The human body has several small, crater-like pockets or channels called sinuses. In common usage, the term sinus is usually applied to those areas located in the nasal cavity, also referred to as paranasal sinuses. These sinuses serve as passageways for mucus drainage. When the sinus passageways are blocked due to excess mucus and/or inflammation, a sinus infection may develop, which is called sinusitis. A form of this condition is allergic fungal sinusitis.
Domino Effect
Scientists believe that AFS is caused by a domino effect. The first component is fungus. Fungus is an organism that reproduces via spores and encompasses more that 8,000 species including molds and yeasts. Various types of fungus are found in the air. When certain parts of fungi are inhaled, some people experience an allergic reaction, which is the second component. An allergic reaction is an abnormal immune system response to substances that are usually considered harmless. The allergic reaction to these fungi causes inflammation and excess mucus in the sinuses. This phenomenon is a catalyst for the third component, which is the development of an infection from the sinus blockage. AFS is characterized by excessive mucus and fungal particles in the sinuses, and is the most prevalent type of fungal infection.
Types of Fungus
AFS is primarily caused by fungi classified in the scientific family Dematiaceous, whose members are prevalent in 87 percent of AFS cases. Some of these fungi members include Bipolaris, which is most commonly present, and Curvularia. Aspergillus, which is a member of the family Trichocomaceae, is found in 13 percent of AFS cases.
Symptoms
Individuals who have AFS experience symptoms that include nasal congestion, facial pain, runny nose, sensitivity to sound and equilibrium problems. Other symptoms may include bad breath due to the fungal accumulation, postnasal drip, and less commonly, nasal bone expansion.
Signs and Diagnostic Tools
Upon medical examination, in addition to an accumulation of fungal debri and mucus, other signs of AFS include nasal polyps and a thinning of bony areas. Some of the tools used to diagnose AFS are X-rays, blood tests, CT scans and culture samples.
Treatments
The goal of treatment consists of fungal and mucus removal, so antihistamines alone are generally ineffective for treating AFS. Treatment options include endoscopic sinus surgery to clear out sinuses and remove polyps as applicable, corticosteroids to reduce sinus inflammation, antifungal medications, saline solution rinses, antibiotics and steam inhalation. Antihistamines are sometimes used in conjunction with these options.
References
- Encyclopedia: The Oxford Companion to the Body; Sinus; Colin Blakemore; 2001
- Encyclopedia: Gale Encyclopedia of Medicine, 3rd ed.; Sinusitis; Rosalyn Carson-DeWitt; 2006
- Encyclopedia: World Encyclopedia; Fungus; 2005
- Encyclopedia: Gale Encyclopedia of Medicine, 3rd ed.; Allergy; Richard Robinson; 2006
- The Aspergillus Website – United Kingdom: Patients Guide for Allergic Fungal Sinusitis
- American Rhinologic Society: “Fungal Sinusitis”; Dan Carothers, MD
- Medscape: “Allergic Fungal Sinusitis – Etiology”; John E McClay, MD, etc.
