Meningitis is the inflammation of the membranes (meninges) surrounding the brain and spinal cord.
It is a medical emergency due to the potential for rapid progression and severe complications, including death.
Signs and Symptoms
General Symptoms:
Severe Headache: A hallmark of meningitis, often described as the worst headache of one's life.
Fever: High temperature, often sudden onset.
Stiff Neck: Difficulty in bending the neck forward due to inflammation of the meninges.
Photophobia: Sensitivity to light, causing discomfort or pain.
Confusion or Altered Consciousness: Can range from mild confusion to complete unresponsiveness.
Vomiting: Often occurs due to increased intracranial pressure.
Seizures: In severe cases, due to inflammation affecting the brain tissue.
Infants and Young Children:
Irritability: Excessive crying and difficulty soothing the child.
Poor Feeding: Refusal to eat or drink.
High-pitched Crying: Especially when the infant is handled.
Bulging Fontanel: Soft spot on the head may appear swollen.
Types of Meningitis
1. Bacterial Meningitis:
Neisseria meningitidis: Common in adolescents and young adults, spread through respiratory droplets.
Streptococcus pneumoniae: Common in all age groups, particularly young children and elderly.
Haemophilus influenzae type b (Hib): Less common now due to vaccination.
2. Viral Meningitis:
Enteroviruses: Most common cause, spread through fecal-oral route.
Herpes Simplex Virus: Can cause severe encephalitis as well.
Mumps Virus: Now rare due to vaccination.
3. Fungal Meningitis:
Cryptococcus: Common in immunocompromised individuals, especially those with HIV/AIDS.
4. Parasitic Meningitis:
Naegleria fowleri: Rare, often fatal, contracted through contaminated water entering the nose.
5. Non-infectious Meningitis:
Causes: Cancer, autoimmune diseases (like lupus), certain drugs, head injury.
Etiology
Bacterial Transmission: Through respiratory droplets, close contact (kissing, coughing), or invasive medical procedures.
Viral Transmission: Often via fecal-oral route, respiratory droplets, or direct contact with infected fluids.
Fungal Transmission: Inhalation of fungal spores, typically affecting those with weakened immune systems.
Parasitic Transmission: Usually contracted through contaminated water, entering through the nasal passages.
Pathogenesis
1. Bacterial Meningitis:
Bacteria enter the bloodstream, cross the blood-brain barrier, and infect the meninges, leading to inflammation and increased intracranial pressure.
2. Viral Meningitis:
Viruses enter the body through the respiratory or gastrointestinal tracts, spread to the central nervous system, causing inflammation of the meninges.
3. Fungal and Parasitic Meningitis:
Similar to bacterial meningitis, fungi and parasites invade the central nervous system, causing inflammation.
Treatment
1. Bacterial Meningitis:
Antibiotics: Immediate intravenous antibiotics like ceftriaxone, vancomycin, or ampicillin.
Corticosteroids: Reduce inflammation (e.g., dexamethasone).
Supportive Care: Includes fluids, pain management, and monitoring for complications.
2. Viral Meningitis:
Supportive Care: Rest, hydration, and pain relief.
Antiviral Medications: Acyclovir for herpes simplex virus
3. Fungal Meningitis:
Antifungal Medications: Amphotericin B, flucytosine, fluconazole.
Supportive Care: Addressing symptoms and supporting organ functions.
4. Parasitic Meningitis:
Antiparasitic Treatment: Depending on the specific parasite.
Supportive Care: Includes managing symptoms and supporting vital functions.