Encephalitis

Disease Description (Causes and Symptoms)

• Definition and pathophysiology: Encephalitis is inflammation of the brain parenchyma. It is classified as primary encephalitis, caused by direct invasion of the brain by a pathogen, or secondary encephalitis, caused by an immune response or spread following an infection in another area. Lesions may be focal or diffuse.
• Main causes (based on the provided information)
  • Viruses: Herpes simplex virus (HSV), varicella-zoster virus (VZV), arboviruses (e.g., Japanese encephalitis virus), Epstein-Barr virus (EBV), cytomegalovirus (CMV), etc.
  • Bacterial associations: Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, Escherichia coli (neonates), Listeria (older adults and immunocompromised individuals), etc.
  • Secondary causes after trauma or surgery: Staphylococcus aureus, Streptococcus, etc.
  • Subacute/chronic: Mycobacterium tuberculosis, fungi, HIV, etc.
• Symptoms (main): Fever, headache, chills, vomiting, clouding or decreased level of consciousness, confusion, disorientation, neck stiffness (nuchal rigidity), photophobia (dislike of bright light), seizures (convulsions), decreased vision, and lack of energy. In infants, bulging of the anterior fontanelle may occur.

Treatment Methods

• Initial and emergency treatment
  • Intensive care unit admission or inpatient observation may be necessary (due to decreased consciousness, seizures, or possible respiratory failure). Stabilization of the airway, breathing, and circulation; fluid and electrolyte correction; and temperature management.
  • Empirical antiviral therapy: Intravenous acyclovir should be started immediately when HSV is suspected (early treatment is important for prognosis).
  • Empirical antibiotic therapy: If a bacterial cause is possible, appropriate antibiotics should be administered concurrently (with combinations depending on age and circumstances).
  • If seizures occur, anticonvulsants (e.g., levetiracetam, phenytoin, etc.) are used.
  • In cases of severe cerebral edema: Elevation of the head, hyperosmolar therapy (mannitol, hypertonic saline), and mechanical ventilation if necessary.
• Specific treatment by cause
  • Viral: Antiviral medication according to the causative virus (HSV → acyclovir, etc.). Supportive care is also provided in most cases.
  • Bacterial: Selection of antibiotics based on blood and cerebrospinal fluid culture results.
  • Tuberculous and fungal: Antituberculosis and antifungal medications.
  • If a brain abscess develops: Drainage and surgical treatment.
  • Immune-mediated (autoimmune) encephalitis: Specialized immunotherapy, including high-dose steroids, IVIG, and plasmapheresis.
• Rehabilitation and follow-up care
  • Rehabilitation, including physical therapy, occupational therapy, and speech therapy, may be necessary for neurological sequelae such as memory impairment, speech impairment, and ataxia.
• Precautions (during treatment/self-care)
  • Visit the emergency department immediately if emergency signs occur, such as fever, decreased level of consciousness, continuous vomiting, or a new seizure.
  • Monitor for medication side effects when taking antivirals or antibiotics (including kidney function and blood tests).
  • If there is a history of seizures, use caution with driving, working at heights, and similar activities.
  • Immunocompromised individuals and older adults have a higher risk of complications.

Checklist Before an Outpatient Visit (Preparation and Example Questions)

• Items to prepare (before visiting the hospital)
  • A list of currently used medications and supplements, and a history of allergies
  • Copies or summaries of recent test results (blood tests, chest X-ray, CT/MRI, cerebrospinal fluid tests, etc.)
  • The time symptoms began and their progression (fever, changes in consciousness, whether seizures occurred, patterns of worsening or improvement)
  • Recent travel history (especially to areas where mosquito-borne diseases are prevalent), outdoor activities, and history of bites
  • A history of recent head trauma, brain surgery, or infection (such as otitis media or sinusitis)
  • Immune status (cancer treatment, use of immunosuppressants, HIV, etc.) and whether you are pregnant
• Items useful to confirm at the outpatient visit (materials to show the doctor)
  • Fever tracking (temperature records), seizure records (video if possible), and whether anticoagulants or immunosuppressants are currently being taken
• Examples of questions to write down before the outpatient visit
  • The date the symptoms were first noticed and the first symptoms (e.g., fever, headache, confusion)
  • Whether a seizure occurred, recovery time, and whether there were changes in the level of consciousness

General Example Questions to Ask the Doctor

• "What is the suspected cause of this condition, and what additional tests are needed?"
• "What medications should be administered as initial treatment (such as acyclovir or antibiotics)? What are the side effects?"
• "What are the criteria for requiring hospitalization or intensive care treatment?"
• "How will rehabilitation proceed after discharge? What is the prognosis?"
• "Are there any recommended vaccines or lifestyle practices for prevention?"

Examples of Condition-Specific Questions

• "HSV encephalitis is suspected. Should acyclovir be started immediately? How long should it be administered, and how should kidney function be monitored?"
• "How should the cerebrospinal fluid test results (cell count, protein and glucose levels, culture/PCR results) be interpreted? When are additional tests (EEG, repeat MRI) necessary?"

Additional precautions: If symptoms worsen acutely or persistent high fever, vomiting, decreased level of consciousness, or a new seizure occurs, visit the emergency department immediately. For prevention, relevant vaccines (e.g., Japanese encephalitis, Hib, pneumococcal, meningococcal, and varicella/zoster vaccines), mosquito avoidance, and hygiene management may be helpful.