meningitis

Meningitis

 

Definition

Meningitis is a serious inflammation of the meninges, the thin, membranous covering of the brain and the spinal cord. Meningitis is most commonly caused by infection (by bacteria, viruses, or fungi), although it can also be caused by bleeding into the meninges, cancer, diseases of the immune system, and an inflammatory response to certain types of chemotherapy or other chemical agents. The most serious and difficult-to-treat types of meningitis tend to be those caused by bacteria. In some cases, meningitis can be a potentially fatal condition.

Description

Meningitis is a particularly dangerous infection because of the very delicate nature of the brain. Brain cells are some of the only cells in the body that, once killed, will not regenerate themselves. Therefore, if enough brain tissue is damaged by an infection, serious, life-long handicaps will remain.

In order to learn about meningitis, it is important to have a basic understanding of the anatomy of the brain. The meninges are three separate membranes, layered together, which encase the brain and spinal cord:

• The dura is the toughest, outermost layer, and is closely attached to the inside of the skull.
• The middle layer, the arachnoid, is important because of its involvement in the normal flow of the cerebrospinal fluid (CSF), a lubricating and nutritive fluid that bathes both the brain and the spinal cord.
• The innermost layer, the pia, helps direct blood vessels into the brain.
• The space between the arachnoid and the pia contains CSF, which helps insulate the brain from trauma. Many blood vessels course through this space.

CSF, produced within specialized chambers deep inside the brain, flows over the surface of the brain and spinal cord. This fluid serves to cushion these relatively delicate structures, as well as supplying important nutrients for brain cells. CSF is reabsorbed by blood vessels located within the meninges. A careful balance between CSF production and reabsorption is important to avoid the accumulation of too much CSF.

Because the brain is enclosed in the hard, bony case of the skull, any disease that produces swelling will be damaging to the brain. The skull cannot expand at all, so when the swollen brain tissue pushes up against the skull's hard bone, the brain tissue becomes damaged and may ultimately die. Furthermore, swelling on the right side of the brain will not only cause pressure and damage to that side of the brain, but by taking up precious space within the tight confines of the skull, the left side of the brain will also be pushed up against the hard surface of the skull, causing damage to the left side of the brain as well.

Another way that infections injure the brain involves the way in which the chemical environment of the brain changes in response to the presence of an infection. The cells of the brain require a very well-regulated environment. Careful balance of oxygen, carbon dioxide, sugar (glucose), sodium, calcium, potassium, and other substances must be maintained in order to avoid damage to brain tissue. An infection upsets this balance, and brain damage can occur when the cells of the brain are either deprived of important nutrients or exposed to toxic levels of particular substances.

The cells lining the brain's tiny blood vessels (capillaries) are specifically designed to prevent many substances from passing into brain tissue. This is commonly referred to as the blood-brain barrier. The blood-brain barrier prevents various substances that could be poisonous to brain tissue (toxins), as well as many agents of infection, from crossing from the blood stream into the brain tissue. While this barrier is obviously an important protective feature for the brain, it also serves to complicate treatment in the case of an infection by making it difficult for medications to pass out of the blood and into the brain tissue where the infection is located.

Causes and symptoms

The most common infectious causes of meningitis vary according to an individual's age, habits, living environment, and health status. While nonbacterial types of meningitis are more common, bacterial meningitis is the more potentially life-threatening. Three bacterial agents are responsible for about 80% of all bacterial meningitis cases. These bacteria are Haemophilus influenzae type b, Neisseria meningitidis (causing meningococcal meningitis), and Streptococcus pneumoniae (causing pneumococcal meningitis).

In newborns, the most common agents of meningitis are those that are contracted from the newborn's mother, including Group B streptococci (becoming an increasingly common infecting organism in the newborn period), Escherichia coli, and Listeria monocytogenes. The highest incidence of meningitis occurs in babies under a month old, with an increased risk of meningitis continuing through about two years of age.

Older children are more frequently infected by the bacteria Haemophilus influenzae, Neisseria meningitidis, and Streptococci pneumoniae.

Adults are most commonly infected by either S. pneumoniae or N. meningitidis, with pneumococcal meningitis the more common. Certain conditions predispose to this type of meningitis, including alcoholism and chronic upper respiratory tract infections (especially of the middle ear, sinuses, and mastoids).

N. meningitidis is the only organism that can cause epidemics of meningitis. In particular, these have occurred when a child in a crowded day-care situation or a military recruit in a crowded training camp has fallen ill with meningococcal meningitis.

Viral causes of meningitis include the herpes simplex virus, the mumps and measles viruses (against which most children are protected due to mass immunization programs), the virus that causes chicken pox, the rabies virus, and a number of viruses that are acquired through the bites of infected mosquitoes.

A number of medical conditions predispose individuals to meningitis caused by specific organisms. Patients with AIDS (acquired immune deficiency syndrome) are more prone to getting meningitis from fungi, as well as from the agent that causes tuberculosis. Patients who have had their spleens removed, or whose spleens are no longer functional (as in the case of patients with sickle cell disease) are more susceptible to other infections, including meningococcal and pneumococcal meningitis.

The majority of meningitis infections are acquired by blood-borne spread. A person may have another type of infection (of the lungs, throat, or tissues of the heart) caused by an organism that can also cause meningitis. If this initial infection is not properly treated, the organism will continue to multiply, find its way into the blood stream, and be delivered in sufficient quantities to invade past the blood brain barrier. Direct spread occurs when an organism spreads to the meninges from infected tissue next to or very near the meninges. This can occur, for example, with a severe, poorly treated ear or sinus infection.

Patients who suffer from skull fractures possess abnormal openings to the sinuses, nasal passages, and middle ears. Organisms that usually live in the human respiratory system without causing disease can pass through openings caused by such fractures, reach the meninges, and cause infection. Similarly, patients who undergo surgical procedures or who have had foreign bodies surgically placed within their skulls (such as tubes to drain abnormal amounts of accumulated CSF) have an increased risk of meningitis.

Organisms can also reach the meninges via an uncommon but interesting method called intraneural spread. This involves an organism invading the body at a considerable distance away from the head, spreading along a nerve, and using that nerve as a kind of ladder into the skull, where the organism can multiply and cause meningitis. Herpes simplex virus is known to use this type of spread, as is the rabies virus.

The most classic symptoms of meningitis (particularly of bacterial meningitis) include fever, headache, vomiting, sensitivity to light (photophobia), irritability, severe fatigue (lethargy), stiff neck, and a reddish purple rash on the skin. Untreated, the disease progresses with seizures, confusion, and eventually coma.

A very young infant may not show the classic signs of meningitis. Early in infancy, a baby's immune system is not yet developed enough to mount a fever in response to infection, so fever may be absent. Some infants with meningitis have seizures as their only identifiable symptom. Similarly, debilitated elderly patients may not have fever or other identifiable symptoms of meningitis.

Damage due to meningitis occurs from a variety of phenomena. The action of infectious agents on the brain tissue is one direct cause of damage. Other types of damage may be due to the mechanical effects of swelling and compression of brain tissue against the bony surface of the skull. Swelling of the meninges may interfere with the normal absorption of CSF by blood vessels, causing accumulation of CSF and damage from the resulting pressure on the brain. Interference with the brain's carefully regulated chemical environment may cause damaging amounts of normally present substances (carbon dioxide, potassium) to accumulate. Inflammation may cause the blood-brain barrier to become less effective at preventing the passage of toxic substances into brain tissue.

Diagnosis

A number of techniques are used when examining a patient suspected of having meningitis to verify the diagnosis. Certain manipulations of the head (lowering the head, chin towards chest, for example) are difficult to perform and painful for a patient with meningitis.

The most important test used to diagnose meningitis is the lumbar puncture (commonly called a spinal tap). Lumbar puncture (LP) involves the insertion of a thin needle into a space between the vertebrae in the lower back and the withdrawal of a small amount of CSF. The CSF is then examined under a microscope to look for bacteria or fungi. Normal CSF contains set percentages of glucose and protein. These percentages will vary with bacterial, viral, or other causes of meningitis. For example, bacterial meningitis causes a greatly lower than normal percentage of glucose to be present in CSF, as the bacteria are essentially "eating" the host's glucose, and using it for their own nutrition and energy production. Normal CSF should contain no infection-fighting cells (white blood cells), so the presence of white blood cells in CSF is another indication of meningitis. Some of the withdrawn CSF is also put into special lab dishes to allow growth of the infecting organism, which can then be identified more easily. Special immunologic and serologic tests may also be used to help identify the infectious agent.

In rare instances, CSF from a lumbar puncture cannot be examined because the amount of swelling within the skull is so great that the pressure within the skull (intracranial pressure) is extremely high. This pressure is always measured immediately upon insertion of the LP needle. If it is found to be very high, no fluid is withdrawn because doing so could cause herniation of the brain stem. Herniation of the brain stem occurs when the part of the brain connecting to the spinal cord is thrust through the opening at the base of the skull into the spinal canal. Such herniation will cause compression of those structures within the brain stem that control the most vital functions of the body (breathing, heart beat, consciousness). Death or permanent debilitation follows herniation of the brain stem.

Treatment

Antibiotic medications (forms of penicillin and cephalosporins, for example) are the most important element of treatment against bacterial agents of meningitis. Because of the effectiveness of the blood-brain barrier in preventing the passage of substances into the brain, medications must be delivered directly into the patient's veins (intravenously, or by IV), at very high doses. Antiviral drugs (acyclovir) may be helpful in shortening the course of viral meningitis, and antifungal medications are available as well.

Other treatments for meningitis involve decreasing inflammation (with steroid preparations) and paying careful attention to the balance of fluids, glucose, sodium, potassium, oxygen, and carbon dioxide in the patient's system. Patients who develop seizures will require medications to halt the seizures and prevent their return.

Prognosis

Viral meningitis is the least severe type of meningitis, and patients usually recover with no long-term effects from the infection. Bacterial infections, however, are much more severe, and progress rapidly. Without very rapid treatment with the appropriate antibiotic, the infection can swiftly lead to coma and death in less than a day's time. While death rates from meningitis vary depending on the specific infecting organism, the overall death rate is just under 20%.

The most frequent long-term effects of meningitis include deafness and blindness, which may be caused by the compression of specific nerves and brain areas responsible for the senses of hearing and sight. Some patients develop permanent seizure disorders, requiring life-long treatment with anti-seizure medications. Scarring of the meninges may result in obstruction of the normal flow of CSF, causing abnormal accumulation of CSF. This may be a chronic problem for some patients, requiring the installation of shunt tubes to drain the accumulation regularly.

Prevention

Prevention of meningitis primarily involves the appropriate treatment of other infections an individual may acquire, particularly those that have a track record of seeding to the meninges (such as ear and sinus infections). Preventive treatment with antibiotics is sometimes recommended for the close contacts of an individual who is ill with meningococcal or H. influenzae type b meningitis. A meningococcal vaccine exists, and is sometimes recommended to individuals who are traveling to very high risk areas. A vaccine for H. influenzae type b is now given to babies as part of the standard array of childhood immunizations.

Resources

Organizations

American Academy of Neurology. 1080 Montreal Ave., St. Paul, MN 55116. (612) 695-1940. http://www.aan.com.

Meningitis Foundation of America. 7155 Shadeland Station, Suite 190, Indianapolis, IN 46256-3922. (800) 668-1129. 〈http://www.musa.org/welcome.htm〉.

meningitis

 [men″in-ji´tis] (pl. meningi´tides)

inflammation of the meninges, usually by either a bacterium (bacterial m.) or a virus (viral m.). When it affects the dura mater it is termed pachymeningitis; when the arachnoid and pia mater are involved, it is called leptomeningitis. The term meningitis does not refer to a specific disease entity but rather to the pathologic condition of inflammation of the tissues of the meninges. The etiologic agent can be anything that activates an inflammatory response, including both pathogenic and nonpathogenic organisms, such as bacteria, viruses, and fungi; chemical toxins such as lead and arsenic; contrast media used in myelography; and metastatic malignant cells. Enteroviruses are the most common causes of aseptic meningitis.

Bacterial Meningitis. This form occurs when pathogenic bacteria enter the subarachnoid space and cause a pyogenic inflammatory response. The most common causes are Streptococcus pneumoniae (pneumococcus), Neisseria meningitidis (meningococcus), and Haemophilus influenzae, which are responsible for approximately 70 per cent of all cases. The incidence is age-related. In adults, S. pneumoniae and N. meningitidis cause most of the cases; in children aged 1 month to 15 years, N. meningitidis and H. influenzae predominate; in neonates less than 1 month old, the disease is usually a nosocomial infection with gram-negative enteric bacilli.

Almost all bacterial infections of the meninges enter the nervous system after having invaded and infected another region of the body and then are spread by local extension, as from the sinuses, or through the blood, as in septicemia. The organisms gain access to the ventriculosubarachnoid spaces and the cerebrospinal fluid where they cause irritation of the tissues bathed by the fluid.

Bacterial meningitis typically begins with headache, nausea and vomiting, stiff neck (nuchal rigidity), and chills and fever. Irritability and confusion occur early in the course of the disease, and convulsive seizures occur in about 25 per cent of patients. As the disease progresses the patient becomes less rational, has decreasing levels of consciousness, and lapses into coma. Inability to straighten the knee when the hip is flexed (a positive kernig's sign) and involuntary flexing of the hip and knee when the neck is flexed forward (a positive brudzinski's sign) are indicative of meningeal irritation.

A diagnosis of bacterial meningitis is verified by isolation of the organism from a specimen of cerebrospinal fluid obtained by lumbar puncture. Treatment with the appropriate antibacterial agent is begun at once to reduce the numbers of proliferating bacteria attacking the central nervous system. Supportive measures include rest, maintenance of fluid and electrolyte balance, and prevention or control of convulsions with anticonvulsant drugs.

The prognosis is generally good, especially for meningococcal meningitis in which residual neurologic deficits and persistent convulsive seizures are rare. Pneumococcal meningitis and meningitis due to Haemophilus influenzae are more likely to be complicated by these sequelae as well as by septic shock and hydrocephalus.

Benign Viral Meningitis. This term encompasses a group of disorders in which there is some meningeal irritation but no pyogenic organism can be found in the cerebrospinal fluid. It is, therefore, called also aseptic meningitis complex, which is somewhat misleading because the meningeal irritation often follows infection with the mumps virus or with one of the picornaviruses.

The patient with this disorder typically complains of headache and signs characteristic of meningeal irritation, intolerance to light, and pain when the eyes are moved from side to side. Most of the symptoms are mild, and treatment is largely supportive and symptomatic; the disease is self-limiting.

Patient Care. Assessment of the patient with meningitis includes monitoring vital signs, neurologic status, and fluid and electrolyte status. The plan of care should include provisions for rest and relief from discomfort, a quiet and nonstimulating environment, protection from injury during convulsions, control of elevated body temperature, and isolation precautions as indicated by the specific causative organism. In general, enteric precautions are indicated for patients with aseptic meningitis caused by an enterovirus. Fungal and meningococcal meningitis require respiratory precautions. Antibiotics must be given precisely as ordered so as to avoid further damage to the central nervous system. Early signs of increased intracranial pressure from brain edema are reported promptly so that measures to reduce pressure can be taken as soon as possible. During the acute phase and convalescence the patient is watched for signs of complications such as septic shock, vascular collapse, and hydrocephalus. Nutritional status must be maintained throughout the course of illness to reinforce the patient's natural resources for combating infection and recovering from its deleterious effects.

Portals of entry resulting in meningitis, meningoencephalitis, and intracranial mass lesions. From Mahon and Manuselis, 2000.

aseptic meningitis any of several mild types of meningitis, most of which are caused by viruses; see viral meningitis.

bacterial meningitis meningitis caused by bacteria; common pathogens are Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, and Mycobacterium tuberculosis. Some types may be serious, acute, or even fulminating. See also viral meningitis.

cerebrospinal meningitis an inflammation of the brain and spinal cord; it may be caused by any of numerous different organisms.

epidemic cerebrospinal meningitis an acute infectious disease with seropurulent inflammation of the membranes of the brain and spinal cord, due to infection by Neisseria meningitidis (meningococcus). It usually occurs in epidemics, and symptoms are those of acute cerebral and spinal meningitis. There is also usually an eruption of erythematous, herpetic, or hemorrhagic spots on the skin. The fulminating or malignant form is known as Waterhouse-Friderichsen syndrome.

spinal meningitis inflammation of the meninges of the spinal cord.

viral meningitis meningitis due to any of various viruses, such as a coxsackievirus or the mumps virus, with lymphocytes in the cerebrospinal fluid. It usually has a short uncomplicated course characterized by malaise, fever, headache, stiffness of neck and back, and nausea. See also aseptic meningitis.

men·in·gi·tis

, pl.

men·in·git·i·des

(men'in-jī'tis, -jit'i-dēz),

Inflammation of the membranes of the brain or spinal cord.
See also: arachnoiditis, leptomeningitis.

Synonym(s): cerebrospinal meningitis

[mening- + G. itis, inflammation]

meningitis

/men·in·gi·tis/ (men″in-ji´tis) pl. meningi´tides   [Gr.] inflammation of the meninges.meningit´ic

---

basilar meningitis  that affecting the meninges at the base of the brain.

cerebral meningitis  inflammation of the membranes of the brain.

cerebrospinal meningitis  inflammation of the membranes of the brain and spinal cord.

chronic meningitis  a variable syndrome of prolonged fever, headache, lethargy, stiff neck, confusion, nausea, and vomiting, with pleocytosis; due to a variety of infectious and noninfectious causes.

cryptococcal meningitis  cryptococcosis in which the meninges are invaded by Cryptococcus .

eosinophilic meningitis  meningitis characterized by an increase in lymphocytes and a high percentage of eosinophils in the cerebrospinal fluid, usually due to Angiostrongylus cantonensis infection.

epidemic cerebrospinal meningitis  meningococcal m.

meningococcal meningitis  an acute infectious, usually epidemic, disease attended by a seropurulent meningitis, due to Neisseria meningitidis, usually with an erythematous, herpetic, or hemorrhagic skin eruption.

occlusive meningitis  leptomeningitis of children, with closure of the lateral and median apertures of the fourth ventricle.

meningitis ossi´ficans  ossification of the cerebral meninges.

otitic meningitis  that secondary to otitis media.

spinal meningitis  inflammation of the membranes of the spinal cord.

tubercular meningitis , tuberculous meningitis severe meningitis due to Mycobacterium tuberculosis.

viral meningitis  that due to a virus, e.g., coxsackieviruses, mumps virus, or the virus of lymphocytic choriomeningitis, marked by malaise, fever, headache and other aches, nausea, and cerebrospinal fluid pleocytosis (mainly lymphocytic); it usually runs a short uncomplicated course.

meningitis

(mĕn′ĭn-jī′tĭs)

n.

Inflammation of the meninges of the brain and the spinal cord, most often caused by a bacterial or viral infection and characterized by fever, vomiting, intense headache, and stiff neck.

---

men′in·git′ic (-jĭt′ĭk) adj.

meningitis

[min′injī′tis] pl. meningitides

Etymology: Gk, meninx + itis, inflammation

any infection or inflammation of the membranes covering the brain and spinal cord. It is usually purulent and involves the fluid in the subarachnoid space. The most common causes in adults are bacterial infection with Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae. Aseptic meningitis may be caused by nonbacterial agents such as a high dose of intravenous immunoglobulin, chemicals, neoplasms, or viruses. Many of these diseases are benign and self-limited, such as meningitis caused by strains of coxsackievirus or echovirus. Others are more severe, such as those involving arboviruses, herpesviruses, or poliomyelitis viruses. Yeasts such as Candida and Cryptococcus may cause a severe, often fatal meningitis. A kind of meningitis is tuberculous meningitis. Compare encephalitis. Also called cerebromeningitis.

observations The onset of meningitis is usually sudden and characterized by severe headache, stiffness of the neck, irritability, malaise, and restlessness. Nausea, vomiting, delirium, and complete disorientation may develop quickly. Temperature, pulse rate, and respirations are increased. Residual damage may include deafness, blindness, paralysis, and mental retardation. Hydrocephalus also may develop.

interventions Bacterial meningitis is treated promptly with antibiotics specific for the causative organism. They are administered intravenously or intrathecally. Antifungal medications, such as amphotericin B, given intravenously or intrathecally for several weeks, may prevent death from fungal meningitis, but serious neurological sequelae may occur.

nursing considerations Constant skilled nursing attention is necessary to ensure early recognition of rising intracranial pressure, to prevent aspiration in the event of convulsive seizures, and to prevent airway obstruction. Except for the first day or two of meningococcal disease, strict isolation procedures are unnecessary. IV fluids and nasogastric tube feeding may be necessary for a prolonged period. Sedatives and narcotic analgesics should not be used because they may obscure important neurological signs in addition to depressing vital functions.

Bacterial meningitis: purulent exudate on surface of cerebral hemisphere

meningitis

Inflammation of the meninges due to microorganisms (viral, bacterial, fungal, parasitic), less commonly due to drugs.

Clinical findings
Headache, neck stiffness, fever, confusion, vomiting, photophobia.

Diagnosis
CT, MRI, EEG (rarely performed), CBC (Lumbar puncture), CSF (increased neutrophils, increased protein).

Management
• Neonates—Ampicillin ±ceftriaxone ±gentamicin.
• Older children—Ceftriaxone, cefotaxime.

Clinical findings by age
Neonates
Irritation, respiratory distress, altered sleep patterns, vomiting, lethargy, labile temperature, shock, bulging fontanelles.
 
Pre-toddlers
Irritation, altered sleep patterns, vomiting, lethargy, fever, shock, nuchal rigidity, coma, shock.
 
Toddlers
Headache, stiff neck, photophobia, myalgia, lethargy, fever, shock, nuchal rigidity, coma, shock.
 
Meningitis pathogens
Bacterial
• Neonates—E coli, group B streptococcus.
• Infants—Streptococcus agalactidae, E coli, Klebsiella, Enterobacter, Pseudomonas, Serratia, Listeria monocytogenes, Citrobacter diversus.
• Children—H influenzae, S pneumoniae, Neisseria meningitidis.
• Adolescents—Neisseria meningitidis, Haemophilus influenzae.
• Elderly—Streptococcus pneumoniae, Listeria monocytogenes.
• Others—TB (often with co-existent encephalitis).

Viral
• Enterovirus
• Echovirus
• Coxsackievirus
• Poliomyelitis
• Herpes simplex virus

meningitis

Neurology A condition characterized by potentially fatal meningeal inflammation Pathogenesi Infants, Streptococcus agalactiae, E coli, Klebsiella-Enterobacter, Pseudomonas, Serratia, Listeria monocytogenes, Citrobacter diversus; children, H influenzae, S pneumoniae, Neisseria meningitidis Workup CT, MRI, EEG–rarely performed, CBC & CSF–↑ WBCs/PMNs, ↑ CSF protein Management Neonates ampicillin ±ceftriaxone ±gentamicin; older children, ceftriaxone, cefotaxime. See Aseptic meningitis, Bacterial meningitis, Cryptococcal meningitis, Eosinophilic meningitis, Gram negative meningitis, H influenzae meningitis, Lymphocytic choriomeningitis, Meningococcal meningitis, Mollaret's meningitis, Neoplastic meningitis, Pneumococcal meningitis, Pseudomeningitis, Purulent meningitis, Staphylococcal meningitis, Tuberculous meningitis.

Meningitis, clinical findings by age

Neonates Irritation, respiratory distress, altered sleep patterns, vomiting, lethargy, labile temperature, shock bulging fontanelles

Pre-toddlers Irritation, altered sleep patterns, vomiting, lethargy, fever, shock, nuchal rigidity, coma, shock

Toddlers Headache, stiff neck, photophobia, myalgia, lethargy, fever, shock, nuchal rigidity, coma, shock

men·in·gi·tis

, pl. meningitides (men'in-jī'tis, -jit'ti-dēz)

Inflammation of the membranes of the brain or spinal cord.
See also: arachnoiditis, leptomeningitis
Synonym(s): cerebrospinal meningitis.

[mening- + G. itis, inflammation]

meningitis

(men-en-jit'is) (-jit'i-dez?) plural.meningitides [ meningo- + -itis]

MENINGITIS: Streptococcus pneumoniae in cerebrospinal fluid (Orig. mag. ×400)

Inflammation of the membranes of the spinal cord or brain, usually but not always caused by an infectious illness. Bacterial meningitis is a medical emergency that must be treated and diagnosed quickly to obtain the best outcome. It is fatal in 10% to 40% of cases, even with optimal therapy, and may result in persistent neurological injury in about 10% of patients who survive the initial infection. In the U.S., bacterial meningitis formerly affected infants and children more than adults; the demographics of the disease changed in the 1990s after vaccines against Haemophilus influenzae were introduced into pediatric care. Infectious meningitis now is largely a disease of adults and usually is caused by Streptococcus pneumoniae or Neisseria meningitidis, although other microbes may be responsible. Intravenous steroids (such as dexamethasone) given at the beginning of therapy decreases the risk of death and disability. illustration; meningitic (men-en-jit'ik), adjective

Etiology

Meningitis may result from infection with bacteria, viruses, mycobacteria, fungi, amebas, or noninfectious sources, such as chemical irritation. Occasionally, infectious meningitis follows head trauma or sinus or ear infection. It also may result from the spread of blood-borne infection.

Symptoms

The symptoms of meningitis include fever, chills, headache, stiff neck, altered mental status, vomiting, and photophobia. Many patients with meningitis present with only two or three of these clinical indicators. Acute bacterial meningitis and meningitis caused by some fungi and amebas may also cause rapid deterioration in mental status, seizures, shock, and death.

Diagnosis

Cerebrospinal fluid (CSF) must be examined. A cell count to assess the level of inflammation, a Gram stain to look for infectious organisms, measurement of spinal fluid pressure, and levels of bacterial antigens, glucose, lactate, and protein are typically obtained. CSF may appear milky-white due to the large numbers of white blood cells present.

Prevention

All children in the U.S. are now vaccinated against H. influenzae type b (Hib) and pneumococcus (Prevnar) as primary prevention against the disease. Meningococcal polysaccharide vaccines are highly effective in preventing the disease during epidemic outbreaks with this organism. Close family contacts of patients with meningococcal meningitis, day care center contacts of infected children, or any persons (including health care workers) with direct contact with the saliva of infected patients are to be treated with antibiotics to prevent disease transmission.

Treatment

Definitive treatment depends on identification of the underlying causes, but empirical therapies for infectious meningitis must be given immediately, hours before the causative agent is identified. Dexamethasone is administered intravenously before starting antibiotic therapy for best response to reduce the incidence of deafness in children (a common complication) and to help prevent death in adults with pneumococcal meningitis. The evolution of penicillin-resistant strains of pneumococci has altered traditional empirical treatments. Third-generation cephalosporins, ampicillin and gentamicin, chloramphenicol, or vancomycin plus rifampin have been given, depending on the patient's age, level of immune function, or clinical presentation. Antibiotic therapy is usually administered intravenously for 2 weeks, then orally for a prescribed period for bacterial infections. Viral meningitis treatment is supportive; recovery usually is complete (within 7 to 10 days). Antipyretic analgesics relieve headache and fever.

Patient care

Specific measures for coexisting conditions and for shock and other complications (disseminated intravascular coagulation, metabolic acidosis, or seizures) should be initiated when indicated. Supportive therapies include bed rest, a dimly lit room, and reduced sensory stimulation. Standard precautions apply, and airborne/droplet precautions are initiated if nasal cultures are positive. Neurologic function is closely monitored for changes in level of consciousness, signs of increasing intracranial pressure (ICP), and indications of cranial nerve involvement. Fluid and electrolyte balance is monitored, and fluids are provided in quantities to prevent or treat dehydration while avoiding fluid overload and resultant cerebral edema. The patient is assessed for adverse effects of antibiotic therapy with peak and trough blood levels assessed to ensure therapeutic levels and avoid toxic overdose. The patient is repositioned carefully and assisted with range-of-motion exercises to prevent skin, muscle, and joint complications. Frequent mouth care is provided and adequate nutrition and elimination are maintained. Small frequent meals, nasogastric or parenteral feedings are provided as required. Constipation is prevented by stool softeners or mild laxatives to prevent straining, which could increase ICP. Basic explanations, realistic reassurance, and support are provided, with reorientation if delirium or confusion is present. Questions from the patient and family should be answered honestly, with reassurance that behavioral changes usually resolve.

The patient with infectious meningitis may need monitoring in an ICU. Patients with neurologic deficits that appear to be continuing should be referred to a rehabilitation program once the acute phase of illness has ended. To help prevent meningitis, patients with chronic sinusitis or other chronic infectious or inflammatory illnesses should be taught the importance of proper hand hygiene and of following through with prescribed treatments. Sterile techniques should be strictly enforced when treating patients with head wounds, skull fractures, or lumbar puncture, ventricular shunting, or other invasive therapies.

MENINGITIS

acute aseptic meningitis

A nonpurulent form of meningitis often due to viral infection. It usually runs a short, benign course, marked by fever and headache and ending with recovery.

illustration

aseptic meningitis

Meningitis without obvious evidence of bacterial infection. It typically results from a viral infection (such as coxsackievirus or other enteroviruses) although frequently no causative organism is identified.

Symptoms

Patients report fever, headache, stiff neck, malaise, and sometimes altered mental status or photophobia.

Patient care

Treatment is supportive, with antipyretics and pain-relieving medications administered as prescribed. The virus can be spread by direct contact with saliva, sputum, mucus, or stools of an infected person. Standard precautions apply, with droplet precautions if nasal cultures are positive; contaminated articles are disposed of by double bagging. Neurological status is monitored for changes in level of consciousness and for increases in intracranial pressure. Personal hygiene is provided, and measures to prevent complications due to immobility are implemented. Gentle position changes are performed to reduce excessive stimulation. Artificial airway, suction, and oxygen are readily available. A quiet, dark atmosphere is provided, and siderails are padded to reduce the risk of injury. Prescribed analgesics are administered, and cool compresses are applied to the forehead to relieve headache. Intravenous fluids or tube feedings are administered as ordered, and intake and output are monitored. Assessments are made for complications such as shock, respiratory distress, and disseminated intravascular coagulation.

Since mosquitoes can spread some viruses that cause meningitis, avoiding mosquito bites during the warm months of the year by wearing insecticides (DEET) and barrier protection, and eliminating standing pools of water, where mosquitoes breed, may help prevent the disease. The public should be made aware of meningitis symptoms (fever, headache, stiff neck, altered levels of consciousness) and the importance of prompt attention for any patient suspected of meningitis.

bacterial meningitis

Meningitis caused by disease-causing and potentially life-threatening organisms, esp. Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and Listeria monocytogenes.

basal meningitis

Meningitis at the base of the brain, usually due to tuberculosis.

carcinomatous meningitis

Meningitis by metastatic tumor cells. It may produce symptoms such as headache, backache, confusion, nerve palsies, or seizures and should be suspected when these symptoms arise in patients with known cancers. The diagnosis is confirmed by lumbar puncture with analysis of the cerebrospinal fluid for tumor cells.

cerebral meningitis

Acute or chronic meningitis of the brain.

cerebrospinal meningitis

Meningitis of the brain and spinal cord.

chronic meningitis

Meningitis marked by persistent fever, headache, and stiff neck (associated, on lumbar puncture, with cerebrospinal fluid pleocytosis and elevated spinal fluid pressure). The underlying cause of this cluster of findings may be initially difficult to determine. Syphilis, cryptococcosis, HIV infection, or invasion of the meninges by cancer cells may be responsible. Occasionally, repeated lumbar punctures reveal a vasculitis of the central nervous system or a partially treated bacterial meningitis.

cryptococcal meningitis

Fungal meningitis due to Cryptococcus neoformans. A rare cause of disease in healthy hosts, cryptococcal meningitis is an opportunistic infection usually seen in patients with advanced AIDS or patients taking high-dose steroids. It usually presents with gradually progressive headache and fever. The serum cryptococcal antigen test is a useful screening test. The diagnosis is established by the results of analysis and culture of cerebral spinal fluid.

Treatment

Treatment options include amphotericin B, often with flucytosine. Fluconazole and/or related antifungals are sometimes used for maintenance therapy.

meningococcal meningitis

Meningitis caused by various serogroups of Neisseria meningitidis.

Mollaret meningitis

See: Mollaret meningitis

pneumococcal meningitis

Meningitis due to Streptococcus pneumoniae, a disease predominantly found in adults. In the U.S., about 20% of affected patients die. Because of the worldwide emergence of streptococcal resistance to penicillins, chloramphenicol, and cephalosporins, vancomycin, rifampin, and other antibacterial agents are used to treat this infection. Intravenous steroids (such as dexamethasone) given at the beginning of therapy decrease the risk of death and disability caused by this infection.

meningitis serosa circumscripta

Meningitis accompanied by the formation of cystic accumulations of fluid that simulate tumors.

serous meningitis

Meningitis with serous exudation into the cerebral ventricles.

spinal meningitis

Inflammation of the spinal cord membranes.

traumatic meningitis

Meningitis resulting from trauma to the meninges.

tuberculous meningitis

Meningitis resulting from the spread of Mycobacterium tuberculosis to the central nervous system, usually from a primary focus of infection in the lungs.

viral meningitis

A form of aseptic meningitis due to infection with adenovirus, coxsackievirus, echovirus, HIV, mumps virus, lymphocytic choriomeningitis virus, polio viruses, and others. Patients report fever, headache, and stiff neck. Lumbar puncture reveals an excessive number of lymphocytes, typically without a decrease in cerebrospinal fluid glucose levels.

illustration

meningitis

Inflammation of the MENINGES. This can be caused by many different organisms, especially the HERPES SIMPLEX virus, the VARICELLA-ZOSTER virus that causes CHICKEN POX and SHINGLES, the meningococcus, the POLIO virus, the echo virus, the COXSACKIE virus and the MUMPS virus. Meningitis may also complicate LYME DISEASE, LEPTOSPIROSIS, TYPHUS, TUBERCULOSIS and other infections. Viral meningitis may be a minor illness but can be acute, with headache, stiff neck, fever and drowsiness progressing rapidly to deep coma. There may be weakness or paralysis of the muscles, speech disturbances, double vision, loss of part of the field of vision and epileptic fits. Most patients recover completely, but some have residual nervous system damage. There is no specific treatment for most virus infections, but herpes meningitis responds to the drug ACYCLOVIR. See also MENINGOCOCCAL MENINGITIS.

meningitis

inflammation of the MENINGES caused by infection, normally by bacteria such as Neisseria meningitidis or STREPTOCOCCUS pneumoniae or viruses such as MUMPS virus.

meningitis (me·nin·jīˑ·tis),

n an infection or inflammation of the membranes that cover the spinal cord and brain because of a virus or a bacterium. Bacterial infection is usually more life-threatening and is indicated by the sudden onset of a stiff neck, headache, fever, and vomiting; may cause stupor, confusion, and convulsions if untreated. Antibiotics for the specific causative agent are prescribed to treat bacterial meningitis.

Meningitis.

men·in·gi·tis

, pl. meningitides (men'in-jī'tis, -jit'ti-dēz)

Inflammation of membranes of brain or spinal cord.
Synonym(s): cerebrospinal meningitis.

[mening- + G. itis, inflammation]

meningitis

(men´injī´tis),
n an infection or inflammation of the membranes covering the brain and spinal cord. It usually is a purulent infection and involves the fluid of the subarachnoid space. The most common causes in adults are bacterial infection with
S. pneumoniae, N. meningitidis, or
H. influenzae. Aseptic meningitis may be caused by chemical irritation, neoplasms, or viruses. Typical signs and symptoms include fever, headache, stiff neck, photophobia, or vomiting.

meningitis

inflammation of the meninges. When the inflammatory process affects the dura mater, the disease is termed pachymeningitis; when the arachnoid and pia mater are involved, it is called leptomeningitis or meningitis proper. It is also classified as fibrinous, hemorrhagic, purulent or eosinophilic, depending on the principal reaction of the tissues.

The term meningitis does not refer to a specific disease entity but rather to the pathological condition of inflammation of the tissues of the meninges. The etiological agent can be anything that activates the inflammatory process, including both pathogenic and nonpathogenic organisms, such as bacteria, viruses and fungi; chemical toxins such as lead and arsenic; contrast media used in myelography; and metastatic malignant cells.

In animals there are no specific meningitides, most cases of meningitis occurring as secondary complications to other diseases and having a bacterial etiology. Clinical signs seen commonly include fever, cutaneous hyperesthesia and rigidity of the muscles of the neck and forelimbs. A cerebrospinal fluid tap should assist in the diagnosis.

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Beagle meningitis

see beagle pain syndrome.

Bernese Mountain Dog meningitis

an acute, aseptic nonsuppurative meningitis seen in young Bernese Mountain Dogs of unknown etiology.

cerebrospinal meningitis

an inflammation of the brain and spinal cord; it may be caused by many different organisms.

Pug meningitis

see Pug meningoencephalitis.

spinal meningitis

inflammation of the meninges of the spinal cord.

Patient discussion about meningitis

Q. What Causes Meningitis? I was told that meningitis is a very infectious disese. What causes meningitis?

A. Most cases of meningitis are caused by microorganisms, such as viruses, bacteria, fungi, or parasites, that spread into the blood and into the cerebrospinal fluid (CSF). Non-infectious causes include cancers, certain drugs and more. The most common cause of meningitis is viral, that is usually less severe. Bacterial meningitis is the second most frequent type and can be serious and life-threatening. Bacterial meningitis is a medical emergency.

Q. does my daughter need a meningitis vaccine?

A. Yes I require all girls to get vaccinated.That makes one less to have HPV or to get cervical cancer.I have a sister who got the vaccine.

Q. i have been in contact with someone whose in contact with bacterial meningitis. is this dangerous?

A. bacterial meningitis is one of the most lethal infections known. when people get infected by it they get a __ load of antibiotics and so are their families. but it all depends on what stage you had contact, and how close contact. in any way- he is probably under treatment now, no? if so, contact the doctors where he is hospitalized and ask them what is the protocol.