Inflammation and infection of paranasal sinuses can often affect more than one sinus, but the maxillary sinus is most frequently involved. Facial pain, fever, and rhinorrhea are some of the main clinical features. The diagnosis could necessitate an extensive clinical, imaging and microbiological workup.
Sinusitis is considered to be one of the most frequently encountered ear, nose, and throat (ENT) infections in medical practice and the maxillary sinus is identified as the predominant site where this infection occurs   . Based on symptoms duration, maxillary sinusitis can be divided into acute, when inflammation of the mucosal lining of the maxillary sinus lasts less than 30 days, or chronic (> 3 months)  . The pathogenesis and appearance of symptoms almost exclusively involve a preceding milder infection of the upper respiratory tract, primarily by viral pathogens (such as rhinoviruses, as well as influenza and parainfluenza viruses)  . A number of studies, however, have confirmed that odontogenic infections are an important cause of maxillary sinusitis, accounting for up to 30-40% of cases   . In addition to viruses, various bacteria may be responsible for sinusitis. However, respiratory infection-induced sinusitis has a different spectrum of bacteria (Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, or Staphylococcal species) than sinusitis stemming from an odontogenic infection, which is caused by Bacteroides spp., Proteus spp., and coliform bacilli, but also streptococci   . Principal manifestations of maxillary sinusitis are a facial pain, mainly in the cheekbones, rhinorrhea, and nasal congestion   . Additional signs and symptoms are a foul breath, a postnasal drip, and toothache, which is not a definite indicator of an odontogenic source  .
Although sinusitis is a common entity in practice, its diagnosis may be difficult to attain due to the nonspecific signs and symptoms that are seen in a myriad of illnesses and infections. But because of its rather high frequency, a clinical suspicion must be present in all patients with unexplained rhinorrhea, fever, and facial pain, especially if a chronic course is reported. Physicians should inquire about the onset and duration of symptoms, after which a complete physical examination, with an emphasis on the ENT exam, is necessary. Identification of areas sensitive to pain is an important part of the exam, but it is not uncommon for sinusitis to be misdiagnosed as tension or migraine headaches, as both can cause tenderness and pain in the sinonasal area . For this reason, detection of pus in the middle nasal meatus on anterior rhinoscopy is considered as a key sign of acute bacterial maxillary sinusitis  . Once clinical findings suggest sinusitis as the probable diagnosis, imaging studies could be employed. Plain radiography of the sinuses can show an air-fluid level but computed tomography (CT) could be necessary in difficult cases  . Ultrasonography has been evaluated as a possible method in the assessment of this infection and seems to be superior to plain X-rays . A panoramic X-ray is recommended if an odontogenic source is suspected  . In addition to clinical and imaging studies, a microbiological investigation is an important step as well. But because swab cultures or cultivation of nasal secretions often provide inadequate results, this part of workup is reserved only for individuals who do not respond to therapy or those at risk for a more severe form of infection (eg. immunocompromised patients)  .