Allergies and the Ear

When people think of allergy problems, what comes to mind most often are the classic symptoms of sneezing, runny nose, and itchy eyes.  Many people don’t realize that the ears can be affected by allergies, too.

The ear can be divided into three sections: outer, middle and inner.

The outer ear is made up of the ear we see, called the pinna, and the ear canal.  The pinna and canal help catch and funnel sound vibrations toward the middle ear.  The middle ear begins with the eardrum or tympanic membrane and contains the auditory bones-hammer, anvil, and stapes(STAY-peas)- which transmit sound vibrations to the inner ear or cochlea (COKE-lee-uh).  The cochlea converts those vibrations into nerve impulses which can be interpreted by the brain as sound.  The cochlea also contains the body’s balance apparatus- the vestibular (ves-TIB-you-luhr) system.

Allergies primarily affect the middle ear.  As you can see, the middle ear has a drainage tube or pressure release valve called the eustachian (you-STAY-shun) tube.  If this tube is clogged with mucus or its opening is blocked by allergy swelling, then pressure and fluid can build up in the middle ear.  This gives us the sensation of being down a well, having the need to “pop” our ears frequently, and can result in diminished hearing.  Fluid build-up also creates a good environment for infection to occur.  Middle ear infections, called otitis media or OM, occur commonly in early childhood and are a frequent reason for antibiotic treatment and missed school days.  Allergies are a well recognized cause for recurrent OM and kids who have more than their share of middle ear infections should be allergy tested.

Disorders affecting the inner ear, such as Meniere’s disease, may have an allergic component as well.  Patients who fail to respond to conservative therapy may benefit from allergy desensitization, though evidence to support this comes largely from case series and anecdotal evidence.

External ear infection, otits externa (OE) or swimmer’s ear, is usually caused by a water loving bacterium called pseudomonas (soo-duh-MOAN-us).  It is usually not related to allergies.

Finally, a word about itchy ears.  You really want to scratch them, don’t you?  Well, remember what your mom said: Never put anything in your ear smaller than your elbow!  The skin in the ear canal is paper thin and very easy to irritate.  Although sticking a Q-tip in there might feel good for a few seconds, it will just make the ears itch more afterward.

Symbicort, Advair, and Safety

Both Symbicort and Advair contain drugs called long acting beta-agonists, or LABAs for short.  Symbicort contains formoterol and Advair contains salmeterol.  Advair and Symbicort also contain inhaled corticosteroids(ICS), fluticasone and budesonide, respectively.  This combination of medications has been repeatedly shown in multiple prospective, randomized placebo-controlled trials to improve symptoms, lung function, and quality of life in asthmatics.  More importantly, combination ICS/LABA medications have been shown to reduce asthma exacerbations.  So what’s the problem?

The problem is, there are now two large meta-analyses which have shown an increased risk of adverse events in patients receiving LABAs.  A meta-analysis pools data from multiple trials in order to achieve higher statistical power.  These meta analyses have serious limitations, however.  

The first meta analysis was published by Dr. Shelley Salpeter, a primary care physician, in June, 2006.  It examined the use of salmeterol.  Among the co-authors were her father, an astrophysicist, and her son, then a high-school student.  Remarkably, and somewhat disconcertingly, the study was published in the Annals of Internal Medicine, one of the most rigorous and respected journals in the field.  It set off a firestorm of controversy in the asthma community and was roundly panned.  The primary flaw in the Salpeter paper was the large number of patients who came from the inaptly named SMART trial, where subjects were not required to utilize ICS along with their salmeterol.  That is a big no-no.  Not surprisingly, the majority of serious adverse events in the meta-analysis came from the SMART trial.  A follow-up meta-analysis published by respected asthma physicians Hal Nelson and Jean Bousquet, among others, confirmed what previous trials had shown- patients receiving combination ICS/LABA medications have fewer exacerbations and no increased risk for serious adverse events.

Now, a new meta-analysis has come out examining formoterol.  Apparently, the authors have not boned up on their recent history, because they repeat the same fatal flaw of the Salpeter paper- they included subjects who were not required to utilize ICS concomitantly with their LABA.  Predictably, the results are similar.  The shock value headline will read, “57% increase in serious non-fatal events!”, but the reality is that for every 1000 asthma patients in the analysis, 16 formoterol patients had a serious event and 10 placebo patients had a serious event, so the absolute risk increase is only 0.6%.  Additionally, the meta-analysis does not tell us whether those 6 extra patients were on formoterol alone or in combination or what dose of formoterol was used.  

The take home message is this: if your asthma is bad enough to require combination ICS/LABA therapy, then you can be reassured that there a wealth of data and experience supporting their effectiveness and safety.

Disclaimer:  I have no financial ties to either GlaxoSmithKline(Advair) or AstraZeneca(Symbicort), or to any other pharmaceutical company for that matter. On occasion,  I eat a grilled chicken salad at lunch with a GSK rep.

Probiotics and eczema

Probiotics are getting plenty of attention these days regarding their potential health benefits.  The general idea is that by introducing “good” bacteria to the gut you can somehow modify disease states.  In the medical community, the idea started to take hold with the advent of the “hygeine hypothesis”, a theory which held that childhood exposure to common infections could reduce allergic sensitization.  Researchers then noticed that children from Estonia, where there is a very low incidence of eczema, had higher levels of the “good” bacteria, lactobacillus, in their stool, than did children from Sweden, where there is a much higher incidence of eczema. (I’m just glad I didn’t have to do my fellowship in Estonia.)

In the years that followed, numerous trials have been done looking at the effect of probiotic supplementation on allergic disease, including this excellent study from New Zealand published in this month’s Journal of Allergy and Clinical Immunology.  The results have been mixed and are complicated by the fact that numerous probiotic bacteria species have been used and the timing of supplementation has varied greatly.  The take home message is this:

• Not all probiotics are created equal.  Lactobacillus rhamnosus is the species most often found to be effective.
• In high risk subjects- those with a strong family history- L rhamnosus reduced the relative risk of eczema by around 50%, from an absolute risk of 28% down to 14%.  Another way of putting it is that 8 kids would have to be treated to prevent one case of eczema.
• Supplementation has worked best when done during pregnancy and breastfeeding by mom and for the first 2 years of the child’s life.
• Despite the reduction in eczema, probiotic supplementation has consistently been shown to not reduce the incidence of either food or inhalant allergies.

Prevention of disease should always be the first goal of medicine. Based on this recent study and others, I think there is enough information to support probiotic supplementaion for the prevention of eczema in high risk individuals.

Dr. O

How do allergy shots work?

Here’s another common question, and an important one for allergy sufferers and people considering immunotherapy.  In order to better understand this, you must first understand a few things about the human immune system.

The primary purpose of the immune system is to fight infection from bacteria, viruses, and parasites.  In order to do this, the immune system must be able to distinguish 1) self from non-self and 2) normal environmental substances from abnormal environmental substances.  When the former breaks down, you get autoimmune diseases such as lupus, rheumatoid arthritis, type I diabetes, and the like.  In these diseases the immune system actually attacks the body, causing injury and disease.  When the latter breaks down, you get allergies.

In an allergic reaction, the immune system incorrectly recognizes a harmless environmental substance, like cat dander or ragweed pollen, as a potentially harmful substance.  In an attempt to rid the body of the offending substance, the immune system attacks it by releasing toxic chemicals- histamine, leukotrienes, platelet activating factor, prostaglandins,and other 50-cent words.  It is the release of these substances that gives you allergic symptoms- sneezing, runny nose, itchy eyes, congestion, wheezing, hives, etc.

Allergy shots teach the immune system to no longer recognize these harmless substances as harmful.  Allergists call this inducing tolerance.  This stops the allergic reaction before it ever starts and works to control allergy symptoms globally, whether they be in the eyes, ears, nose, throat or lungs.  Allergy shots also help to control the whole body symptoms of allergies such as fatigue, malaise, and sleep disturbance, that medications do a very poor job of controlling.

The immune system is incredibly complex so if this explanation isn’t clear, please ask questions and I’ll try to clear up any confusion.