Meningitis: Types and Assessment

Meningitis: Types and Assessment

• Meningitis is inflammation of the membranes and fluid surrounding the brain and spinal cord.
• Types include:
  • Septic (bacterial): Caused by bacteria like Streptococcus pneumoniae, Neisseria meningitidis.
  • Aseptic (viral): Caused by viruses, lymphoma, leukemia, or brain abscess.
• Neisseria meningitidis is transmitted through secretions or aerosol contamination, commonly in densely populated areas like college campuses.
• Manifestations frequently include headache, fever, altered level of consciousness, behavioral changes, stiff neck (nuchal rigidity), positive Kernig's sign, positive Brudzinski's sign, and sensitivity to light (photophobia).

Bacterial Meningitis (Septic)

• Most common in fall and winter, often linked to upper respiratory infections (URIs).
• Transmission is via secretions or aerosol contamination.
• Common causative organisms include:
  • Neisseria meningitidis
  • Haemophilus influenzae: Primarily affects young children.
  • Streptococcus pneumoniae: Causes other infections like pneumonia and ear infections, spread through coughs, sneezes, and close contact.
• Meningococcal disease specifically refers to the bacteria Neisseria meningitidis.
• Risk factors include smoking and living in high-population density areas.

Meningococcal Disease (Meningococcemia)

• Neisseria meningitidis infection.
• High risk groups include children under 4 and those aged 11-26.
• Rapid progression and can be fatal.
• Current prevention is primarily through immunization.

Viral Meningitis (Aseptic)

• Caused by various viruses like measles, mumps, herpes simplex, and herpes zoster.
• Inflammation can affect the cerebral cortex, white matter, and meninges.
• Pathophysiology varies depending on the causative virus.

Assessment of Meningitis

• Initial signs often include headache and fever; a rash may accompany N. meningitidis.
• Meningeal Irritation includes:
  • Stiff neck (nuchal rigidity)
  • Kernig's sign: Pain when extending the knee while the hip is flexed.
  • Brudzinski's sign: Pain and involuntary flexion of the hip and knee when the neck is flexed.
• Photophobia (sensitivity to light) is common.

Increased Intracranial Pressure (ICP)

• The Monro-Kellie hypothesis describes the limited space within the skull and how increases in one component (brain, blood, or CSF) necessitate changes in the others.
• Normal ICP is 10-20 mm Hg.
• Compensation mechanisms are exhausted with severe disease.
• Increased ICP decreases cerebral perfusion, causing ischemia, cell death, and further edema.
• The earliest sign of increasing ICP is a change in level of consciousness.

Differential Diagnosis Question

• The positive Babinski sign is not a common symptom of all types of meningitis. Options that are often present include photophobia, positive Brudzinski's sign, and positive Kernig's sign.