Which sinus is most commonly affected in adults with sinusitis, particularly those with a history of allergic rhinitis (AR) or asthma?

Most Common Sinus Affected in Adults with Sinusitis

The maxillary sinus is the most commonly affected sinus in adults with sinusitis. 1

Anatomical Distribution

• Maxillary sinusitis represents the most frequent presentation in adult patients with acute sinusitis, making it the primary focus of diagnostic and therapeutic approaches 1
• The maxillary sinus is particularly vulnerable due to its anatomical position and drainage patterns, with the ostium located superiorly, making gravitational drainage less efficient 1

Clinical Relevance in Allergic Rhinitis and Asthma Patients

While the maxillary sinus remains most commonly affected overall, patients with allergic rhinitis warrant special consideration:

• Allergic rhinitis commonly precedes the development of recurrent or chronic sinusitis, with 40-84% of adults with chronic rhinosinusitis having coexisting allergic rhinitis 2, 3
• The pathophysiological mechanism involves allergic inflammation causing nasal congestion and mucosal swelling that obstructs sinus drainage through the ostia, creating conditions favorable for bacterial superinfection 2, 3
• Patients with both allergic rhinitis and chronic rhinosinusitis demonstrate more extensive abnormalities on CT scans compared to those without allergic rhinitis (67% versus 33% abnormal scans) 3, 4

Diagnostic Implications

The clinical signs most helpful in diagnosing maxillary sinusitis specifically include:

• Maxillary toothache 1
• Purulent nasal discharge 1
• Abnormal transillumination 1
• Sinus tenderness on palpation over the maxillary region 1
• Lack of improvement with decongestants 1

Other Sinus Involvement

While maxillary sinusitis is most common, other sinuses require attention due to potential complications:

• Sphenoid, frontal, and ethmoid sinusitis carry higher risk of serious complications due to proximity to vital anatomic structures and venous drainage systems, including meningitis, periorbital infections, subdural empyema, brain abscess, and cavernous sinus thrombosis 1
• Plain film radiographs inadequately visualize the anterior ethmoid sinuses, making CT the preferred imaging modality when complications are suspected 1

Management Considerations for Allergic Patients

Patients with recurrent or chronic sinusitis should be evaluated for the presence of underlying allergy, as effective treatment of allergic rhinitis may decrease sinusitis frequency 2, 3, 4