Meningitis
Definition
-it is an inflammation of the lining around the brain and spinal cord caused by
bacteria /viruses.
Meningitis
is classified as
Aseptic- the cause is viral or secondary to
lymphoma , leukemia, HIV
Septic - it is caused by bacteria
·
Bacteria
: streptococcus pneumoniae and Neisseria meningitides are responsible for 80%
of cases of meningitis in adults.
·
Neisseria
meningitides infection are most likely to occur in dense community groups such
as college campuses and military installations. The peak incidence is in the
winter and early spring
Risk factors for
bacterial meningitis
·
Tobacco
use
·
Viral
upper respiratory infections
·
Otitis
media and mastoiditis — because bacteria can cross the epithelial membrane and
enter the subarachnoid space.
·
People
with immune deficiency
Pathophysiology
·
Meningeal
infections generally originate in one of two ways: through the bloodstream because
of other infections or by direct spread, such as might occur after a traumatic
injury to the facial bones or secondary to invasive procedures.
·
N.
meningitides concentrates in the nasopharynx and is transmitted by secretion or
aerosol contamination.
·
Bacterial
or meningococcal meningitis also occurs as an opportunistic infection in
patients with acquired immunodeficiency syndrome (AIDS) and as a complication
of Lyme disease.
·
Once
the causative organism enters the bloodstream, it crosses the blood-brain
barrier and proliferates in the cerebrospinal fluid (CSF).
·
The
host immune response stimulates the release of cell wall fragments and
lipopolysaccharides, facilitating inflammation of the subarachnoid and pia
mater.
·
Because
the cranial vault contains little room for expansion, the inflammation may
cause increased intracranial pressure (ICP). CSF circulates through the
subarachnoid space, where inflammatory cellular materials from the affected
meningeal tissue enter and accumulate.
Prognosis
·
The
prognosis for bacterial meningitis depends on the causative organism, the
severity of the infection and illness, and the timeliness of treatment.
·
Acute
fulminant presentation may include adrenal damage, circulatory collapse, and
widespread hemorrhages (Waterhouse-Friderichsen syndrome).
·
This
syndrome is the result of endothelial damage and vascular necrosis caused by
the bacteria. Complications include visual impairment, deafness, seizures,
paralysis, hydrocephalus, and septic shock.
Clinical symptoms
·
Headache
and fever are frequently the initial symptoms
·
Fever
tends to remain high throughout the course of illness
·
The
headache is usually either steady or throbbing and very severe as a result of
meningeal irritation
·
Neck
mobility —a stiff and painful neck (nuchal rigidity) can be early sign and any
attempts at flexion of the head are difficult because of spasm in the muscles
of the neck.
·
Positive
kernig's Sign — when the patient is lying with the thigh flexed on the abdomen,
the leg cannot be completely extended.
·
Positive
brudzinski's sign — when the patients neck is flexed (after ruling out cervical
trauma or injury), flexion of the knees and hips is produced; when the lower
extremity of one side is passively flexed, a similar movement is seen in the
opposite extremity. Brudzinkis sign is a more sensitive indicator of meningeal
irritation than kernigs sign.
·
Photophobia:
(extreme sensitive light) this finding is common, although the cause is unclear
·
A
rash can be a striking feature of N. meningitidis infection, occurring in about
half of patients with this type of meningitis. Skin lesions develop, ranging
from a petechial rash with purpuric lesions to large areas of ecchymosis.
·
Disorientation
and memory impairment are common early in the course of the illness. The
changes depend on the severity of the infection as well as the individual
response to the physiologic processes. Behavioral manifestations are also
common. As the illness progresses, lethargy, unresponsiveness, and coma may
develop.
·
Seizures
can occur and are the result of areas of irritability in the brain. ICP
increases secondary to diffuse brain swelling or hydrocephalus
·
The
initial signs of increased ICP include decreased level of consciousness and
focal motor deficits. If ICP is not controlled, the uncus of the temporal lobe
may herniate through the tentorium, causing pressure on the brain stem. Brain
stem herniation is a life-threatening event that causes cranial nerve
dysfunction and depresses the centers of vital functions, such as the medulla.
·
Clinical
manifestations suggests meningitis
·
A
computed tomography (CT) scan or magnetic resonance imaging (MRI) scan is used
to detect a shift in brain contents (which may lead to herniation) prior to a
lumbar puncture
·
Bacterial
culture and Gram staining of CSF and blood are key diagnostic tests. CSF
studies demonstrate low glucose, high protein levels, and high white blood cell
count. Gram staining allows for rapid identification of the causative bacteria
and initiation of appropriate antibiotic therapy.
Prevention
·
Meningococcal
conjugated vaccine should be given to adolescents entering high school and to
college freshmen living in dormitories.
·
People
in close contact with patients with meningococcal meningitis should be treated
with antimicrobial chemoprophylaxis using rifampin (Rifadin), ciprofloxacin
hydrochloride (Cipro), or ceftriaxone sodium (Rocephin).
·
Therapy
should be started within 24 hours after exposure because a delay in the
initiation of therapy limits the effectiveness of the prophylaxis. Vaccination
should also be considered as an adjunct to antibiotic chemoprophylaxis for
anyone living with a person who develops meningococcal infection.
·
Vaccination
against H. influenza and S. Pneumonia should be encouraged for children and
at-risk adults.
Medical management
·
Successful
outcomes depend on the early administration of an antibiotic that crosses the
blood-brain barrier into the subarachnoid space in sufficient concentration to
halt the multiplication of bacteria.
·
Vancomycin
hydrochloride in combination with one of the cephalosporin (eg, ceftriaxone
sodium, cefotaxime sodium) is administered intravenously (IV)
·
Dexamethasone
(Decadron) has been shown to be beneficial as adjunct therapy in the treatment
of acute bacterial meningitis and in pneumococcal meningitis if it is
administered 15 to 20 minutes before the first dose of antibiotic and every 6
hours for the next 4 days.
·
Dehydration
and shock are treated with fluid volume expanders.
·
Seizures,
which may occur early in the course of the disease, are controlled with
phenytoin (Dilantin).
·
Increased
ICP is treated as necessary
Nursing management
·
Neurologic
status and vital signs are continually assessed.
·
Pulse
oximetry and arterial blood gas values are used to quickly identify the need
for respiratory support if increasing ICP compromises the brain stem.
·
Insertion
of a cuffed endotracheal tube (or tracheotomy) and mechanical ventilation may
be necessary to maintain adequate tissue oxygenation.
·
Blood
pressure is assessed for incipient shock , which precedes cardiac or respiratory failure.
·
Rapid
IV fluid replacement may be prescribed , but care is to be taken to prevent
fluid overload
·
Fever
also increases the workload of the heart and cerebral metabolism .ICP will
increase in response to increased cerebral metabolic demands. Therefore,
measures are taken to reduce body temperature as quickly as possible.
·
Protecting
the patient from injury secondary to seizure activity or altered LOC
·
Monitoring
daily body weight; serum electrolytes; and urine volume, specific gravity, and
osmolality, especially if syndrome of inappropriate antidiuretic hormone
(SIADH) is suspected
·
Preventing
complications associated with immobility, such as pressure ulcers and pneumonia
·
Instituting
infection control precautions until 24 hours after initiation of antibiotic
therapy (oral and nasal discharge is considered infectious)
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