Sinusitis is inflammation of the sinus or nasal passage. Chronic sinusitis is chronic inflammation of the sinus or nasal passages occurring for more than 12 weeks at a time. Recurrent sinusitis is defined as greater than four episodes of sinusitis within a one-year period. The evaluation and management of acute and chronic sinusitis are similar. Chronic sinusitis may present as 1) chronic sinusitis without nasal polyps 2) chronic sinusitis with nasal polyps and 3) allergic fungal rhinosinusitis. 
As stated in the acute sinusitis chapter, viruses and bacteria are the most common etiologies for sinusitis. Streptococcus, pneumococcus, Hemophilus, and Moraxella are the most common bacterial causes. Chronic sinusitis is multifactorial in nature and can include infectious, inflammatory, or structural factors. Thus, other etiologies such as allergic rhinitis (dust mites, molds), exposures (airborne irritants, cigarette smoke or other toxins), structural causes (nasal polyps, deviated nasal septum), ciliary dysfunction, immunodeficiencies, and fungal infections should be considered. Otitis media, asthma, AIDS, and cystic fibrosis, are other medical conditions that can be associated with chronic rhinosinusitis.
When the inflammatory process involves the paranasal sinus, it is sinusitis. It can often involve accompanying nasal airway inflammation, and when involves both, this is then called rhinosinusitis. Chronic rhinosinusitis is one of the most common chronic conditions. It is prevalent among all age groups and is the fifth most common reason for an antibiotic prescription.
There are four paired sinus cavities: the ethmoid, sphenoid, frontal, and maxillary sinus cavities. These paired cavities allow air to be filtered during inhalation. For the antigens to be filtered and expelled, sinuses need to drain. Chronic inflammation can cause obstruction to the nasal passage, hinder drainage, and lead to lower oxygen tension. This creates foci for bacteria to build up. Ciliary dysfunction or structural abnormalities can further exacerbate this process. 
Biopsy samples will usually reveal thickened basement membrane, goblet cell hyperplasia, atypical gland architecture and infiltration with monocytes. Sometimes one may also see neutrophils and eosinophils in chronic cases.
The three cardinal symptoms of sinusitis are:
1) Purulent drainage: green or yellow nasal discharge2) Facial/dental pain: aching, fullness or pressure like pain 3) Nasal obstruction: this can cause difficulty breathing from one or both nasal passages or cause mouth breathing
Other symptoms of chronic sinusitis include hyposmia (decreased sense of smell), headache, ear pain, halitosis (bad breath), dental pain, cough, or fatigue. Fever only has a 50% sensitivity but is an important factor in determining the severity of sinusitis. The duration of symptoms is the key factor in diagnosing chronic sinusitis. Symptoms should occur for more than 12 weeks. Recurrent sinusitis occurs with four episodes of sinusitis within one year.
Chronic sinusitis is diagnosed when at least two of the following four symptoms are present and occur for more than 12 weeks: (1) purulent drainage, (2) facial and/or dental pain, (3) nasal obstruction, (4) hyposmia). The Infectious Disease Society of America (IDSA) defines sinusitis as two of the following major clinical symptoms: purulent nasal discharge, nasal congestion or obstruction, facial congestion or fullness, facial pain or pressure, hyposmia, anosmia. Alternatively, ISDA defines sinusitis as one of the aforementioned major symptoms plus two or more minor criteria such as a headache, ear pain, pressure, or fullness, halitosis or bad breath, dental pain, cough, or fatigue.
During the history and physical examination evaluation, practitioners should examine the patient for other causes such as nasal polyps. Chronic sinusitis is less common than acute sinusitis. Acute sinusitis can last up to four weeks. However, chronic sinusitis lasts twelve weeks or longer. Practitioners can seek other non-infectious etiologies such as gastric gastroesophageal reflux, anatomical variations or structural problems of the nasal cavity, history of immunodeficiencies, history of ciliary dysfunction, and history consistent fungal infections.
Either CT or nasal endoscopy confirming the presence of inflammation must be documented to confirm the diagnosis of chronic sinusitis. CT is more sensitive, but also more expensive than nasal endoscopy. Anterior rhinoscopy has limited visualization and has lower sensitivity and should not be used to confirm chronic sinusitis. There is a large role for shared decision-making when discussing which option to choose. Cone-beam CT scanning has become a point-of-care alternative imaging study.
Routine labwork is not necessary to diagnose chronic rhinosinusitis. Cultures are not necessary but can be helpful in treatment. If a practitioner does a nasal endoscopy, the sinus cultures should be drawn and are much more accurate than nasopharyngeal swabs. This can assist in providing targeted antibiotic therapy.
If an underlying medical condition is found, then therapy should target the underlying condition. This could include surgical and medical approaches to fungal sinusitis or Intravenous immunoglobulin for immunodeficiencies. Management for both of these conditions is beyond the scope of this chapter.
Other associated and predisposing medical conditions should also be treated. These includes asthma, otitis media, and cystic fibrosis.
The management of chronic sinusitis is best done with an interprofessional team of healthcare workers that includes infectious disease expert, ENT surgeon, internist, radiologist, and pulmonologist. At the same time, the nurse should educate the patient on controlling the trigger factors like avoiding tobacco and getting the annual influenza vaccine-both of which can exacerbate the symptoms of chronic sinusitis. The pharmacist should educate the patient on antiallergy therapies that can help control the symptoms. The patients should also be told to manage GERD because reflux disease is a known trigger for chronic sinusitis. Finally, the patients should be educated on the possible complications of chronic sinusitis and when to seek medical assistance. (Level V)
Chronic sinusitis may be a benign disorder, but it has significant morbidity. If not treated, the quality of life is poor. The condition is known to exacerbate asthma and can even lead to meningitis and brain abscess formation- which increases the morbidity and mortality. Patients with chronic sinusitis who are treated do have satisfactory outcomes. Symptom relief can be obtained after functional endoscopic sinus surgery in about 75% of patients who fail to respond to medical management. In rare cases, chronic sinusitis can result in orbital and intracranial infections, leading to visual and neurological deficits. (Level V)