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What
are the sinuses and what do they do?
What are
sinuses?
The sinuses are hollow cavities within the bones of the skull.
They lie adjacent to the nasal cavity and are therefore anatomically
named the "paranasal" sinuses. Four sets of sinuses lie on each
side of the nasal cavity: frontal, ethmoid, maxillary, and sphenoid
sinuses. The frontal sinuses occupy the bone over the eyes in
the forehead while the maxillary sinuses are under the eyes in
the cheekbones. The ethmoid sinuses are actually a collection
of sinuses, like a honeycomb, which lie between the eyes. The
sphenoid sinuses are placed behind the nasal cavity and eyes,
near the center of the head.
The paranasal sinuses are similar to rooms lying off a main hallway,
the nasal cavity. Air flows up and down this hallway as we breathe
in and out through our noses. A special "wallpaper" lines the
nasal "hallway" and each sinus "room." This lining is the mucosa,
which swells and thickens with irritation or inflammation. The
sinuses are connected to the hallway through very narrow openings,
sometimes only one or two millimeters wide. When the "wallpaper"
lining these narrow openings swells, it can block the openings
and result in a sinus infection. (See " What
causes sinusitis?")
What is the purpose of sinuses?
The simple answer to this question is that no one knows for certain.
Many theories have been proposed, all of which may be correct.
By creating air-filled chambers within the skull bones, the sinuses
may serve to decrease the weight of the head. They also add resonance
to the voice; when they are blocked up we sound like we are talking
through our noses. In a more practical sense, the sinuses form
a sort of "crumple zone" that protects the eyes and brain in case
of a severe injury to the face. Sinuses also help warm and humidify
the air that passes through the nose.
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What
is sinusitis and what causes it?
What is sinusitis?
Sinusitis is defined as inflammation of the sinuses. The sinuses
are chambers that communicate with the nasal cavity through tiny
openings (See "What are sinuses?"). They
become inflamed due to a variety of causes but typical sinusitis
is due to a bacterial infection. Often the problem in the sinuses
occurs in association with a condition that affects the nasal cavity,
such as allergies, a viral infection, or irritation. Because the
nasal cavity and the sinuses typically react in conjunction with
one another, some experts have suggested that the term "sinusitis"
be replaced with "rhinosinusitis" (rhino = nose) to emphasize
this association.
Sinusitis is a common condition that affects millions of people
across the world. It has been estimated that as many as 35 million
Americans suffer from this disease at that it accounts for at least
$2.4 billion in direct medical costs alone. This figure does not
take into account the economic impact of lost productivity, work
days lost for illness, and time lost for doctor's office visits.
What causes sinusitis?
As mentioned earlier, sinusitis typically occurs in association
with conditions that affect the nasal cavity, such as allergies,
irritations to the nose, or a viral infection (like a common cold).
All of these conditions cause the lining of the nose (the "mucosa")
to swell. This swelling, often called "edema," further constricts
the already narrow openings through which mucus leaves the sinus.
Air circulation into and out of the sinuses is also impaired. With
further inflammation, the movement of mucus out of the sinuses by
the microscopic hairs called cilia slows and the secretions become
stagnant. These conditions favor growth of bacteria and an infection
sets in. Once the bacterial infection begins, it causes more inflammation
and swelling and leading to increased mucus production. More swelling
only worsens the mucus transport and air exchange, favoring more
bacterial growth and the cycle continues.
Symptoms of sinusitis can be quite variable, both in whether or
not they are present and how severe they are. They can mimic many
other conditions, including the common cold, allergies, migraines
and other types of headaches, and jaw problems. Patients with sinusitis
typically have at least one of the following symptoms:
- discolored
nasal discharge - often yellow or green
- facial
fullness, heaviness, or congestion
- facial
pain or pressure
- decrease
or loss of the sense of smell (the sense of taste may also be
affected)
- decrease
in the ability to breathe through the nose
Other symptoms
that patients may have in association with the ones above are:
- fever
- often low grade and variable
- fatigue
or malaise (flu-like symptoms)
- pain in
the upper teeth
- pressure
or fullness in the ears
- chronic
cough
- bad breath
Clearly, these
symptoms are not specific and could be from a number of conditions.
It is for this reason that sinusitis can be difficult to diagnose.
Fortunately, recent diagnostic advances have improved our ability
to accurately identify patients with sinusitis so that they can
be appropriately treated.
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How
is sinusitis diagnosed?
Because the
symptoms of sinusitis can mimic other diseases, a careful history
of the problem is important. While facial pain and discolored nasal
discharge or mucus is most often associated with sinusitis, other
more subtle symptoms like cough, malaise, or fatigue should also
be sought out. Questions about each specific symptom, including
its duration and severity, and about the success or failure of past
interventions can help to shed light on the nature of the problem.
In order to be thorough and complete, we use a questionnaire to
gather information about a patient's symptoms. The patient's responses
then form a basis for a more thorough discussion of the history
of the illness.
An equally thorough physical examination then compliments the history
of the illness. Because symptoms within the nose and sinuses can
be associated with findings within the ears, throat, and neck, a
complete otolaryngological (ENT) examination is warranted.
Often a more thorough examination of the nose, called a "diagnostic
nasal endoscopy" is performed. This procedure involves passing a
fiber-optic telescope, or "endoscope," into the nose and examining
the interior of the nasal cavity. In this manner, the condition
of the mucosal lining surrounding the sinus openings can be examined.
Nasal endoscopy has greatly advanced the diagnosis and treatment
of sinusitis. By providing superb illumination and magnification,
it gives physicians the ability to closely examine conditions deep
within the nose. It allows precise identification and targeting
of problem areas and gives physicians an increased ability to monitor
a patient's response to therapy.
Despite the great advances brought about by nasal endoscopy, this
procedure can only give information about the openings of the sinuses.
Unless a patient has had previous sinus surgery, the examiner cannot
see the interior of the sinuses. Even in patients who have had sinus
surgery, scarring can obscure the view into the previously opened
sinuses. For this reason, another tool is used to visualize the
sinus interior: computerized tomography, also known as a CT scan.
(Previously the procedure was also referred to as a CAT scan, for
computerized axial tomography). The CT scan provides information
about swelling within the sinuses and also provides a road map of
sinus anatomy should surgery be necessary.
CT scanning can be a powerful tool in diagnosing sinusitis but must
be performed under the right conditions. In patients with "chronic
sinusitis," the procedure should be performed when the patient is
at his/her best. Patients should have received appropriate medical
therapy and the scan should be performed no sooner than four weeks
after the last flare-up. Otherwise, residual acute (short-term)
inflammation will show up on the CT scan and give a false impression
about the severity of the disease. If a patient undergoes a scan
during an acute flare of sinusitis - or even during an episode of
the common cold - the scan may show inflammation that will completely
resolve. Such inflammation does not necessitate long-term medications
and especially does not require surgery. In contrast, patients with
"recurrent acute sinusitis," a less common variation of sinus problems,
sometimes have CT scanning performed during the acute exacerbation
in order to demonstrate that sinusitis is truly occurring and which
sinuses are affected.
"Recurrent acute sinusitis" is much less common than "chronic sinusitis"
but the difference shows the importance of a thorough evaluation.
All components of each patient's assessment - history, general otolaryngological
examination, nasal endoscopy, and CT scanning - must be considered
before embarking upon a course of treatment. Trying to use just
one without the others can lead to errors in diagnosis and delays
in instituting the correct therapy.
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How
is sinusitis treated?
The goal in
treating sinusitis is to re-open the narrow communication between
the sinuses and the nasal cavity (See "What are
sinuses?"). This in turn promotes movement of mucus out of the
sinus and re-establishes normal oxygen levels within the sinuses.
In chronic sinusitis, the principal way to accomplish this goal
remains medications. In some patients, medical therapy fails to
provide relief of their symptoms. These patients may be considered
for surgery (See "What is Endoscopic Sinus Surgery?").
Often the treatment of chronic sinusitis involves combining a number
of medications. Each class of drugs is summarized below.
STEROID NASAL SPRAYS
This class of medications works to diminish the nasal lining's inflammatory
response, resulting in less swelling and better mucus transport.
These sprays form the first in the treatment of a number of inflammatory
conditions within the nose (See "What
about other sinus conditions?"). They are typically sprayed
into both sides of the nose and work directly on the lining they
come into contact with. Their onset of action is relatively slow
and patients may not feel their effect for days or weeks.
For this reason, often patients give up on this method of treatment
too soon.
Steroid nasal sprays are generally well tolerated. Side effects
from these medications include irritation within the nose and nasal
bleeding. This bleeding can be avoided by pointing the spray bottle
away from the nasal septum (the bone and cartilage that runs down
the middle of the nasal cavity). Because the sprays are minimally
absorbed throughout the rest of the body, side effects seen with
taking steroid pills (see below) are extremely rare.
ANTIBIOTICS
The vast majority of cases of chronic sinusitis are due to bacteria.
For this reason, antibiotics are another mainstay of treatment.
Most patients who see a specialist regarding their sinuses have
previously been on many courses of numerous antibiotics. In many
cases, these courses are for only seven to ten days, usually insufficient
to stamp out the bacteria in a chronic infection. Most experts now
believe that antibiotics for chronic sinus infections should be
maintained for a minimum of three to four weeks. Ideally, the antibiotic
should be chosen based on the results of a culture, where a sample
of the bacteria is sent to the laboratory for identification and
other testing. Because the openings of the sinuses cannot be seen
without an endoscope (See "How is sinusitis
diagnosed?"), blind sampling of the nasal cavity using conventional
equipment is nearly useless. Nevertheless, endoscopically directed
cultures have proven quite useful and specific.
Antibiotics have a number of side effects, many of which are specific
to each different type of drug. Nevertheless, some are common including
rash and diarrhea. If these occur, the drug should be discontinued
and the symptoms immediately reported to your physician. While most
reactions are mild, some can be serious and may require additional
medical attention.
ANTIHISTAMINES
Antihistamines combat the allergic response within the nose. Many
patients with chronic sinusitis have symptoms of allergies including
itchy nose or eyes, sneezing, watery eyes, and nasal congestion.
Patients with chronic allergies may not experience the typical itching
and sneezing symptoms, but may have chronic congestion, runny nose,
and fatigue. The allergic response to an irritant (commonly dust
mites, pet fur, or pollen) results in inflammation within the nose,
precipitating or worsening the sinus condition. Blocking this response
can improve sinus function and reduce symptoms of sinusitis.
One problem with many older antihistamines is the fact that they
can cause sedation as well as drying and thickening of nasal secretions.
Many new antihistamines have little or no sedative side effects
and don't cause problems with secretions. Some are also combined
with a decongestant to further reduce swelling within the nose and
sinuses. While most antihistamines come in the form of pills taken
once or twice a day, others can be sprayed into the nose or come
as eye drops to control specific symptoms.
DECONGESTANTS
Decongestants act specifically to decrease swelling within the nose.
They work directly on the blood vessels within the nose that control
the thickness of the lining. They may also affect blood vessels
throughout the body and should be used with caution (if at all)
in individuals with certain disorders, particularly difficult to
control hypertension or high blood pressure. Most decongestants
are available "over the counter" and they are often combined with
antihistamines. They can cause jitteriness or difficulty sleeping
for some patients and should not be used in men with prostate problems.
Decongestant nasal sprays merit a special word of caution. They
are particularly useful in diminishing swelling within the nose
for a short period of time. If used for more than
three days in a row, they can lead to a "rebound effect" and actually
worsen nasal swelling. Often patients will then increase the dosage
or the frequency with which they use the sprays in order to diminish
the rebound swelling. This leads to a vicious cycle of decongestion
followed by rebound swelling, a condition known as "rhinitis medicamentosa"
(See "What about other sinus conditions?").
MUCOLYTICS
These drugs, also known as expectorants, are common ingredients
in cough syrups to loosen and thin mucus. Because mucus often becomes
thick and stagnant in chronic sinusitis, many physicians believe
these medications may be helpful in this condition as well. The
mucolytics are usually well tolerated with almost no side effects.
In higher doses they can cause nausea and, because these drugs act
to thin mucus, they can increase fertility in women.
NASAL SALINE SPRAY
Like mucolytics, nasal saline (salt water) has been theorized to
improve mucus transport. While there are no good studies to support
this claim, saline sprays are relatively innocuous and inexpensive.
They appear to be helpful in some patients, especially those with
dryness or crusting as a major symptom. Other sprays, which have
various herbal additives, have given some patients relief as well.
IRRIGATIONS
Some physicians advocate rinsing the nose with saline or other solutions.
The fluid can be delivered using a rubber bulb or with an attachment
to a Water Pik machine. Irrigations can assist in removing thick
or dried mucus. Antibiotics are sometimes added to the solution
to decrease infection as well. If irrigations are used within the
nose, great care should be taken to keep all items as clean as possible.
This will prevent introducing new bacteria from the irrigation system
into the nose, which can perpetuate an infection.
ORAL STEROIDS
In severe cases of chronic sinusitis, oral steroids (steroid pills
taken by mouth) may be used. These drugs augment the action of the
nasal steroid sprays in decreasing the inflammatory response within
the nose and sinuses. While they are quite effective, because these
drugs are taken in pill form the medication spreads throughout the
body and may have significant side effects. These include osteoporosis,
liver abnormalities, cataracts, glaucoma, weight gain, emotional
changes, and joint problems. With the exception of emotional changes
and weight gain, most of the side effects are rarely seen unless
the drug is used for a prolonged period of time. Oral steroids are
often given to patients with nasal polyps (See "Other
Conditions Affecting the Nose and Sinuses") or asthma in preparation
for surgery. They may be continued for a few weeks following the
procedure to diminish the inflammatory response during healing.
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