INTRODUCTION

Acute rhinosinusitis is an illness that results from infection of one or more of the paranasal sinuses. A viral infection associated with the common cold is the most frequent etiology of acute rhinosinusitis, more properly called viral rhinosinusitis. (See "The common cold in children: Clinical features and diagnosis" and "The common cold in children: Treatment and prevention".)

Uncomplicated viral rhinosinusitis usually resolves without treatment in 7 to 10 days. Although acute bacterial rhinosinusitis (ABRS) also may resolve without treatment, treatment with antibiotics hastens recovery [1,2]. It is important to distinguish between uncomplicated viral rhinosinusitis and ABRS to prevent unnecessary use of antibiotics (table 1).

The clinical features and diagnosis of ABRS in children will be discussed here. The microbiology and treatment of ABRS in children and acute sinusitis and rhinosinusitis in adults are discussed separately. (See "Acute bacterial rhinosinusitis in children: Microbiology and treatment" and "Acute sinusitis and rhinosinusitis in adults: Clinical manifestations and diagnosis" and "Acute sinusitis and rhinosinusitis in adults: Treatment".)

ANATOMY

The paranasal sinuses develop as outpouchings of the nasal cavity (figure 1) [3]. The onset and duration of development of the paranasal sinuses vary depending upon the location, as described below. Development of the paranasal sinuses may not be fully completed until 20 years of age; however, by 12 years of age, the nasal cavity and paranasal sinuses in most individuals have nearly reached adult proportions [4].

• The maxillary sinuses are present at birth and expand rapidly by four years of age [4]. Ciliary activity is necessary for drainage of secretions from the maxillary sinus into the nose because the ostia are located high on the medial walls of the maxillary sinus [5].
• The ethmoid sinuses are present at birth; they are comprised of a collection of tiny air cells, each with its own opening into the nose [4].
• The sphenoid sinuses, which begin to develop during the first two years of life, are typically pneumatized by five years of age, and attain their permanent size by 12 years [4,6].
• Development of the frontal sinuses is variable [3]. By six to eight years of age, the frontal sinuses can be distinguished radiographically from the ethmoid sinuses [5], but they do not complete their development for another 8 to 10 years. Between 1 and 4 percent of adults have agenesis of the frontal sinuses, 80 percent have bilateral frontal sinuses, and the remainder has unilateral frontal sinus hypoplasia [3].