Paranasal Sinuses Week 10 Fall 2009 DRAFT

Anterior Sinus Anatomy Purpose of sinuses ________________ 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.

Lateral Sinus Anatomy Aerated at birth Age 6-7 _____________ Age 6-7 ___________ Puberty- approx 17-18 yrs 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 17-18 years of age. When the sinuses are fully developed they communicate with each other and with the nasal cavity.

Maxillary Sinuses ___________ sinuses Within maxilla 3.5 cm high 2.5 – 3 cm wide Within maxilla Above upper teeth Paired & symmetric Communicates with _________________ 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. Copyright © 2005, Mosby, Inc.

Frontal Sinuses _______ largest sinuses Normally: Rarely ____________ 2 – 2.5 cm Normally: Between tables of vertical plate in frontal bone Can extend beyond frontal bone inot the orbital plates Rarely ____________ Number varies (occassionally absent) Drain into __________________ 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. Copyright © 2005, Mosby, Inc.

Sphenoid Sinuses _______ sella turcica Can be single or paired Extends between dorsum sellae and post clinoid processes Can be single or paired Usually no more than _________ Drains into _________________ 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

Ethmoid Sinuses Within _________ masses of ethmoid bone Three groups: Anterior, middle & posterior _________________ 2-8 cells Drains into middle nasal meatus 2-6 cells Drain into superior nasal meatus Copyright © 2005, Mosby, Inc

Osteomeatal complex – coronal view _____________ Frontal, ethmoid and maxillary 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.

Osteomeatal Complex

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

Technical Considerations Radiographic density is critical ______diminishes or obliterates pathology _______________ can simulate pathology _____________focal spot Clean screens Perfect film/screen contact No ___________ contrast

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.

Lateral Projection Methods: Lines and planes: CR: ________________ ________________________________ 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. 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

Lateral Sinuses

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

Caldwell Methods: ____grid 15 degrees: _____________grid: CR ________________ ____grid 15 degrees: OML & MSP perp Nose & forehead _____________grid: Tip of nose on grid and use sponge OML 15 from CR CR horizontal to exit nasion 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.

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.

Waters for Maxillary sinuses Methods: _____________ Lines and planes: CR: __________________________ 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.

Waters

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

Open Mouth Waters for Maxillary / sphenoid sinuses Methods: _____________ Lines and Planes: CR: __________________________ Excellent view for a patient who cannot do a SMV postion.

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

SMV for ethmoidal and sphenoidal sinuses Methods: ______________ Lines and planes: CR:

SMV Sinuses

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.

Pathologic Indications _______________ Acute Chronic Secondary _____________________ ______________________ 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 http://www.meei.harvard.edu/patient/pted.php 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 http://www.ohsu.edu/ent/sinus/polyps.htm 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.

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____________ 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).

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Mastoiditis

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