1. What is a sinus?
A sinus is a hollow, air-filled cavity. For the purposes of this article, a sinus will referred to those hollow
cavities 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 cavities
each referred to as the:
frontal sinus (in forehead),
maxillary sinus (behind cheeks),
ethmoid sinus (between the eyes), and
sphenoid sinus (deep behind the ethmoids).
The four pair of sinuses are often described as a unit and termed the "paranasal sinuses." The cells of
the inner lining of each sinus are mucus-secreting cells, epithelial cells and some cells that are part of
the immune system (macrophages, lymphocytes, and eosinophils).
Functions of the sinuses include humidifying and warming inspired air, insulation of surrounding
structures (eyes, nerves), increasing voice resonance, and as buffers against facial trauma. The sinuses
decrease the weight of the skull.
Picture of the anatomy of the sinuses

2. What is a sinus infection?
A sinus infection occurs when a pathogenic microorganism (virus, bacterium, or a fungus) grows within a
sinus and causes intermittent blockage of the sinus ostium. Drainage of mucus and pus often occur
when the blockage is relieved. The drainage usually goes from the nasal passages to the throat or out
the nostrils. Such infections also cause inflammation (an influx of immune cells and swelling of the sinus
tissue) 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 as
sinusitis. Sinusitis can be caused by infection, but can also be caused by allergy and irritation of the
sinuses.
Sinusitis is one of the more common conditions that can afflict people throughout their lives. Sinusitis
commonly 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 adults
have "sinusitis."
2011 is a year that sinus infections are getting much lay press as sinus infections have been reported in
several sports figures in basketball and baseball. The sinus infections have been reported to alter the
ability of the athletes to play at their peak performance. One young (18yr old) professional baseball

3. player reportedly died from a bacterial sinus infection that spread to his brain. Also, about 15 trauma
victims 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 drainage
of mucus out of the sinuses. The sinus openings (ostea) may be blocked by swelling of the tissue lining
and adjacent nasal passage tissue, for example with common colds, allergies, and tissue irritants such as
OTC nasal sprays, cocaine, and cigarette smoke. Sinuses can also become blocked by tumors or growths
that 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), drying
medications (antihistamines), and lack of sufficient humidity in the air. The epithelial cells have small
hairlike fibers, called cilia, which move back and forth to help the mucus move out of the sinuses. These
small cilia may be damaged by many irritants, especially smoke. This can prevent them from assisting
the mucus in draining from the sinuses.
Stagnated mucus provides an environment for bacteria, viruses and in some circumstances (for
example, AIDS or immunodepressed persons) fungus to grow within the sinus cavities. In addition, the
microbes themselves can initiate and exacerbate sinus blockage. The most commonly infected sinuses
are 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 over
a week, the fungi can grow and cut off blood supply to almost any type of tissue, especially in the nose
and eyes. These infections, although rare, are serious and can be deadly and require immediate medical
and surgical care. Although the fungal infection may resemble common bacterial sinusitis initially, it is a
disease 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, or
chronic) 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 less
than 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.

4. There is no medical consensus on the above time periods.
Infected sinusitis usually is caused by uncomplicated virus infection. Less frequently, bacterial growth
causes sinus infection and fungal sinus infection is very infrequent. Subacute and chronic forms of sinus
infection 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 time
line 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. Other
common symptoms include:
cloudy, discolored nasal drainage,
a feeling of nasal stuffiness,
sore throat, and
cough.
Some people notice an increased sensitivity or headache when they lean forward because of the
additional pressure placed on the sinuses. Others may experience tooth or ear pain, fatigue, or bad
breath. In noninfectious sinusitis, other associated allergy symptoms of itching eyes and sneezing may
be common, but may include some of the symptoms listed above for infectious sinusitis. Nasal drainage
is 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. This
requires immediate medical evaluation.
How is sinus infection diagnosed?
Sinus infection is most often diagnosed based on a history and examination made by a doctor. Because
plain X-ray studies of the sinuses may be misleading and procedures such as CT and MRI scans, which
are much more sensitive in their ability to diagnose sinus infection, are so expensive and not available in
most doctors offices, most cases of sinus infection are initially diagnosed and treated based on clinical
findings on examination. These physical findings may include:
redness and swelling of the nasal passages, purulent (pus like) drainage from the nasal passages (the
symptom most likely to clinically diagnose a sinus infection), tenderness to percussion (tapping) over the
cheeks or forehead region of the sinuses, and swelling about the eyes and cheeks.

5. Occasionally, nasal secretions are examined for secreted cells that may help differentiate between
infectious 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 against
viral infections; many physicians then treat the symptoms.
If sinus infection fails to respond to the initial treatment prescribed, then more in-depth studies such as
CT or MRI scans may be performed. Ultrasound has been used to diagnose sinus infections in pregnant
women, but is not as accurate as CT or MRI. Rhinoscopy, a procedure for directly looking in the back of
the nasal passages with a small flexible fiber optic tube, may be used to directly look at the sinus
openings (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 get
infected material to culture to determine what pathogen is actually causing the sinus infection. Cultures
of the nasal passages are rarely helpful in determining what bacteria or fungus is causing a sinus
infection since the nasal passages are often colonized by non-infecting bacteria. The needle puncture
procedure 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 general
anesthesia. The sinus is aspirated, the contents sent for culture and staining, and the sinus may be
flushed 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 otolaryngologist
who may need to sedate the patient. Some investigators suggest that endoscopy specimens are
comparable to those obtained by needle puncture.
Fungal infections are usually diagnosed by such biopsy procedures and tissue removed by a surgeon, or
by fungal culture and microscopic identification by a microbiologist or pathologist trained to identify
fungi.
Are there home remedies for a sinus infection?
Sinus infections caused by viruses can use home (over-the-counter) treatments such as pain and fever
medications (acetaminophen [Tylenol]), decongestants, and mucolytics. In addition, some health care
providers suggest that nasal irrigation or a sinus rinse solution will help relieve symptoms of sinus
infections, even chronic sinusitis symptoms. This irrigation is accomplished with a "Neti-Pot" or a sinus
rinse kit (sometimes termed a nasal bidet). The last reference of this article shows a video of a sinus
rinse procedure.
Bacterial and fungal sinus infections usually require antibiotic or antifungal therapy so home treatments
without them are often not successful. However, some authors suggest home treatments may reduce
symptoms after medical therapy has begun; some health care practitioners recommend nasal irrigation
after sinus surgery.

6. What are complications of sinus infection?
While serious complications do not occur frequently, it is possible for sinus infection to cause a direct
extension of infection into the brain through a sinus wall, creating a life-threatening emergency (for
example, meningitis or brain abscess). In addition, other adjacent structures can become infected and
develop problems, such as osteomyelitis of bones in the skull and infection around the eye (orbital
cellulitis). Rarely, these infections (mainly bacterial and fungal organisms) may cause death. The most
susceptible individuals to complications are patients with suppressed immune systems and relatively
rarely 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 are
vaccines 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 the
chance of getting the disease but there are no specific studies to support this assumption. There are no
fungal vaccines against sinusitis.
If a person is prone to recurrent bouts of "yearly sinus infection" it may be important to consider allergy
testing to see if this is the underlying cause of the recurring problem. Treatment of the allergy may
prevent secondary bacterial sinus infections. In addition, sinus infections may be due to other problems
such as nasal polyps, tumors or diseases that obstruct normal mucus flow. Treatment of these
underlying causes may prevent recurrent sinus infections.