1. Paranasal Sinuses
Week 10

2. Anterior Sinus Anatomy
Purpose of sinuses
Resonating chamber for voice
Decrease weight of skull
Warm & moisten air
Shock absorbers
Immune system
Sinuses are air containing cavities situated in the frontal, ethmoidal and sphenoid bones of the cranium and the maxillary b ones of the face. They are known as the paranasal sinuses because of their formation from the nasal mucosa and their continued communication with nasal fossas.
These cavities serve five purposes:
1) serve as a resonating chamber for the voice
2) Decrease the weight of the skull
3) Help wam and moisten inhaled air
4) Act as shock absorbers in trauma (like air bags in a car)
5) Possibly help control immune system.

3. Lateral Sinus Anatomy Aerated at birth Age 6-7
Maxillary sinuses
Age 6-7
Frontal /sphenoidal sinuses
Puberty- approx yrs
Ethmoid
The sinuses begin developing as a fetus and first appear as small sacculations of the mucosa of the nasal meatus and recesses.
As the pouches or sacs develop and grow they gradually invade the respective bones to for air sinuses and cells.
The maxillary sinuses are usually developed and aerated at birth and can be demonstrated radiographically.
Sphenoid and frontal sinuses develop at approximately age 6-7 yrs. At this time they are distinguishable from the ethmoid air cells.
The ethmoid air cells develop during puberty and develop slowly until approximately years of age.
When the sinuses are fully developed they communicate with each other and with the nasal cavity.

4. Maxillary Sinuses Largest sinuses Within maxilla Paired & symmetric
3.5 cm high
2.5 – 3 cm wide
Within maxilla
Above upper teeth
Paired & symmetric
Communicates with middle nasal meatus
The maxillary sinuses appear rectangular in the lateral image but they are really pyramidal in shape and have 3 walls.
The apices project inferiorly and laterally
There are several conic elevations at the floor of the maxillary sinuses for roots of the first and second molar teeth. Occasionally these roots can allow infections originating int eh teeth to travel to the sinuses.
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5. Frontal Sinuses Second largest sinuses Normally: Rarely symmetrical
2 – 2.5 cm
Normally:
Between tables of vertical plate in frontal bone
Can extend beyond frontal bone inot the orbital plates
Rarely symmetrical
Number varies (occassionally absent)
Drain into middle nasal meatus
Posterior to the glabella between the inner and outer tables of the skull.
Rarely aerated before 6 years of age.
Larger in men than women.
Can both be on one side in some cases. Or missing on one side and only one of either the left or right.
There is a septum called the intersinus septum that divides the frontal sinuses tha is often deviated from the midline causing the asymmetric frontal sinsuses.
Sometimes there are multiple septum.
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6. Sphenoid Sinuses Below sella turcica Can be single or paired
Extends between dorsum sellae and post clinoid processes
Can be single or paired
Usually no more than two
Drains into sphenoethmoidal recess of nasal cavity
When there is sphenoid effusion it may indicate a basal skull fracture.
Since the sphenoid sinues are so close to the base or floor of the cranium, pathologic processes make their presence known by the effect on these sinuses.
One example is a air-fluid level with skull trauma. This may be evidence that there is a basal skull fracture and either blood or CSF is lekaing through the fracture into the sinuses….called sphenoid effusion.
Copyright © 2005, Mosby, Inc

7. Ethmoid Sinuses Within lateral masses of ethmoid bone Three groups:
Anterior, middle & posterior
Anterior & middle
2-8 cells
Drains into middle nasal meatus
Posterior
2-6 cells
Drain into superior nasal meatus
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8. Osteomeatal complex – coronal view
Pathways of communication
Frontal, ethmoid and maxillary
2 key passageways
Infundibulum
Middle nasal meatus
The pathways of communication between frontal, maxillary, ethmoid sinuses provide drainage between these sinus cavities.
When these pathways are obstructed it can lead to infections of the sinuses called sinusitis.
Maxillary sinuses drain into the infundibulum down through the middle nasal meatus into the inferior nasal meatus.
The ethmoid bulla receives drainage from the frontal and ethmoid sinus cells which then drains to the medical nasal meatus on to the inferior nasal meatus. Then it exits through the exterior nasal orifice.

9. Osteomeatal Complex

10. Paranasal Sinuses Protocols
Lateral
PA (Caldwell)
Parietoacanthial (Waters)
Parietoacanthial (Open mouth Waters)
SMV

11. Technical Considerations
Radiographic density is critical
Overpenetration diminishes or obliterates patholgy
Underpenetration can simulate pathology
Small focal spot
Clean screens
Perfect film/screen contact
No high contrast

12. Air Fluid Levels
The first image is done in vertical position and the air fluid level is clearly demonstrated.
The second image is done vertically but the CR is angled 45 degrees and demonstrates the gradual fading of the fluid line.
The third is done horizontally and the CR is vertical. This radiograph demonstrates a homogeneous denisty throughout the cavity, with no evidence of an air-fluid level.
Exudate is in the sinuses and is not a fluid but is commonly a heavy semigelatinous material the clings to the walls of cavity and takes several minutes to shift position.
For this reason you must positon the patient for severla minutes to allow the exudate to gravitate toe the desired location before the exposure is made.

13. Pathologic Indications
Inflammatory conditions:
Sinusitis
Acute
Chronic
Secondary Osteomyelitis
Sinus Polyps
Trauma
Sinusitis simply means your sinuses are infected or inflamed, but this gives little indication of the misery and pain this condition can cause. Health care experts usually divide sinusitis cases into:
Acute, which last for 3 weeks or less
Chronic, which usually last for 3 to 8 weeks but can continue for months or even years
Recurrent, which are several acute attacks within a year
Symptoms of Sinusitis
The location of your sinus pain depends on which sinus is affected.
Headache when you wake up in the morning is typical of a sinus problem.
Pain when your forehead over the frontal sinuses is touched may indicate that your frontal sinuses are inflamed.
Infection in the maxillary sinuses can cause your upper jaw and teeth to ache and your cheeks to become tender to the touch.
Other symptoms of sinusitis can include:
Fever
Weakness
Tiredness
A cough that may be more severe at night
Runny nose (rhinitis) or nasal congestion
In addition, the drainage of mucus from the sphenoid or other sinuses down the back of your throat (postnasal drip) can cause you to have a sore throat. Mucus drainage also can irritate the membranes lining your larynx (upper windpipe). Not everyone with these symptoms, however, has sinusitis
Information from the National Institutes of Health
Retrieved October 19, 2007 from
Secondary Osteomyelitis- an infection of the bone and marrow secondary to sinusitis, results in erosion of the bony margins of the sinus. It is can also be caused by chronic cocaine usage.
Polyps are tissue swellings within the nose and sinuses that can be responsible for many of the symptoms described by patients with rhinosinusitis. Polyps may simply block the nasal airway creating difficulty in nasal breathing, or they may block the proper drainage of the sinus cavities leading to stagnant secretions within the sinuses that may become infected.
Polyps are generally thought to occur as a result of an ongoing inflammatory process within the nose and sinuses. Although this may be related to allergies, most cases of polyps occur as a result of non-allergic processes. 
Whatever the cause, polyps can wreck havoc in the nose and sinuses and make patients miserable. Common symptoms in patients with nasal and sinus polyps include nasal obstruction, decreased sense of smell, recurrent sinus infections, and profuse nasal drainage. Many of these patients feel as though they have a cold all of the time. 
Retreived October 19, 2007 from
Nasal & Sinus Polyps
By: Timothy L. Smith, MD, MPH, FACS
Professor and Director, Oregon Sinus Center
Rhinisits: Inflammation of the nasal mucous membrane is called rhinitis. The symptoms include sneezing and runny and/or itchy nose, caused by irritation and congestion in the nose. There are two types: allergic rhinitis and non-allergic rhinitis.

14. Lateral Projection Upright or cross table IPL perp to IR
MSP and IOML parallel to IR
CR horizontal entering ½ - 1” post to outer canthus
Suspend respiration
If the projection is being done for preoperative measures us 72” SID to minimize magnification and distortion.
If patient is unable to assume upright postion, use dorsal decubitus and use a horizontal CR.

15. Lateral Sinuses

16. Lateral Radiograph All 4 sinuses No rotation
Sphenoid of primary interest
No rotation
SI orbital roofs, mandibular rami
Close beam restriction
Clear air-fluid levels

17. Caldwell Seated upright Angled grid 15 degrees: Vertical grid:
OML & MSP perp
Nose & forehead
Vertical grid:
Tip of nose on grid and use sponge
OML 15 from CR
CR horizontal to exit nasion
Suspend respiration
Angled grid is preferred because it brings IR closer to sinuses. It is also a natural postion for the patient to hold by placing nose and forehead on IR.

18. Caldwell Radiograph Frontal & Anterior ethmoid
No rotation
Petrous ridges symmetric
Petrous ridge in lower 1/3 of orbits
Frontal sinus above frontonasal suture
Anterior ethmoid cells above petrous ridges
Frontal &ethmoid air cells
Air fluid levels
Close beam restriction
Equal distance from lateral margin of orbits to lateral border of skull, indicating no rotation.

19. Waters for Maxillary sinuses
Upright
Chin on IR
MSP &MML perp
OML 37 degrees
Suspend respiration
CR horizontal and exiting acanthion
Goal of this projection is to place the petosae just below the maxillary sinuses.
Underextension places the petrose in the inferior portions of maxillary sinuses obstructing possible fluid levels.
Overextension causes the maxillary sinuses to be foreshortened and the antral floors are not demonstrated.
This image shoes the maxillary sinuses.

20. Waters

21. Waters Radiograph Petrose just below maxillary sinuses No rotation
Orbits & maxillary sinuses symmetric
Close beam restriction
Clear air-fluid levels

22. Open Mouth Waters for Maxillary / sphenoid sinuses
Upright
Chin on grid
OML 37 degrees
Open mouth
Suspend respiration
CR horizontal and exiting acanthion
Excellent view for a patient who cannot do a SMV postion.

23. Open mouth Waters Radiograph
Petrous ridges below maxillary sinuses
No rotation
Maxillary sinuses
Close beam restriction
Clear air-fluid levels
Sphenoid sinuses through open mouth

24. SMV for ethmoidal and sphenoidal sinuses
Seated upright
IOML parallel to IR
Backed strip of adhesive tape
Suspend respiration
CR horizontal and perp to IOML through the sella turcica
CR enters MSP ¾” anterior to level of EAM

25. SMV Sinuses

26. SMV Radiograph No tilt or rotation
Anterior frontal bone SI over mental protuberance
Mandibular condyles anterior to petrous pyramids
Clear air-fluid levels
Equal distance from the lateral border of the skull to the mandibular condyles on both sides indicating that the MSP is perpendicular- not tilt.

27. Acute Sinusitis

28. Acute Sinusitis

29. Mucous Retention Cysts
The drainage of a solitary mucous gland can become obstructed leading to the formation of a mucous retention cyst. These cyst are often discovered by accident since they usually do not cause any symptoms. On the plain radiograph they can be seen as a smoothly outlined soft tissue density without any surrounding mucosal thickening (Fig 13).
Mucous retention cysts (description of radiograph) Water's view shows bilateral smoothly outlined retetion cysts in otherwise normally aerated maxillary sinuses (arrows).

30. Tripod Fracture
Tri-pod fracture (description of tripod waters view sinus radiograph) a) Water's view. A fracture system is seen extending through the inferior orbital rim and floor continuing down through the maxilla (white arrows). The frontozygomatic suture is also separated (open arrow).

31. Chronic Sinusitis MMT: mucous membrane thickening
OFS: opacified frontal sinus
OES: opacified ethmoid sinus
OMS: opacified maxillary sinus
M: mucocoele
Mucocoele: a sharply circumscribed rounded soft tissue mass, typically in maxillary sinuses. Also known as a cyst or polyp