Meningitis is an infection of the subarachnoid space (located between the middle arachnid matter and the inner pia mater) of the meninges, which is the thin layer of tissues that line the brain and the spinal cord. Cerebrospinal fluid flows through the subarachnoid space and the meninges, providing cushion for the brain and the spinal cord, and filling the internal spaces within the brain. There are 2 main types of meningitis, including bacterial meningitis and viral meningitis. There are other forms of meningitis, including fungal and amoebic, but they are extremely rare. Bacterial meningitis, which is the less common form of the disease, is associated with serious and severe illness. There are many major intracranial effects of bacterial meningitis. The dangerous inflammation that is caused by bacterial meningitis can cause brain edema, brain damage and increased pressure within the brain, and therefore lead to learning disabilities, hearing loss, or even death without treatment for the specific type of bacteria. This inflammation can produce a wide range of symptoms, including fever, headache, or confusion and, in extreme cases, can cause brain damage, stroke, seizures, or even death. The purpose of this paper is to discuss the pathogenesis of bacterial meningitis.
The Effects of Bacterial Meningitis on the Brain
Bacterial meningitis is a very serious disease that is fatal in between 5% and 40% of patients and is known to cause neurological sequelae in 30% of survivors (Leib & Tauber, 1999). Bacterial meningitis can be caused by a number of different bacteria, including the most common; meningococcal bacteria, Haemophilus influenza and streptococcal infection (Department of Health, 2010). Unlike viral meningitis, it can potentially kill an otherwise healthy young person within 1 day after the first symptoms appear. The illness and death that is associated with bacterial meningitis remains high, despite the fact that treatments and antibiotic therapy has been enhanced in recent times. There are many major intracranial effects of bacterial meningitis (Jacewicz, 2008).
Complications from bacterial meningitis can be divided into 2 groups: systemic and neurologic. The systemic complications include septic shock, disseminated intravascular coagulation, acute respiratory distress syndrome, and septic or reactive arthritis. Theses complications are usually the consequence of the bacteremia that usually comes along with meningitis. The neurological complications of bacterial meningitis include: impaired mental status, increased pressure within the cranium and brain swelling, seizures, focal neurological deficits (such as cranial nerve palsy and hemipareses), abnormalities in the vessels and arteries within the brain, sensorineural hearing loss (hearing impairment of the inner ear resulting from damage to the sensory hair cells or to the nerves that supply the inner ear.) and intellectual impairment. All of these complications may come about suddenly or there may be a gradual onset and can appear at any time after the onset of symptoms. The complications may even come about once treatment or thererapy has been completed. Although many of the neurologic complications are severe, others complications, such as hearing loss, may be subtle or barely visible during the early phases of infection (Sexton, 2010).
The bacterium that is responsible for causing bacterial meningitis, most commonly Neisseria meningitides (which causes meningococcal meningitis) or Streptococcus pneumoniae, group together in the nasopharynx. These species of bacteria are normally present in the environment and sometimes live in the nose and the upper respiratory system without causing any problems. At times, these organisms infect the brain without reason. From the nasopharynx, the bacteria enter into the blood stream and enter the subarachnoid space through...