What is a sinus?A sinus is a hollow, air-filled cavity. For the purposes of this article, a sinus will referred to those hollowcavities that are in the skull and connected to the nasal airway by a narrow hole in the bone (ostium).Normally all are open to the nasal airway through an ostium. Humans have four pair of these cavitieseach referred to as the:frontal sinus (in forehead),maxillary sinus (behind cheeks),ethmoid sinus (between the eyes), andsphenoid sinus (deep behind the ethmoids).The four pair of sinuses are often described as a unit and termed the "paranasal sinuses." The cells ofthe inner lining of each sinus are mucus-secreting cells, epithelial cells and some cells that are part ofthe immune system (macrophages, lymphocytes, and eosinophils). Functions of the sinuses include humidifying and warming inspired air, insulation of surroundingstructures (eyes, nerves), increasing voice resonance, and as buffers against facial trauma. The sinusesdecrease the weight of the skull.Picture of the anatomy of the sinuses
What is a sinus infection?A sinus infection occurs when a pathogenic microorganism (virus, bacterium, or a fungus) grows within asinus and causes intermittent blockage of the sinus ostium. Drainage of mucus and pus often occurwhen the blockage is relieved. The drainage usually goes from the nasal passages to the throat or outthe nostrils. Such infections also cause inflammation (an influx of immune cells and swelling of the sinustissue) of one or more sinuses. This can to block the openings of the sinuses and leads to discomfort.Inflammation of the air cavities within the passages of the nose (paranasal sinuses) is referred to assinusitis. Sinusitis can be caused by infection, but can also be caused by allergy and irritation of thesinuses.Sinusitis is one of the more common conditions that can afflict people throughout their lives. Sinusitiscommonly occurs when environmental pollens irritate the nasal passages, such as with hay fever.Sinusitis can also result from irritants, such as chemicals or the use and/or abuse of over-the-counter(OTC) nasal sprays, and illegal substances that may be snorted through the nose. About 30 million adultshave "sinusitis."2011 is a year that sinus infections are getting much lay press as sinus infections have been reported inseveral sports figures in basketball and baseball. The sinus infections have been reported to alter theability of the athletes to play at their peak performance. One young (18yr old) professional baseball
player reportedly died from a bacterial sinus infection that spread to his brain. Also, about 15 traumavictims of the May tornado disaster in Joplin, Missouri developed fungal infections that are rarely seen(some of them in the sinuses).What causes sinus infections?Sinus infection may be caused by anything that interferes with airflow into the sinuses and the drainageof mucus out of the sinuses. The sinus openings (ostea) may be blocked by swelling of the tissue liningand adjacent nasal passage tissue, for example with common colds, allergies, and tissue irritants such asOTC nasal sprays, cocaine, and cigarette smoke. Sinuses can also become blocked by tumors or growthsthat are near the sinus openings. The drainage of mucous from the sinuses can also be impaired by thickening of the mucous secretions,by decrease in hydration (water content) of the mucous brought on by disease (cystic fibrosis), dryingmedications (antihistamines), and lack of sufficient humidity in the air. The epithelial cells have smallhairlike fibers, called cilia, which move back and forth to help the mucus move out of the sinuses. Thesesmall cilia may be damaged by many irritants, especially smoke. This can prevent them from assistingthe mucus in draining from the sinuses.Stagnated mucus provides an environment for bacteria, viruses and in some circumstances (forexample, AIDS or immunodepressed persons) fungus to grow within the sinus cavities. In addition, themicrobes themselves can initiate and exacerbate sinus blockage. The most commonly infected sinusesare the maxillary and ethmoid sinuses.Rarely, immunodepressed or victims of multiple traumas in disasters such as tsunamis, hurricanes,earthquakes, or tornadoes may breathe in fungi from the soil or water. Eventually, in a few days to overa week, the fungi can grow and cut off blood supply to almost any type of tissue, especially in the noseand eyes. These infections, although rare, are serious and can be deadly and require immediate medicaland surgical care. Although the fungal infection may resemble common bacterial sinusitis initially, it is adisease termed zygomycosis or mucormycosis.What are the types of sinusitis? Sinusitis may be classified in several ways, based on the time span of the problem (acute, subacute, orchronic) and the type of inflammation (either infectious or noninfectious).Acute sinus infection (also termed acute sinusitis caused by infection) is usually defined as being of lessthan 30 days duration.Subacute sinus infection as being over 1 month but less than 3 months.Chronic sinus infection as being greater than 3 months duration.
There is no medical consensus on the above time periods.Infected sinusitis usually is caused by uncomplicated virus infection. Less frequently, bacterial growthcauses sinus infection and fungal sinus infection is very infrequent. Subacute and chronic forms of sinusinfection usually are the result of incomplete treatment of an acute sinus infection.Noninfectious sinusitis is caused by irritants and allergic conditions and follows the same general timeline for acute, subacute and chronic as infectious sinusitis.What are the signs and symptoms of sinus infection?Commonly the symptoms of sinus infection are headache, facial tenderness, pressure or pain, and fever.However, as few as 25% of patients may have fever associated with acute sinus infection. Othercommon symptoms include:cloudy, discolored nasal drainage,a feeling of nasal stuffiness,sore throat, andcough.Some people notice an increased sensitivity or headache when they lean forward because of theadditional pressure placed on the sinuses. Others may experience tooth or ear pain, fatigue, or badbreath. In noninfectious sinusitis, other associated allergy symptoms of itching eyes and sneezing maybe common, but may include some of the symptoms listed above for infectious sinusitis. Nasal drainageis usually clear or whitish-colored in people with noninfectious sinusitis.With rare fulminant fungal infections, there may be ulceration, with sharply defined edges and a black,necrotic center in the nasal area. Some fungal infections cause a dark, black-appearing exudates. Thisrequires immediate medical evaluation.How is sinus infection diagnosed?Sinus infection is most often diagnosed based on a history and examination made by a doctor. Becauseplain X-ray studies of the sinuses may be misleading and procedures such as CT and MRI scans, whichare much more sensitive in their ability to diagnose sinus infection, are so expensive and not available inmost doctors offices, most cases of sinus infection are initially diagnosed and treated based on clinicalfindings on examination. These physical findings may include:redness and swelling of the nasal passages, purulent (pus like) drainage from the nasal passages (thesymptom most likely to clinically diagnose a sinus infection), tenderness to percussion (tapping) over thecheeks or forehead region of the sinuses, and swelling about the eyes and cheeks.
Occasionally, nasal secretions are examined for secreted cells that may help differentiate betweeninfectious and allergic sinusitis. Infectious sinusitis may show specialized cells of infection(polymorphonuclear cells) while allergic sinusitis may show specialized cells of allergy (eosinophils).Physicians prescribe antibiotics if bacterial infection is suspected. Antibiotics are not effective againstviral infections; many physicians then treat the symptoms. If sinus infection fails to respond to the initial treatment prescribed, then more in-depth studies such asCT or MRI scans may be performed. Ultrasound has been used to diagnose sinus infections in pregnantwomen, but is not as accurate as CT or MRI. Rhinoscopy, a procedure for directly looking in the back ofthe nasal passages with a small flexible fiber optic tube, may be used to directly look at the sinusopenings (ostea) and check for obstruction of these openings by either swelling or growths. It may sometimes be necessary to perform a needle aspiration (needle puncture) of a sinus to getinfected material to culture to determine what pathogen is actually causing the sinus infection. Culturesof the nasal passages are rarely helpful in determining what bacteria or fungus is causing a sinusinfection since the nasal passages are often colonized by non-infecting bacteria. The needle punctureprocedure is usually done by an otolaryngologist when treatments have failed to alleviate the disease.The procedure is uncomfortable and requires local anesthesia; some patients require generalanesthesia. The sinus is aspirated, the contents sent for culture and staining, and the sinus may beflushed with a saline solution. This is technically the most accurate way to diagnose infectious sinusitis. In addition, both rigid and flexible endoscopy has been used to obtain diagnostic material from sinuses.Unfortunately, these procedures are also uncomfortable and need to be done by an otolaryngologistwho may need to sedate the patient. Some investigators suggest that endoscopy specimens arecomparable to those obtained by needle puncture. Fungal infections are usually diagnosed by such biopsy procedures and tissue removed by a surgeon, orby fungal culture and microscopic identification by a microbiologist or pathologist trained to identifyfungi.Are there home remedies for a sinus infection?Sinus infections caused by viruses can use home (over-the-counter) treatments such as pain and fevermedications (acetaminophen [Tylenol]), decongestants, and mucolytics. In addition, some health careproviders suggest that nasal irrigation or a sinus rinse solution will help relieve symptoms of sinusinfections, even chronic sinusitis symptoms. This irrigation is accomplished with a "Neti-Pot" or a sinusrinse kit (sometimes termed a nasal bidet). The last reference of this article shows a video of a sinusrinse procedure. Bacterial and fungal sinus infections usually require antibiotic or antifungal therapy so home treatmentswithout them are often not successful. However, some authors suggest home treatments may reducesymptoms after medical therapy has begun; some health care practitioners recommend nasal irrigationafter sinus surgery.
What are complications of sinus infection?While serious complications do not occur frequently, it is possible for sinus infection to cause a directextension of infection into the brain through a sinus wall, creating a life-threatening emergency (forexample, meningitis or brain abscess). In addition, other adjacent structures can become infected anddevelop problems, such as osteomyelitis of bones in the skull and infection around the eye (orbitalcellulitis). Rarely, these infections (mainly bacterial and fungal organisms) may cause death. The mostsusceptible individuals to complications are patients with suppressed immune systems and relativelyrarely from multiple trauma injuries that may occur in natural disasters.Can sinus infection be prevented?Currently, there are no vaccines designed specifically against infectious sinusitis. However, there arevaccines against viruses (influenza) and bacteria (pneumococci) that may cause some infectious sinusitis.Vaccination against pathogens known to cause infectious sinusitis may indirectly reduce or prevent thechance of getting the disease but there are no specific studies to support this assumption. There are nofungal vaccines against sinusitis. If a person is prone to recurrent bouts of "yearly sinus infection" it may be important to consider allergytesting to see if this is the underlying cause of the recurring problem. Treatment of the allergy mayprevent secondary bacterial sinus infections. In addition, sinus infections may be due to other problemssuch as nasal polyps, tumors or diseases that obstruct normal mucus flow. Treatment of theseunderlying causes may prevent recurrent sinus infections.