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The link between allergic rhinitis and otitis media
1Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, 3705 Fifth Avenue, Pittsburgh, PA 15213, USA. Docdoyle2@aol.com
Abstract:
Past studies implicated allergy in the pathogenesis of otitis media. However, definitive proof of the assertion is lacking. Epidemiologic studies, including one recently published by Rylander and Megevand, consistently identify allergy as a risk factor for otitis media. Also, higher than expected frequencies of allergy are reported for patients with otitis media, but it is unclear if this is an epiphenomenon associated with referral bias. This possibility is exemplified by the results of two reviewed papers where Velepic and colleagues reported a 25% prevalence of allergy in otitis media patients while Alles and colleagues reported a prevalence of 89%. Other studies documented biochemical components of allergic inflammation in the effusions recovered from children with otitis media, and Hurst and colleagues published a recent paper continuing on that theme. However, it is not known if a local allergic reaction is required for the production of these components and if they are produced exclusive of other inflammatory products. Three published studies explored mechanisms by which allergy could cause otitis media. Tikkanen and colleagues reexamined at age 10 a group of 56 subjects with previously diagnosed milk allergy and showed that despite decreased reactivity to milk protein a high prevalence of otitis media was retained. This suggests that it is the allergic condition, not the specific allergy to milk that increases otitis media risk. Downs and colleagues exposed the middle ears of rats to histamine and provoked changes in the pressure regulating and clearance functions of the Eustachian tube. Those changes could prolong an otitis media episode, but middle ear histamine is not limited to the allergic condition. Gentile and colleagues challenged the nose of allergic and nonallergic subjects with histamine followed by interleukin-6 or placebo and measured nasal, pulmonary, Eustachian tube and middle ear functions. Interleukin-6 did not change the Eustachian tube or middle ear functions but did cause increased secretions in allergic patients.
Insights
While allergy is a known risk factor for otitis media, definitive proof is lacking. Research suggests the allergic condition, not specific allergies, may increase otitis media risk.
Area of Science:
- Immunology
- Otolaryngology
- Epidemiology
Background:
- Otitis media is a common condition, and allergy has been frequently implicated in its pathogenesis.
- However, conclusive evidence directly linking allergy to the development of otitis media remains elusive.
- Existing studies show a correlation, but potential biases like referral bias complicate interpretation.
Purpose of the Study:
- To review and synthesize existing evidence on the role of allergy in the pathogenesis of otitis media.
- To explore potential mechanisms by which allergic conditions might contribute to otitis media development.
- To clarify whether specific allergic reactions or the general allergic state is more relevant to otitis media risk.
Main Methods:
- Review of epidemiological studies identifying allergy as a risk factor for otitis media.
- Analysis of studies examining biochemical markers of allergic inflammation in middle ear effusions.
- Examination of experimental studies investigating the effects of histamine and other mediators on Eustachian tube and middle ear function.
Main Results:
- Epidemiological data consistently suggest allergy is a risk factor, though prevalence estimates vary widely.
- Biochemical evidence shows allergic inflammation markers in middle ear effusions, but their origin (local vs. systemic) is unclear.
- Studies suggest the underlying allergic condition, rather than specific allergen reactivity, may be key; histamine's role in Eustachian tube dysfunction is noted, but not exclusively allergic.
Conclusions:
- While a strong association exists, definitive proof of allergy causing otitis media is still lacking.
- The allergic state, potentially through mediators like histamine affecting Eustachian tube function, appears more critical than specific allergies.
- Further research is needed to elucidate the precise mechanisms linking allergy to otitis media pathogenesis.