Meningitis is an inflammation of the meninges, the protective membranes that surround the brain and spinal cord. Meningitis is classified as aseptic or septic. In aseptic meningitis, bacteria are not the cause of the inflammation; the cause is viral or secondary to lymphoma, leukemia, or brain abscess. Septic meningitis refers to meningitis caused by bacteria, most commonly Neisseria meningitidis, although Haemophilus influenzae and Streptococcus pneumoniae are also causative agents.
Pathophysiology of MeningitisMeningeal infections generally originate in one of two ways:
through the bloodstream as a consequence of other infections, or by direct extension, such as might occur after a traumatic injury to the facial bones, or secondary to invasive procedures.N. meningitidis 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 . S. pneumoniae is the most frequent causative agent of bacterial meningitis associated with AIDS (Rosenstein, Perkins, Stephens et al.,2001).
Once the causative organism enters the bloodstream, it crosses the blood–brain barrier and causes an inflammatory reaction in the meninges. Independent of the causative agent, inflammation of the subarachnoid space and pia mater occurs. Since there is little room for expansion within the cranial vault, the inflammation may cause increased intracranial pressure. Cerebrospinal fluid (CSF) flows in the subarachnoid space, where inflammatory cellular material from the affected meningeal tissue enters and accumulates in the subarachnoid space, thereby increasing the CSF cell count (Coyle, 1999).
The prognosis for bacterial meningitis depends on the causative organism, the severity of the infection and illness, and the timeliness of treatment. In acute fulminant presentations there may be 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.
Causes of Meningitis
Many of the bacteria and viruses that cause meningitis are fairly common and associated with other routine illnesses. Bacteria and viruses that infect the skin, urinary system, gastrointestinal or respiratory tract can spread by the bloodstream to the meninges through cerebrospinal fluid, the fluid that circulates in and around the spinal cord.
In some cases of bacterial meningitis, the bacteria spread to the meninges from a severe head trauma or a severe local infection, such as a serious ear infection (otitis media) or nasal sinus infection (sinusitis).
Symptoms of Meningitis
* fever
* lethargy (decreased consciousness)
* irritability
* headache
* photophobia (eye sensitivity to light)
* stiff neck
* skin rashes
* seizures
Meningitis Treatment
Routine vaccination protects against some types of bacterial meningitis, including those caused by one type of meningococcus (MenC), Haemophilus influenzae (Hib vaccine) and invasive pneumococcal disease (PCV vaccine).
Vaccination against the mumps virus (for example with the MMR vaccine given routinely to children) protects against viral meningitis caused by mumps.
People who have been in close contact with someone who has bacterial meningitis may need to take antibiotics as a preventative measure.
The diagnosis is confirmed using blood tests and a test called a lumbar puncture. A fine needle is insertedinto the person's spine to draw out fluid that can then be examined in a laboratory for infectious organisms.
Treatment depends on the cause of the meningitis, but intravenous antibiotics will be started immediately and continued if tests confirm the bacterial form.
If other causes are diagnosed they will be treated accordingly. Different medicines may be needed to control symptoms such as seizures.
Delays in treatment increase the risk of long-term damage. If you suspect meningitis, get urgent medical advice.
Pathophysiology of MeningitisMeningeal infections generally originate in one of two ways:
through the bloodstream as a consequence of other infections, or by direct extension, such as might occur after a traumatic injury to the facial bones, or secondary to invasive procedures.N. meningitidis 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 . S. pneumoniae is the most frequent causative agent of bacterial meningitis associated with AIDS (Rosenstein, Perkins, Stephens et al.,2001).
Once the causative organism enters the bloodstream, it crosses the blood–brain barrier and causes an inflammatory reaction in the meninges. Independent of the causative agent, inflammation of the subarachnoid space and pia mater occurs. Since there is little room for expansion within the cranial vault, the inflammation may cause increased intracranial pressure. Cerebrospinal fluid (CSF) flows in the subarachnoid space, where inflammatory cellular material from the affected meningeal tissue enters and accumulates in the subarachnoid space, thereby increasing the CSF cell count (Coyle, 1999).
The prognosis for bacterial meningitis depends on the causative organism, the severity of the infection and illness, and the timeliness of treatment. In acute fulminant presentations there may be 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.
Causes of Meningitis
Many of the bacteria and viruses that cause meningitis are fairly common and associated with other routine illnesses. Bacteria and viruses that infect the skin, urinary system, gastrointestinal or respiratory tract can spread by the bloodstream to the meninges through cerebrospinal fluid, the fluid that circulates in and around the spinal cord.
In some cases of bacterial meningitis, the bacteria spread to the meninges from a severe head trauma or a severe local infection, such as a serious ear infection (otitis media) or nasal sinus infection (sinusitis).
Symptoms of Meningitis
* fever
* lethargy (decreased consciousness)
* irritability
* headache
* photophobia (eye sensitivity to light)
* stiff neck
* skin rashes
* seizures
Meningitis Treatment
Routine vaccination protects against some types of bacterial meningitis, including those caused by one type of meningococcus (MenC), Haemophilus influenzae (Hib vaccine) and invasive pneumococcal disease (PCV vaccine).
Vaccination against the mumps virus (for example with the MMR vaccine given routinely to children) protects against viral meningitis caused by mumps.
People who have been in close contact with someone who has bacterial meningitis may need to take antibiotics as a preventative measure.
The diagnosis is confirmed using blood tests and a test called a lumbar puncture. A fine needle is insertedinto the person's spine to draw out fluid that can then be examined in a laboratory for infectious organisms.
Treatment depends on the cause of the meningitis, but intravenous antibiotics will be started immediately and continued if tests confirm the bacterial form.
If other causes are diagnosed they will be treated accordingly. Different medicines may be needed to control symptoms such as seizures.
Delays in treatment increase the risk of long-term damage. If you suspect meningitis, get urgent medical advice.
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Unknown - Saturday, 26 March 2011
