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Meningitis.pdf
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INFECTIOUS NEUROLOGICDISORDERS
On completion of this chapter, the learner will be able to:
1. Differentiate among the infectious disorders of the nervous system
according to causes, manifestations, medical care, and nursing
management.
The infectious disorders of the nervous system include meningitis, brain
abscesses, &various types of encephalitis.
Meningitis
Meningitis is inflammation of the meninges, which cover and protect the
brain and spinal cord. The three major causes of meningitis are bacterial,
viral, and fungal infections.
Meningitis can be the main reason a patient is hospitalized, or it can
develop during hospitalization; it is classified as Septic meningitis which
is caused by bacteria.
The bacteria Streptococcus pneumoniae and Neisseria meningitidis are
responsible for the majority of cases of bacterial meningitis in adults.
Or aseptic meningitis, the cause is viral or secondary to cancer or having
a weakened immune system, such as in human immune deficiency virus
(HIV). The most common causative agents are the enteroviruses.
Aseptic meningitis occurs more frequently in the summer and early fall.
Outbreaks of N. meningitidis infection are most likely to occur in dense
community groups, such as college campuses and military installations.
Factors that increase the risk of bacterial meningitisinclude;
1- Tobacco use
2- Viral upper respiratory infection
3- Otitis media and mastoiditis
4- People with immune system deficiencies
Pathophysiology
Meningeal infections generally originate in one of two ways: through the
bloodstream as a consequence of other infections or by direct spread, such
as might occur after a traumatic injury to the facial bones or secondary to
invasive procedures.
Once the causative organism enters the bloodstream, it crosses the blood–
brain barrier and proliferates in the cerebrospinal fluid (CSF). The
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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.
Clinical Manifestations
Headache and fever are frequently the initial symptoms. Fever tends to
remain high throughout the course of the illness. The headache is usually
either steady or throbbing and very severe as a result of meningeal
irritation.Meningeal irritation results in a number of other well-recognized
signs common to all types of meningitis:
Neck immobility: A stiff and painful neck (nuchal rigidity)
Positive Kernig sign: When the patient is lying with the thigh flexed
on the abdomen, the leg cannot be completely extended (Fig. 69- 1)
Positive Brudzinski sign: When the patient’s neck is flexed , 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 (Fig. 69-1).
Photophobia (extreme sensitivity to light): This finding is common
due to irritation of the meninges, especially around the diaphragm
sellae.
A rash can be a striking feature of N. meningitidis infection.
Figure 69-1 • Testing for
meningeal irritation. A. Kernig sign.
Flex the patient’s leg at both the hip
and knee and then straighten the
knee. B. Brudzinski sign. As theneck
is flexed, watch the hips and knees
for a reaction.
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Disorientation and memory impairment are common early in the course of
the illness. Behavioral manifestations are also common. As the illness
progresses, lethargy, unresponsiveness, and coma may develop.
Seizures can occur. ICP increases secondary to diffuse brain swelling or
hydrocephalus. The initial signs of increased ICP include decreased level
of consciousness (LOC) and focal motor deficits.
Complications of meningitis:
- Sepsis; an abrupt onset of high fever, extensive purpuric lesions
(over the face and extremities), shock, and signs of disseminated
intravascular coagulation
- Death may occur within a few hours after onset of the infection.
Assessment and Diagnostic Findings
If the clinical presentation suggests meningitis, diagnostic testing is
conducted to identify the causative organism.
- A computed tomography (CT) scan is used to detect a shift in brain
contents (which may lead to herniation) prior to a lumbar puncture in
patient with altered LOC, papilledema, neurologic deficits, new onset
of seizure, immunocompromised state, or history of central nervous
system (CNS) disease.
- Bacterial culture and Gram staining of CSF and blood are key
diagnostic tests.
Prevention
- Meningococcal conjugated vaccine be given to youth at 11 to 12
years of age, with a booster dose at 16 years of age.
- People in close contact with patients with meningococcal meningitis
should be treated with antimicrobial chemoprophylaxis
- Vaccination against Haemophilus influenzae and S. pneumoniae
should be encouraged for children and adults who are at-risk .
Medical Management
- Successful outcomes depend on the early administration of an
antibiotic agent
- Penicillin G in combination with one of the cephalosporins (e.g.,
ceftriaxone sodium, cefotaxime sodium) is most often administered
intravenously (IV), optimally within 30 minutes of hospital arrival
- Dexamethasone has been shown to be beneficial as adjunct
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therapy in the treatment of acute bacterial meningitis. Research
suggests that dexamethasone improves the outcome in adults.
- Dehydration and shock are treated with fluid volume
expanders.
- Seizures, which may occur early in the course of the disease,
are treated with anticonvulsant medications.
- Increased ICP is treated as necessary.
Nursing Management
The patient with meningitis is critically ill; therefore, many of the nursing
interventions are collaborative with the physician, respiratory therapist,
and other members of the health care team.
Most patients will need the following nursing interventions:
1- Instituting infection control precautions until 24 hours after initiation of
antibiotic therapy (oral and nasal discharge is considered infectious)
2- Assisting with pain management due to overall body aches and neck
pain
3- Assisting with getting rest in a quiet, darkened room
4- Implementing interventions to treat the elevated temperature, such as
antipyretic agents and cooling blankets
5- Encouraging the patient to stay hydrated either orally or peripherally
6- Ensuring close neurologic monitoring
7- Neurologic status and vital signs are continually assessed.
8- Pulse oximetry and arterial blood gas values are used to quickly
identify the need for respiratory support if increasing ICP compromises
the brainstem.
9- Insertion of a cuffed endotracheal tube (or tracheotomy) and
mechanical ventilation may be necessary to maintain adequate tissue
oxygenation.
10- Blood pressure (usually monitored using an arterial line) is assessed
for early manifestations of shock, which precedes cardiac or
respiratory failure.
11- Rapid IV fluid replacement may be prescribed, but care is taken to
prevent fluid overload.
12- 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.
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Other important components of nursing care include the following
measures:
a) Protecting the patient from injury secondary to seizure activity or
altered LOC
b) Monitoring daily body weight; serum electrolytes; and urine volume,
specific gravity, and osmolality
c) Preventing complications associated with immobility, such as
pressure ulcers and pneumonia
d) Periodic family visits are essential to facilitate coping of the patient
and family.
e) An important aspect of the nurse’s role is to support the family and
assist them in identifying others who can be supportive to them during the
crisis.
hematologic spread from the lungs, gums, tongue, or heart, or from a
wound or intra-abdominal infection.