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- 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.
Causes and symptoms
meningitis[men″in-ji´tis] (pl. meningi´tides)
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.
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.
meningitisInflammation of the meninges due to microorganisms (viral, bacterial, fungal, parasitic), less commonly due to drugs.
Headache, neck stiffness, fever, confusion, vomiting, photophobia.
CT, MRI, EEG (rarely performed), CBC (Lumbar puncture), CSF (increased neutrophils, increased protein).
• Neonates—Ampicillin ±ceftriaxone ±gentamicin.
• Older children—Ceftriaxone, cefotaxime.
Clinical findings by age
Irritation, respiratory distress, altered sleep patterns, vomiting, lethargy, labile temperature, shock, bulging fontanelles.
Irritation, altered sleep patterns, vomiting, lethargy, fever, shock, nuchal rigidity, coma, shock.
Headache, stiff neck, photophobia, myalgia, lethargy, fever, shock, nuchal rigidity, coma, shock.
• 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).
• Herpes simplex virus
meningitisNeurology 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.
men·in·gi·tis, pl. meningitides (men'in-jī'tis, -jit'ti-dēz)
See also: arachnoiditis, leptomeningitis
Synonym(s): cerebrospinal meningitis.
meningitis(men-en-jit'is) (-jit'i-dez?) plural.meningitides [ meningo- + -itis]
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.
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.
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.
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.
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.
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.
acute aseptic meningitis
Patients report fever, headache, stiff neck, malaise, and sometimes altered mental status or photophobia.
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.
Treatment options include amphotericin B, often with flucytosine. Fluconazole and/or related antifungals are sometimes used for maintenance therapy.
Mollaret meningitisSee: Mollaret meningitis
meningitis serosa circumscripta
meningitisInflammation 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.
meningitisinflammation of the MENINGES caused by infection, normally by bacteria such as Neisseria meningitidis or STREPTOCOCCUS pneumoniae or viruses such as MUMPS virus.
men·in·gi·tis, pl. meningitides (men'in-jī'tis, -jit'ti-dēz)
Synonym(s): cerebrospinal meningitis.
Patient discussion about meningitis
Q. What Causes Meningitis? I was told that meningitis is a very infectious disese. What causes meningitis?
Q. does my daughter need a meningitis vaccine?
Q. i have been in contact with someone whose in contact with bacterial meningitis. is this dangerous?