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Oral Board Review Textbook > Orthognathic Surgery, OSA > Flashcards

Orthognathic Surgery, OSA Flashcards

1
Q

What are the indications for orthognathic surgery?

A

When dentofacial deformities cannot be corrected by conventional orthodontic compensation, including growth modification and camouflage techniques as well as for treatment of OSA

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1
Q

What are the approximate AP, vertical and transverse discrepancies that would require orthognathic surgery to correct?

A

-AP: OJ 5 mm or more, or zero to negative value. Molar discrepancy of 4 mm or more
-Vertical: 2 standard deviations from normal, open bite or 2 mm posterior open bite, deep overbite with irritation of tissues, supraeruption of dentoalveolar segment
-Transverse: 2 or more standard deviations from normal. 3 mm or greater unilaterally or 4 mm bilaterally. Need to differentiate between dental tipping

-3 mm or greater of any asymmetry

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2
Q

What are the goals of presurgical orthodontics?

A

-Decompensation of teeth
-Arch alignment and leveling
-Bolton analysis
-Arch coordination
-Final presurgical orthodontic preparation

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3
Q

What are the goals of decompensation of teeth?

A

-House teeth within alveolous
-Maxillary incisors: 102 degrees to SN
-Mandibular incisors 90-95 degrees to mandibular plane

-Class II patients have retroclined upper incisors and proclined mandibular incisors
-Class III patients usually have proclined upper incisors and proclined mandibular incisors

-May require extractions to make space

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4
Q

What are the goals of arch alignment and leveling?

A

-Teeth aligned
-Adjust for tooth size discrepancy (Bolton’s analysis)
-Create divergence of roots for planned osteotomy sites
-Lingual cusps of mandibular posterior teeth should be 1 mm below the buccal cusp
-Palatal cusps of maxillary posterior teeth should be 1 mm below the buccal cusps

-Plunging cusps can create open bites post-op

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5
Q

What is a Bolton’s analysis?

A

-Determined the disproportion of the size of the permanent maxillary and mandibular teeth
-Overall ratio takes the sum of mesio-distal width of 1st molar to 1st molar
-Mandibular / Maxillary
-91.3% is ideal. If less than 91.3%, maxillary teeth are too big
-Anterior ratio (canine to canine) should be 77.2%

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6
Q

What are the goals of arch coordination?

A

-Dental arches should be reasonably compatible with one another at time of surgery to allow for maximum intercuspation post-surgically
-Need SARPE or segmental osteotomy if transverse greater than 5 mm

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7
Q

What are the goals of final presurgical orthodontic preparation?

A

-Need full dimension rectangular steel arch wire that fills the bracket slow (Ball hook)
-No movement of teeth for 4 weeks prior to models
-Passive stabilizing wire
-Surgical hooks (ball hooks)

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8
Q

What anatomical mandible shape supports a vertical ramus osteotomy vs a BSSO

A

-V shaped mandible: IVRO for setback
-U shaped mandible: BSSO for setback

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9
Q

Describe your upper facial third evaluation.

A

From trichion (hairline), to glabella.
Look for craniofacial deformity
Assess eyebrow shape, position and symmetry

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10
Q

Describe your middle facial third evaluation.

A

From glabella to subnasale.
-Look at eyes, nose and cheeks
-Scleral show and flattening of cheek bones/paranasal region may indicate midface deficiency
-Nose, center of lips, middle of chin should fall on true vertical line
-Cheek bone-nasal base lip contour line, evaluates harmony of the structures of midface and paranasal area of lip

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11
Q

Describe your lower facial third evaluation.

A

From subnasale to menton
Also subdivided into subnasale to stomion superius and stomion inferius to menton (Ratio is 5:6)

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12
Q

Describe your transverse facial fifth evaluation.

A

-Outer canthi should coincide with gonial angle
-Medial canthi should coincide with alar bases of nose
-Interpupillary distance should coincide with corners of mouth

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13
Q

What is normal tooth show at repose and smiling?

A

-2-4 mm at repose
-Full crown length smiling (men), 2 mm gingiva (female)

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14
Q

What are potential causes of excessive tooth display at rest?

A

-Short philtrum height
-Vertical maxillary excess
-Excessive crown height
-Lingually tipped incisors

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15
Q

Describe the cheek in a sagittal view.

A

-Lateral orbital rim lies 8-12 mm behind the globe
-The globe projects 0-2 mm ahead of infraorbital rim
-Malar eminence should be 10-15 mm lateral and 15-20 mm inferior to the lateral canthus

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16
Q

Describe normal measurements in Steiner analysis

A

-SNA: 82 (Greater than 82 means maxillary protrusion, less than 82 means maxillary retrusion)
-SNB: 80 (Greater means mandibular protrusion, less means mandibular retrusion)
-ANB: 2 (Class 3 is less, class 2 is greater)

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17
Q

What is Wits appraisal?

A

-AP relationship between maxilla and mandible not influenced by cranium
-Drop a perpendicular line from A point and B point to occlusal plane
-In male, BO 1 mm ahead of AO
-In female AO and BO equal

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18
Q

Describe the holdaway ratio.

A

-Extend NB line to inferior border of mandible
-Measure to incisal edge and pogonion
-Ideal 1:1 ratio (slightly less in females)
-Lower incisor must be in proper position

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19
Q

How can you eval growth on a lateral ceph?

A

-Cervical vertebrae
-Start developing concavity
-This indicates they are past stage 3/4 (growth likely stopped)

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20
Q

Describe your steps in a Lefort I osteotomy.

A

-GA with nasal intubation, discuss permissive hypotension
-K wire
-Full thickness flap, 5 mm of nonkeratinized mucosa
-Expose maxilla (nasal aperture, infraorbital nerve, pterygoid plates)
-Dissect anterior nasal spine
-Make osteotomy
-Lateral nasal wall osteotomies
-Nasal septum
-Pterygoid plates
-Downfracture 60 MAP
-Mobilize
-Splint, remove interferences
-Seat condyles
-Plate
-Suture

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21
Q

What are potential sources of bleeding with a Lefort I osteotomy?

A

-Pterygoid plexus
-PSA
-Greater palatine artery
-Terminal branches of maxillary artery
-Internal maxillary artery (25 mm superior to base of junction of pterygoid plate)

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22
Q

How would you treat a bleed during a Lefort I?

A

-Pressure packing with gauze or hemostatic agent
-Thrombin (Promotes clot formation through activated bovine prothrombin, activates IIA, converts fibrinogen to fibrin)
-Surgicel (oxidized cellulose that binds platelets, negative pH precipitates fibrin)

-Try to identify vessel for cautery
-Consider IR for embolization

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23
Q

How do you treat an anterior open bite after MMF release?

A

-Likely condyles not seated or area of premature bony contact
-Remove fixation
-Check bony interferences
-Ensure passive condylar positioning, replace fixation

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24
Q

How do you treat a palatal mucosa cut/tear in a multi-piece lefort?

A

-Repair small tear with single suture
-Large tear consider replacing maxilla back to original position to avoid avascular necrosis

-Local irrigation, cover with non-compressive splint
-Formal closure when revascularization is confirmed

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25
Q

How do you treat a vertical posterior maxillary wall fracture?

A

-Check globe for increased pressure
-Re-direct fracture with osteotome
-Check globe post-op (IOP, visual acuity, proptosis), consider optho consult

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26
Q

How do you treat an intra-op midline discrpancy?

A

-Etiology: Error in work-up, mounting or splint fabrication

-Attempt to reposition maxilla using facial midline or dental midline/stable jaw

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27
Q

How would you treat decreased maxillary perfusion intra-op?

A

-Poor capillary refill or purple gingiva
-Replace and fixate maxilla to original position
-Keep area clean and prevent infection (antibiotics, chlorhexidine)
-Consider hyperbaric oxygen

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28
Q

How would you treat a post-op nose bleed?

A

-Pack nose with nasal packing
-Consider OR for maxilla take-down and control bleeding
-Consider embolization

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29
Q

What would you do if the heart rate dropped intra-operatively?

A

-Likely trigeminocaridac reflex
-Stop stretch on maxilla
-Anesthesia may need to treat with atropine or glycopyrrolate

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30
Q

How would you treat post-op epiphora?

A

-More common in high Lefort osteotomies due to damage to nasolacrimal system
-May see naasoseptal deviation or swelling
-May self-resolve in up to 6 weeks
-CT scan to r/o source
-May require dacryocystorhinostomy or nasoseptoplasty

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31
Q

How would you treat a post-op pseudoaneurysm?

A

-CT angio, IR consult

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32
Q

How do you treat nasal septum deviation or buckling?

A

-Suture septum to the ANS to prevent deviation
-Trim cartilaginous septum or crest for buckling

-Post-op try to straighten, consider post-op surgery septoplasty

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33
Q

How do you treat a post-op infection of a Lefort?

A

-Imaging, antibiotics, I&D, debridement
-If hardware is source, must remove

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34
Q

How do you treat hardware failure?

A

-Replace hardware, consider more rigid fixation

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35
Q

How much transverse space can be obtained from dental tipping?

A

-5 mm
-High relapse

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36
Q

How much transverse space can be obtained with a segmental lefort?

A

-7 mm
-More posterior expansion

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37
Q

Where is most expansion during a SARPE?

A

-At canines

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38
Q

What is a key aspect of a SARPE to allow for expansion?

A

-Remove bony interference at buttress

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39
Q

How much latency is required in a SARPE

A

5-7 days

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40
Q

What is the rate of expansion, how long of a consolidation phase?

A

-0.5 mm/day
-4 months consolidation

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41
Q

How do you manage periodontal compromise between central incisors after a SARPE?

A

-Decrease appliance back a few notches, reduce rate of expansion

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42
Q

How do you manage an asymmetric expansion after a SARPE?

A

-Happens from incomplete release of pterygomaxillary junction on one side
-Half of time this corrects itself
-May require segmental osteotomy to correct the asymmetry 4 weeks after SARPE

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43
Q

How do you manage inadequate expansion after a SARPE?

A

-Adequate mobilization and removal of bony interferences

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44
Q

What is the Hunsuck modification?

A

-Medial osteotomy does not extend to the posterior ramus
-Allows for shorter split, less soft tissue stripping, improved mandibular contour

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45
Q

What is the Dal Pont modification?

A

-Advanced the vertical osteotomy on the buccal cortex between the first and second molar
-Allows for greater advancement and more bony contact

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46
Q

What is the Epker-Schendel modification?

A

-Reduced stripping of the masseter and soft tissue of the medial ramus
-Cut at inferior border to extend to lingual side, including entire inferior border in the proximal segment
-Decreased post-op swelling, hemorrhage and manipulation of neurovascular bundle
-Easier repositioning of TMJ, reduction of relapse and more blood flow to proximal segment

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47
Q

Describe your BSSO technique.

A

-Incision over anterior border of ramus, 5 mm non-keratinized tissue cuff
-Dissection and exposure of mandible
-Medial dissection above lingula, ID mandibular foramen
-Make corticotomies with oscillating saw (medial, sagittal, vertical)
-Chisel, split mandible
-J stripper to remove medial pterygoid attachment
-Splint, remove interferences
-Seat condyle
-Fixate (positional screws)

48
Q

How do you manage a nerve transection during a BSSO?

A

-Epineural repair with 7/0 non-resorbable suture (nylon)

49
Q

How do you manage a buccal or lingual plate fracture during a BSSO?

A

-Complete osteotomies
-Set to planned occlusion
-Fixate fractures with plates and screws (bicortical positional screw can be used for a lingual plate fracture)
-Stabilize as planned to new position
-If segment is small and attached to periosteum, consider leaving it

50
Q

How is a subcondylar fracture managed during a BSSO?

A

-Complete osteotomies
-Set to planned occlusion
-Fixation with plates and screws vs IMF

51
Q

How is a post-op infection managed from a BSSO?

A

-Review imaging for hardware/screw loosening
-Antibiotics, incision and drainage, debride, or hardware removal if needed

52
Q

How is a malocclusion managed from a BSSO?

A

-Peri-op: Remove fixation, ensure condyles seated and replace fixation
-Post-op: Evaluate, consider going back to OR vs close with ortho

53
Q

How is condylar sag managed from a BSSO?

A

-Manifests as unilateral malocclusion after removing IMF
-Remove fixation
-Reposition condyle
-Reapply fixation

54
Q

How is condylar resorption managed from a BSSO?

A

-Associated with skeletal class 2 deformities with high mandibular plane (female predilection)
-Treat with bite splint therapy and anti-inflammatory medications
-More severe cases may warrant synovectomy, costochondral grafting or TMJ replacement

55
Q

How is a non-union managed from a BSSO?

A

-Re-operation of the site
-Freshen bony margins
-Remove fibrous tissue
-Apply more rigid fixation
-Consider bone grafting
-Consider period of IMF

56
Q

When should a bilateral intraoral vertical ramus osteotomy be considered?

A

-Mandibular set-back
-Best for V-shaped mandible (divergent ramus pattern)
-Less likely to have paraesthesia (both short and long term)
-Thin mandible with little marrow space
-Pt with symptomatic TMD

57
Q

What are potential consequences of an IVRO?

A

-If CCW movement is planned, proximal end of distal segment will rotate inferiorly and may pull on proximal segment
-Can create splaying of proximal bony segment and create fullness in mandibular angle

58
Q

What is the technique for an IVRO?

A

-Incision over anterior border of the ramus into the mandibular vestibule
-Full thickness flap exposing the lateral ramus and inferior border up to the sigmoid notch
-Bauer retractors into the sigmoid notch and along inferior border of mandible
-Identify the antilingula (anterior limit of osteotomy) or 7-10 mm anterior to posterior border
-Make vertical cut using oscillating saw blade
-Make superior osteotomy last as risk for bleed from masseteric artery
-Develop a subperiosteal pocket on medial aspect of mandible to accept the overlapping segment
-Manipulate proximal segment laterally
-Trim excess inferior portion of bony proximal segment
-Establish occlusion with MMF x6 weeks
-If segments are passively positioned and in approximation, rigid fixation with two or three screws can be completed through trochar

59
Q

How is an infection managed s/p IVRO?

A

-Antibiotics, I&D, debridement as needed

60
Q

How is bleeding managed during an IVRO?

A

-Most likely from internal maxillary artery branches (massetric branch at sigmoid notch; 8 mm above sigmoid notch and 25 mm from anterior border of ramus)
-Direct pressure with gauze
-Consider hemostatic agents
-Identify bleeding vessel, consider hemoclips
-If uncontrolled, consider embolization

61
Q

How is a displaced proximal segment managed during an IVRO?

A

-Distract mandible anteriorly and reposition
-Evaluate for medial bony interferenced and reduce as necessary

62
Q

How is distraction of the condylar segment managed during an IVRO?

A

-May occur early in treatment or weeks after surgery
-Aggressive elastic traction should be attempted
-May require revision and placement of fixation/wire

63
Q

How is an inadvertent subcondylar osteotomy managed during an IVRO?

A

-Place pt in IMF x6 weeks
-Complete surgery after establishment of bony union

64
Q

What is the procedure called to advance airway during genioplasty, what must be included in the osteotomy?

A

-Anterior mandibular osteotomy with genioglossus advancement
-Need to include the genial tubercles

65
Q

Describe the surgical technique of a genioplasty.

A

-Incision is half the distance between the vestibule and the wet line of the lip from canine to canine
-Incise through mucosa, submucosa, through mentalis then to bony mandible
-Subperiosteal dissection, identify mental nerves bilaterally
-Mark midline of chin
-Make osteotomy (5 mm below foramina and 5 mm below apicies of teeth), also need 10 mm above inferior border of mandible at midline
-Bony chin mobilized and repositioned (bone plate)
-Closure in layers (mentalis to prevent ptosis of the chin), then mucosa

66
Q

How is chin ptosis managed s/p genioplasty?

A

-Avoid complication: ensure reapproximating the mentalis and aggressive soft tissue dissection
-Reopen wound and reapproximate mentalis
-Placement of pressure dressing

67
Q

How is a malposition of the chin managed s/p genioplasty?

A

-Remove plate and realign

68
Q

How are injured root apicies managed s/p genioplasty?

A

-Observe, possible root canal in future

69
Q

How is a nerve injury managed s/p genoiplasty?

A

-Ensure dissection is 5-6 mm away from mental formaina
-Epineural repair with 7/0 suture for observed transection

70
Q

How is a malunion managed s/p genioplasty?

A

-Debride interposing fibrous tissue and reposition with new hardware
-Consider bone grafting

71
Q

How are infections/hardware failure managed s/p genioplasty?

A

-I&D, antibiotics, debridement, remove hardware possibly
-Hardware failure: Remove hardware and replace if no evidence of union

72
Q

What is the hierarchy of stability in orthognathic surgery?

A

-Maxilla up
-Mandible forward
-Maxilla forward
-Maxilla up/mandible forward
-Maxilla forward/mandible back
-Mandible back
-Maxilla down
-Maxilla wider

73
Q

Who are the members of the cleft lip/palate team?

A

-Patient care coordinator
-Pediatrics/primary care/geneticist
-Surgeon (OMFS, plastic, ENT)
-Pediatric dentist
-Orthodontist
-Speech pathology
-Audiology
-Psychology
-Social work

74
Q

What is timing of orthognathic surgery?

A

-When growth is complete (same as normal)
-Before secondary nasal revision

75
Q

What are treatment planning considerations (in diagnosis) and how is this translated in planned surgery?

A

-Primary deficiency is maxillary hypoplasia
-Try to address this, limit mandibular setback
-May need to do distraction osteogenesis to achieve desired outcome

76
Q

What are intubation considerations in a cleft orthognathic surgery procedure?

A

-Patient may have had a velopharyngeal flap procedure
-Need to ensure atraumatic placement of nasal tube through a lateral port of the pharyngeal flap

-Can pass red rubber catheter for visualization and safe pull-through
-Endoscopic or fiberoptic guidance
-NPA to guide bougie and pass ETT along bougie

77
Q

What are incision design considerations in a cleft orthognathic surgery procedure?

A

-Want to maximize blood supply

-Shortened circumvestibular incision leaving a large buccal soft tissue pedicle
-An anterior midline pedicle can be left with a vertical incision at midline and two lateral vestibular incisions

78
Q

Where is most of the blood supply to the mobilized maxilla derived from in a cleft orthognathic patient?

A

-Palatal tissues

79
Q

What are considerations of osteotomy and down fracture in the cleft orthognathic patient?

A

-Greatest areas of buttressing in the maxilla are pyriform and pterygomaxillary buttresses. Care must be taken when completing the osteotomy
-Unfavorable fracture to skull base or orbit from poor osteotomy/seperation.
-Too much pressure can lead to fracture of thin grafted alveolar bone and transverse instability

80
Q

How is the nasal floor managed after downfracture for a cleft orthognathic?

A

-Examine for: Residual oronasal fistula, septal deviation, enlarged inferior turbinates, alar support

-Close any residual fistula, place any bone graft needed
-Pt may need septoplasty
-Inferior turbinectomy can be considered at this juncture as well
-Take time to stretch soft tissue to allow for planned moves

81
Q

Describe fixation and bone grafting considerations in cleft orthognathic patient?

A

-Likely need bone graft because you want good bony contact
-Rigid fixation with largest/strongest system

82
Q

Describe rigid external maxillary distraction technique/principals.

A

-Orthodontist makes an intra-oral splint that attaches to orthodontic appliances with extra-oral extensions
-Lefort I osteotomy the same
-Adequate mobilization is critical
-Cranial halo placed with an external adjustable distraction screw system. A rigid down-rod is attached to the halo which is used to attach wires to the extra-oral component of the splint

-Latency 5-7 days, activation and consolidation

83
Q

What are the advantages of rigid external maxillary distraction?

A

Advantages:
-Adjustable vector of distraction throughout activation phase
-Does not require secondary surgery for removal

Disadvantages:
-Psychosocial aspect of wearing a large extra-oral appliance
-Does not offer retention and requires use of reverse ull headgear after removal

84
Q

What are the advantages/disadvantages of internal maxillary distraction?

A

Advantages:
-No halo device needed
-Reverse pull head gear not necessary (leave device in place with removal of activation arm

Disadvantages:
-Unidirectional vector that cannot be altered
-Second surgery required for removal

85
Q

What is OSA?

A

-A sleep disorder characterized by obstructive apneas and hypopneas caused by collapse of the upper airway during sleep

86
Q

What is central sleep apnea?

A

-The absence of respiration associated with an absence of respiration effort

87
Q

What is PSG?

A

Polysommography is a diagnostic test used for the evaluation of sleep disorders.

-Includes EEG, EOG, EMG, ECG and pulse ox with or without video recording of the subject

88
Q

What is apnea and hypopnea?

A

-Apnea: Cessation of airflow at the nostrils and mouth for at least 10 seconds

-Hypopnea: Reduction in airflow resulting in a drop in oxygen saturation followed by arousal

89
Q

What is the apnea/hypopnea index?

A

-Average number of apnea and hypopnea events per hour

90
Q

What are Cheyne Stokes Breathing?

A

-Breathing pattern marked by crescendo-decrescendo changes in airflow and respiratory effort that often ends with apnea (typical in central apnea syndrome)

91
Q

What is Muller’s maneuver?

A

-Inhalation with nasal passages occluded and mouth closed with an endoscope inserted through one nostril to observe the location of airway collapse

92
Q

How is OSA classified?

A

Fujita Classification:
-Indicates level of obstruction identified by nasopharyngoscopy in conjunction witha Mueller’s maneuver during sleep induced nasopharyngoscopy. Useful guide to determine surgical interventions may be helpufl

93
Q

How is OSA graded with AHI values?

A

-Normal: 0-4 AHI
-Mild OSA: 5-15 AHI
-Moderate: 15-30 AHI
-Severe: >30 AHI

94
Q

Describe Fujita Type I-III.

A

-Type I: Upper pharynx to include the palate, uvula, and tonsils
-Type II: Upper and lower pharynx
-Type III: Lower pharynx to include the tongue base, lingual tonsils and supraglottic region

95
Q

What are the stages of sleep?

A

N1, N2, N3 and REM (phasic/tonic).

96
Q

What is the pathophysiology of OSA?

A

-Increased sympathetic tone tone leads to autonomic arousals
-Hypoxia leads to sleep fragmentation and restriction
-Hypoxia followed by oxygenation can lead to free radicals and endothelial damage (hypoxia repurfusion injury), also activation o f PMNs and inflammatory mediators
-Leads to chronic inflammatory state

-Most common in males aged 18-60

97
Q

What are medical co-morbidities associated with OSA?

A

-CV: HTN, arrhythmias, CHF
-Neuro: Stroke, parkinsons, seizure
-Endocrine: DM
-Psychatric: Cognitive function, depression
-Pulmonary: Pulmonary hypertension
-Digestive: Acid reflux
-Other: Decreased wound healing, headaches, immune system impairment

98
Q

What subjective screening tools can be used in the diagnosis/work-up of OSA?

A

STOP BANG questionnaire, Epworth Sleepiness Scale

99
Q

What is the STOP BANG questionnaire?

A

-Snore loudly
-Tired or fatigued
-Observed apneas
-Pressure (HTN)

-BMI >35
-Age >50
-Neck circumference >16”
-Gender (male)

1 point each, 5-8 points high risk

100
Q

What is the Epworth sleepiness scale?

A
  • 0-3 scale of chance of dozing during situations
  • 8 situations: Sitting/reading, watching TV, sitting in public place, passenger in car, lying down to rest, sitting and talking, sitting after lunch, in car while driving stopped in traffic

11-24 excessive daytime sleepiness

101
Q

What are pertinent physical exam findings with OSA?

A

-BMI >30, neck/waist circumference
-Fat deposition in uvula, tonsils, tongue, lateral pharyngeal wall
-Neck circumference bigger than 17 (16 in female)
-Decreased FRC

102
Q

Describe the airway examination in an OSA patient.

A

-Look at occlusion (clinical and lateral ceph)
-Class II from retrognathia may have narrow posterior airway space
-Macroglossia
-Elongated uvula/soft palate, nasal septal deformities, enlarged turbinates, tonsillar hypertrophy
-Evaluate mallampati score

103
Q

What is nasopharyngoscopy and how is it used in OSA?

A

-Use of flexible fiberoptic laryngoscope to examine the lumen of nasal passages, oropharynx and vocal cords
-Used with Mueller’s maneuver to identify potential sites of obstruction, can be performed supine or sitting positions
-Can be performed in office setting

104
Q

What is drug induced sleep endoscopy (DISE) and how is it used in OSA?

A

-Nasopharyngoscopy performed on a patient undergoing sedative induced sleep
-Anesthetic agents blunt negative pressure reflex and mimic conditions of REM sleep
-Usually performed in OR (may need to take over airway)
-Can identify specific areas of collapse in the pharynx and direct site specific surgical intervention

105
Q

What is polysomnography and how is it used in OSA?

A

-Full night, in lab PSG is considered gold standard in diagnosis
-Negative result should be viewed with skepticism with patient’s with high suspicion of OSA (difficult to fully translate info due to environment)

106
Q

What is home sleep apnea testing?

A

-High sensitivity in appropriate patients, sleep study done at home
-Useful in patients suspicious of moderate to severe sleep apnea
-Often underestimates AHI

107
Q

How is posterior airway space (PAS) measured on a lateral ceph?

A

-A line that bisects B point and gonion through the posterior airway space.
-A PAS less than 11 may indicate base of tongue obstruction (pt therefore a poor candidate for upper airway surgery)

108
Q

What does a decreased posterior airway space correlate to?

A

-PAS less than 11
-May indicate base of tongue obstruction
-Patient would be a poor candidate of UPPP

109
Q

How is the length of the soft palate measured on a lateral ceph?

A

-P to PNS
-Length of soft palate measured from the posterior nasal spine to the tip of the soft palate
-Normal measurement is 37
-Increased length associated with OSA

110
Q

How is the position of the hyoid measured on a lateral ceph?

A

-H to MP
-Distance of the hyoid bone to the iinferior border of the mandible along a line perpendicular to the mandibular plane angle
-Normal is 15 mm
-An inferior positioned hyoid is indicative of a longer airway and UPPP failure

111
Q

How can a CBCT be used in the diagnosis of OSA?

A

-Can examine airway in axial, coronal and sagittal planes
-Can allow for volumetric 3D reconstruction of the airway

112
Q

How can MRI be used in diagnosis of OSA?

A

-Can be done under sedation to detect site of obstruction
-Can give anatomic detail of the soft tissues surrounding the airway and can detect fatty deposits around the pharynx

113
Q

What are non-surgical therapies for OSA management?

A

-Weight reduction: Can reduce severity of OSA, lower pressure of CPAP, can offer resolution.

-Oral appliances

114
Q

Describe oral appliances in the management of OSA.

A

-Can be used for patients with mild-moderate OSA
-Can be used in severe OSA as adjunct to CPAP
-Adverse effects: Retroclined maxillary teeth, proclined mandibular teeth, bruxism, dry mouth, TMJ
-Need q6 month dental follow-up x1 year followed by yearly

115
Q

What is the Stanford Protocol for OSA management?

A

-Surgical approach aimed at standardizing OSA procedures among surgeons
-Not a cookbook approach, merely classifies as Phase I or Phase II of where surgery is performed, not timing of surgery
-Surgery should be addressed to the site of obstruction

116
Q

What are Phase I surgeries for OSA and where is the obstruction addressed?

A

-Nasal obstruction: Septoplasty, turbinectomy, alar collapse, valve deformities
-Retropalatal Obstruction: UPPP with tonsillectomy
-Retrolingual Obstruction: Genioglossus advancement

117
Q

What are phase II surgeries and where is the obstruction addressed?

A

-MMA (Global airway surgery)
-Tracheostomy (100% success rate)

118
Q

What are considerations of MMA for OSA?

A

-Patient may not have a dentoskeletal malocclusion (may not require ortho)
-Need to counsel patient on change in appearance
-May need arch bars during/after surgery
-Maximize movement (10 mm), may need CCW movement
-May have had previous soft tissue surgeries, may be difficult to get full movement
-High relapse, consider bicortical screws/heavier plates to reinforce osteotomies
-Consider bone grafts
-Post-op ICU with continuous pulse ox

Oral Board Review Textbook (26 decks)

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