Brain abscess

Disease Description (Causes and Symptoms)

• Definition: A condition in which pus (an abscess) collects within the brain tissue; bacterial infection is the most common cause.
• Main causes and pathophysiology:
  • Direct extension of a localized infection: Inflammation may extend to the brain from chronic otitis media, acute otitis media, sinusitis, periodontal or dental infections, and other infections.
  • Hematogenous spread: In systemic infections such as bacterial endocarditis or pulmonary infection, bacteria may seed the brain through the bloodstream and form an abscess.
  • The risk increases in immunocompromised states.
  • Common causative organisms: Streptococci, staphylococci, and anaerobic bacteria; mixed infections have become common in recent years.
• Main symptoms:
  • Headache (usually dull and gradually worsening), fever (low-grade to high), nausea and vomiting
  • Focal neurological deficits (such as motor or sensory weakness depending on the location), personality changes, and decreased consciousness
  • Seizures may occur
  • Symptoms vary depending on the size and location of the abscess and whether cerebral edema is present

Treatment Methods (Standard Treatment, Medications, Procedures/Surgery, Lifestyle Management and Precautions)

• Initial evaluation and diagnosis:
  • Contrast-enhanced CT or MRI is essential for diagnosis. Because of the risk of rupture into the ventricles, lumbar puncture is generally not recommended when there is no supporting evidence.
  • When possible, abscess aspiration or biopsy is performed for culture. Blood cultures are also recommended.
• Antibiotic treatment:
  • Start empiric broad-spectrum antibiotics immediately (targeting streptococci, staphylococci, gram-negative bacteria, and anaerobic bacteria). Treatment is usually administered IV for several weeks (generally 6–8 weeks), with a possible switch to oral medication depending on clinical and imaging findings.
  • The specific drug selection is determined based on locally prevalent organisms, resistance rates, and the patient's condition (such as allergies and kidney function) (e.g., a third-generation cephalosporin + metronidazole ± vancomycin; however, combination therapy must be determined by the medical team).
• Surgical treatment:
  • Transcranial aspiration (stereotactic) is performed to drain the pus and obtain diagnostic material and cultures (useful when a capsule has formed).
  • When the abscess is large, has a thick capsule, and is readily accessible, craniotomy with excision (complete removal) may be considered.
  • Whether to perform surgery is determined based on the abscess size, location, whether it is multiple, and the clinical condition (including deep location or life-threatening circumstances).
• Adjunctive treatment:
  • Steroids (short-term when necessary) and osmotic agents may be used for cerebral edema and increased intracranial pressure, depending on the situation, such as chronic hypertension.
  • Anticonvulsants are administered when seizures occur or the risk of seizures is high (seizures may continue even after treatment).
• Lifestyle management and precautions:
  • Regular neurological evaluations and follow-up imaging (CT/MRI) are necessary during and after treatment.
  • Monitor for medication side effects during antibiotic treatment (including liver and kidney function and bone marrow suppression).
  • Procedures such as lumbar puncture should be performed only after safety has been confirmed under the judgment of a specialist.
  • Because delays in treatment can be fatal, prompt medical attention is necessary when the condition is suspected.

Checklist Before an Outpatient Visit (Including Items to Bring and Example Questions)

• Items to bring and information to provide:
  • A list of all medications currently being taken (including prescription and nonprescription medications and supplements) and the times they are taken
  • History of allergies (especially antibiotic allergies)
  • Medical history: congenital heart disease, endocarditis, immunocompromised states (e.g., steroids or immunosuppressants), and recent ear, dental, or sinus infections or surgical history
  • Copies or records of recent tests and imaging (CT/MRI, blood tests, and culture tests)
  • The time of symptom onset and course (headache, fever, seizures, etc.), including records of worsening or improvement
• Items to show the medical team immediately at the outpatient visit:
  • Recent fever records, the time and type of any seizures, and whether focal neurological symptoms (such as language difficulties or one-sided weakness) occurred
• Items to confirm before testing:
  • Confirm whether blood tests (including blood cultures) and imaging (contrast-enhanced CT/MRI) have been scheduled
  • If emergency symptoms occur (such as a sudden decrease in consciousness, severe focal neurological symptoms, or ongoing seizures), visiting the emergency department is recommended

Examples of General Questions to Ask the Doctor

• "What antibiotics will be used until the causative organism is identified? What are the side effects?"
• "How do you determine whether surgery is necessary or whether aspiration alone is sufficient?"
• "How long will treatment take, and what will the hospitalization period and follow-up tests involve?"
• "How long should anticonvulsants be used to prevent seizures?"
• "What is the likelihood of long-term neurological sequelae (motor, cognitive, or personality changes) after treatment?"

Examples of Disease-Specific Questions

• "Considering my case (for example, a recent history of otitis media, sinusitis, or endocarditis), what is the most likely causative organism and what empiric antibiotic is recommended?"
• "Based on the abscess size and location and the degree of cerebral edema on imaging (CT/MRI), which treatment do you recommend—surgical aspiration or excision—and why?"