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Coding nasal procedures can be difficult because so much
of the anatomy of the nose and sinuses is difficult to visualize.
Let’s start with what we can see and proceed to the interior
of the nasal cavity and the paranasal sinuses so that we can
get a clearer picture of how all the pieces fit together.
The Nose and Nasal Cavity
The nose is a fibrocartilaginous extension of the nasal cavity
and septum. The nasal cavity begins with the outside openings
of the nostrils, which are called the external nares
or anterior choanae, and ends with internal openings
called the posterior choanae. Air enters via the external
nares and travels to the vestibule of the nose. The
lower part of the vestibule is lined with tiny hairs (vibrissae),
that act as filters to prevent foreign bodies from progressing
further into the respiratory system. The nasal bones
form the bridge of the nose, while the rest of the framework
is plates of cartilage. One of those plates, the septal
cartilage, can be felt at the tip of the nose. It usually
lies directly in the center of the nose dividing the nasal
cavity into right and left halves, and rests on a bony ridge
called the maxillary crest. In front, the septum is
made of flexible cartilage. Posteriorly, the septum is made
of the thin bone of the perpendicular plate of the
ethmoid.
The top, or roof, of the nasal cavity is made of the perforated
(cribiform) plate of the ethmoid bone. The lateral
walls are formed by the superior, middle and inferior
turbinates. Beneath the shelves of the turbinates are
small recesses called the superior, middle, and
inferior meatuses. The floor of the nasal cavity is the
palate, both the hard bony palate and the more
posterior and muscular soft palate. The palate is also
the roof of the oral cavity, thus separating the nasal and
oral cavities. The posterior choanae are the internal
openings of the nasal cavity which connect the nasal cavity
to the nasopharynx.
The mucosal lining of the nasal cavity is made up of ciliated
epithelial cells. The cilia sweep small particulate matter
down into the nasopharynx, where it can then be removed either
by swallowing or coughing. The turbinates have the same mucosal
lining, and serve to enlarge the surface area of the nasal
cavity, thereby providing more heat and moisture to air as
it enters the body. Occasionally the middle turbinate may
have a developmental abnormality within it called a concha
bullosa. The concha bullosa is actually an extra sinus
within the turbinate which enlarges and obstructs airflow.
The condition is corrected by excision of the affected turbinate.
Specialized cells called the olfactory epithelium are
found at the roof of the nasal cavity just beneath the cribiform
ethmoid. They are receptive to chemicals in solution and transmit
electrochemical impulses down the 1st cranial nerve
(the olfactory nerve).
The Sinuses
The paranasal sinuses are air filled spaces in the skull.
There are four groups of sinuses:
- The maxillary sinuses located below the eyes and
lateral to the nasal cavity.
- The ethmoid sinuses, which are arranged in a honeycomb
pattern between the eyes. There are anterior and posterior
ethmoids.
- The frontal sinus, a large cavity above the eyebrows
which may be either single or divided.
- The sphenoid sinus, again a cavity which may be
either single or divided, and which is found behind the
nose almost in the center of the skull.
The sinuses serve to lighten the skull and add timbre to
the voice. They are lined with respiratory epithelium which
is continuous with the epithelium of the nasal cavity. The
mucus secretions from these epithelial linings travel down
canals and enter the nasal cavity just under the meatuses.
All the paranasal sinuses drain into the osteomeatal complex.
Neoplasms
Unilateral bloody nasal discharge, obstruction, facial swelling
or facial numbness may be symptoms of possible cancer of the
nose or paranasal sinuses. Squamous cell carcinomas are the
most common malignancy in the nose and paranasal sinuses.
Exophytic papillomas are squamous cell papillomas with fingerlike
surface projections. They have a benign course in the nasal
cavity but require frequent surgical reexcisions. Inverted
papillomas are squamous cell papillomas which are invasive.
Excision often includes the bone of the lateral wall of the
nasal cavity in a procedure called a lateral rhinotomy.
Benign tumors that occur in the nasal cavity are fibromas,
hemangiomas, and neurofibromas. Fibromas, neurilemomas, and
ossifying fibromas occur in the paranasal sinuses.
Infections
Nasal congestion or obstruction of nasal breathing is one
of humanity’s oldest and most common complaints. While
it may be a nuisance to some people, to others it is a source
of pain and discomfort that detracts from the quality of their
lives.
A common cold or upper respiratory infection may be caused
by a number of viruses, most of which are transmitted from
hand-to-nose contact. Once the virus gets into the nose it
causes the body to release histamine, which causes the increased
blood flow to the nose, swelling and congestion of nasal tissues,
and production of mucus.
During a viral infection, the nose has poor resistance to
bacterial infections, which explains why bacterial infections
such as sinusitis often follow a cold. Acute sinusitis may
be caused by streptococci, pneumococci, Hemophilus influenzae,
or staphylococci. Acute infections produce nasal congestion,
discharge, and pain and tenderness in the cheeks, teeth, between
and behind the eyes, or above the eyes in the forehead, depending
on which sinuses are involved. Exacerbations of chronic sinusitis
may be caused by a gram-negative rod or anaerobic microorganisms.
In about 25% of cases, chronic maxillary sinusitis is secondary
to a dental infection.
In radiographs, healthy sinuses full of air appear black.
In acute and chronic sinusitis, swollen mucous membranes and
retained exudate cause the affected sinuses to be opaque on
x-rays. CT scans of the sinuses are used to better define
the extent of the infection. In cases of chronic maxillary
sinusitis, a CT scan of the apices of the teeth may be done
to rule out a periapical abscess.
Acute sinusitis usually responds to antibiotic treatment.
Chronic sinusitis often requires surgery (Caldwell-Luc operation
for the maxillary sinuses, ethmoidectomy for the ethmoid sinuses,
and sphenoid sinusotomy for the sphenoid sinuses) to improve
ventilation and drainage and to remove mucopurulent material,
debris, and hypertrophic mucous membrane. Some people develop
polyps, which are fleshy growths in the nasal or sinus
cavities as a result of chronic sinusitis, and these also
may be surgically excised.
Polyps
Allergic rhinitis, acute and chronic sinusitis often set
the stage for nasal or sinus polyp formation. Nasal polyps
usually form around the ostia of the maxillary sinuses. A
developing polyp is teardrop-shaped; when mature, it resembles
a peeled seedless grape. In acute infections, polyps may shrink
once the infection resolves. Unilateral polyps occasionally
occur in association with benign or malignant neoplasms of
the nose or paranasal sinuses.
Polyps that obstruct the airway or cause recurrent sinusitis
are surgically removed. In severe and recurrent cases, maxillary
sinusotomy or ethmoidectomy may be indicated.
Most sinus surgery is now done with endoscopes. The surgeon
may look directly into the sinuses through the scope, or hook
up a small camera to the endoscope, and display images on
a large monitor in the operating room. The endoscopes give
the surgeon a clear magnified view of the interior of the
nasal cavity and sinuses.
Nasal Fractures
Various forms of blunt trauma may cause a fracture of one
of more nasal bones, which can be confirmed by x-ray. The
most common deformity is deviation of the dorsum of the nose
in one direction and depression of the nasal bone on the other
side.
Nasal fractures may be reduced under general or local anesthesia.
The fracture is manipulated into position by internal and
external traction. A blunt elevator is placed under the depressed
nasal bone to lift it anteriorly and laterally, while pressure
is applied to the other side of the nose to bring the nasal
dorsum to the midline. Internal packing and/or external splinting
then keep the position of the nose stable.
Septal Deviation and Perforation
Deviations of the nasal septum are usually due to an injury
at some time. These deviations sometimes cause nasal airway
obstruction and predispose a patient to sinusitis (particularly
if the deviation obstructs an ostium of a paranasal sinus)
and to epistaxis as a result of drying air currents. Treatment
of symptomatic deviation of the nasal septum is by septoplasty
or nasal septal reconstruction.
Septal ulcers and perforations may follow nasal surgery,
repeated trauma or granulomatous infections such as TB. Perforations
may be repaired by using buccal or septal mucous membrane
flaps, or by closing the perforation with a Silastic septal
button.
Epistaxis
Bleeding from the nose occurs secondary to local infections;
drying of the nasal mucous membrane; trauma; arteriosclerosis;
hypertension; and bleeding disorders.
Most nasal bleeding occurs from a network of blood vessels
in the anteroinferior septum (Kiesselbach's area or plexus).
If pinching the nose fails to control the bleeding, then the
bleeding site must be found. The site is anesthetized with
a topical agent and cauterized.
In arteriosclerosis and hypertension, nasal bleeding is often
far posterior in the inferior meatus and may be difficult
to control. Ligating the internal maxillary artery and its
branches or packing the posterior part of the nasal cavity
is required to control the bleeding. The arteries may be ligated
with clips under microscopic control, using a surgical approach
through the maxillary sinus. The posterior choanae may be
obstructed with placement of a posterior nasal pack. The packing
remains in place for about 4 days.
Sleep Apnea
Snoring (partially obstructed breathing during sleep), is
3 times more common in obese people, and can range from being
an annoying social problem to obstructive sleep apnea.
Symptoms of obstructive sleep apnea include upper airway
narrowing, glottic obstruction, and potential pulmonary failure.
Repeated nighttime obstruction may cause further respiratory
failure and create a cycle of night and day episodes of sleep,
obstructive choking, startled awakening with gasping, and
drowsiness. Complications include cardiac dysrhythmias, excessive
daytime sleepiness, and morning headache.
Weight reduction is helpful in minimizing episodes of sleep
apnea. Surgical enlargement of the pharyngeal air space via
uvulopalatopharyngoplasty also helps in some cases.
Treatments for heavy snorers range from relieving a nasal
infection or allergy to corrective surgery of obstructive
conditions in the nose, pharynx, or uvula.
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Anatomy
Diseases
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