What is the treatment for chronic fungal mastoiditis?

Treatment of Chronic Fungal Mastoiditis

The treatment of chronic fungal mastoiditis requires aggressive combined surgical debridement with clean margins followed by appropriate systemic antifungal therapy, as this approach offers the best chance for cure and prevention of complications.

Diagnostic Approach

Before initiating treatment, proper diagnosis is essential:

• High-resolution temporal bone CT scan with contrast is the first-line imaging modality to assess bone destruction and identify complications 1
• MRI with diffusion and T1 sequences with/without gadolinium should be considered when intracranial complications are suspected 1
• Tissue samples should be obtained for culture and histopathology to identify the specific fungal pathogen

Treatment Algorithm

1. Surgical Management (Primary Intervention)

• Surgical debridement with clean margins is strongly recommended as the cornerstone of treatment 2
• Complete removal of all infected tissue through mastoidectomy is necessary to:
  • Eliminate fungal burden
  • Obtain diagnostic specimens
  • Prevent disease progression and complications
  • Create access for local antifungal therapy

2. Systemic Antifungal Therapy

The choice of antifungal depends on the identified pathogen:

For Aspergillus species:

• First-line: Voriconazole 6 mg/kg IV twice daily for 2 doses, then 3-4 mg/kg twice daily 2, 3
• Alternative: Isavuconazole 200 mg three times daily for days 1-2, then 200 mg daily 2
• Alternative: Liposomal amphotericin B 3-5 mg/kg/day for severe cases 2

For Candida species:

• First-line: Fluconazole 400-800 mg daily for 14-21 days 2
• Alternative for fluconazole-resistant species: Echinocandin (micafungin 150 mg daily, caspofungin 70 mg loading dose then 50 mg daily, or anidulafungin 200 mg daily) 2

For Mucormycosis:

• First-line: Liposomal amphotericin B 5-10 mg/kg/day 2
• Alternative: Isavuconazole or posaconazole (if renal compromise) 2

3. Local Antifungal Therapy

• Local irrigation of the mastoid cavity with amphotericin B deoxycholate (25-50 mg in 200-500 mL sterile water) is recommended as adjunctive therapy 2
• For recalcitrant cases, innovative approaches such as polyhexamethylene biguanide (swimming pool biocide) have been reported as successful adjunctive local therapy 4

4. Duration of Therapy

• Systemic antifungal therapy should continue for a minimum of 6-8 weeks 1
• For invasive fungal infections, treatment may need to be extended for 3-6 months or until complete resolution of radiographic findings
• Regular follow-up imaging (CT or MRI) is necessary to assess treatment response

Special Considerations

Immunocompromised Patients

• More aggressive surgical debridement and longer duration of antifungal therapy is required 5, 6
• Addressing the underlying immunodeficiency is crucial for treatment success 5
• Close monitoring for disease progression and complications is essential

Complications to Monitor

• Intracranial extension (brain abscess)
• Facial nerve paralysis
• Venous sinus thrombosis
• Septicemia

Treatment Challenges

• Fungal mastoiditis can be recalcitrant to standard therapy, particularly in immunocompromised hosts 7
• Some cases may require multiple surgical debridements
• Antifungal resistance may develop, necessitating alternative agents
• Prolonged therapy may lead to drug toxicity, requiring monitoring of liver and kidney function

Prognosis

The prognosis depends on:

• Extent of infection at diagnosis
• Underlying immune status
• Causative organism
• Timeliness of surgical intervention
• Appropriate antifungal selection

Early aggressive combined surgical and medical therapy offers the best chance for cure and prevention of complications.