Paranasal Sinusitis

Ellen R. Wald

Acute infection of the paranasal sinuses is a common complication of allergic or infectious inflammation of the upper respiratory tract. Approximately 5% of upper respiratory infections are complicated by acute sinusitis. Because adults average two to three colds per year and children experience six to eight, sinusitis is a problem seen commonly in clinical practice.

Of the four paired paranasal sinuses—ethmoid, maxillary, sphenoid, and frontal—all but the frontal sinuses are present at birth. The frontal sinuses develop from the anterior ethmoid sinuses and become clinically important after the tenth birthday. The maxillary and ethmoid sinuses are the principal sites of sinus infection in young children.

ANATOMY

The anatomic relationship between the nose and the paranasal sinuses is shown in Fig. 246.1. The nose is divided in the midline by the nasal septum. From the lateral wall of the nose emerge three shelf-like structures: the inferior, middle, and superior turbinates. Beneath the middle and the superior turbinates is a natural meatus that drains two or more of the paranasal sinuses. The posterior ethmoid sinus and the sphenoid sinuses drain into
the superior meatus, and the anterior ethmoid sinuses, the frontal sinuses, and the maxillary sinuses drain into the middle meatus; only the lacrimal duct drains into the inferior meatus. The position of the outflow tract of the maxillary sinus, high on the medial wall of the sinus cavity, impedes gravitational drainage of secretions and accounts for the frequency of involvement of the maxillary sinuses when upper respiratory tract inflammation becomes complicated by bacterial superinfection.

FIGURE 246.1. Anatomy of the paranasal sinuses. A: Coronal section demonstrating the relationship between the nose and the ethmoid and maxillary sinuses. B: Sagittal section showing the nasal turbinates as well as the frontal, ethmoid, and sphenoidal sinus. C: Parasaggital section shows the body of the maxillary and sphenoid sinus.

PATHOPHYSIOLOGY AND PATHOGENESIS

Three elements are important to the normal physiology of the paranasal sinuses: the patency of the ostia, the function of the ciliary apparatus, and, integral to the latter, the quality of secretions. Retention of secretions in the paranasal sinuses is caused by one or more of the following: obstruction of the ostia, reduction in the number (or impaired function) of the cilia, or overproduction or change in the viscosity of the secretions.

Ostial Obstruction

The ostia of the paranasal sinuses are the key to disorders in the sinus area. The ostia of the maxillary sinuses are small, tubular structures having a diameter of 2.5 mm (cross-sectional area, approximately 5 mm) and a length of 6 mm. The diameter of the ostium of each of the individual ethmoid air cells that drains independently into the middle meatus is even smaller, measuring 1 to 2 mm. The narrow caliber of these individual ostia sets the stage for obstruction to occur easily and often.

The factors predisposing to ostial obstruction can be divided into those that cause mucosal swelling and those that result from mechanical obstruction (Box 246.1). Although many conditions may lead to ostial closure, viral upper respiratory infection and allergic inflammation are by far the most common and most important.

Alternation in Ciliary Number or Function

In the posterior two-thirds of the nasal cavity and within the sinuses, the epithelium is pseudostratified columnar, in which most of the cells are ciliated. Usually, the normal motility of the cilia and the adhesive properties of the mucous layer protect the respiratory epithelium from bacterial invasion. However, certain respiratory viruses (influenza, adenovirus) may have a direct cytotoxic effect on the cilia. The alteration of cilia number, morphology, and function may facilitate secondary bacterial invasion of the nose and the paranasal sinuses.

Microbiology

Maxillary sinus aspiration in children with acute bacterial sinusitis has shown the microbiologic features of sinus secretions to be similar to those found in acute otitis media. The predominant organisms are Streptococcus pneumoniae, Moraxella catarrhalis, and nontypeable Haemophilus influenzae. Both H. influenzae and M. catarrhalis may produce beta-lactamase and, consequently, may be resistant to amoxicillin. In addition, a dramatic increase has been seen in the frequency of S. pneumoniae isolates not susceptible to penicillin. As many as 50% of maxillary sinus isolates have a minimum inhibitory concentration of more than 0.1 μg/mL for penicillin. The risk factors that predispose to penicillin-nonsusceptible isolates of S. pneumoniae are recent receipt of antimicrobials, attendance at day care, and age less than 2 years. Anaerobic isolates and staphylococci rarely are recovered. Several viruses, including adenoviruses, influenza viruses, parainfluenza viruses, and rhinoviruses, have been isolated from maxillary sinus aspirates. Summary figures for the prevalence of various bacterial species in children with acute sinusitis are shown in Table 246.1. The performance of nasal, throat, or nasopharyngeal cultures is of no value in patients with acute sinusitis, because the results are not predictive of the bacterial isolates within the maxillary sinus cavity. The microbiology of chronic sinusitis differs slightly from that of acute sinusitis. Anaerobes of the respiratory tract, viridans streptococci, and, occasionally, Staphylococcus aureus are found in addition to the aerobes of acute sinusitis.

CLINICAL MANIFESTATIONS

In most children with acute or chronic sinusitis, the respiratory symptoms of nasal discharge, nasal congestion, and cough are prominent. During the course of an apparent viral upper respiratory tract infection, two common clinical presentations suggest a diagnosis of acute sinusitis.

TABLE 246.1. BACTERIOLOGY OF ACUTE SINUSITIS

Bacterial species	Prevalence (%)
Streptococcus pneumoniae	25–30
Moraxella catarrhalis	15–20
Haemophilus influenzae	15–20
Streptococcus pyogenes	2–5
Anaerobes	2–5
Sterile	20–35

The first, most common clinical situation raising suspicion of sinusitis is the presence of persistent signs and symptoms of a cold. Nasal discharge and daytime cough that continue beyond 10 days and are not improving are the principal complaints. Most uncomplicated upper respiratory tract infections last for 5 to 7 days; although patients may not be asymptomatic by the tenth day, usually their condition has improved. The persistence of respiratory symptoms without appreciable improvement beyond the 10-day mark suggests that a complication has developed. The nasal discharge may be of any quality (thin or thick, clear, mucoid, or purulent), and usually the cough (which may be dry or wet) is present in the daytime, although often it is noted to be worse at night. Cough occurring only at night is a common residual symptom of an upper respiratory tract infection. When it is the only residual symptom, usually it is nonspecific and does not suggest a sinus infection; it is more likely to represent reactive airways disease. Conversely, the persistence of daytime cough frequently is the symptom that brings affected children to medical attention. Such children may not appear ill; usually, if fever is present, it will be low grade. Often, malodorous breath is reported by parents of affected preschoolers. The complaint of malodorous breath accompanied by respiratory symptoms (in the absence of exudative pharyngitis, dental decay, or nasal foreign body) is a clue to the presence of a sinus infection. Facial pain rarely is present, although intermittent, painless, periorbital swelling (present in the morning and resolving later in the day) may have been noted by observant parents. In this case, the persistence, not the severity, of the clinical symptoms calls for attention.

The second, less common presentation is a cold that seems more severe than usual. The fever is high (greater than 39°C), the nasal discharge is purulent and copious, and associated periorbital swelling or facial pain may be present. The periorbital swelling may involve the upper or lower eyelid; it is gradual in onset (evolving over hours to days) and most obvious in the morning after awakening. The swelling may decrease and actually disappear during the day, only to reappear the following day. A less common complaint is headache (a feeling of fullness or a dull ache either behind or above the eyes), reported most often in children older than 5 years. Occasionally, such children complain of dental pain, either from infection originating in the teeth or from pain referred from the sinus infection.

Headache is not a common complaint in children with acute sinusitis. When headache is a symptom of acute sinusitis, it is almost always accompanied by prominent respiratory complaints. Usually, the headache is most severe on awakening and is relieved partially when affected patients are up and about. Chronic sinusitis is distinguished from acute sinusitis by the persistence of respiratory symptoms (nasal discharge or cough or both) beyond 4 to 6 weeks.

DIAGNOSIS

Physical Examination

On physical examination, patients with acute sinusitis may display mucopurulent discharge in the nose or posterior pharynx. The nasal mucosa is erythematous; the throat may show moderate injection. The cervical lymph nodes are neither enlarged significantly nor tender. None of these characteristics differentiates rhinitis from sinusitis. Occasionally, as the examiner palpates over or percusses the paranasal sinuses, tenderness will be apparent, or appreciable periorbital edema will be seen (soft, nontender swelling of the upper and lower eyelid with discoloration of the overlying skin), or both may occur. Malodorous breath in concert with nasal discharge or cough suggests bacterial sinusitis.

In general, for most children younger than age 10 years, the physical examination is not very helpful in making a specific diagnosis of acute sinusitis. However, if the mucopurulent material can be removed from the nose and the nasal mucosa is treated with topical vasoconstrictors, pus may be seen coming from the middle meatus. The latter observation, the presence of periorbital swelling, or a combination is the most specific finding in acute sinusitis.

Radiography

Traditionally, radiography has been used to determine the presence or absence of sinus disease. Standard radiographic projections include an anteroposterior, a lateral, and an occipitomental view. The anteroposterior view is optimal for evaluation of the ethmoid sinuses, and the lateral view is best for viewing the frontal and sphenoid sinuses. The occipitomental view, taken after tilting the chin upward 45 degrees from the horizontal, allows evaluation of the maxillary sinuses. The radiographic findings most diagnostic of bacterial sinusitis are the presence of an air-fluid level in, or complete opacification of, the sinus cavities (Fig. 246.2). However, an air-fluid level is an uncommon radiographic finding in children with acute sinusitis who are younger than 7 or 8 years old. In the absence of an air-fluid level or complete opacification of the sinuses, measuring the degree of mucosal swelling may be useful. If the width of the sinus mucosa is 5 mm or greater in adults or 4 mm or greater in children, the sinus aspirate likely will contain pus or will yield a positive bacterial culture. When clinical signs and symptoms suggesting acute sinusitis are accompanied by abnormal maxillary sinus radiographic findings, bacteria will be present in a sinus aspirate 70% of the time. A normal radiograph is strong evidence that a sinus is free of disease.

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