Sinus411.org

The web site for people with sinus problems

Sinusitis is inflammation of the nose and sinus cavities that results from any number of causes including cold viruses, bacterial infections, fungal infections, severe allergies, and other, more unusua,l causes as well.

In order to understand sinusitis well, you really should understand the anatomy of the sinuses and the nose. If you have a moment, its worthwhile learning about what is "near" the sinuses as well, since it makes it easier to understand what goes on with sinusitis, and why certain symptoms develop with sinusitis (for instance ear symptoms).

Anatomy Of The Sinuses
In order to understand sinusitis, sinus symptoms, and the medical or surgical treatment of sinus disease, it is first important to understand a bit of anatomy of the sinuses as well as how the sinuses work (the physiology of the sinuses).  The sinuses are air-filled spaces located above, below, between, and behind the eyes.  Each of the sinuses have a specific name which is important to learn in order to follow the discussion that follows the remainder of these chapters.  The sinuses above the eyes, known as the frontal sinuses, can vary in size and adults, ranging from completely undeveloped (nonexistent), to small (the size of the grape), or average (equivalent of three or four tablespoons), or very large (about the size of one third of an orange).  The sinuses below the highs, also known as the maxillary sinuses, can also vary substantially in size.  It is rare to have a absent maxillary sinus as an adult, but occasionally there are poorly developed (called hypoplastic).  The average maxillary sinus is about four tablespoons in size.  The sinuses between the eyes are called ethmoid sinuses.  The ethmoid sinuses consist of a group of small air cells divided by thin bony walls and might best be described as somewhat similar to a honeycomb, the thin bony walls representing the comb and the honey representing the air between these thin bony walls.  The sphenoid sinuses are located behind the eyes, almost between the ears, near the center of the skull.  The sphenoid sinuses are about one tablespoon in size.  There is a set of frontal, maxillary, ethmoid, and sphenoid sinuses on each side of the nose.

Each sinus is blinded by thin, pink, moist membrane called mucosa.  The mucosal membrane  is about 1 mm thick and it  it is covered by a thin layer of mucus called mucus blanket.  The cells in the mucosal layer produce and secrete this mucus blanket.  The mucosal cells also have fine cilia, or hair cells, on the surface which are continuously vibrating in a specific pattern and frequency.  The movement of the hair cells propels the mucus in a specific, predetermined pathway, which drives the mucus out of the sinuses, into the nose or nasal cavity.   When the mucus reaches the nose, and similar mucosal membranes and their cilia will propel the mucus into the back of the nose (also called the nasopharynx), and then into the back of the throat.

Each of the sinuses has one or more small openings that connect the sinus with in nose or nasal cavity.  These openings are called Ostia.  The Ostia are typically quite small, on the range of two to 4 mm in opening.  The Ostia itself is also lined by this mucosal membrane.  If the mucosal membrane becomes very swollen, inflamed, or thickened because of some disease process, the small Ostia can become blocked.  If the Ostia become blocked, the mucus cannot escape and it will remain within the sinuses.  Unfortunately, the mucus that remains in the sinuses may become infected with bacteria, causing a bacterial sinusitis in a typical symptoms of bacterial sinusitis.  We'll discuss sinusitis more soon.

Each of the sinuses has nerve endings associated with it, nerves that transmit the sense of pain or discomfort when there is a sinus infection or some other process irritating the sinuses and the nerves that line the sinuses.  These nerve endings in the sinuses feed into larger nerves around the face and eyes, and these nerves then travel back towards the brain, sometimes joining other nerves.  Because the nerves of the sinuses travel near or join with other nerves, the signals to the brain from the sinuses and from these other nerves, for instance a nerve from the ear, travel the same pathway.  This can sometimes cause a sensation in called referred to pain, whereby patient feels pain in a different area than the actual source of the pain.  This referred to pain occurs in the sinuses.  Pain in the maxillary sinus for instance will sometimes be felt in the temple or in the ear.   Pain in the sphenoid sinus will sometimes be referred to other areas, particularly above the eyes, behind the eyes, over the temple along the side of the head, to the top of the head, or to the very back of the head.  Frontal sinus pain is typically not referred very far, if at all.  Frontal sinus pain is typically over the brow or occurs under the eyebrow along the top of the eye socket.  Ethmoid sinus pain typically is experience between the eyes.

Anatomy of the Nose

The sinuses opened and drain into the nose or nasal cavity.  The nasal cavity is much larger than most people imagine.  It's divided into a left and right side by the nasal septum, which one can feel just inside the nostril, along the midline of the  nose.  Each nasal cavity is lined by this same thin mucosal lining or respiratory epithelium, which also produces mucus, is covered by mucus blanket, and has hair cells that move this mucus like it.  The mucus blanket in the nose is propelled into the nasopharynx (which lies behind the nose and above the soft palate the, in a position that is just about between the ears.

 The nose is divided in half by the nasal septum which begins just inside the nostril and extends about 3 inches back into the center of the skill.  The septum is made out of cartilage and bone and is covered by a tough layer of tissue that provides nutrients to the cartilage) and bone(pericondrium and periosteum) as well as a layer of thin, pink mucosa.  Is very unusual for any person to have a perfectly straight   septum.  The vast majority of patients have at least some bowing, or curve to the septum, or even an s-shaped septum.    A minimal or mild curvature to septum is considered to be a normal state of affairs, and typically does not cause any symptoms.  However, it is not unusual for patients to have a moderate or severe deviated septum as well.  Many patients with a  moderate or severely deviated septum have minimal symptoms or simply have learned to tolerate the symptoms of nasal obstruction.  Others with a moderate or severe nasal septal deviation will be significantly symptomatic.   The symptom of a deviated nasal septum is nasal obstruction.  Because the nasal septum does not change shape substantially (unless there’s a history of significant trauma), a deviated septum usually causes a long-standing history of nasal blockage.    A recent worsening of nasal obstruction is therefore unlikely to be due solely to in deviated septum because, as you might imagine, most patients have the same septum today as they had one year ago or five years ago.  A recent problem with nasal obstruction is often related to allergies or some other disease (perhaps in addition to a deviated septum), rather than a sudden change in this cartilaginous  or boney structure of the septum.    So the septum doesn’t change much, but the side walls of the nose, which include structures called the “turbinates” do change quite a bit in many people.  The anatomy of the side walls of the nose is very important, so read on.  

Within the nose, there are tissues known as turbinates  that arise in the side wall of the of the nose and hang into the nasal cavity, partially blocking the passage of air that flows from nostril back to the nasopharynx.  There are typically three sets of turbinates on each side of the nose, the inferior turbinate, the middle turbinate, and a superior turbinate.  The inferior turbinate is the largest of the three and is visible to inspection if one were to use a small flashlight, but often just out of reach if one were to touch the inside of the nose with one's finger. These turbinates are formed of a thin bony way limb that is covered by soft, fleshy tissue and that same thin mucosal membrane, with its hair cells and mucus blanket.  The turbinates serve many functions.  The turbinates slow the airflow through their nose, allowing the air to become moistened or humidified as it passes through the nose and later through the larynx (the voice box), the trachea, and bronchi, and finally the lungs.  The turbinates also warm the air as it passes through this respiratory system, so the air reaching the lungs as warm as well as moist.  The mucus blanket on the turbinates also  traps small particles, thereby filtering particles out of the air stream before they can irritate the larynx or lungs.

Because nose is triangular, with a larger base towards the upper lip and a more narrow passageway at the top of the nose, near the eyes, most of the airflow through the nose goes through the lower half of the nasal passageways, with more air circulating around the inferior turbinate.  Interestingly, the inferior turbinate itself varies in size considerably over the course of the day.  In fact, in the inferior  turbinates in each side go through a "nasal cycle" where the turbinate on one side will become enlarged and the turbinate on the opposite side of the nose will become a bit smaller.  This cycle of swelling and shrinking is under control of the nervous system.  During the swelling process, blood vessels open up and small  “venous lakes” fill with venous blood, allowing the turbinates to substantially increase in size.   For this part of the nasal cycle,  airflow will therefore be predominantly directed towards the side of the smaller turbinate.  Over many minutes to several hours, the cycle will reverse.  The turbinate size will alternate.  The large turbinates it will become smaller, the smaller turbinate will become an enlarged, now allowing more air through the opposite side.  The nasal cycle time can vary considerably from person to person and can be affected by disease states as well.   If a patient has one nostril blocked because of a polyp or severely deviated septum and then the other nostril becomes obstructed by an exaggerated nasal cycle, the resulting bilateral nasal obstruction can be quite bothersome, usually enough to motivate patients to seek medical care.

The turbinates also play an important role in a very common disorder: allergic rhinitis.  You're probably familiar with patients that have allergies to cats, dust, molds, trees, pollens, or grasses.  A patient with allergies that inhales these particles, called allergens, will usually have a response the nose, and one of the first responders is the inferior turbinate.  Not surprisingly, much of the particles that we inhale are first encountered by the inferior turbinate.  If one has allergies, more of the allergen particles will be deposited on  the inferior turbinate than the middle or the superior turbinate.  Not surprisingly, the allergic reaction, that is the swelling of the turbinate tissue, occurs more  along the inferior turbinate.  The turbinate becomes swollen, enlarged, and thickened, and begins to obstruct more the airway, causing a sense of nasal obstruction or inability to pass air through the nasal cavity.  With treatment, the turbinate can return to a reasonably normal size.  However, patients who do not seek treatment for significant allergic rhinitis may have enough long term allergic stimulation of the turbinate that will cause irreversible changes.   Then, even after receiving treatment, the turbinate may become permanently enlarged and may require surgical intervention to “debulk” the turbinate to a reasonable size. 

The Turbinates

Each of the four sinuses on each side of the nose drains into space underneath the turbinates.  This space underneath the turbinates is called the meatus.  The maxillary, frontal, and some of the ethmoid sinuses drain underneath the middle turbinate, in the middle meatus, while the sphenoid and part of the ethmoid sinuses drain underneath the superior turbinate, in the superior meatus which is located high and deep in the back of the nose. 

As you recall, the sinuses drain into the middle or superior meatus through a small boat opening or ostia. If there is allergic disease, mass, growth, or inflammation around the turbinates or in the meatus, the sinuses do not drain well.  The mucus may "backup" in the sinuses and this may lead to infections of the mucus, also known as sinusitis.  There are a number of diseases that can cause swelling of the turbinates, the tissues in the meatus, or swelling of the linings of the sinuses.  The viral illnesses such as the common cold,b acterial infections, allergic rhinitis, nasal polyps, and many other less common disorders can cause swelling of these tissues and problems with the functioning of the sinuses.  Treating these various conditions successfully will typically require medicines or surgery to return the tissues of the turbinates, the meati, and the sinuses to a normal, thin, healthy state, where the mucosa is thin and normal, the hair cells function properly, the mucus blanket is moist and mobile, and the sinus Ostia are wide open to allow drainage from the sinuses into the nose. 

This is an important concept to grasp: that the nose and sinuses function well if the membranes are not thickened or inflamed but rather thin, pink, and moist; if the sinus openings or ostia are open and allow the sinus to drain; if the cilia are functioning well, beating and moving the mucus blanket; and if the mucus blanket itself is normal and constantly moving to clear particles from the sinuses and nose.

Finally, it's important to understand the mucus itself has important properties.  Aside from being a thin moist blanket that traps particles and clears them from the nasal passageways, the mucus also contains proteins, antibodies, chemicals, and other substances that help protect the body from bacterial, viral, and fungal diseases.  The mucus blanket serves as a barrier, protecting the thin mucosal lining from invasion and disease.  Although there are probably many diseases of the mucus itself, that is diseases where these proteins, chemicals, or antibodies are deficient, generally speaking there is not a lot known about how these proteins function or how frequent diseases of the mucus itself occur.  More research and better understanding of the content and function of the mucus itself will undoubtably occur in the near future.

Anatomy of Smell and taste perception

In the very top part of the nose, small nerve endings from the olfactory nerve, that is this nerve of sense of smell, penetrate from the brain, through a small bone, into the top of the nasal cavity.  The small nerve endings are at about the level of the corners of the eyes (or little higher) and are near the midline of the nose.  The actual nerve endings, called olfactory epithelium, lies within the mucosa at the very top of the nasal septum and along the very top of the middle and superior turbinates.  The olfactory epithelium extends several millimeters from the top of the nose along the side of the septum and the turbinates.  The olfactory nerves are stimulated by chemicals or odorants that pass through the nose, and diffuse through the air to the roof of the nasal cavity, and then diffuse into the mucus itself.  The chemical odorants stick to a variety of receptors in the olfactory nerve endings.  When the chemical odors bind to these receptors, the odor is changed into an electrical impulse which travels to the olfactory centers of the brain where, through complex array of nerve endings and processing pathways (that are only partially understood), we become aware of the sense of smell.

In order for the sense of smell to work properly, at the bare minimum, several processes need to work well.  First, the nasal passageways around the nostrils must be open.  Second, the nasal passageways near the top of the nose must be open, not blocked by swelling, polyp, abnormal tissue, or any type of growth.  Third, the mucus over the olfactory epithelium (nerve endings) must be normal, and so that the telco odors can't is all but the mucus.  Next, the mucosa in which the nerve endings are sitting must be normal.  The mucosa can't be            abnormally thickened, inflamed, or swollen.  The nerve endings need to be functioning normally, not affected by any inflammation from a core and the other pathology.  Finally, the nerve connections between the nose and the brain (in the brain processing centers as well) must be functioning normally.  There will be a number of conditions described in this book, not the least of which is acute or chronic sinusitis, that have great potential to disrupt the functioning of the olfactory nerves and in payer the sense of smell for a patient with these disorders.  Interestingly, when the sense of smell is disrupted, many patients actually complained most bitterly about a symptom of ”loss of taste”, so any discussion of sense of smell is incomplete without at least a brief discussion of the sense of taste.

The sense of taste is derived from the tongue as well as other receptors in the mouth and throat.  Although we all typically believe we perceive a rich variety of tastes, the fact is that we can only truly taste four different things: sweet, sour, salty, and bitter.  The remainder of the “ taste" that we experience are, in fact, odors that occur simultaneously with the tastes noted above.  If one’s sense of smell is absent, the rich variety of tastes are dramatically affected and, in fact, most patients complain more of loss of taste than actual loss of smell.   However, patients fully do acknowledge that there sense of smell is indeed absent as well.

Anatomy of structures near the sinuses

It's critical to understand the other structures near the nose and sinuses, because symptoms of sinus disease can affect these different structures and complications of sinus disease almost always involve the structures that are adjacent to the nose and sinuses.  Moreover, any surgical procedure near the nose or sinuses will entail the possibility of some injury to these associated structures.  The structures closest to the nose and sinuses include the orbit or the eye socket and the structures of the eye, the brain, the teeth and talent, the lacrimal or tier system, in the nasopharynx.

The bony structure of the eye, also known as the orbit, lies below the frontal sinus, above the maxillary sinus and decide the ethmoid sinuses.  Within the orbit lies the eyeball or globe, the muscles that move the globe, the optic nerve that supplies the retina and carries the visual signals, the lacrimal gland that produces tears, the lacrimal sac and docs that carries tears to the nose, and a number of small blood vessels and nerves.  The thin wall between the ethmoid sinuses and the orbit is called the lamina papyracea, which is Latin for “paper thin” bone.  In fact, in some cases, the thin bone of the lamina is in fact absent.  This thin bone serves as a barrier for the spread of infection between the sinuses and the eye, but very occasionally infections of the sinuses will penetrate this bony barrier and infection can spread to the orbit causing redness, swelling, change in vision, or rarely blindness.  Although this is rare, this complication of sinus disease is an emergency because it can affect vision, sometimes over very short period of time.  Disease is of the sinuses can affect the lacrimal system, that is the tear doc system, causing infections of the tear duct or blockage of the tear duct.  A blockage of a tear duct will cause a symptom that doctors call epiphora, or excessive tearing. 

The anatomy of the orbit and its relation to the sinuses is especially important during sinus surgery because of the risk of complications occurring to the structures around the eye. 

The brain is directly adjacent to several of the sinuses, particularly the frontal, ethmoid comment sphenoid sinuses.  Generally, there is in fact lay or a bone that protects the brain from infections spreading out of the sinuses and towards the brain.  On very rare occasions, a sinus infection can spread to the brain and cause meningitis, or an abscess around or in the brain.  These are life threatening conditions, but it's important to note that they are very rare.  Likewise, because the brain is so close the sinuses, there is the potential tampering complications with sinus surgery.  It is been reported, but it's quite rare, for a surgeon to become temporarily disoriented and to enter the brain.  This can cause a spinal fluid leak, infection of the brain, or trauma to the brain.

Below the maxillary sinus is the maxilla.  It's rare for infections or diseases of the maxillary sinus to effect the maxilla, or more specifically the hard palate (roof of mouth) or teeth of the maxilla.  However, in some very rare conditions, there can be aggressive, invasive infections that spread from the maxillary sinus to the hard palate and teeth and affect these areas.  Likewise, there can be infections that break out of the sinuses towards the skin and affect the skin of the cheek or forehead.  These types of infection are rare, and for the most part only occur in patients with severe immune compromise, usually from treatment of some cancer  or some other serious condition .

 In the nasopharynx and eustachian tubehind the nose is a space called the nasopharynx.  The nasopharynx is almost in the center of the skull.  It lives above the roof of the mouth and soft palate, about three to 4 inches back behind the nostrils.  In children, the nasopharynx  is partially filled with tissue called an adenoid, which is similar to a tonsil in its physical features (though a bit smaller) and in its function.  Adenoids are filled with lymphoid tissues which are the first tissues of the immune system to see bacterial, viruses and other organisms.   Just like tonsils, the adenoids can become larger when a person has an infection of the nose or throat or respiratory tract.  In children, frequent infections or chronic allergies can stimulate the adenoids grow quite large, and the adenoids can sometimes block the entire nasopharynx or much of the nasopharynx, causing children to have severe nasal obstruction symptoms.  These children frequently become “mouth breathe errors” because their noses nearly completely or completely obstructed.  They will typically have their mouth open most of the day.  Unfortunately, breathing through one’s mouth has an effect on growth of the mid-face and pallets.  These patients that are “mouth breeders” will tend to develop long, thin-appearing faces.  Show a high, arched hard palate and poor occlusion of the upper teeth with the lower teeth.  If not corrected, many of these patients will require orthodontia to spread the palate and correct the occlusion of the teeth.

The nasopharynx is also the site of the eustachian tube orifices.  The eustachian tubes connect the nasopharynx to the middle year.  Proper eustachian tube functioning is critical to prevent middle ear infections.  The eustachian tube typically pops open and closed each time a person swallows.  An exaggerated sensation of the eustachian tube opening and closing can be felt with a simple maneuver that can be done at home.  This is how it works.  Pincher nostrils tightly shut with your index finger and thumb.  Swallow forcefully.  Most people will feel their years pop opened and pop closed.  This is the eustachian tube opening and closing when one swallows.  Many people will

perform this maneuver when changing altitude in a plane, going up or down a mountain in a car, or otherwise changing altitudes.  Other people find it difficult to perform this maneuver.  During this "ear popping" maneuver, the eustachian tube is opening for short.  Time and air will equal a break between the nasopharynx in the middle ear.  A slight popping sound or crackle may be heard in the year.  Sometimes a hearing is altered for a few seconds, but restored when the patient swallows one more time (without his or her nose pinched).

The openings to the eustachian tubes are directly adjacent to the adenoid pads.  Therefore, any viral syndrome, bacterial disease of the nose or throat, allergies, or disease that causes inflammation in the area of the eustachian tubes may cause difficulties with the eustachian tubes and middle ear.  Patients may complain of difficulty popping their ears, fluid in the ears, full list of the ears, hearing loss, or pressure in the ears.   Although the sinuses are not directly adjacent to the eustachian tubes, when there is a sinus infection, the infected mucus will typically drain in the pathway that brings the infected very close to the eustachian tubes.  Therefore, with a sinus infection, it is not unusual for patients to have difficulty popping their ears are to have a sense of fluid in their ears.  Similarly, allergies can cause inflammation in the nasopharynx and nasal cavity.  The tissues of the eustachian tube opening can become inflamed from the allergies.  The inflamed, swollen tissue make it difficult for the eustachian tubes to pop open and therefore patients with allergies will also complain of difficulties in with their ears.