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 Sinus pain
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I have been surprised at how many of my patients are asking about the relationship of fungus to their sinus problems. Most of the questions stem from a report by the Mayo Clinic several years ago and the resultant media coverage. They basically concluded that most chronic sinusitis was fungus related.
Suffice it to say that there is a lot that we don't know about chronic rhino-sinusitis (CRS). CRS almost certainly has several different specific etiologies despite a common final presentation. Many cases are undoubtedly multifactorial. It will probably be shown that fungus does play a more frequent role in the pathogenesis than we currently believe, but I don't think that the conclusions of the Mayo study are the basis on which that should rest. Let’s examine a few things about chronic sinusitis and the role fungus plays in it.
Fungal sinusitis comes in several well defined forms, and perhaps in a few forms that we are just beginning to learn about. They fall into 4 categories:
1) The most apparent type is the invasive fungal infections such as invasive mucor; an immunocompromised patient develops a life threatening invasive fungal infection. This can occur in immunocompetent patients, but it is rare in either case. This diagnosis is usually made by CT or MRI; it is clearly the result of invasive fungus, it requires systemic antifungals such as Amphoteracin B, and also requires aggressive surgical debridement. This can be fatal, and often results in loss of an eye, or neurological deficit. You may never see this type of infection.
2) The next most obvious situation is called a fungus ball. It usually presents as one sinus, usually the maxillary, with a ball of fungal hyphae, not invasive and with minimal inflammatory response. The symptoms are varied, usually not severe, and the treatment is removal of the fungus ball.
3) About 7% - 10% of patients with chronic sinusitis who come to surgery have a somewhat clearly defined process termed Allergic Fungal Sinusitis. This process is some type of inflammatory reaction to non-invasive fungal growth. The most characteristic finding is a large amount of so called allergic fungal mucin. The material in the involved sinus is a thick, sticky, tenacious goo that contains fungal hyphae and eosinophil breakdown products noted on cytology. Fungus can often be cultured. The patients almost always have polyps, and the process is often unilateral. The CT scan is often characteristic with areas of mixed density in the sinus, sort of a marbled appearance. The treatment involves allergy testing to fungal antigens and immunotherapy, surgical debridement of the allergic fungal mucin, creating wide drainage pathways, perioperative oral steroids, and aggressive post operative care with frequent cleanings using oral steroids for any signs of recurrence.
The prognosis is not as good as for most other types of chronic sinusitis in that a higher percentage of patients have recurrence and more patients eventually undergo revision surgery. Oral steroids have a remarkable and dramatic effect in this process and the key to therapy is adequate surgery and balancing the concerns of oral steroid use with the dramatic help they provide this process.
Neither oral nor topical antifungals have yet shown effectiveness. They are being evaluated.
4) There is probably some role that fungus plays in some cases of chronic sinusitis, even though that role is not as clear as in the above category. In a microscopic fashion, the sinuses and contents demonstrate some or all of the criteria for allergic fungal sinusitis, but do not have the gross evidence of allergic fungal mucin. The Mayo study shows that there are a lot of these patients out there. I currently call this chronic sinusitis with possible fungal involvement. In my practice, these patients often respond to long term antibiotic treatment. The fact that antibiotics are so often effective goes against fungus being a primary cause. Antibiotics don’t often help in an obvious case of Allergic Fungal Sinusitis.
First, let’s consider their conclusion. "...the diagnostic criteria for AFS (allergic fungal sinusitis) are present in the majority of patients with CRS (chronic rhino-sinusitis) with or without polyposis."
The most common diagnostic criteria are:
- Culture proven fungus or histologic evidence of fungus
- Characteristic allergic fungal mucin
- Nasal polyps
- CT scan evidence of chronic sinusitis
The Mayo study used a modified technique to culture fungus from patients’ nasal secretions. They found that 100% of healthy controls have positive fungal cultures of their nasal mucous and 97% of patients with chronic sinusitis had such evidence. They determined that most patients with CRS that they suspect is fungal do not have mast cell involvement; neither do they have fungal specific IgE. This, they say, shows that the nature of fungal sinusitis is not allergic. We must remember though, they think nearly everyone with CRS has fungal sinusitis.
Patients with CRS have a much higher incidence of eosinophilia seen in histology than is historically seen in controls. The conclusion is that a the vast majority of patients with sinusitis have fungus as a root cause and that some non-allergic immunologic reaction to the fungus with eosinophils as a key cellular agent is the pathophysiology. They agree that the fact that eosinophils and fungus are both in the mucus does not necessarily represent a cause and effect, but this main premise is put forth nonetheless.
Well, this is a simplified version of their findings and is subject to my interpretation, but I have read the entire study several times and have read the opinion of several sinus experts around the country regarding their study. Basically I believe that their conclusion is not valid. It will likely be shown that fungus does play a bigger role in sinusitis than we had previously thought, but I doubt it will have a direct causative role in most situations and that the role of fungus is as pervasive as they suggest.
:
1) Many but not all cases of sinusitis that fit the criteria of chronic sinusitis can be cleared up completely with long term appropriate antibiotics and other ancillary medicines. So how can a fungus be the root cause here?
2) In many cases of clearly diagnosed allergic fungal sinusitis, the problem is unilateral. If the problem is a systemic host reaction to ubiquitous fungus, why would it so often be unilateral? Anatomic variations seem to play a role here.
3) If 100% of controls have evidence of fungus, how can the fungus be implicated (by their techniques) at all as a culprit in fungal sinusitis? Sure, they may prove to be the cause, but you can’t make that conclusion simply because fungus is present; fungus is present in everyone (using their culture technique).
4) In the majority of patients with chronic sinusitis that are unresponsive to antibiotics, surgical intervention is clearly helpful. Post-operatively, many patients don't manifest inflammation. If the pervasive fungus is present, and according to them it should be, why is there not a clear continued host response? Patients with "clearly" defined allergic fungal sinusitis are much more likely to manifest persistent inflammation. There is a big difference in the natural history of the 7% of patients who have "clearly" defined allergic fungal sinusitis and most of the remainder. There may be some connection, but all chronic sinusitis cases are not alike.
:
Chronic sinusitis is almost certainly a process with multiple etiologies. The Mayo study investigates the possibility that an immunologic reaction to airborne fungus may be a more common eitiology than was previously thought. Their results are preliminary and do not demonstrate a clear cause and effect relationship but do bring to the forefront the need to further investigate this particular phenomenon. The fact that their premise would categorize the majority of Chronic Sinusitis patients as having Allergic Fungal Sinusitis is not yet helpful clinically.
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