CNS, size of inoculum, age
and immune status of host, protection provided by
clothing.
Mode of Transmission
» Bites of rabid animals
» Human-to-human transmission has only occurred
with corneal transplants.
» Transmission of virus in saliva through mucous
membranes, open wounds, or scratches is possible
but rarely documented.
Signs and Symptoms
» Rabid dog: withdrawn, dumb, paralytic; furious
stage: bites without provocation.
» In man:
Prodromal: headache; malaise; anorexia; sore
throat; salivation; diaphoresis; tingling sensation;
numbness at site of bite; low grade fever
Excitement/maniacal:
hydrophobia; aerophobia;
increased anxiety; cranial
affectation
Paralytic stage: die of paralysis
or respiratory arrest
Diagnosis
» History of exposure to saliva of infected animal
» Negri bodies in samples of brain tissue of infected
animal; Fluorescent Rabies Antibody Staining
Treatment
» Symptomatic and supportive
» Wash area of bite with soap
and running water.
Nursing Interventions/Considerations
» Strict isolation of aeg throughout the course of
illness; caution against contamination of open wound
or mucous membrane with aeg’s saliva.
» Immunization:
Active
« Purified Verocell Rabies Vaccine (PVRV)
0.5ml/vial
« Purified Duck Embryo Vaccine (PDEV) 1ml/vial
« Purified Chick Embryo Cell Vaccine (PCECV)
1ml/vial
« May be administered IM/ID
Passive
« Rabies Human Immune Globulin
ENCEPHALITIS
» Acute viral encephalitis (enkephalos + -itis, meaning
brain inflammation) is often an unusual
manifestation of common viral infections and most
commonly affects children and young adults.
» In general, viral encephalitides can be divided into 4
separate categories based on the cause and
pathogenesis of the following complications:
Acute viral encephalitis;
Postinfectious encephalomyelitis;
Slow viral infections of the CNS;
And chronic degenerative diseases of the CNS,
which are presumed to be of viral origin.
Etiology
» Person-person spread
Mumps: frequent in unimmunized population
Measles
Enterovirus group: more serious in neonates
Rubella: uncommon
Herpesvirus group: HSV 1&2; VZV; CMV; EBV
» Arthropod-borne
Arbovirus: spread by mosquitoes or ticks; Japanese
encephalitis is the most common
» Spread by mammals
Rabies

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Diseases of the Central Nervous System  Brain & Meninges » Meningitis » Rabies » Encephalitis  Nerve Diseases » Hansen’s disease » Tetanus » Poliomyelitis » Transmissible Spongiform Encephalopathy MENINGITIS » Inflammation of the meninges » May be bacterial or viral (aseptic) » May result from complications of neurosurgery, trauma, infection or the sinus or ears, or systemic infections Etiologic Agents » Streptococcus pneumoniae » Heamophilus influenza type B » Neisseria meningitidis » Enterovirus » HSV » Mumps virus Pathophysiology » Initially, the infectious agent colonizes or establishes a localized infection in the host. This may be in the form of colonization or infection of the skin, nasopharynx, respiratory tract, gastrointestinal tract, or genitourinary tract. Most meningeal pathogens are transmitted through the respiratory route, as exemplified by the nasopharyngeal carriage of Neisseria meningitidis (meningococcus) and nasopharyngeal colonization with S. pneumoniae (pneumococcus). » From this site, the organism invades the submucosa by circumventing host defenses (e.g., physical barriers, local immunity, phagocytes/macrophages) and gains access to the CNS by (1) invasion of the bloodstream (i.e., bacteremia, viremia, fungemia, parasitemia) and subsequent hematogenous seeding of the CNS, which is the most common mode of spread for most agents (e.g., meningococcal, cryptococcal, syphilitic, and pneumococcal meningitis); (2) a retrograde ne ...
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