Pediatric allergic rhinitis and comorbid disorders.

Allergic rhinitis (AR) is rarely found in isolation and needs to be considered in the context of systemic allergic disease associated with numerous comorbid disorders, including asthma, chronic middle ear effusions, sinusitis, lymphoid hypertrophy with obstructive sleep apnea, disordered sleep, and consequent behavioral and educational effects. The coexistence of AR and asthma is complex. First, the diagnosis of asthma may be confounded by symptoms of cough caused by rhinitis and postnasal drip. This may lead to either inaccurate diagnosis of asthma or inappropriate assessment of asthma severity with over treatment of the patient. The term "cough variant rhinitis" is therefore proposed to describe rhinitis that manifests itself primarily as cough that results from postnasal drip. AR, however, also has a causal role in asthma; it appears both to be responsible for exacerbating asthma and to have a role in its pathogenesis. Postnasal drip with nasopharyngeal inflammation leads to a number of other conditions. Thus sinusitis is a frequent extension of rhinitis and is one of the most frequently missed diagnoses in children. Allergen exposure in the nasopharynx with release of histamine and other mediators can cause Eustachian tube obstruction possibly leading to middle ear effusions. Chronic allergic inflammation of the upper airway causes lymphoid hypertrophy with prominence of adenoidal and tonsillar tissue. This may be associated with poor appetite, poor growth, and obstructive sleep apnea. AR is therefore part of a spectrum of allergic disorders that can profoundly affect the well being and quality of life of a child. Prospective cohort studies are required to assess the disease burden caused by AR in childhood and to further assess the potential educational impairment that may result. Because AR is part of a systemic disease process, its management requires a coordinated approach rather than a fragmented, organ-based approach.